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Sample records for quantum non-local complex

  1. Origin of Dynamical Quantum Non-locality

    NASA Astrophysics Data System (ADS)

    Pachon, Cesar E.; Pachon, Leonardo A.

    2014-03-01

    Non-locality is one of the hallmarks of quantum mechanics and is responsible for paradigmatic features such as entanglement and the Aharonov-Bohm effect. Non-locality comes in two ``flavours'': a kinematic non-locality- arising from the structure of the Hilbert space- and a dynamical non-locality- arising from the quantum equations of motion-. Kinematic non-locality is unable to induce any change in the probability distributions, so that the ``action-at-a-distance'' cannot manifest. Conversely, dynamical non-locality does create explicit changes in probability, though in a ``causality-preserving'' manner. The origin of non-locality of quantum measurements and its relations to the fundamental postulates of quantum mechanics, such as the uncertainty principle, have been only recently elucidated. Here we trace the origin of dynamical non-locality to the superposition principle. This relation allows us to establish and identify how the uncertainty and the superposition principles determine the non-local character of the outcome of a quantum measurement. Being based on group theoretical and path integral formulations, our formulation admits immediate generalizations and extensions to to, e.g., quantum field theory. This work was supported by the Departamento Administrativo de Ciencia, Tecnologia e Innovacion -COLCIENCIAS- of Colombia under the grant number 111556934912.

  2. Understanding quantum non-locality through pseudo-telepathy game

    NASA Astrophysics Data System (ADS)

    Kunkri, Samir

    2006-11-01

    Usually by quantum non-locality we mean that quantum mechanics can not be replaced by local realistic theory. On the other hand this nonlocal feature of quantum mechanics can not be used for instantaneous communication and hence it respect Einstein's special theory of relativity. But still it is not trivial as proved by various quantum information processing using entangled states. Recently there have been studies of hypothetical non-local system again respecting no-signalling which is beyond quantum mechanics. Here we study the power of such a hypothetical nonlocal box first suggested by Popescu et.al. in the context of recently suggested pseudo-telepathy game constructed from a Kochen-Specker set.

  3. On some neglected thermodynamic peculiarities of quantum non-locality

    NASA Astrophysics Data System (ADS)

    Elitzur, Avshalom C.

    1990-12-01

    The existence of non-local correlations has been discussed so far almost exclusively in the context of its apparent incompatibility with relativity theory. However, it also involves some intriguing thermodynamic problems. These problems are demonstrated by analyzing the EPR experiment. It is then shown that the “transactional” interpretation of quantum mechanics, originally devised to meet the relativistic problem associated with the EPR, provides an elegant solution for the thermodynamic problems as well.

  4. Entanglement and Quantum non-locality: an experimental perspective

    NASA Astrophysics Data System (ADS)

    Avella, Alessio; Gramegna, Marco; Genovese, Marco

    2013-09-01

    The theory of Quantum Mechanics is one of the mainstay of modern physics, a well-established mathematical clockwork whose strength and accuracy in predictions are currently experienced in worldwide research laboratories. As a matter of fact, Quantum Mechanics laid the groundwork of a rich variety of studies ranging from solid state physics to cosmology, from bio-physics to particle physics. The up-to-date ability of manipulating single quantum states is paving the way for emergent quantum technologies as quantum information and computation, quantum communication, quantum metrology and quantum imaging. In spite of the impressive matemathical capacity, a long-standing debate is even revolving around the foundational axioms of this theory, the main bones of content being the non-local effects of entangled states, the wave function collapse and the concept of measurement in Quantum Mechanics, the macro-objectivation problem (the transition from a microscopic probabilistic world to a macroscopic deterministic world described by classical mechanics). Problems that, beyond their fundamental interest in basic science, now also concern the impact of these developing technologies. Without claiming to be complete, this article provides in outline the living matter concerning some of these problems, the implications of which extend deeply on the connection between entanglement and space-time structure.

  5. The philosophical implications of quantum non-locality

    NASA Astrophysics Data System (ADS)

    Jeffries, Paul Christopher

    2000-07-01

    The overarching metaphysics encompassing almost all of science incorporates notions readily recognizable as basic intuitions, such as the separability of nature into parts, and a causal architecture necessitating that influences going from one place to another transit every point in between. Astonishingly, developments in quantum mechanics have all but proven this metaphysics false. An overview of Bell's Theorem sets the stage for a discussion of the philosophical significance of quantum non-locality. An account of the overarching metaphysics of Western science explicates why the violation of the Bell Inequalities is so astonishing, drawing particular attention to the historical and metaphysical issues surrounding action-at-a-distance, and the demands for causal continuity and a finite propagation speed for causal influences. The Chapter Three exegesis of the Einstein-Podolsky-Rosen (EPR) argument contends that a modified version of their ``reality criterion'' side-steps the impression that the argument only goes through under an overly strong realist position, but the truly surprising story underlying the EPR correlations-unforeseen by Einstein and Bohr-comes in the next chapter's examination of Jon P. Jarrett's analysis of non-locality into two composite conditions associated with Einstein's underlying metaphysical principles. This in turn leads to a deeper analysis of the philosophical basis for Einstein's resistance to quantum mechanics. Having seen that a range of ordinary causal and common- cause explanations for the EPR correlations are excluded or burdened with untoward implications, Chapter Seven proposes an information-theoretic analysis of the holistic connection exhibited in quantum phenomena, helping us to better understand in what way constraints on relational holism are responsible for the world appearing to be causally classical. These constraints lead to ``local locality'': the apparent manifestation of a local causal structure when the domain is

  6. Non-Local Propagation of Correlations in Quantum Systems with Long-Range Interactions

    DTIC Science & Technology

    2014-07-10

    LETTER doi:10.1038/nature13450 Non-local propagation of correlations in quantum systems with long-range interactions Philip Richerme1, Zhe -Xuan Gong1...2013). 29. James, D. F. V. Quantum dynamics of cold trapped ions with application to quantum computation. Appl. Phys. B 66, 181–190 (1998). 30. Wang

  7. Non-local classical optical correlation and implementing analogy of quantum teleportation.

    PubMed

    Sun, Yifan; Song, Xinbing; Qin, Hongwei; Zhang, Xiong; Yang, Zhenwei; Zhang, Xiangdong

    2015-03-17

    This study reports an experimental realization of non-local classical optical correlation from the Bell's measurement used in tests of quantum non-locality. Based on such a classical Einstein-Podolsky-Rosen optical correlation, a classical analogy has been implemented to the true meaning of quantum teleportation. In the experimental teleportation protocol, the initial teleported information can be unknown to anyone and the information transfer can happen over arbitrary distances. The obtained results give novel insight into quantum physics and may open a new field of applications in quantum information.

  8. Entangled State Preparation in Experiments on Quantum Non-Locality

    NASA Astrophysics Data System (ADS)

    Berardi, V.; Garuccio, A.

    2006-06-01

    In the last decade a growing number of experiments for testing local realism via Bell-type inequalities using spontaneous parametric down-conversion (SPDC) photon sources have been performed. In this short paper we demonstrate that experiments based on the use of TYPE-I SPDC sources cannot discriminate between quantum mechanics and local realism, since TYPE-I SPDC sources do not allow to define correctly dichotomic observables.

  9. How the Relativistic Motion Affect Quantum Fisher Information and Bell Non-locality for Multipartite state

    NASA Astrophysics Data System (ADS)

    Huang, Chun Yu; Ma, Wenchao; Wang, Dong; Ye, Liu

    2017-02-01

    In this work, the quantum fisher information (QFI) and Bell non-locality of a multipartite fermionic system are investigated. Unlike the currently existing research of QFI, we focus our attention on the differences between quantum fisher information and Bell non-locality under the relativistic framework. The results show that although the relativistic motion affects the strength of the non-locality, it does not change the physical structure of non-locality. However, unlike the case of non-locality, the relativistic motion not only influence the precision of the QFI Fϕ but also broke the symmetry of the function Fϕ. The results also show that for a special multipartite system, , the number of particles of a initial state do not affect the Fθ. Furthermore, we also find that Fθ is completely unaffected in non-inertial frame if there are inertial observers. Finally, in view of the decay behavior of QFI and non-locality under the non-inertial frame, we proposed a effective scheme to battle against Unruh effect.

  10. Novel non-local effects in three-terminal hybrid devices with quantum dot.

    PubMed

    Michałek, G; Domański, T; Bułka, B R; Wysokiński, K I

    2015-09-29

    We predict non-local effect in the three-terminal hybrid device consisting of the quantum dot (QD) tunnel coupled to two normal and one superconducting reservoirs. It manifests itself as the negative non-local resistance and results from the competition between the ballistic electron transfer (ET) and the crossed Andreev scattering (CAR). The effect is robust both in the linear and non-linear regimes. In the latter case the screening of charges and the long-range interactions play significant role. We show that sign change of the non-local conductance depends on the subgap Shiba/Andreev states, and it takes place even in absence of the Coulomb interactions. The effect is large and can be experimentally verified using the four probe setup. Since the induced non-local voltage changes sign and magnitude upon varying the gate potential and/or coupling of the quantum dot to the superconducting lead, such measurement could hence provide a controlled and precise method to determine the positions of the Shiba/Andreev states. Our predictions ought to be contrasted with non-local effects observed hitherto in the three-terminal planar junctions where the residual negative non-local conductance has been observed at large voltages, related to the Thouless energy of quasiparticles tunneling through the superconducting slab.

  11. Novel non-local effects in three-terminal hybrid devices with quantum dot

    NASA Astrophysics Data System (ADS)

    Michałek, G.; Domański, T.; Bułka, B. R.; Wysokiński, K. I.

    2015-09-01

    We predict non-local effect in the three-terminal hybrid device consisting of the quantum dot (QD) tunnel coupled to two normal and one superconducting reservoirs. It manifests itself as the negative non-local resistance and results from the competition between the ballistic electron transfer (ET) and the crossed Andreev scattering (CAR). The effect is robust both in the linear and non-linear regimes. In the latter case the screening of charges and the long-range interactions play significant role. We show that sign change of the non-local conductance depends on the subgap Shiba/Andreev states, and it takes place even in absence of the Coulomb interactions. The effect is large and can be experimentally verified using the four probe setup. Since the induced non-local voltage changes sign and magnitude upon varying the gate potential and/or coupling of the quantum dot to the superconducting lead, such measurement could hence provide a controlled and precise method to determine the positions of the Shiba/Andreev states. Our predictions ought to be contrasted with non-local effects observed hitherto in the three-terminal planar junctions where the residual negative non-local conductance has been observed at large voltages, related to the Thouless energy of quasiparticles tunneling through the superconducting slab.

  12. How the Relativistic Motion Affect Quantum Fisher Information and Bell Non-locality for Multipartite state

    PubMed Central

    Huang, Chun Yu; Ma, Wenchao; Wang, Dong; Ye, Liu

    2017-01-01

    In this work, the quantum fisher information (QFI) and Bell non-locality of a multipartite fermionic system are investigated. Unlike the currently existing research of QFI, we focus our attention on the differences between quantum fisher information and Bell non-locality under the relativistic framework. The results show that although the relativistic motion affects the strength of the non-locality, it does not change the physical structure of non-locality. However, unlike the case of non-locality, the relativistic motion not only influence the precision of the QFI Fϕ but also broke the symmetry of the function Fϕ. The results also show that for a special multipartite system, , the number of particles of a initial state do not affect the Fθ. Furthermore, we also find that Fθ is completely unaffected in non-inertial frame if there are inertial observers. Finally, in view of the decay behavior of QFI and non-locality under the non-inertial frame, we proposed a effective scheme to battle against Unruh effect. PMID:28145437

  13. Non Locality Proofs in Quantum Mechanics Analyzed by Ordinary Mathematical Logic

    NASA Astrophysics Data System (ADS)

    Nisticò, Giuseppe

    2014-10-01

    The so-called non-locality theorems aim to show that Quantum Mechanics is not consistent with the Locality Principle. Their proofs require, besides the standard postulates of Quantum Theory, further conditions, as for instance the Criterion of Reality, which cannot be formulated in the language of Standard Quantum Theory; this difficulty makes the proofs not verifiable according to usual logico-mathematical methods, and therefore it is a source of the controversial debate about the real implications of these theorems. The present work addresses this difficulty for Bell-type and Stapp's arguments of non-locality. We supplement the formalism of Quantum Mechanics with formal statements inferred from the further conditions in the two different cases. Then an analysis of the two arguments is performed according to ordinary mathematical logic.

  14. Multipartite non-locality and entanglement signatures of a field-induced quantum phase transition

    NASA Astrophysics Data System (ADS)

    Batle, Josep; Alkhambashi, Majid; Farouk, Ahmed; Naseri, Mosayeb; Ghoranneviss, Mahmood

    2017-02-01

    Quantum correlation measures are limited in practice to a few number of parties, since no general theory is still capable of reaching the thermodynamic limit. In the present work we study entanglement and non-locality for a cluster of spins belonging to a compound that displays a magnetocaloric effect. A quantum phase transition (QPT) is induced by an external magnetic field B, in such a way that the corresponding quantum fluctuations are reproduced at a much smaller scale than the experimental outcomes, and then described by means of the aforementioned quantum measures.

  15. Quantum non-locality in a two-slit interferometer for short-lived particles

    SciTech Connect

    Klein, Spencer R.; Nystrand, Joakim

    2001-12-01

    We describe a new test of quantum nonlocality, using an interferometer for short-lived particles. The separation is large compared with the particle lifetimes. This interferometer is realized by vector meson production in distant heavy ion collisions. The mesons decay before waves from the two sources (ions) can overlap, so interference is only possible among the decay products. The post-decay wave function must retain amplitudes for all possible decays. The decay products are spatially separated, necessitating a non-local wave function. The interference is measurable by summing the product momenta. Alternately, the products positions could be observed, allowing new tests of the EPR paradox.

  16. Tunnelling of the 3rd kind: A test of the effective non-locality of quantum field theory

    NASA Astrophysics Data System (ADS)

    Gardiner, Simon A.; Gies, Holger; Jaeckel, Joerg; Wallace, Chris J.

    2013-03-01

    Integrating out virtual quantum fluctuations in an originally local quantum field theory results in an effective theory which is non-local. In this letter we argue that tunnelling of the 3rd kind —where particles traverse a barrier by splitting into a pair of virtual particles which recombine only after a finite distance— provides a direct test of this non-locality. We sketch a quantum-optical setup to test this effect, and investigate observable effects in a simple toy model.

  17. Temporal Non-locality

    NASA Astrophysics Data System (ADS)

    Filk, Thomas

    2013-04-01

    In this article I investigate several possibilities to define the concept of "temporal non-locality" within the standard framework of quantum theory. In particular, I analyze the notions of "temporally non-local states", "temporally non-local events" and "temporally non-local observables". The idea of temporally non-local events is already inherent in the standard formalism of quantum mechanics, and Basil Hiley recently defined an operator in order to measure the degree of such a temporal non-locality. The concept of temporally non-local states enters as soon as "clock-representing states" are introduced in the context of special and general relativity. It is discussed in which way temporally non-local measurements may find an interesting application for experiments which test temporal versions of Bell inequalities.

  18. Non-local correlation and quantum discord in two atoms in the non-degenerate model

    SciTech Connect

    Mohamed, A.-B.A.

    2012-12-15

    By using geometric quantum discord (GQD) and measurement-induced nonlocality (MIN), quantum correlation is investigated for two atoms in the non-degenerate two-photon Tavis-Cummings model. It is shown that there is no asymptotic decay for MIN while asymptotic decay exists for GQD. Quantum correlations can be strengthened by introducing the dipole-dipole interaction. The evolvement period of quantum correlation gets shorter with the increase in the dipole-dipole parameter. It is found that there exists not only quantum nonlocality without entanglement but also quantum nonlocality without quantum discord. Also, the MIN and GQD are raised rather than entanglement, and also with weak initial entanglement, there are MIN and entanglement in a interval of death quantum discord. - Highlights: Black-Right-Pointing-Pointer Geometric quantum discord (GQD) and measurement induced nonlocality (MIN) are used to investigate the correlations of two two-level atoms. Black-Right-Pointing-Pointer There is no asymptotic decay for MIN while asymptotic decay exists for GQD. Black-Right-Pointing-Pointer Quantum correlations can be strengthened by introducing the dipole-dipole interaction. Black-Right-Pointing-Pointer There exists not only quantum nonlocality without entanglement but also without discord. Black-Right-Pointing-Pointer Weak initial entanglement leads to MIN and entanglement in intervals of death discord.

  19. Influence of non-gaussian statistics and dynamic non-locality in temporal evolution of open quantum systems

    NASA Astrophysics Data System (ADS)

    Florez, Carlos; Pachón, Leonardo

    2015-03-01

    The study of quantum dissipation and non-local dynamics in phase space demands an extension of the Ullersma-Caldeira-Leggett framework to include non-linearities either in the system or the bath or even in the couplings between them. In this work, the special case of a linear open system interacting with a harmonic thermal bath by means of non-linear couplings is considered. This framework is constructed by extending the path integral formulation into phase space and applying the Feynam-Vernon influence functional theory to study the perturbative regime at different orders in the couplings. In doing so, the formal correspondence between the perturbative contributions and the Feynman diagrams that arise from the n-point correlation functions in the canonical variables are used. The effect of the non-local behavior induced by the non-linear contributions on the dissipative and decohering mechanisms are analyzed. The main features are the presence of non-Gaussian statistics and multiplicative, instead of additive, noises.

  20. Randomness and Non-Locality

    NASA Astrophysics Data System (ADS)

    Senno, Gabriel; Bendersky, Ariel; Figueira, Santiago

    2016-07-01

    The concepts of randomness and non-locality are intimately intertwined outcomes of randomly chosen measurements over entangled systems exhibiting non-local correlations are, if we preclude instantaneous influence between distant measurement choices and outcomes, random. In this paper, we survey some recent advances in the knowledge of the interplay between these two important notions from a quantum information science perspective.

  1. Quantum Complexity in Graphene

    NASA Astrophysics Data System (ADS)

    Baskaran, G.

    Carbon has a unique position among elements in the periodic table. It produces an allotrope, graphene, a mechanically robust two dimensional semimetal. The multifarious properties that graphene exhibits has few parallels among elemental metals. From simplicity, namely carbon atoms connected by pure sp2 bonds, a wealth of novel quantum properties emerge. In classical complex systems such as a spin glass or a finance market, several competing agents or elements are responsible for unanticipated and difficult to predict emergent properties. The complex (sic) structure of quantum mechanics is responsbile for an unanticipated set of emergent properties in graphene. We call this quantum complexity. In fact, most quantum systems, phenomena and modern quantum field theory could be viewed as examples of quantum complexity. After giving a brief introduction to the quantum complexity we focus on our own work, which indicates the breadth in the type of quantum phenomena that graphene could support. We review our theoretical suggestions of, (i) spin-1 collective mode in netural graphene, (ii) relativistic type of phenomena in crossed electric and magnetic fields, (iii) room temperature superconductivity in doped graphene and (iv) composite Fermi sea in neutral graphene in uniform magnetic field and (v) two-channel Kondo effect. Except for the relativistic type of phenomena, the rest depend in a fundamental way on a weak electron correlation that exists in the broad two-dimensional band of graphene.

  2. Quantum Complexity in Graphene

    NASA Astrophysics Data System (ADS)

    Baskaran, G.

    Carbon has a unique position among elements in the periodic table. It produces an allotrope, graphene, a mechanically robust two dimensional semimetal. The multifarious properties that graphene exhibits has few parallels among elemental metals. From simplicity, namely carbon atoms connected by pure sp2 bonds, a wealth of novel quantum properties emerge. In classical complex systems such as a spin glass or a finance market, several competing agents or elements are responsible for unanticipated and difficult to predict emergent properties. The complex (sic) structure of quantum mechanics is responsbile for an unanticipated set of emergent properties in graphene. We call this quantum complexity. Infact, most quantum systems, phenomena and modern quantum field theory could be viewed as examples of quantum complexity. After giving a brief introduction to the quantum complexity we focus on our own work, which indicates the breadth in the type of quantum phenomena that graphene could support. We review our theoretical suggestions of, (i) spin-1 collective mode in netural graphene, (ii) relativistic type of phenomena in crossed electric and magnetic fields, (iii) room temperature superconductivity in doped graphene and (iv) composite Fermi sea in neutral graphene in uniform magnetic field and (v) 2-channel Kondo effect. Except for the relativistic type of phenomena and Kondo effect, the rest depend in a fundamental way on a weak electron correlations that exist in graphene.

  3. Morphogenetic fields in embryogenesis, regeneration, and cancer: Non-local control of complex patterning

    PubMed Central

    Levin, Michael

    2012-01-01

    Establishment of shape during embryonic development, and the maintenance of shape against injury or tumorigenesis, requires constant coordination of cell behaviors toward the patterning needs of the host organism. Molecular cell biology and genetics have made great strides in understanding the mechanisms that regulate cell function. However, generalized rational control of shape is still largely beyond our current capabilities. Significant instructive signals function at long range to provide positional information and other cues to regulate organism-wide systems properties like anatomical polarity and size control. Is complex morphogenesis best understood as the emergent property of local cell interactions, or as the outcome of a computational process that is guided by a physically-encoded map or template of the final goal state? Here I review recent data and molecular mechanisms relevant to morphogenetic fields: large-scale systems of physical properties that have been proposed to store patterning information during embryogenesis, regenerative repair, and cancer suppression that ultimately controls anatomy. Placing special emphasis on the role of endogenous bioelectric signals as an important component of the morphogenetic field, I speculate on novel approaches for the computational modeling and control of these fields with applications to synthetic biology, regenerative medicine, and evolutionary developmental biology. PMID:22542702

  4. Increasing complexity with quantum physics.

    PubMed

    Anders, Janet; Wiesner, Karoline

    2011-09-01

    We argue that complex systems science and the rules of quantum physics are intricately related. We discuss a range of quantum phenomena, such as cryptography, computation and quantum phases, and the rules responsible for their complexity. We identify correlations as a central concept connecting quantum information and complex systems science. We present two examples for the power of correlations: using quantum resources to simulate the correlations of a stochastic process and to implement a classically impossible computational task.

  5. Quantum Kolmogorov complexity and bounded quantum memory

    SciTech Connect

    Miyadera, Takayuki

    2011-04-15

    The effect of bounded quantum memory in a primitive information protocol has been examined using the quantum Kolmogorov complexity as a measure of information. We employed a toy two-party protocol in which Bob, by using a bounded quantum memory and an unbounded classical memory, estimates a message that was encoded in qubits by Alice in one of the bases X or Z. Our theorem gave a nontrivial effect of the memory boundedness. In addition, a generalization of the uncertainty principle in the presence of quantum memory has been obtained.

  6. Experimental linear-optics simulation of multipartite non-locality in the ground state of a quantum Ising ring

    PubMed Central

    Orieux, Adeline; Boutari, Joelle; Barbieri, Marco; Paternostro, Mauro; Mataloni, Paolo

    2014-01-01

    Critical phenomena involve structural changes in the correlations of its constituents. Such changes can be reproduced and characterized in quantum simulators able to tackle medium-to-large-size systems. We demonstrate these concepts by engineering the ground state of a three-spin Ising ring by using a pair of entangled photons. The effect of a simulated magnetic field, leading to a critical modification of the correlations within the ring, is analysed by studying two- and three-spin entanglement. In particular, we connect the violation of a multipartite Bell inequality with the amount of tripartite entanglement in our ring. PMID:25418153

  7. Generalized conservation laws in non-local field theories

    NASA Astrophysics Data System (ADS)

    Kegeles, Alexander; Oriti, Daniele

    2016-04-01

    We propose a geometrical treatment of symmetries in non-local field theories, where the non-locality is due to a lack of identification of field arguments in the action. We show that the existence of a symmetry of the action leads to a generalized conservation law, in which the usual conserved current acquires an additional non-local correction term, obtaining a generalization of the standard Noether theorem. We illustrate the general formalism by discussing the specific physical example of complex scalar field theory of the type describing the hydrodynamic approximation of Bose-Einstein condensates. We expect our analysis and results to be of particular interest for the group field theory formulation of quantum gravity.

  8. Quantum Computing: Solving Complex Problems

    ScienceCinema

    DiVincenzo, David [IBM Watson Research Center

    2016-07-12

    One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.

  9. Quantum complexity: Quantum mutual information, complex networks, and emergent phenomena in quantum cellular automata

    NASA Astrophysics Data System (ADS)

    Vargas, David L.

    Emerging quantum simulator technologies provide a new challenge to quantum many body theory. Quantifying the emergent order in and predicting the dynamics of such complex quantum systems requires a new approach. We develop such an approach based on complex network analysis of quantum mutual information. First, we establish the usefulness of quantum mutual information complex networks by reproducing the phase diagrams of transverse Ising and Bose-Hubbard models. By quantifying the complexity of quantum cellular automata we then demonstrate the applicability of complex network theory to non-equilibrium quantum dynamics. We conclude with a study of student collaboration networks, correlating a student's role in a collaboration network with their grades. This work thus initiates a quantitative theory of quantum complexity and provides a new tool for physics education research. (Abstract shortened by ProQuest.).

  10. Quantum Tunneling and Complex Trajectories

    NASA Astrophysics Data System (ADS)

    Meynig, Max; Haggard, Hal

    2017-01-01

    In general, the semiclassical approximation of quantum mechanical tunneling fails to treat tunneling through barriers if real initial conditions and trajectories are used. By analytically continuing classical dynamics to the complex plane the problems encountered in the approximation can be resolved. While, the complex methods discussed here have been previously explored, no one has exhibited an analytically solvable case. The essential features of the complex method will be discussed in the context of a novel, analytically solvable problem. These methods could be useful in quantum gravity, with applications to the tunneling of spacetime geometries.

  11. Non-Local Euclidean Medians.

    PubMed

    Chaudhury, Kunal N; Singer, Amit

    2012-11-01

    In this letter, we note that the denoising performance of Non-Local Means (NLM) can be improved at large noise levels by replacing the mean by the Euclidean median. We call this new denoising algorithm the Non-Local Euclidean Medians (NLEM). At the heart of NLEM is the observation that the median is more robust to outliers than the mean. In particular, we provide a simple geometric insight that explains why NLEM performs better than NLM in the vicinity of edges, particularly at large noise levels. NLEM can be efficiently implemented using iteratively reweighted least squares, and its computational complexity is comparable to that of NLM. We provide some preliminary results to study the proposed algorithm and to compare it with NLM.

  12. Quantum physics and complex networks

    NASA Astrophysics Data System (ADS)

    Biamonte, Jacob

    2014-03-01

    There is a widely used and successful theory of ``chemical reaction networks,'' which provides a framework describing systems governed by mass action kinetics. Computer science and population biology use the same ideas under a different name: ``stochastic Petri nets.'' But if we look at these theories from the perspective of quantum theory, they turn out to involve creation and annihilation operators, coherent states and other well-known ideas--yet in a context where probabilities replace amplitudes. I will explain this connection as part of a detailed analogy between quantum mechanics and stochastic mechanics which we've produced several results on recently, including the recent analytical results uniting quantum physics and complex networks. Our general idea is about merging concepts from quantum physics and complex network theory to provide a bidirectional bridge between both disciplines. Support is acknowledged from the Foundational Questions Institute (FQXi) and the Compagnia di San Paolo Foundation.

  13. Non-locality in Modern Physics: Counter Arguments

    NASA Astrophysics Data System (ADS)

    Kracklauer, A. F.

    Non-locality, i.e., some sort of instantaneous interaction or correlation determination, has been identified with the theory of Quantum Mechanics in recent times. Being in direct conflict with the basic principles of Relativity Theory, it posses a challenge. Herein various critical arguments raised in the past and judged to be particularly incisive are reviewed. These include, the identification of an error in the derivation of Bell Inequalities, the observation that Bohm inadvertently selected a non-quantum venue for experimental tests of Bell Inequalities and finally, an examination of the complexities that have rendered classical simulations of these experiments unsatisfactory.

  14. Quantum complexity and negative curvature

    NASA Astrophysics Data System (ADS)

    Brown, Adam R.; Susskind, Leonard; Zhao, Ying

    2017-02-01

    As time passes, once simple quantum states tend to become more complex. For strongly coupled k -local Hamiltonians, this growth of computational complexity has been conjectured to follow a distinctive and universal pattern. In this paper we show that the same pattern is exhibited by a much simpler system—classical geodesics on a compact two-dimensional geometry of uniform negative curvature. This striking parallel persists whether the system is allowed to evolve naturally or is perturbed from the outside.

  15. Quantum query complexity for qutrits

    NASA Astrophysics Data System (ADS)

    Tamir, Boaz

    2008-02-01

    We compute lower bounds for the exact quantum query complexity of a ternary function f . The lower bound is of order O(log3(n)) . In case f is symmetric on a sphere then the lower bound is of order O(n) . This work is a natural continuation of the work of Beals, Buhrman, Cleve, Mosca, and de Wolf on lower limits for binary functions.

  16. Bohmian mechanics with complex action: A new trajectory-based formulation of quantum mechanics

    SciTech Connect

    Goldfarb, Yair; Degani, Ilan; Tannor, David J.

    2006-12-21

    In recent years there has been a resurgence of interest in Bohmian mechanics as a numerical tool because of its local dynamics, which suggest the possibility of significant computational advantages for the simulation of large quantum systems. However, closer inspection of the Bohmian formulation reveals that the nonlocality of quantum mechanics has not disappeared--it has simply been swept under the rug into the quantum force. In this paper we present a new formulation of Bohmian mechanics in which the quantum action, S, is taken to be complex. This leads to a single equation for complex S, and ultimately complex x and p but there is a reward for this complexification - a significantly higher degree of localization. The quantum force in the new approach vanishes for Gaussian wave packet dynamics, and its effect on barrier tunneling processes is orders of magnitude lower than that of the classical force. In fact, the current method is shown to be a rigorous extension of generalized Gaussian wave packet dynamics to give exact quantum mechanics. We demonstrate tunneling probabilities that are in virtually perfect agreement with the exact quantum mechanics down to 10{sup -7} calculated from strictly localized quantum trajectories that do not communicate with their neighbors. The new formulation may have significant implications for fundamental quantum mechanics, ranging from the interpretation of non-locality to measures of quantum complexity.

  17. Bohmian mechanics with complex action: a new trajectory-based formulation of quantum mechanics.

    PubMed

    Goldfarb, Yair; Degani, Ilan; Tannor, David J

    2006-12-21

    In recent years there has been a resurgence of interest in Bohmian mechanics as a numerical tool because of its local dynamics, which suggest the possibility of significant computational advantages for the simulation of large quantum systems. However, closer inspection of the Bohmian formulation reveals that the nonlocality of quantum mechanics has not disappeared-it has simply been swept under the rug into the quantum force. In this paper we present a new formulation of Bohmian mechanics in which the quantum action, S, is taken to be complex. This leads to a single equation for complex S, and ultimately complex x and p but there is a reward for this complexification-a significantly higher degree of localization. The quantum force in the new approach vanishes for Gaussian wave packet dynamics, and its effect on barrier tunneling processes is orders of magnitude lower than that of the classical force. In fact, the current method is shown to be a rigorous extension of generalized Gaussian wave packet dynamics to give exact quantum mechanics. We demonstrate tunneling probabilities that are in virtually perfect agreement with the exact quantum mechanics down to 10(-7) calculated from strictly localized quantum trajectories that do not communicate with their neighbors. The new formulation may have significant implications for fundamental quantum mechanics, ranging from the interpretation of non-locality to measures of quantum complexity.

  18. Non-local Optical Potentials

    NASA Astrophysics Data System (ADS)

    Thompson, Ian

    2010-11-01

    In all direct reactions to probe the structure of exotic nuclei at FRIB, optical potentials will be needed in the entrance and exit channels. At high energies Glauber approximations may be useful, but a low energies (5 to 20 MeV/nucleon) other approaches are required. Recent work of the UNEDF project [1] has shown that reaction cross sections at these energies can be accounted for by calculating all inelastic and transfer channels reachable by one particle-hole transitions from the elastic channel. In this model space, we may also calculate the two-step dynamic polarization potential (DPP) that adds to the bare folded potential to form the complex optical potential. Our calculations of the DPP, however, show that its non-localities are very significant, as well as the partial-wave dependence of both its real and imaginary components. The Perey factors (the wave function ratio to that from an equivalent local potential) are more than 20% different from unity, especially for partial waves inside grazing. These factors combine to suggest a reexamination of the validity of local and L-independent fitted optical potentials, especially for capture reactions that are dominated by low partial waves. Prepared by LLNL under Contract DE-AC52-07NA27344. [1] G.P.A. Nobre, F.S. Dietrich, J.E. Escher, I.J. Thompson, M. Dupuis, J. Terasaki and J. Engel, submitted to Phys. Rev. Letts., 2010.

  19. Quantum Navigation and Ranking in Complex Networks

    PubMed Central

    Sánchez-Burillo, Eduardo; Duch, Jordi; Gómez-Gardeñes, Jesús; Zueco, David

    2012-01-01

    Complex networks are formal frameworks capturing the interdependencies between the elements of large systems and databases. This formalism allows to use network navigation methods to rank the importance that each constituent has on the global organization of the system. A key example is Pagerank navigation which is at the core of the most used search engine of the World Wide Web. Inspired in this classical algorithm, we define a quantum navigation method providing a unique ranking of the elements of a network. We analyze the convergence of quantum navigation to the stationary rank of networks and show that quantumness decreases the number of navigation steps before convergence. In addition, we show that quantum navigation allows to solve degeneracies found in classical ranks. By implementing the quantum algorithm in real networks, we confirm these improvements and show that quantum coherence unveils new hierarchical features about the global organization of complex systems. PMID:22930671

  20. Quantum Navigation and Ranking in Complex Networks

    NASA Astrophysics Data System (ADS)

    Sánchez-Burillo, Eduardo; Duch, Jordi; Gómez-Gardeñes, Jesús; Zueco, David

    2012-08-01

    Complex networks are formal frameworks capturing the interdependencies between the elements of large systems and databases. This formalism allows to use network navigation methods to rank the importance that each constituent has on the global organization of the system. A key example is Pagerank navigation which is at the core of the most used search engine of the World Wide Web. Inspired in this classical algorithm, we define a quantum navigation method providing a unique ranking of the elements of a network. We analyze the convergence of quantum navigation to the stationary rank of networks and show that quantumness decreases the number of navigation steps before convergence. In addition, we show that quantum navigation allows to solve degeneracies found in classical ranks. By implementing the quantum algorithm in real networks, we confirm these improvements and show that quantum coherence unveils new hierarchical features about the global organization of complex systems.

  1. A Systems-Theoretical Generalization of Non-Local Correlations

    NASA Astrophysics Data System (ADS)

    von Stillfried, Nikolaus

    Non-local correlations between quantum events are not due to a causal interaction in the sense of one being the cause for the other. In principle, the correlated events can thus occur simultaneously. Generalized Quantum Theory (GQT) formalizes the idea that non-local phenomena are not exclusive to quantum mechanics, e.g. due to some specific properties of (sub)atomic particles, but that they instead arise as a consequence of the way such particles are arranged into systems. Non-local phenomena should hence occur in any system which fulfils the necessary systems-theoretical parameters. The two most important parameters with respect to non-local correlations seem to be a conserved global property of the system as a whole and sufficient degrees of freedom of the corresponding property of its subsystems. Both factors place severe limitations on experimental observability of the phenomena, especially in terms of replicability. It has been suggested that reported phenomena of a so-called synchronistic, parapsychological or paranormal kind could be understood as instances of systems-inherent non-local correlations. From a systems-theoretical perspective, their phenomenology (including the favorable conditions for their occurrence and their lack of replicability) displays substantial similarities to non-local correlations in quantum systems and matches well with systems-theoretical parameters, thus providing circumstantial evidence for this hypothesis.

  2. Efficient quantum computing of complex dynamics.

    PubMed

    Benenti, G; Casati, G; Montangero, S; Shepelyansky, D L

    2001-11-26

    We propose a quantum algorithm which uses the number of qubits in an optimal way and efficiently simulates a physical model with rich and complex dynamics described by the quantum sawtooth map. The numerical study of the effect of static imperfections in the quantum computer hardware shows that the main elements of the phase space structures are accurately reproduced up to a time scale which is polynomial in the number of qubits. The errors generated by these imperfections are more significant than the errors of random noise in gate operations.

  3. Quantum mechanics in complex systems

    NASA Astrophysics Data System (ADS)

    Hoehn, Ross Douglas

    This document should be considered in its separation; there are three distinct topics contained within and three distinct chapters within the body of works. In a similar fashion, this abstract should be considered in three parts. Firstly, we explored the existence of multiply-charged atomic ions by having developed a new set of dimensional scaling equations as well as a series of relativistic augmentations to the standard dimensional scaling procedure and to the self-consistent field calculations. Secondly, we propose a novel method of predicting drug efficacy in hopes to facilitate the discovery of new small molecule therapeutics by modeling the agonist-protein system as being similar to the process of Inelastic Electron Tunneling Spectroscopy. Finally, we facilitate the instruction in basic quantum mechanical topics through the use of quantum games; this method of approach allows for the generation of exercises with the intent of conveying the fundamental concepts within a first year quantum mechanics classroom. Furthermore, no to be mentioned within the body of the text, yet presented in appendix form, certain works modeling the proliferation of cells types within the confines of man-made lattices for the purpose of facilitating artificial vascular transplants. In Chapter 2, we present a theoretical framework which describes multiply-charged atomic ions, their stability within super-intense laser fields, also lay corrections to the systems due to relativistic effects. Dimensional scaling calculations with relativistic corrections for systems: H, H-, H 2-, He, He-, He2-, He3- within super-intense laser fields were completed. Also completed were three-dimensional self consistent field calculations to verify the dimensionally scaled quantities. With the aforementioned methods the system's ability to stably bind 'additional' electrons through the development of multiple isolated regions of high potential energy leading to nodes of high electron density is shown

  4. Complex quantum network model of energy transfer in photosynthetic complexes.

    PubMed

    Ai, Bao-Quan; Zhu, Shi-Liang

    2012-12-01

    The quantum network model with real variables is usually used to describe the excitation energy transfer (EET) in the Fenna-Matthews-Olson (FMO) complexes. In this paper we add the quantum phase factors to the hopping terms and find that the quantum phase factors play an important role in the EET. The quantum phase factors allow us to consider the space structure of the pigments. It is found that phase coherence within the complexes would allow quantum interference to affect the dynamics of the EET. There exist some optimal phase regions where the transfer efficiency takes its maxima, which indicates that when the pigments are optimally spaced, the exciton can pass through the FMO with perfect efficiency. Moreover, the optimal phase regions almost do not change with the environments. In addition, we find that the phase factors are useful in the EET just in the case of multiple pathways. Therefore, we demonstrate that the quantum phases may bring the other two factors, the optimal space of the pigments and multiple pathways, together to contribute the EET in photosynthetic complexes with perfect efficiency.

  5. Complex numbers in quantum theory

    NASA Astrophysics Data System (ADS)

    Maynard, Glenn

    In 1927, Nobel prize winning physicist, E. Schrodinger, in correspondence with Ehrenfest, wrote the following about the new theory: "What is unpleasant here, and indeed directly to be objected to, is the use of complex numbers. Psi is surely fundamentally a real function." This seemingly simple issue remains unexplained almost ninety years later. In this dissertation I elucidate the physical and theoretical origins of the complex requirement. (Abstract shortened by ProQuest.).

  6. Relativistic three-partite non-locality

    NASA Astrophysics Data System (ADS)

    Moradpour, Hooman; Montakhab, Afshin

    2016-05-01

    Bell-like inequalities have been used in order to distinguish non-local quantum pure states by various authors. The behavior of such inequalities under Lorentz transformation (LT) has been a source of debate and controversies in the past. In this paper, we consider the two most commonly studied three-particle pure states, that of W and Greenberger-Horne-Zeilinger (GHZ) states which exhibit distinctly different types of entanglement. We discuss the various types of three-particle inequalities used in previous studies and point to their corresponding shortcomings and strengths. Our main result is that if one uses Czachor’s relativistic spin operator and Svetlichny’s inequality as the main measure of non-locality and uses the same angles in the rest frame (S) as well as the moving frame (S‧), then maximally violated inequality in S will decrease in the moving frame, and will eventually lead to lack of non-locality (i.e. satisfaction of inequality) in the v→c limit. This is shown for both the GHZ and W states and in two different configurations which are commonly studied (Cases 1 and 2). Our results are in line with a more familiar case of two particle case. We also show that the satisfaction of Svetlichny’s inequality in the v→c limit is independent of initial particles’ velocity. Our study shows that whenever we use Czachor’s relativistic spin operator, results draws a clear picture of three-particle non-locality making its general properties consistent with previous studies on two-particle systems regardless of the W state or the GHZ state is involved. Throughout the paper, we also address the results of using Pauli’s operator in investigating the behavior of |Sv| under LT for both of the GHZ and W states and two cases (Cases 1 and 2). Our investigation shows that the violation of |Sv| in moving frame depends on the particle’s energy in the lab frame, which is in agreement with some previous works on two and three-particle systems. Our work may

  7. Toward simulating complex systems with quantum effects

    NASA Astrophysics Data System (ADS)

    Kenion-Hanrath, Rachel Lynn

    Quantum effects like tunneling, coherence, and zero point energy often play a significant role in phenomena on the scales of atoms and molecules. However, the exact quantum treatment of a system scales exponentially with dimensionality, making it impractical for characterizing reaction rates and mechanisms in complex systems. An ongoing effort in the field of theoretical chemistry and physics is extending scalable, classical trajectory-based simulation methods capable of capturing quantum effects to describe dynamic processes in many-body systems; in the work presented here we explore two such techniques. First, we detail an explicit electron, path integral (PI)-based simulation protocol for predicting the rate of electron transfer in condensed-phase transition metal complex systems. Using a PI representation of the transferring electron and a classical representation of the transition metal complex and solvent atoms, we compute the outer sphere free energy barrier and dynamical recrossing factor of the electron transfer rate while accounting for quantum tunneling and zero point energy effects. We are able to achieve this employing only a single set of force field parameters to describe the system rather than parameterizing along the reaction coordinate. Following our success in describing a simple model system, we discuss our next steps in extending our protocol to technologically relevant materials systems. The latter half focuses on the Mixed Quantum-Classical Initial Value Representation (MQC-IVR) of real-time correlation functions, a semiclassical method which has demonstrated its ability to "tune'' between quantum- and classical-limit correlation functions while maintaining dynamic consistency. Specifically, this is achieved through a parameter that determines the quantumness of individual degrees of freedom. Here, we derive a semiclassical correction term for the MQC-IVR to systematically characterize the error introduced by different choices of simulation

  8. Quantum electrodynamics with complex fermion mass

    SciTech Connect

    McKellar, B.J.H. . School of Physics); Wu, D.D. . School of Physics Academia Sinica, Beijing, BJ . Inst. of High Energy Physics Superconducting Super Collider Lab., Dallas, TX )

    1991-08-01

    The quantum electrodynamics (QED) with a complex fermion mass -- that is, a fermion mass with a chiral phase -- is restudied, together with its chirally rotated version. We show how fake electric dipole moment can be obtained and how to avoid it. 10 refs.

  9. Liouville quantum gravity on complex tori

    SciTech Connect

    David, François; Rhodes, Rémi; Vargas, Vincent

    2016-02-15

    In this paper, we construct Liouville Quantum Field Theory (LQFT) on the toroidal topology in the spirit of the 1981 seminal work by Polyakov [Phys. Lett. B 103, 207 (1981)]. Our approach follows the construction carried out by the authors together with Kupiainen in the case of the Riemann sphere [“Liouville quantum gravity on the Riemann sphere,” e-print arXiv:1410.7318]. The difference is here that the moduli space for complex tori is non-trivial. Modular properties of LQFT are thus investigated. This allows us to integrate the LQFT on complex tori over the moduli space, to compute the law of the random Liouville modulus, therefore recovering (and extending) formulae obtained by physicists, and make conjectures about the relationship with random planar maps of genus one, eventually weighted by a conformal field theory and conformally embedded onto the torus.

  10. Liouville quantum gravity on complex tori

    NASA Astrophysics Data System (ADS)

    David, François; Rhodes, Rémi; Vargas, Vincent

    2016-02-01

    In this paper, we construct Liouville Quantum Field Theory (LQFT) on the toroidal topology in the spirit of the 1981 seminal work by Polyakov [Phys. Lett. B 103, 207 (1981)]. Our approach follows the construction carried out by the authors together with Kupiainen in the case of the Riemann sphere ["Liouville quantum gravity on the Riemann sphere," e-print arXiv:1410.7318]. The difference is here that the moduli space for complex tori is non-trivial. Modular properties of LQFT are thus investigated. This allows us to integrate the LQFT on complex tori over the moduli space, to compute the law of the random Liouville modulus, therefore recovering (and extending) formulae obtained by physicists, and make conjectures about the relationship with random planar maps of genus one, eventually weighted by a conformal field theory and conformally embedded onto the torus.

  11. On Complexity of the Quantum Ising Model

    NASA Astrophysics Data System (ADS)

    Bravyi, Sergey; Hastings, Matthew

    2017-01-01

    We study complexity of several problems related to the Transverse field Ising Model (TIM). First, we consider the problem of estimating the ground state energy known as the Local Hamiltonian Problem (LHP). It is shown that the LHP for TIM on degree-3 graphs is equivalent modulo polynomial reductions to the LHP for general k-local `stoquastic' Hamiltonians with any constant {k ≥ 2}. This result implies that estimating the ground state energy of TIM on degree-3 graphs is a complete problem for the complexity class {StoqMA} —an extension of the classical class {MA}. As a corollary, we complete the complexity classification of 2-local Hamiltonians with a fixed set of interactions proposed recently by Cubitt and Montanaro. Secondly, we study quantum annealing algorithms for finding ground states of classical spin Hamiltonians associated with hard optimization problems. We prove that the quantum annealing with TIM Hamiltonians is equivalent modulo polynomial reductions to the quantum annealing with a certain subclass of k-local stoquastic Hamiltonians. This subclass includes all Hamiltonians representable as a sum of a k-local diagonal Hamiltonian and a 2-local stoquastic Hamiltonian.

  12. The Origin of Complex Quantum Amplitudes

    NASA Astrophysics Data System (ADS)

    Goyal, Philip; Knuth, Kevin H.; Skilling, John

    2009-12-01

    Physics is real. Measurement produces real numbers. Yet quantum mechanics uses complex arithmetic, in which √-1 is necessary but mysteriously relates to nothing else. By applying the same sort of symmetry arguments that Cox [1, 2] used to justify probability calculus, we are now able to explain this puzzle. The dual device/object nature of observation requires us to describe the world in terms of pairs of real numbers about which we never have full knowledge. These pairs combine according to complex arithmetic, using Feynman's rules.

  13. Quantum streamlines within the complex quantum Hamilton-Jacobi formalism.

    PubMed

    Chou, Chia-Chun; Wyatt, Robert E

    2008-09-28

    Quantum streamlines are investigated in the framework of the quantum Hamilton-Jacobi formalism. The local structures of the quantum momentum function (QMF) and the Polya vector field near a stagnation point or a pole are analyzed. Streamlines near a stagnation point of the QMF may spiral into or away from it, or they may become circles centered on this point or straight lines. Additionally, streamlines near a pole display east-west and north-south opening hyperbolic structure. On the other hand, streamlines near a stagnation point of the Polya vector field for the QMF display general hyperbolic structure, and streamlines near a pole become circles enclosing the pole. Furthermore, the local structures of the QMF and the Polya vector field around a stagnation point are related to the first derivative of the QMF; however, the magnitude of the asymptotic structures for these two fields near a pole depends only on the order of the node in the wave function. Two nonstationary states constructed from the eigenstates of the harmonic oscillator are used to illustrate the local structures of these two fields and the dynamics of the streamlines near a stagnation point or a pole. This study presents the abundant dynamics of the streamlines in the complex space for one-dimensional time-dependent problems.

  14. Optimal control of complex atomic quantum systems

    PubMed Central

    van Frank, S.; Bonneau, M.; Schmiedmayer, J.; Hild, S.; Gross, C.; Cheneau, M.; Bloch, I.; Pichler, T.; Negretti, A.; Calarco, T.; Montangero, S.

    2016-01-01

    Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications. Indeed, it can engineer protocols at the quantum speed limit – the fastest achievable timescale of the transformation. Here, we demonstrate such potential by computing theoretically and verifying experimentally the optimal transformations in two very different interacting systems: the coherent manipulation of motional states of an atomic Bose-Einstein condensate and the crossing of a quantum phase transition in small systems of cold atoms in optical lattices. We also show that such processes are robust with respect to perturbations, including temperature and atom number fluctuations. PMID:27725688

  15. Optimal control of complex atomic quantum systems

    NASA Astrophysics Data System (ADS)

    van Frank, S.; Bonneau, M.; Schmiedmayer, J.; Hild, S.; Gross, C.; Cheneau, M.; Bloch, I.; Pichler, T.; Negretti, A.; Calarco, T.; Montangero, S.

    2016-10-01

    Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications. Indeed, it can engineer protocols at the quantum speed limit – the fastest achievable timescale of the transformation. Here, we demonstrate such potential by computing theoretically and verifying experimentally the optimal transformations in two very different interacting systems: the coherent manipulation of motional states of an atomic Bose-Einstein condensate and the crossing of a quantum phase transition in small systems of cold atoms in optical lattices. We also show that such processes are robust with respect to perturbations, including temperature and atom number fluctuations.

  16. Complex Rotation Quantum Dynamic Neural Networks (CRQDNN) using Complex Quantum Neuron (CQN): Applications to time series prediction.

    PubMed

    Cui, Yiqian; Shi, Junyou; Wang, Zili

    2015-11-01

    Quantum Neural Networks (QNN) models have attracted great attention since it innovates a new neural computing manner based on quantum entanglement. However, the existing QNN models are mainly based on the real quantum operations, and the potential of quantum entanglement is not fully exploited. In this paper, we proposes a novel quantum neuron model called Complex Quantum Neuron (CQN) that realizes a deep quantum entanglement. Also, a novel hybrid networks model Complex Rotation Quantum Dynamic Neural Networks (CRQDNN) is proposed based on Complex Quantum Neuron (CQN). CRQDNN is a three layer model with both CQN and classical neurons. An infinite impulse response (IIR) filter is embedded in the Networks model to enable the memory function to process time series inputs. The Levenberg-Marquardt (LM) algorithm is used for fast parameter learning. The networks model is developed to conduct time series predictions. Two application studies are done in this paper, including the chaotic time series prediction and electronic remaining useful life (RUL) prediction.

  17. Multi-scale non-local denoising method in neuroimaging.

    PubMed

    Chen, Yiping; Wang, Cheng; Wang, Liansheng

    2016-03-17

    Non-local means algorithm can remove image noise in a unique way that is contrary to traditional techniques. This is because it not only smooths the image but it also preserves the information details of the image. However, this method suffers from high computational complexity. We propose a multi-scale non-local means method in which adaptive multi-scale technique is implemented. In practice, based on each selected scale, the input image is divided into small blocks. Then, we remove the noise in the given pixel by using only one block. This can overcome the low efficiency problem caused by the original non-local means method. Our proposed method also benefits from the local average gradient orientation. In order to perform evaluation, we compared the processed images based on our technique with the ones by the original and the improved non-local means denoising method. Extensive experiments are conducted and results shows that our method is faster than the original and the improved non-local means method. It is also proven that our implemented method is robust enough to remove noise in the application of neuroimaging.

  18. Quantum electron tunneling in respiratory complex I.

    PubMed

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2011-05-12

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. While the one-electron tunneling approximation is found to hold in electron tunneling between the antiferromagnetic binuclear and tetranuclear Fe/S clusters without major orbital or spin rearrangement of the core electrons, induced polarization of the core electrons contributes significantly to decrease the electron transfer rates to 19-56 %. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of the electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A signature of the wave properties of electrons is observed as distinct quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included is in good agreement with a reported phenomenological relation.

  19. Dissipative quantum trajectories in complex space: Damped harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Chou, Chia-Chun

    2016-10-01

    Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton-Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.

  20. Solution of the Time-dependent Schrodinger Equation via Complex Quantum Trajectories

    NASA Astrophysics Data System (ADS)

    Goldfarb, Yair

    Ever since the advent of Quantum Mechanics, there has been a quest for a trajectory based formulation of quantum theory that is exact. In the 1950's, David Bohm, building on earlier work of Madelung and de Broglie, developed an exact formulation of quantum mechanics in which trajectories evolve in the presence of the usual Newtonian force plus an additional quantum force. In recent years, there has been a resurgence of interest in Bohmian Mechanics as a numerical tool because of its apparently local dynamics, which could lead to significant computational advantages for the simulation of large quantum systems. However, closer inspection of the Bohmian formulation reveals that the non-locality of quantum mechanics has not disappeared --- it has simply been swept under the rug into the quantum force. In the first part of the thesis we present several new formulations, inspired by Bohmian mechanics, in which the quantum action, S, is taken to be complex. The starting point of the formulations is the complex quantum Hamilton-Jacobi equation. Although this equation is equivalent to the time-dependent Schrodinger equation it has been relatively unexplored in comparison with other quantum mechanical formulations. In all the formulations presented, we propagate trajectories that do not communicate with their neighbors, allowing for local approximations to the quantum wavefunction. Importantly, we show that the new formulations allow for the description of nodal patterns as a sum of the contribution from several crossing trajectories. The new formulations are applied to one- and two-dimensional barrier scattering, thermal rate constants and the calculation of eigenvalues. In the second part of the thesis we explore a new mapping procedure developed for use with the mapped Fourier method. The conventional procedure uses the classical action function to generate a coordinate mapping that equalizes the spacing between extrema and nodal positions of the specified wavefunction

  1. Quantum communication complexity advantage implies violation of a Bell inequality

    NASA Astrophysics Data System (ADS)

    Buhrman, Harry; Czekaj, Łukasz; Grudka, Andrzej; Horodecki, Michał; Horodecki, Paweł; Markiewicz, Marcin; Speelman, Florian; Strelchuk, Sergii

    2016-03-01

    We obtain a general connection between a large quantum advantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that violate some Bell inequality. Our main tool is port-based teleportation. If the gap between quantum and classical communication complexity can grow arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs.

  2. Quantum communication complexity advantage implies violation of a Bell inequality.

    PubMed

    Buhrman, Harry; Czekaj, Łukasz; Grudka, Andrzej; Horodecki, Michał; Horodecki, Paweł; Markiewicz, Marcin; Speelman, Florian; Strelchuk, Sergii

    2016-03-22

    We obtain a general connection between a large quantum advantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that violate some Bell inequality. Our main tool is port-based teleportation. If the gap between quantum and classical communication complexity can grow arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs.

  3. Quantum communication complexity advantage implies violation of a Bell inequality

    PubMed Central

    Buhrman, Harry; Czekaj, Łukasz; Grudka, Andrzej; Horodecki, Michał; Horodecki, Paweł; Markiewicz, Marcin; Speelman, Florian; Strelchuk, Sergii

    2016-01-01

    We obtain a general connection between a large quantum advantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that violate some Bell inequality. Our main tool is port-based teleportation. If the gap between quantum and classical communication complexity can grow arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs. PMID:26957600

  4. Palatini formulation of non-local gravity

    NASA Astrophysics Data System (ADS)

    Briscese, F.; Pucheu, M. L.

    We derive the dynamical equations for a non-local gravity model in the Palatini formalism and we discuss some of the properties of this model. We have show that, in some specific case, the vacuum solutions of general relativity are also vacuum solutions of the non-local model, so we conclude that, at least in this case, the singularities of Einstein’s gravity are not removed.

  5. Robust non-local median filter

    NASA Astrophysics Data System (ADS)

    Matsuoka, Jyohei; Koga, Takanori; Suetake, Noriaki; Uchino, Eiji

    2017-01-01

    This paper describes a novel image filter with superior performance on detail-preserving removal of random-valued impulse noise superimposed on natural gray-scale images. The non-local means filter is in the limelight as a way of Gaussian noise removal with superior performance on detail preservation. By referring the fundamental concept of the non-local means, we had proposed a non-local median filter as a specialized way for random-valued impulse noise removal so far. In the non-local processing, the output of a filter is calculated from pixels in blocks which are similar to the block centered at a pixel of interest. As a result, aggressive noise removal is conducted without destroying the detailed structures in an original image. However, the performance of non-local processing decreases enormously in the case of high noise occurrence probability. A cause of this problem is that the superimposed noise disturbs accurate calculation of the similarity between the blocks. To cope with this problem, we propose an improved non-local median filter which is robust to the high level of corruption by introducing a new similarity measure considering possibility of being the original signal. The effectiveness and validity of the proposed method are verified in a series of experiments using natural gray-scale images.

  6. Complex quantum network geometries: Evolution and phase transitions

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph; Wu, Zhihao

    2015-08-01

    Networks are topological and geometric structures used to describe systems as different as the Internet, the brain, or the quantum structure of space-time. Here we define complex quantum network geometries, describing the underlying structure of growing simplicial 2-complexes, i.e., simplicial complexes formed by triangles. These networks are geometric networks with energies of the links that grow according to a nonequilibrium dynamics. The evolution in time of the geometric networks is a classical evolution describing a given path of a path integral defining the evolution of quantum network states. The quantum network states are characterized by quantum occupation numbers that can be mapped, respectively, to the nodes, links, and triangles incident to each link of the network. We call the geometric networks describing the evolution of quantum network states the quantum geometric networks. The quantum geometric networks have many properties common to complex networks, including small-world property, high clustering coefficient, high modularity, and scale-free degree distribution. Moreover, they can be distinguished between the Fermi-Dirac network and the Bose-Einstein network obeying, respectively, the Fermi-Dirac and Bose-Einstein statistics. We show that these networks can undergo structural phase transitions where the geometrical properties of the networks change drastically. Finally, we comment on the relation between quantum complex network geometries, spin networks, and triangulations.

  7. Reducing computational complexity of quantum correlations

    NASA Astrophysics Data System (ADS)

    Chanda, Titas; Das, Tamoghna; Sadhukhan, Debasis; Pal, Amit Kumar; SenDe, Aditi; Sen, Ujjwal

    2015-12-01

    We address the issue of reducing the resource required to compute information-theoretic quantum correlation measures such as quantum discord and quantum work deficit in two qubits and higher-dimensional systems. We show that determination of the quantum correlation measure is possible even if we utilize a restricted set of local measurements. We find that the determination allows us to obtain a closed form of quantum discord and quantum work deficit for several classes of states, with a low error. We show that the computational error caused by the constraint over the complete set of local measurements reduces fast with an increase in the size of the restricted set, implying usefulness of constrained optimization, especially with the increase of dimensions. We perform quantitative analysis to investigate how the error scales with the system size, taking into account a set of plausible constructions of the constrained set. Carrying out a comparative study, we show that the resource required to optimize quantum work deficit is usually higher than that required for quantum discord. We also demonstrate that minimization of quantum discord and quantum work deficit is easier in the case of two-qubit mixed states of fixed ranks and with positive partial transpose in comparison to the corresponding states having nonpositive partial transpose. Applying the methodology to quantum spin models, we show that the constrained optimization can be used with advantage in analyzing such systems in quantum information-theoretic language. For bound entangled states, we show that the error is significantly low when the measurements correspond to the spin observables along the three Cartesian coordinates, and thereby we obtain expressions of quantum discord and quantum work deficit for these bound entangled states.

  8. Quantum scattering model of energy transfer in photosynthetic complexes

    NASA Astrophysics Data System (ADS)

    Ai, Bao-quan; Zhu, Shi-Liang

    2015-12-01

    We develop a quantum scattering model to describe the exciton transport through the Fenna-Matthews-Olson (FMO) complex. It is found that the exciton transport involving the optimal quantum coherence is more efficient than that involving classical behaviour alone. Furthermore, we also find that the quantum resonance condition is easier to be fulfilled in multiple pathways than that in one pathway. We then definitely demonstrate that the optimal distribution of the pigments, the multitude of energy delivery pathways and the quantum effects are combined together to contribute to the perfect energy transport in the FMO complex.

  9. Exponential rise of dynamical complexity in quantum computing through projections.

    PubMed

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-10-10

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once 'observed' as outlined above. Conversely, we show that any complex quantum dynamics can be 'purified' into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics.

  10. Exponential rise of dynamical complexity in quantum computing through projections

    PubMed Central

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-01-01

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once ‘observed’ as outlined above. Conversely, we show that any complex quantum dynamics can be ‘purified’ into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics. PMID:25300692

  11. Minimized state complexity of quantum-encoded cryptic processes

    NASA Astrophysics Data System (ADS)

    Riechers, Paul M.; Mahoney, John R.; Aghamohammadi, Cina; Crutchfield, James P.

    2016-05-01

    The predictive information required for proper trajectory sampling of a stochastic process can be more efficiently transmitted via a quantum channel than a classical one. This recent discovery allows quantum information processing to drastically reduce the memory necessary to simulate complex classical stochastic processes. It also points to a new perspective on the intrinsic complexity that nature must employ in generating the processes we observe. The quantum advantage increases with codeword length: the length of process sequences used in constructing the quantum communication scheme. In analogy with the classical complexity measure, statistical complexity, we use this reduced communication cost as an entropic measure of state complexity in the quantum representation. Previously difficult to compute, the quantum advantage is expressed here in closed form using spectral decomposition. This allows for efficient numerical computation of the quantum-reduced state complexity at all encoding lengths, including infinite. Additionally, it makes clear how finite-codeword reduction in state complexity is controlled by the classical process's cryptic order, and it allows asymptotic analysis of infinite-cryptic-order processes.

  12. Complexity of the Quantum Adiabatic Algorithm

    NASA Technical Reports Server (NTRS)

    Hen, Itay

    2013-01-01

    The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.

  13. Apparatus independence in proofs of non-locality

    NASA Astrophysics Data System (ADS)

    Arntzenius, Frank

    1992-12-01

    In standard proofs of non-locality in quantum mechanics assumptions regarding the statistical independence of the states of the measuring apparatuses are made. Recently, proofs by A. Elby [1], and by R. Clifton, M. Redhead, and J. Butterfield [2,3] have been put forward in which it is claimed that such assumptions are not needed. In this paper I argue that Elby's proof and the first proof of Clifton, Redhead, and Butterfield are fallacious, and that their second proof, though valid, does make assumptions regarding the statistical independence of apparatus states. I further argue that any valid proof must make assumptions regarding the probabilities of apparatus states.

  14. Consistent theory for causal non-locality beyond the Born's rule

    NASA Astrophysics Data System (ADS)

    Son, Wonmin

    2014-02-01

    According to the theory of relativity and causality, a special type of correlation beyond quantum mechanics is possible in principle under the name of a non-local box. The concept has been introduced from the principle of non-locality, which satisfies relativistic causality. In this paper, we show that a correlation leading to the non-local box can be derived consistently if we release one of major axioms in quantum mechanics, Born's rule. This allows us to obtain a theory that in one end of the spectrum agrees with the classical probability and in the other end agrees with the theory of non-local causality. At the same time, we argue that the correlation lies in a space with special mathematical constraints such that a physical realization of the correlation through a probability measure is not possible in one direction of its limit, but is possible in the other limit.

  15. Quantum synchronization and quantum state sharing in an irregular complex network

    NASA Astrophysics Data System (ADS)

    Li, Wenlin; Li, Chong; Song, Heshan

    2017-02-01

    We investigate the quantum synchronization phenomenon of the complex network constituted by coupled optomechanical systems and prove that the unknown identical quantum states can be shared or distributed in the quantum network even though the topology is varying. Considering a channel constructed by quantum correlation, we show that quantum synchronization can sustain and maintain high levels in Markovian dissipation for a long time. We also analyze the state-sharing process between two typical complex networks, and the results predict that linked nodes can be directly synchronized, but the whole network will be synchronized only if some specific synchronization conditions are satisfied. Furthermore, we give the synchronization conditions analytically through analyzing network dynamics. This proposal paves the way for studying multi-interaction synchronization and achieving effective quantum information processing in a complex network.

  16. Bellʼs inequality and extremal non-local box from Hardyʼs test for non-locality

    NASA Astrophysics Data System (ADS)

    Yu, Sixia

    2014-10-01

    Bell showed 50 years ago that quantum theory is non-local via his celebrated inequalities, turning the issue of quantum non-locality from a matter of taste into a matter of test. Years later, Hardy proposed a test for non-locality without inequality, which is a kind of ‘something-versus-nothing’ argument. Hardy's test for n particles induces an n-partite Bell's inequality with two dichotomic local measurements for each observer, which has been shown to be violated by all entangled pure states. Our first result is to show that the Bell-Hardy inequality arising form Hardy's non-locality test is tight for an arbitrary number of parties, i.e., it defines a facet of the Bell polytope in the given scenario. On the other hand quantum theory is not that non-local since it forbids signaling and even not as non-local as allowed by non-signaling conditions, i.e., quantum mechanical predictions form a strict subset of the so called non-signaling polytope. In the scenario of each observer measuring two dichotomic observables, Fritz established a duality between the Bell polytope and the non-signaling polytope: tight Bell's inequalities, the facets of the Bell polytope, are in a one-to-one correspondence with extremal non-signaling boxes, the vertices of the non-signaling polytope. Our second result is to provide an alternative and more direct formula for this duality. As an example, the tight Bell-Hardy inequality gives rise to an extremal non-signaling box that serves as a natural multipartite generalization of Popescu-Rohrlich box. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘50 years of Bell’s theorem’.

  17. Non-local MRI denoising using random sampling.

    PubMed

    Hu, Jinrong; Zhou, Jiliu; Wu, Xi

    2016-09-01

    In this paper, we propose a random sampling non-local mean (SNLM) algorithm to eliminate noise in 3D MRI datasets. Non-local means (NLM) algorithms have been implemented efficiently for MRI denoising, but are always limited by high computational complexity. Compared to conventional methods, which raster through the entire search window when computing similarity weights, the proposed SNLM algorithm randomly selects a small subset of voxels which dramatically decreases the computational burden, together with competitive denoising result. Moreover, structure tensor which encapsulates high-order information was introduced as an optimal sampling pattern for further improvement. Numerical experiments demonstrated that the proposed SNLM method can get a good balance between denoising quality and computation efficiency. At a relative sampling ratio (i.e. ξ=0.05), SNLM can remove noise as effectively as full NLM, meanwhile the running time can be reduced to 1/20 of NLM's.

  18. Complex Wavelet Transform of the Two-mode Quantum States

    NASA Astrophysics Data System (ADS)

    Song, Jun; Zhou, Jun; Yuan, Hao; He, Rui; Fan, Hong-Yi

    2016-08-01

    By employing the bipartite entangled state representation and the technique of integration within an ordered product of operators, the classical complex wavelet transform of a complex signal function can be recast to a matrix element of the squeezing-displacing operator U 2( μ, σ) between the mother wavelet vector < ψ| and the two-mode quantum state vector | f> to be transformed. < ψ| U 2( μ, σ)| f> can be considered as the spectrum for analyzing the two-mode quantum state | f>. In this way, for some typical two-mode quantum states, such as two-mode coherent state and two-mode Fock state, we derive the complex wavelet transform spectrum and carry out the numerical calculation. This kind of wavelet-transform spectrum can be used to recognize quantum states.

  19. Identifying the quantum correlations in light-harvesting complexes

    SciTech Connect

    Bradler, Kamil; Wilde, Mark M.; Vinjanampathy, Sai; Uskov, Dmitry B.

    2010-12-15

    One of the major efforts in the quantum biological program is to subject biological systems to standard tests or measures of quantumness. These tests and measures should elucidate whether nontrivial quantum effects may be present in biological systems. Two such measures of quantum correlations are the quantum discord and the relative entropy of entanglement. Here, we show that the relative entropy of entanglement admits a simple analytic form when dynamics and accessible degrees of freedom are restricted to a zero- and single-excitation subspace. We also simulate and calculate the amount of quantum discord that is present in the Fenna-Matthews-Olson protein complex during the transfer of an excitation from a chlorosome antenna to a reaction center. We find that the single-excitation quantum discord and single-excitation relative entropy of entanglement are equal for all of our numerical simulations, but a proof of their general equality for this setting evades us for now. Also, some of our simulations demonstrate that the relative entropy of entanglement without the single-excitation restriction is much lower than the quantum discord. The first picosecond of dynamics is the relevant time scale for the transfer of the excitation, according to some sources in the literature. Our simulation results indicate that quantum correlations contribute a significant fraction of the total correlation during this first picosecond in many cases, at both cryogenic and physiological temperatures.

  20. Quantum Computational Complexity of Spin Glasses

    DTIC Science & Technology

    2011-03-19

    the absence of an external magnetic field, and the Robertson - Seymour theorem from graph theory. We gave as an example a set of quantum circuits with a...classical algorithm for the Ising partition function of any planar graph in the absence of an external magnetic field, and the Robertson - Seymour theorem

  1. Statistical measures of complexity for quantum systems with continuous variables

    NASA Astrophysics Data System (ADS)

    Manzano, D.

    2012-12-01

    The Fisher-Shannon statistical measure of complexity is analyzed for a continuous manifold of quantum observables. It is shown that evaluating this measure only in the configuration or in the momentum spaces does not provide an adequate characterization of the complexity of some quantum systems. In order to obtain a more complete description of complexity two new measures, respectively based on the minimization and the integration of the usual Fisher-Shannon measure over all the parameter space, are proposed and compared. Finally, these measures are applied to the concrete case of a free particle in a box.

  2. Complex Chemical Reaction Networks from Heuristics-Aided Quantum Chemistry.

    PubMed

    Rappoport, Dmitrij; Galvin, Cooper J; Zubarev, Dmitry Yu; Aspuru-Guzik, Alán

    2014-03-11

    While structures and reactivities of many small molecules can be computed efficiently and accurately using quantum chemical methods, heuristic approaches remain essential for modeling complex structures and large-scale chemical systems. Here, we present a heuristics-aided quantum chemical methodology applicable to complex chemical reaction networks such as those arising in cell metabolism and prebiotic chemistry. Chemical heuristics offer an expedient way of traversing high-dimensional reactive potential energy surfaces and are combined here with quantum chemical structure optimizations, which yield the structures and energies of the reaction intermediates and products. Application of heuristics-aided quantum chemical methodology to the formose reaction reproduces the experimentally observed reaction products, major reaction pathways, and autocatalytic cycles.

  3. Thermal Quantum Correlations in Photosynthetic Light-Harvesting Complexes

    NASA Astrophysics Data System (ADS)

    Mahdian, M.; Kouhestani, H.

    2015-08-01

    Photosynthesis is one of the ancient biological processes, playing crucial role converting solar energy to cellular usable currency. Environmental factors and external perturbations has forced nature to choose systems with the highest efficiency and performance. Recent theoretical and experimental studies have proved the presence of quantum properties in biological systems. Energy transfer systems like Fenna-Matthews-Olson (FMO) complex shows quantum entanglement between sites of Bacteriophylla molecules in protein environment and presence of decoherence. Complex biological systems implement more truthful mechanisms beside chemical-quantum correlations to assure system's efficiency. In this study we investigate thermal quantum correlations in FMO protein of the photosynthetic apparatus of green sulfur bacteria by quantum discord measure. The results confirmed existence of remarkable quantum correlations of of BChla pigments in room temperature. This results approve involvement of quantum correlation mechanisms for information storage and retention in living organisms that could be useful for further evolutionary studies. Inspired idea of this study is potentially interesting to practice by the same procedure in genetic data transfer mechanisms.

  4. Complex scattering dynamics and the quantum Hall effects

    SciTech Connect

    Trugman, S.A.

    1994-12-16

    We review both classical and quantum potential scattering in two dimensions in a magnetic field, with applications to the quantum Hall effect. Classical scattering is complex, due to the approach of scattering states to an infinite number of dynamically bound states. Quantum scattering follows the classical behavior rather closely, exhibiting sharp resonances in place of the classical bound states. Extended scatterers provide a quantitative explanation for the breakdown of the QHE at a comparatively small Hall voltage as seen by Kawaji et al., and possibly for noise effects.

  5. Complex quantum networks as structured environments: engineering and probing

    NASA Astrophysics Data System (ADS)

    Nokkala, Johannes; Galve, Fernando; Zambrini, Roberta; Maniscalco, Sabrina; Piilo, Jyrki

    2016-05-01

    We consider structured environments modeled by bosonic quantum networks and investigate the probing of their spectral density, structure, and topology. We demonstrate how to engineer a desired spectral density by changing the network structure. Our results show that the spectral density can be very accurately detected via a locally immersed quantum probe for virtually any network configuration. Moreover, we show how the entire network structure can be reconstructed by using a single quantum probe. We illustrate our findings presenting examples of spectral densities and topology probing for networks of genuine complexity.

  6. Complex quantum networks as structured environments: engineering and probing

    PubMed Central

    Nokkala, Johannes; Galve, Fernando; Zambrini, Roberta; Maniscalco, Sabrina; Piilo, Jyrki

    2016-01-01

    We consider structured environments modeled by bosonic quantum networks and investigate the probing of their spectral density, structure, and topology. We demonstrate how to engineer a desired spectral density by changing the network structure. Our results show that the spectral density can be very accurately detected via a locally immersed quantum probe for virtually any network configuration. Moreover, we show how the entire network structure can be reconstructed by using a single quantum probe. We illustrate our findings presenting examples of spectral densities and topology probing for networks of genuine complexity. PMID:27230125

  7. Dimensional discontinuity in quantum communication complexity at dimension seven

    NASA Astrophysics Data System (ADS)

    Tavakoli, Armin; Pawłowski, Marcin; Żukowski, Marek; Bourennane, Mohamed

    2017-02-01

    Entanglement-assisted classical communication and transmission of a quantum system are the two quantum resources for information processing. Many information tasks can be performed using either quantum resource. However, this equivalence is not always present since entanglement-assisted classical communication is sometimes known to be the better performing resource. Here, we show not only the opposite phenomenon, that there exist tasks for which transmission of a quantum system is a more powerful resource than entanglement-assisted classical communication, but also that such phenomena can have a surprisingly strong dependence on the dimension of Hilbert space. We introduce a family of communication complexity problems parametrized by the dimension of Hilbert space and study the performance of each quantum resource. Under an additional assumption of a linear strategy for the receiving party, we find that for low dimensions the two resources perform equally well, whereas for dimension seven and above the equivalence is suddenly broken and transmission of a quantum system becomes more powerful than entanglement-assisted classical communication. Moreover, we find that transmission of a quantum system may even outperform classical communication assisted by the stronger-than-quantum correlations obtained from the principle of macroscopic locality.

  8. Retro-causation, Minimum Contradictions and Non-locality

    NASA Astrophysics Data System (ADS)

    Kafatos, Menas; Nassikas, Athanassios A.

    2011-11-01

    Retro-causation has been experimentally verified by Bem and proposed by Kafatos in the form of space-time non-locality in the quantum framework. Every theory includes, beyond its specific axioms, the principles of logical communication (logical language), through which it is defined. This communication obeys the Aristotelian logic (Classical Logic), the Leibniz Sufficient Reason Principle, and a hidden axiom, which basically states that there is anterior-posterior relationship everywhere in communication. By means of a theorem discussed here, it can be proved that the communication mentioned implies contradictory statements, which can only be transcended through silence, i.e. the absence of any statements. Moreover, the breaking of silence is meaningful through the claim for minimum contradictions, which implies the existence of both a logical and an illogical dimension; contradictions refer to causality, implying its opposite, namely retro-causation, and the anterior posterior axiom, implying space-time non-locality. The purpose of this paper is to outline a framework accounting for retro-causation, through both purely theoretical and reality based points of view.

  9. Estimation of Mueller matrices using non-local means filtering.

    PubMed

    Faisan, Sylvain; Heinrich, Christian; Sfikas, Giorgos; Zallat, Jihad

    2013-02-25

    This article addresses the estimation of polarization signatures in the Mueller imaging framework by non-local means filtering. This is an extension of previous work dealing with Stokes signatures. The extension is not straightforward because of the gap in complexity between the Mueller framework and the Stokes framework. The estimation procedure relies on the Cholesky decomposition of the coherency matrix, thereby ensuring the physical admissibility of the estimate. We propose an original parameterization of the boundary of the set of Mueller matrices, which makes our approach possible. The proposed method is fully unsupervised. It allows noise removal and the preservation of edges. Applications to synthetic as well as real data are presented.

  10. Extended non-local games and monogamy-of-entanglement games.

    PubMed

    Johnston, Nathaniel; Mittal, Rajat; Russo, Vincent; Watrous, John

    2016-05-01

    We study a generalization of non-local games-which we call extended non-local games-in which the players, Alice and Bob, initially share a tripartite quantum state with the referee. In such games, the winning conditions for Alice and Bob may depend on the outcomes of measurements made by the referee, on its part of the shared quantum state, in addition to Alice and Bob's answers to randomly selected questions. Our study of this class of games was inspired by the monogamy-of-entanglement games introduced by Tomamichel, Fehr, Kaniewski and Wehner, which they also generalize. We prove that a natural extension of the Navascués-Pironio-Acín hierarchy of semidefinite programmes converges to the optimal commuting measurement value of extended non-local games, and we prove two extensions of results of Tomamichel et al. concerning monogamy-of-entanglement games.

  11. Non-local models for ductile failure

    NASA Astrophysics Data System (ADS)

    César de Sá, José; Azinpour, Erfan; Santos, Abel

    2016-08-01

    Ductile damage can be dealt with continuous descriptions of material, resorting, for example, to continuous damage mechanic descriptions or micromechanical constitutive models. When it comes to describe material behaviour near and beyond fracture these approaches are no longer sufficient or valid and continuous/discontinuous approaches can be adopted to track fracture initiation and propagation. Apart from more pragmatic solutions like element erosion or remeshing techniques more advanced approaches based on the X-FEM concept, in particular associated with non-local formulations, may be adopted to numerically model these problems. Nevertheless, very often, for practical reasons, some important aspects are somewhat left behind, specially energetic requirements to promote the necessary transition of energy release associated with material damage and fracture energy associated to a crack creation and evolution. Phase-field methods may combine advantages of regularised continuous models by providing a similar description to non-local thermodynamical continuous damage mechanics, as well as, a "continuous" approach to numerically follow crack evolution and branching

  12. Scaling of Quantum Walks on Complex Networks

    NASA Astrophysics Data System (ADS)

    Boettcher, Stefan; Falkner, Stefan; Portugal, Renato

    2015-03-01

    I will describe the renormalization group method (RG) as applied to master equations with a unitary propagator. It allows to determine many asymptotic properties of quantum walks, although I will focus here on the walk dimension dw, which describes the similarity solution, ρ (x , t) ~ f| x | dw / t , for the probability density function ρ. We can calculate dw to arbitrary accuracy for a number of networks, such as the dual Sierpinksi gasket, small-world Hanoi networks, or Migdal-Kadanoff lattices, which we have verified with direct simulations. However, due to unitarity, the asymptotic solution of the RG equations as well as procedures to implement RG approximately for arbitrary networks remain elusive. Yet, based on the exact RG for those fractal networks, we can conjecture a few general conclusions, for instance, that dw for a discrete-time quantum walk is always half of that for the random walk on the same r-regular network, when driven with the Grover coin. (This talk summarizes our work in http://dx.doi.org/10.1103/PhysRevA.90.032324 and http://arxiv.org/abs/1410.7034.) We acknowledge financial support from the U.S. National Science Foundation through Grant DMR-1207431.

  13. On the experimental verification of quantum complexity in linear optics

    NASA Astrophysics Data System (ADS)

    Carolan, Jacques; Meinecke, Jasmin D. A.; Shadbolt, Peter J.; Russell, Nicholas J.; Ismail, Nur; Wörhoff, Kerstin; Rudolph, Terry; Thompson, Mark G.; O'Brien, Jeremy L.; Matthews, Jonathan C. F.; Laing, Anthony

    2014-08-01

    Quantum computers promise to solve certain problems that are forever intractable to classical computers. The first of these devices are likely to tackle bespoke problems suited to their own particular physical capabilities. Sampling the probability distribution from many bosons interfering quantum-mechanically is conjectured to be intractable to a classical computer but solvable with photons in linear optics. However, the complexity of this type of problem means its solution is mathematically unverifiable, so the task of establishing successful operation becomes one of gathering sufficiently convincing circumstantial or experimental evidence. Here, we develop scalable methods to experimentally establish correct operation for this class of computation, which we implement for three, four and five photons in integrated optical circuits, on Hilbert spaces of up to 50,000 dimensions. Our broad approach is practical for all quantum computational architectures where formal verification methods for quantum algorithms are either intractable or unknown.

  14. Minimal classical communication and measurement complexity for quantum information splitting

    NASA Astrophysics Data System (ADS)

    Zhang, Zhan-jun; Cheung, Chi-Yee

    2008-01-01

    We present two quantum information splitting schemes using respectively tripartite GHZ and asymmetric W states as quantum channels. We show that if the secret state is chosen from a special ensemble and known to the sender (Alice), then she can split and distribute it to the receivers Bob and Charlie by performing only a single-qubit measurement and broadcasting a one-cbit message. It is clear that no other schemes could possibly achieve the same goal with simpler measurement and less classical communication. In comparison, existing schemes work for arbitrary quantum states which need not be known to Alice; however she is required to perform a two-qubit Bell measurement and communicate a two-cbit message. Hence there is a trade-off between flexibility and measurement complexity plus classical resource. In situations where our schemes are applicable, they will greatly reduce the measurement complexity and at the same time cut the communication overhead by one half.

  15. MRI denoising using non-local means.

    PubMed

    Manjón, José V; Carbonell-Caballero, José; Lull, Juan J; García-Martí, Gracián; Martí-Bonmatí, Luís; Robles, Montserrat

    2008-08-01

    Magnetic Resonance (MR) images are affected by random noise which limits the accuracy of any quantitative measurements from the data. In the present work, a recently proposed filter for random noise removal is analyzed and adapted to reduce this noise in MR magnitude images. This parametric filter, named Non-Local Means (NLM), is highly dependent on the setting of its parameters. The aim of this paper is to find the optimal parameter selection for MR magnitude image denoising. For this purpose, experiments have been conducted to find the optimum parameters for different noise levels. Besides, the filter has been adapted to fit with specific characteristics of the noise in MR image magnitude images (i.e. Rician noise). From the results over synthetic and real images we can conclude that this filter can be successfully used for automatic MR denoising.

  16. Origin of complex quantum amplitudes and Feynman's rules

    NASA Astrophysics Data System (ADS)

    Goyal, Philip; Knuth, Kevin H.; Skilling, John

    2010-02-01

    Complex numbers are an intrinsic part of the mathematical formalism of quantum theory and are perhaps its most characteristic feature. In this article, we show that the complex nature of the quantum formalism can be derived directly from the assumption that a pair of real numbers is associated with each sequence of measurement outcomes, with the probability of this sequence being a real-valued function of this number pair. By making use of elementary symmetry conditions, and without assuming that these real number pairs have any other algebraic structure, we show that these pairs must be manipulated according to the rules of complex arithmetic. We demonstrate that these complex numbers combine according to Feynman’s sum and product rules, with the modulus-squared yielding the probability of a sequence of outcomes.

  17. Quantum simulations of small electron-hole complexes

    SciTech Connect

    Lee, M.A.; Kalia, R.K.; Vashishta, P.D.

    1984-09-01

    The Green's Function Monte Carlo method is applied to the calculation of the binding energies of electron-hole complexes in semiconductors. The quantum simulation method allows the unambiguous determination of the ground state energy and the effects of band anisotropy on the binding energy. 22 refs., 1 fig.

  18. Phase transition of light on complex quantum networks.

    PubMed

    Halu, Arda; Garnerone, Silvano; Vezzani, Alessandro; Bianconi, Ginestra

    2013-02-01

    Recent advances in quantum optics and atomic physics allow for an unprecedented level of control over light-matter interactions, which can be exploited to investigate new physical phenomena. In this work we are interested in the role played by the topology of quantum networks describing coupled optical cavities and local atomic degrees of freedom. In particular, using a mean-field approximation, we study the phase diagram of the Jaynes-Cummings-Hubbard model on complex networks topologies, and we characterize the transition between a Mott-like phase of localized polaritons and a superfluid phase. We found that, for complex topologies, the phase diagram is nontrivial and well defined in the thermodynamic limit only if the hopping coefficient scales like the inverse of the maximal eigenvalue of the adjacency matrix of the network. Furthermore we provide numerical evidences that, for some complex network topologies, this scaling implies an asymptotically vanishing hopping coefficient in the limit of large network sizes. The latter result suggests the interesting possibility of observing quantum phase transitions of light on complex quantum networks even with very small couplings between the optical cavities.

  19. Network geometry with flavor: From complexity to quantum geometry.

    PubMed

    Bianconi, Ginestra; Rahmede, Christoph

    2016-03-01

    Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d-dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s=-1,0,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d. In d=1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d>1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t. Interestingly the NGF remains fully classical but its

  20. Network geometry with flavor: From complexity to quantum geometry

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph

    2016-03-01

    Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d -dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s =-1 ,0 ,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d . In d =1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d >1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t . Interestingly the NGF remains fully classical but

  1. Non-locality Sudden Death in Tripartite Systems

    SciTech Connect

    Jaeger, Gregg; Ann, Kevin

    2009-03-10

    Bell non-locality sudden death is the disappearance of non-local properties in finite times under local phase noise, which decoheres states only in the infinite-time limit. We consider the relationship between decoherence, disentanglement, and Bell non-locality sudden death in bipartite and tripartite systems in specific large classes of state preparation.

  2. Center for Quantum Algorithms and Complexity

    DTIC Science & Technology

    2014-05-12

    condensed matter physics. Of particular importance are 1D Hamiltonians . We give a new combinatorial approach to proving the area law for 1D systems via...Dorit Aharonov, Lior Eldar. On the Complexity of Commuting Local Hamiltonians , and Tight Conditions for Topological Order in Such Systems , 2011...natural setting to explore this question. These systems are generally described by a local Hamiltonian that models interactions between neighboring

  3. Complexity of controlling quantum many-body dynamics

    NASA Astrophysics Data System (ADS)

    Caneva, T.; Silva, A.; Fazio, R.; Lloyd, S.; Calarco, T.; Montangero, S.

    2014-04-01

    We demonstrate that arbitrary time evolutions of many-body quantum systems can be reversed even in cases when only part of the Hamiltonian can be controlled. The reversed dynamics obtained via optimal control—contrary to standard time-reversal procedures—is extremely robust to external sources of noise. We provide a lower bound on the control complexity of a many-body quantum dynamics in terms of the dimension of the manifold supporting it, elucidating the role played by integrability in this context.

  4. Quantum trajectories in complex phase space: multidimensional barrier transmission.

    PubMed

    Wyatt, Robert E; Rowland, Brad A

    2007-07-28

    The quantum Hamilton-Jacobi equation for the action function is approximately solved by propagating individual Lagrangian quantum trajectories in complex-valued phase space. Equations of motion for these trajectories are derived through use of the derivative propagation method (DPM), which leads to a hierarchy of coupled differential equations for the action function and its spatial derivatives along each trajectory. In this study, complex-valued classical trajectories (second order DPM), along which is transported quantum phase information, are used to study low energy barrier transmission for a model two-dimensional system involving either an Eckart or Gaussian barrier along the reaction coordinate coupled to a harmonic oscillator. The arrival time for trajectories to reach the transmitted (product) region is studied. Trajectories launched from an "equal arrival time surface," defined as an isochrone, all reach the real-valued subspace in the transmitted region at the same time. The Rutherford-type diffraction of trajectories around poles in the complex extended Eckart potential energy surface is described. For thin barriers, these poles are close to the real axis and present problems for computing the transmitted density. In contrast, for the Gaussian barrier or the thick Eckart barrier where the poles are further from the real axis, smooth transmitted densities are obtained. Results obtained using higher-order quantum trajectories (third order DPM) are described for both thick and thin barriers, and some issues that arise for thin barriers are examined.

  5. Quantum ferroelectricity in charge-transfer complex crystals

    PubMed Central

    Horiuchi, Sachio; Kobayashi, Kensuke; Kumai, Reiji; Minami, Nao; Kagawa, Fumitaka; Tokura, Yoshinori

    2015-01-01

    Quantum phase transition achieved by fine tuning the continuous phase transition down to zero kelvin is a challenge for solid state science. Critical phenomena distinct from the effects of thermal fluctuations can materialize when the electronic, structural or magnetic long-range order is perturbed by quantum fluctuations between degenerate ground states. Here we have developed chemically pure tetrahalo-p-benzoquinones of n iodine and 4–n bromine substituents (QBr4–nIn, n=0–4) to search for ferroelectric charge-transfer complexes with tetrathiafulvalene (TTF). Among them, TTF–QBr2I2 exhibits a ferroelectric neutral–ionic phase transition, which is continuously controlled over a wide temperature range from near-zero kelvin to room temperature under hydrostatic pressure. Quantum critical behaviour is accompanied by a much larger permittivity than those of other neutral–ionic transition compounds, such as well-known ferroelectric complex of TTF–QCl4 and quantum antiferroelectric of dimethyl–TTF–QBr4. By contrast, TTF–QBr3I complex, another member of this compound family, shows complete suppression of the ferroelectric spin-Peierls-type phase transition. PMID:26076656

  6. Complex Squeezing and Force Measurement Beyond the Standard Quantum Limit

    NASA Astrophysics Data System (ADS)

    Buchmann, L. F.; Schreppler, S.; Kohler, J.; Spethmann, N.; Stamper-Kurn, D. M.

    2016-07-01

    A continuous quantum field, such as a propagating beam of light, may be characterized by a squeezing spectrum that is inhomogeneous in frequency. We point out that homodyne detectors, which are commonly employed to detect quantum squeezing, are blind to squeezing spectra in which the correlation between amplitude and phase fluctuations is complex. We find theoretically that such complex squeezing is a component of ponderomotive squeezing of light through cavity optomechanics. We propose a detection scheme called synodyne detection, which reveals complex squeezing and allows the accounting of measurement backaction. Even with the optomechanical system subject to continuous measurement, such detection allows the measurement of one component of an external force with sensitivity only limited by the mechanical oscillator's thermal occupation.

  7. Complex Squeezing and Force Measurement Beyond the Standard Quantum Limit.

    PubMed

    Buchmann, L F; Schreppler, S; Kohler, J; Spethmann, N; Stamper-Kurn, D M

    2016-07-15

    A continuous quantum field, such as a propagating beam of light, may be characterized by a squeezing spectrum that is inhomogeneous in frequency. We point out that homodyne detectors, which are commonly employed to detect quantum squeezing, are blind to squeezing spectra in which the correlation between amplitude and phase fluctuations is complex. We find theoretically that such complex squeezing is a component of ponderomotive squeezing of light through cavity optomechanics. We propose a detection scheme called synodyne detection, which reveals complex squeezing and allows the accounting of measurement backaction. Even with the optomechanical system subject to continuous measurement, such detection allows the measurement of one component of an external force with sensitivity only limited by the mechanical oscillator's thermal occupation.

  8. On the complexity of search for keys in quantum cryptography

    NASA Astrophysics Data System (ADS)

    Molotkov, S. N.

    2016-03-01

    The trace distance is used as a security criterion in proofs of security of keys in quantum cryptography. Some authors doubted that this criterion can be reduced to criteria used in classical cryptography. The following question has been answered in this work. Let a quantum cryptography system provide an ɛ-secure key such that ½‖ρ XE - ρ U ⊗ ρ E ‖1 < ɛ, which will be repeatedly used in classical encryption algorithms. To what extent does the ɛ-secure key reduce the number of search steps (guesswork) as compared to the use of ideal keys? A direct relation has been demonstrated between the complexity of the complete consideration of keys, which is one of the main security criteria in classical systems, and the trace distance used in quantum cryptography. Bounds for the minimum and maximum numbers of search steps for the determination of the actual key have been presented.

  9. The Aharonov-Bohm Effect and the Non-Locality Debate

    NASA Astrophysics Data System (ADS)

    Kennedy, John Bernard, Jr.

    The Aharonov-Bohm effect is a celebrated quantum mechanical effect which some have claimed is an example of non-locality, i.e., of action at a distance. This thesis examines the theory and experimental tests of the effect, and compares it to another supposed example of non-locality, the EPR correlations. The role of the electromagnetic potentials in the quantum formalism, and especially gauge invariance and the physical significance of the vector potential, is detailed. I argue that K. H. Yang's proofs of the gauge arbitrariness of the conventional formalism are mistaken. Four central and conflicting theories of the AB effect are reviewed and critiqued: (i) physically significant potentials, (ii) local effects of electromagnetic fluxes, (iii) multi-valued wave functions, and (iv) non-locality. An entire chapter is devoted to the topological interpretations of the effect which model the potentials as connections in higher-dimensional fiber bundle geometries. The relation between the AB effect and geometric phase phenomena, like Berry's phase, is studied. The new geometric models inherit the merits and demerits of the potentials interpretation. The quantum no-signalling proofs for the case of the EPR-Bohm-Bell experiments are analyzed and unified in a single theorem: they are simple consequences of the tenstor product representation of combined quantum systems. All proposed local theories of the AB effect are finally unsatisfactory--for a variety of reasons. However, given the lack of a clear criterion for non-locality, there are no decisive grounds for the claim that the AB effect is non-local.

  10. Quantum Non-Locality and the Mathematical Representation of Experience

    NASA Astrophysics Data System (ADS)

    Fano, Vincenzo

    2006-06-01

    Four possible solutions of the Kantian problem "how the mathematisation of experience is possible?" are presented: Platonism, critical materialism, operationism and empiricism. Then the experimental violation of Bell's inequality is discussed. To avoid the proof of Bell's inequality, it is possible to deny different conditions, but experiments support only the refutation of factorizability as a whole. It is argued that this implies a confirmation of the empiricist's point of view.

  11. Design of magnetic coordination complexes for quantum computing.

    PubMed

    Aromí, Guillem; Aguilà, David; Gamez, Patrick; Luis, Fernando; Roubeau, Olivier

    2012-01-21

    A very exciting prospect in coordination chemistry is to manipulate spins within magnetic complexes for the realization of quantum logic operations. An introduction to the requirements for a paramagnetic molecule to act as a 2-qubit quantum gate is provided in this tutorial review. We propose synthetic methods aimed at accessing such type of functional molecules, based on ligand design and inorganic synthesis. Two strategies are presented: (i) the first consists in targeting molecules containing a pair of well-defined and weakly coupled paramagnetic metal aggregates, each acting as a carrier of one potential qubit, (ii) the second is the design of dinuclear complexes of anisotropic metal ions, exhibiting dissimilar environments and feeble magnetic coupling. The first systems obtained from this synthetic program are presented here and their properties are discussed.

  12. Complex quantum networks: From universal breakdown to optimal transport.

    PubMed

    Mülken, Oliver; Dolgushev, Maxim; Galiceanu, Mircea

    2016-02-01

    We study the transport efficiency of excitations on complex quantum networks with loops. For this we consider sequentially growing networks with different topologies of the sequential subgraphs. This can lead either to a universal complete breakdown of transport for complete-graph-like sequential subgraphs or to optimal transport for ringlike sequential subgraphs. The transition to optimal transport can be triggered by systematically reducing the number of loops of complete-graph-like sequential subgraphs in a small-world procedure. These effects are explained on the basis of the spectral properties of the network's Hamiltonian. Our theoretical considerations are supported by numerical Monte Carlo simulations for complex quantum networks with a scale-free size distribution of sequential subgraphs and a small-world-type transition to optimal transport.

  13. Complex quantum networks: From universal breakdown to optimal transport

    NASA Astrophysics Data System (ADS)

    Mülken, Oliver; Dolgushev, Maxim; Galiceanu, Mircea

    2016-02-01

    We study the transport efficiency of excitations on complex quantum networks with loops. For this we consider sequentially growing networks with different topologies of the sequential subgraphs. This can lead either to a universal complete breakdown of transport for complete-graph-like sequential subgraphs or to optimal transport for ringlike sequential subgraphs. The transition to optimal transport can be triggered by systematically reducing the number of loops of complete-graph-like sequential subgraphs in a small-world procedure. These effects are explained on the basis of the spectral properties of the network's Hamiltonian. Our theoretical considerations are supported by numerical Monte Carlo simulations for complex quantum networks with a scale-free size distribution of sequential subgraphs and a small-world-type transition to optimal transport.

  14. Quantum coherence, decoherence and entanglement in light harvesting complexes

    NASA Astrophysics Data System (ADS)

    Plenio, Martin; Caruso, Filippo; Chin, Alex; Datta, Animesh; Huelga, Susana

    2009-03-01

    Transport phenomena in networks allow for information and energy to be exchanged between individual constituents of communication systems, networks or light-harvesting complexes. Environmental noise is generally expected to hinder transport. Here we show that transport of excitations across dissipative quantum networks can be enhanced by dephasing noise. We identify two key processes that underly this phenomenon and provide instructive examples of quantum networks for each. We argue that Nature may be routinely exploiting this effect by showing that exciton transport in light harvesting complexes and other networks benefits from noise and is remarkably robust against static disorder. These results point towards the possibility for designing optimized structures for transport, for example in artificial nano-structures, assisted by noise. Furthermore, we demonstrate that quantum entanglement may be present for short times in light-harvesting complexes. We describe how the presence of such entanglement may be verified without the need for full state tomography and with minimal model assumptions. This work is based on M.B. Plenio & S.F. Huelga, New J. Phys. 10, 113019 (2008) and F. Caruso, A. Chin, A. Datta, S.F. Huelga & M.B. Plenio, in preparation

  15. Denoising Magnetic Resonance Images Using Collaborative Non-Local Means.

    PubMed

    Chen, Geng; Zhang, Pei; Wu, Yafeng; Shen, Dinggang; Yap, Pew-Thian

    2016-02-12

    Noise artifacts in magnetic resonance (MR) images increase the complexity of image processing workflows and decrease the reliability of inferences drawn from the images. It is thus often desirable to remove such artifacts beforehand for more robust and effective quantitative analysis. It is important to preserve the integrity of relevant image information while removing noise in MR images. A variety of approaches have been developed for this purpose, and the non-local means (NLM) filter has been shown to be able to achieve state-of-the-art denoising performance. For effective denoising, NLM relies heavily on the existence of repeating structural patterns, which however might not always be present within a single image. This is especially true when one considers the fact that the human brain is complex and contains a lot of unique structures. In this paper we propose to leverage the repeating structures from multiple images to collaboratively denoise an image. The underlying assumption is that it is more likely to find repeating structures from multiple scans than from a single scan. Specifically, to denoise a target image, multiple images, which may be acquired from different subjects, are spatially aligned to the target image, and an NLM-like block matching is performed on these aligned images with the target image as the reference. This will significantly increase the number of matching structures and thus boost the denoising performance. Experiments on both synthetic and real data show that the proposed approach, collaborative non-local means (CNLM), outperforms the classic NLM and yields results with markedly improved structural details.

  16. NON-LOCALITY OF HYDRODYNAMIC AND MAGNETOHYDRODYNAMIC TURBULENCE

    SciTech Connect

    Cho, Jungyeon

    2010-12-20

    We compare non-locality of interactions between different scales in hydrodynamic (HD) turbulence and magnetohydrodynamic (MHD) turbulence in a strongly magnetized medium. We use three-dimensional incompressible direct numerical simulations to evaluate non-locality of interactions. Our results show that non-locality in MHD turbulence is much more pronounced than that in HD turbulence. Roughly speaking, non-local interactions count for more than 10% of total interactions in our MHD simulation on a grid of 512{sup 3} points. However, there is no evidence that non-local interactions are important in our HD simulation with the same numerical resolution. We briefly discuss how non-locality affects the energy spectrum.

  17. What can quantum optics say about computational complexity theory?

    PubMed

    Rahimi-Keshari, Saleh; Lund, Austin P; Ralph, Timothy C

    2015-02-13

    Considering the problem of sampling from the output photon-counting probability distribution of a linear-optical network for input Gaussian states, we obtain results that are of interest from both quantum theory and the computational complexity theory point of view. We derive a general formula for calculating the output probabilities, and by considering input thermal states, we show that the output probabilities are proportional to permanents of positive-semidefinite Hermitian matrices. It is believed that approximating permanents of complex matrices in general is a #P-hard problem. However, we show that these permanents can be approximated with an algorithm in the BPP^{NP} complexity class, as there exists an efficient classical algorithm for sampling from the output probability distribution. We further consider input squeezed-vacuum states and discuss the complexity of sampling from the probability distribution at the output.

  18. Quantum Fourier Transforms and the Complexity of Link Invariants for Quantum Doubles of Finite Groups

    NASA Astrophysics Data System (ADS)

    Krovi, Hari; Russell, Alexander

    2015-03-01

    Knot and link invariants naturally arise from any braided Hopf algebra. We consider the computational complexity of the invariants arising from an elementary family of finite-dimensional Hopf algebras: quantum doubles of finite groups [denoted , for a group G]. These induce a rich family of knot invariants and, additionally, are directly related to topological quantum computation. Regarding algorithms for these invariants, we develop quantum circuits for the quantum Fourier transform over ; in general, we show that when one can uniformly and efficiently carry out the quantum Fourier transform over the centralizers Z( g) of the elements of G, one can efficiently carry out the quantum Fourier transform over . We apply these results to the symmetric groups to yield efficient circuits for the quantum Fourier transform over . With such a Fourier transform, it is straightforward to obtain additive approximation algorithms for the related link invariant. As for hardness results, first we note that in contrast to those concerning the Jones polynomial—where the images of the braid group representations are dense in the unitary group—the images of the representations arising from are finite. This important difference appears to be directly reflected in the complexity of these invariants. While additively approximating "dense" invariants is -complete and multiplicatively approximating them is -complete, we show that certain invariants (such as invariants) are -hard to additively approximate, -hard to multiplicatively approximate, and -hard to exactly evaluate. To show this, we prove that, for groups (such as A n ) which satisfy certain properties, the probability of success of any randomized computation can be approximated to within any by the plat closure. Finally, we make partial progress on the question of simulating anyonic computation in groups uniformly as a function of the group size. In this direction, we provide efficient quantum circuits for the Clebsch

  19. Non-Markovian Complexity in the Quantum-to-Classical Transition.

    PubMed

    Xiong, Heng-Na; Lo, Ping-Yuan; Zhang, Wei-Min; Feng, Da Hsuan; Nori, Franco

    2015-08-25

    The quantum-to-classical transition is due to environment-induced decoherence, and it depicts how classical dynamics emerges from quantum systems. Previously, the quantum-to-classical transition has mainly been described with memory-less (Markovian) quantum processes. Here we study the complexity of the quantum-to-classical transition through general non-Markovian memory processes. That is, the influence of various reservoirs results in a given initial quantum state evolving into one of the following four scenarios: thermal state, thermal-like state, quantum steady state, or oscillating quantum nonstationary state. In the latter two scenarios, the system maintains partial or full quantum coherence due to the strong non-Markovian memory effect, so that in these cases, the quantum-to-classical transition never occurs. This unexpected new feature provides a new avenue for the development of future quantum technologies because the remaining quantum oscillations in steady states are decoherence-free.

  20. Non-Markovian Complexity in the Quantum-to-Classical Transition

    PubMed Central

    Xiong, Heng-Na; Lo, Ping-Yuan; Zhang, Wei-Min; Feng, Da Hsuan; Nori, Franco

    2015-01-01

    The quantum-to-classical transition is due to environment-induced decoherence, and it depicts how classical dynamics emerges from quantum systems. Previously, the quantum-to-classical transition has mainly been described with memory-less (Markovian) quantum processes. Here we study the complexity of the quantum-to-classical transition through general non-Markovian memory processes. That is, the influence of various reservoirs results in a given initial quantum state evolving into one of the following four scenarios: thermal state, thermal-like state, quantum steady state, or oscillating quantum nonstationary state. In the latter two scenarios, the system maintains partial or full quantum coherence due to the strong non-Markovian memory effect, so that in these cases, the quantum-to-classical transition never occurs. This unexpected new feature provides a new avenue for the development of future quantum technologies because the remaining quantum oscillations in steady states are decoherence-free. PMID:26303002

  1. Commuting quantum circuits and complexity of Ising partition functions

    NASA Astrophysics Data System (ADS)

    Fujii, Keisuke; Morimae, Tomoyuki

    2017-03-01

    Instantaneous quantum polynomial-time (IQP) computation is a class of quantum computation consisting only of commuting two-qubit gates and is not universal. Nevertheless, it has been shown that if there is a classical algorithm that can simulate IQP efficiently, the polynomial hierarchy collapses to the third level, which is highly implausible. However, the origin of the classical intractability is still less understood. Here we establish a relationship between IQP and computational complexity of calculating the imaginary-valued partition functions of Ising models. We apply the established relationship in two opposite directions. One direction is to find subclasses of IQP that are classically efficiently simulatable by using exact solvability of certain types of Ising models. Another direction is applying quantum computational complexity of IQP to investigate (im)possibility of efficient classical approximations of Ising partition functions with imaginary coupling constants. Specifically, we show that a multiplicative approximation of Ising partition functions is #P-hard for almost all imaginary coupling constants even on planar lattices of a bounded degree.

  2. Rooted-tree network for optimal non-local gate implementation

    NASA Astrophysics Data System (ADS)

    Vyas, Nilesh; Saha, Debashis; Panigrahi, Prasanta K.

    2016-09-01

    A general quantum network for implementing non-local control-unitary gates, between remote parties at minimal entanglement cost, is shown to be a rooted-tree structure. Starting from a five-party scenario, we demonstrate the local implementation of simultaneous class of control-unitary(Hermitian) and multiparty control-unitary gates in an arbitrary n-party network. Previously, established networks are turned out to be special cases of this general construct.

  3. Quantum Computer Games: Quantum Minesweeper

    ERIC Educational Resources Information Center

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  4. Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes

    NASA Astrophysics Data System (ADS)

    Gromova, Yulia A.; Orlova, Anna O.; Maslov, Vladimir G.; Fedorov, Anatoly V.; Baranov, Alexander V.

    2013-10-01

    Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed.

  5. Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes.

    PubMed

    Gromova, Yulia A; Orlova, Anna O; Maslov, Vladimir G; Fedorov, Anatoly V; Baranov, Alexander V

    2013-10-31

    Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed.

  6. Tests of non-local interferences in kaon physics at asymmetric {phi}-factories

    SciTech Connect

    Eberhard, P.H.

    1993-04-16

    Tests of non-local interference effects in the two-kaon system are proposed. The first kind of tests consists of measuring the amount of destructive interference between K{sub S} {yields} K{sub L} regeneration processes of two distant kaons. The second kind deals with constructive interference. These tests could be performed at an asymmetric {phi}-factory. Estimates are given of the number of events predicted by orthodox quantum mechanics and kaon regeneration theory in various suitable experimental conditions. The impact on local theories if the predictions of quantum mechanics hold is discussed.

  7. Tests of non-local interferences in kaon physics at asymmetric [phi]-factories

    SciTech Connect

    Eberhard, P.H.

    1993-04-16

    Tests of non-local interference effects in the two-kaon system are proposed. The first kind of tests consists of measuring the amount of destructive interference between K[sub S] [yields] K[sub L] regeneration processes of two distant kaons. The second kind deals with constructive interference. These tests could be performed at an asymmetric [phi]-factory. Estimates are given of the number of events predicted by orthodox quantum mechanics and kaon regeneration theory in various suitable experimental conditions. The impact on local theories if the predictions of quantum mechanics hold is discussed.

  8. Chimera states and the interplay between initial conditions and non-local coupling

    NASA Astrophysics Data System (ADS)

    Kalle, Peter; Sawicki, Jakub; Zakharova, Anna; Schöll, Eckehard

    2017-03-01

    Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We study chimera states in a network of non-locally coupled Stuart-Landau oscillators. We investigate the impact of initial conditions in combination with non-local coupling. Based on an analytical argument, we show how the coupling phase and the coupling strength are linked to the occurrence of chimera states, flipped profiles of the mean phase velocity, and the transition from a phase- to an amplitude-mediated chimera state.

  9. Scalability, Complexity and Reliability in Quantum Information Processing

    DTIC Science & Technology

    2007-03-01

    Information and Quantum Computation, Abdus Salam International Centre for Theoretical Physics, Trieste, Italy, “Quantum algorithm for the hidden shift...Future (and Past) of Quantum Lower Bounds by Polynomials,” October 17, 2002 W. van Dam, Workshop on Quantum Information and Quantum Computation, Abdus ... Salam International Centre for Theoretical Physics, Trieste, Italy, “Quantum algorithms: Fourier transforms and group theory,” October 21, 2002 K

  10. Effect of the interface resistance in non-local Hanle measurements

    SciTech Connect

    Villamor, Estitxu; Hueso, Luis E.; Casanova, Fèlix

    2015-06-14

    We use lateral spin valves with varying interface resistance to measure non-local Hanle effect in order to extract the spin-diffusion length of the non-magnetic channel. A general expression that describes spin injection and transport, taking into account the influence of the interface resistance, is used to fit our results. Whereas the fitted spin-diffusion length value is in agreement with the one obtained from standard non-local measurements in the case of a finite interface resistance, in the case of transparent contacts a clear disagreement is observed. The use of a corrected expression, recently proposed to account for the anisotropy of the spin absorption at the ferromagnetic electrodes, still yields a deviation of the fitted spin-diffusion length which increases for shorter channel distances. This deviation shows how sensitive the non-local Hanle fittings are, evidencing the complexity of obtaining spin transport information from such type of measurements.

  11. Algebraic and group structure for bipartite anisotropic Ising model on a non-local basis

    NASA Astrophysics Data System (ADS)

    Delgado, Francisco

    2015-01-01

    Entanglement is considered a basic physical resource for modern quantum applications as Quantum Information and Quantum Computation. Interactions based on specific physical systems able to generate and sustain entanglement are subject to deep research to get understanding and control on it. Atoms, ions or quantum dots are considered key pieces in quantum applications because they are elements in the development toward a scalable spin-based quantum computer through universal and basic quantum operations. Ising model is a type of interaction generating entanglement in quantum systems based on matter. In this work, a general bipartite anisotropic Ising model including an inhomogeneous magnetic field is analyzed in a non-local basis. This model summarizes several particular models presented in literature. When evolution is expressed in the Bell basis, it shows a regular block structure suggesting a SU(2) decomposition. Then, their algebraic properties are analyzed in terms of a set of physical parameters which define their group structure. In particular, finite products of pulses in this interaction are analyzed in terms of SU(4) covering. Thus, evolution denotes remarkable properties, in particular those related potentially with entanglement and control, which give a fruitful arena for further quantum developments and generalization.

  12. PRINCIPAL COMPONENTS FOR NON-LOCAL MEANS IMAGE DENOISING.

    PubMed

    Tasdizen, Tolga

    2008-01-01

    This paper presents an image denoising algorithm that uses principal component analysis (PCA) in conjunction with the non-local means image denoising. Image neighborhood vectors used in the non-local means algorithm are first projected onto a lower-dimensional subspace using PCA. Consequently, neighborhood similarity weights for denoising are computed using distances in this subspace rather than the full space. This modification to the non-local means algorithm results in improved accuracy and computational performance. We present an analysis of the proposed method's accuracy as a function of the dimensionality of the projection subspace and demonstrate that denoising accuracy peaks at a relatively low number of dimensions.

  13. Non-local gravity and comparison with observational datasets

    SciTech Connect

    Dirian, Yves; Foffa, Stefano; Kunz, Martin; Maggiore, Michele; Pettorino, Valeria E-mail: stefano.foffa@unige.ch E-mail: michele.maggiore@unige.ch

    2015-04-01

    We study the cosmological predictions of two recently proposed non-local modifications of General Relativity. Both models have the same number of parameters as ΛCDM, with a mass parameter m replacing the cosmological constant. We implement the cosmological perturbations of the non-local models into a modification of the CLASS Boltzmann code, and we make a full comparison to CMB, BAO and supernova data. We find that the non-local models fit these datasets very well, at the same level as ΛCDM. Among the vast literature on modified gravity models, this is, to our knowledge, the only example which fits data as well as ΛCDM without requiring any additional parameter. For both non-local models parameter estimation using Planck +JLA+BAO data gives a value of H{sub 0} slightly higher than in ΛCDM.

  14. [A non-local means approach for PET image denoising].

    PubMed

    Yin, Yong; Sun, Weifeng; Lu, Jie; Liu, Tonghai

    2010-04-01

    Denoising is an important issue for medical image processing. Based on the analysis of the Non-local means algorithm recently reported by Buades A, et al. in international journals we herein propose adapting it for PET image denoising. Experimental de-noising results for real clinical PET images show that Non-local means method is superior to median filtering and wiener filtering methods and it can suppress noise in PET images effectively and preserve important details of structure for diagnosis.

  15. Non-local F(R)-mimetic gravity

    NASA Astrophysics Data System (ADS)

    Myrzakulov, Ratbay; Sebastiani, Lorenzo

    2016-06-01

    In this paper, we study non-local F(R)-mimetic gravity. We implement mimetic gravity in the framework of non-local F(R)-theories of gravity. Given some specific class of models and using a potential on the mimetic field, we investigate some scenarios related to the early-time universe, namely the inflation and the cosmological bounce, which bring to Einstein's gravity with cold dark matter at the late-time.

  16. Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph

    2015-09-01

    In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension . We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the -faces of the -dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the -faces.

  17. Do Quantum Dice Remember?

    NASA Astrophysics Data System (ADS)

    Durt, Thomas

    2014-03-01

    We shall present certain experiments aimed at testing the Markovian nature of the quantum statistical distributions and comment their results, which confirmed the standard quantum interpretation. We shall also show how certain sophisticated experiments that were realized in the framework of quantum optics during the last decade in order to test fundamental effects such as quantum non-locality also lead us to eliminate certain (non-Markovian and non-local) alternatives to the standard quantum theory.

  18. Universality at Breakdown of Quantum Transport on Complex Networks.

    PubMed

    Kulvelis, Nikolaj; Dolgushev, Maxim; Mülken, Oliver

    2015-09-18

    We consider single-particle quantum transport on parametrized complex networks. Based on general arguments regarding the spectrum of the corresponding Hamiltonian, we derive bounds for a measure of the global transport efficiency defined by the time-averaged return probability. For treelike networks, we show analytically that a transition from efficient to inefficient transport occurs depending on the (average) functionality of the nodes of the network. In the infinite system size limit, this transition can be characterized by an exponent which is universal for all treelike networks. Our findings are corroborated by analytic results for specific deterministic networks, dendrimers and Vicsek fractals, and by Monte Carlo simulations of iteratively built scale-free trees.

  19. Reducing the quantum-computing overhead with complex gate distillation

    NASA Astrophysics Data System (ADS)

    Duclos-Cianci, Guillaume; Poulin, David

    2015-04-01

    In leading fault-tolerant quantum-computing schemes, accurate transformations are obtained by a two-stage process. In a first stage, a discrete universal set of fault-tolerant operations is obtained by error-correcting noisy transformations and distilling resource states. In a second stage, arbitrary transformations are synthesized to desired accuracy by combining elements of this set into a circuit. Here we present a scheme that merges these two stages into a single one, directly distilling complex transformations. We find that our scheme can reduce the total overhead to realize certain gates by up to a few orders of magnitude. In contrast to other schemes, this efficient gate synthesis does not require computationally intensive compilation algorithms and a straightforward generalization of our scheme circumvents compilation and synthesis altogether.

  20. Quantum Chemistry Meets Rotational Spectroscopy for Astrochemistry: Increasing Molecular Complexity

    NASA Astrophysics Data System (ADS)

    Puzzarini, Cristina

    2016-06-01

    For many years, scientists suspected that the interstellar medium was too hostile for organic species and that only a few simple molecules could be formed under such extreme conditions. However, the detection of approximately 180 molecules in interstellar or circumstellar environments in recent decades has changed this view dramatically. A rich chemistry has emerged, and relatively complex molecules such as C60 and C70 are formed. Recently, researchers have also detected complex organic and potentially prebiotic molecules, such as amino acids, in meteorites and in other space environments. Those discoveries have further stimulated the debate on the origin of the building blocks of life in the universe. Rotational spectroscopy plays a crucial role in the investigation of planetary atmosphere and the interstellar medium. Increasingly these astrochemical investigations are assisted by quantum-mechanical calculations of structures as well as spectroscopic and thermodynamic properties to guide and support observations, line assignments, and data analysis in these new and chemically complicated situations. However, it has proved challenging to extend accurate quantum-chemical computational approaches to larger systems because of the unfavorable scaling with the number of degrees of freedom (both electronic and nuclear). In this contribution, it is demonstrated that it is now possible to compute physicochemical properties of building blocks of biomolecules with an accuracy rivaling that of the most sophisticated experimental techniques. We analyze the spectroscopic properties of representative building blocks of DNA bases (uracil and thiouracil), of proteins (glycine and glycine dipeptide analogue), and also of PAH (phenalenyl radical and cation). V. Barone, M. Biczysko, C. Puzzarini 2015, Acc. Chem. Res., 48, 1413

  1. Quantum Dynamical Behaviour in Complex Systems - A Semiclassical Approach

    SciTech Connect

    Ananth, Nandini

    2008-01-01

    One of the biggest challenges in Chemical Dynamics is describing the behavior of complex systems accurately. Classical MD simulations have evolved to a point where calculations involving thousands of atoms are routinely carried out. Capturing coherence, tunneling and other such quantum effects for these systems, however, has proven considerably harder. Semiclassical methods such as the Initial Value Representation (SC-IVR) provide a practical way to include quantum effects while still utilizing only classical trajectory information. For smaller systems, this method has been proven to be most effective, encouraging the hope that it can be extended to deal with a large number of degrees of freedom. Several variations upon the original idea of the SCIVR have been developed to help make these larger calculations more tractable; these range from the simplest, classical limit form, the Linearized IVR (LSC-IVR) to the quantum limit form, the Exact Forward-Backward version (EFB-IVR). In this thesis a method to tune between these limits is described which allows us to choose exactly which degrees of freedom we wish to treat in a more quantum mechanical fashion and to what extent. This formulation is called the Tuning IVR (TIVR). We further describe methodology being developed to evaluate the prefactor term that appears in the IVR formalism. The regular prefactor is composed of the Monodromy matrices (jacobians of the transformation from initial to finial coordinates and momenta) which are time evolved using the Hessian. Standard MD simulations require the potential surfaces and their gradients, but very rarely is there any information on the second derivative. We would like to be able to carry out the SC-IVR calculation without this information too. With this in mind a finite difference scheme to obtain the Hessian on-the-fly is proposed. Wealso apply the IVR formalism to a few problems of current interest. A method to obtain energy eigenvalues accurately for complex

  2. Quantum Matching Theory (with new complexity-theoretic, combinatorial and topical insights on the nature of the quantum entanglement)

    SciTech Connect

    Gurvits, L.

    2002-01-01

    Classical matching theory can be defined in terms of matrices with nonnegative entries. The notion of Positive operator, central in Quantum Theory, is a natural generalization of matrices with non-negative entries. Based on this point of view, we introduce a definition of perfect Quantum (operator) matching. We show that the new notion inherits many 'classical' properties, but not all of them. This new notion goes somewhere beyound matroids. For separable bipartite quantum states this new notion coinsides with the full rank property of the intersection of two corresponding geometric matroids. In the classical situation, permanents are naturally associated with perfects matchings. We introduce an analog of permanents for positive operators, called Quantum Permanent and show how this generalization of the permanent is related to the Quantum Entanglement. Besides many other things, Quantum Permanents provide new rational inequalities necessary for the separability of bipartite quantum states. Using Quantum Permanents, we give deterministic poly-time algorithm to solve Hidden Matroids Intersection Problem and indicate some 'classical' complexity difficulties associated with the Quantum Entanglement. Finally, we prove that the weak membership problem for the convex set of separable bipartite density matrices is NP-HARD.

  3. Non-local magnetoresistance in YIG/Pt nanostructures

    SciTech Connect

    Goennenwein, Sebastian T. B. Pernpeintner, Matthias; Gross, Rudolf; Huebl, Hans; Schlitz, Richard; Ganzhorn, Kathrin; Althammer, Matthias

    2015-10-26

    We study the local and non-local magnetoresistance of thin Pt strips deposited onto yttrium iron garnet. The local magnetoresistive response, inferred from the voltage drop measured along one given Pt strip upon current-biasing it, shows the characteristic magnetization orientation dependence of the spin Hall magnetoresistance. We simultaneously also record the non-local voltage appearing along a second, electrically isolated, Pt strip, separated from the current carrying one by a gap of a few 100 nm. The corresponding non-local magnetoresistance exhibits the symmetry expected for a magnon spin accumulation-driven process, confirming the results recently put forward by Cornelissen et al. [“Long-distance transport of magnon spin information in a magnetic insulator at room temperature,” Nat. Phys. (published online 14 September 2015)]. Our magnetotransport data, taken at a series of different temperatures as a function of magnetic field orientation, rotating the externally applied field in three mutually orthogonal planes, show that the mechanisms behind the spin Hall and the non-local magnetoresistance are qualitatively different. In particular, the non-local magnetoresistance vanishes at liquid Helium temperatures, while the spin Hall magnetoresistance prevails.

  4. Determining the Complexity of the Quantum Adiabatic Algorithm using Quantum Monte Carlo Simulations

    DTIC Science & Technology

    2012-12-18

    efficiently a quantum computer could solve optimization problems using the quantum adiabatic algorithm (QAA). Comparisons were made with a classical...Park, NC 27709-2211 15. SUBJECT TERMS Quantum Adiabatic Algorithm , Optimization, Monte Carlo, quantum computer, satisfiability problems, spin glass... quantum adiabatic algorithm (QAA). Comparisons were made with a classical heuristic algorithm , WalkSAT. A preliminary study was also made to see if the

  5. Emulation of complex open quantum systems using superconducting qubits

    NASA Astrophysics Data System (ADS)

    Mostame, Sarah; Huh, Joonsuk; Kreisbeck, Christoph; Kerman, Andrew J.; Fujita, Takatoshi; Eisfeld, Alexander; Aspuru-Guzik, Alán

    2017-02-01

    With quantum computers being out of reach for now, quantum simulators are alternative devices for efficient and accurate simulation of problems that are challenging to tackle using conventional computers. Quantum simulators are classified into analog and digital, with the possibility of constructing "hybrid" simulators by combining both techniques. Here we focus on analog quantum simulators of open quantum systems and address the limit that they can beat classical computers. In particular, as an example, we discuss simulation of the chlorosome light-harvesting antenna from green sulfur bacteria with over 250 phonon modes coupled to each electronic state. Furthermore, we propose physical setups that can be used to reproduce the quantum dynamics of a standard and multiple-mode Holstein model. The proposed scheme is based on currently available technology of superconducting circuits consist of flux qubits and quantum oscillators.

  6. Dynamics of Crowd Behaviors: From Complex Plane to Quantum Random Fields

    NASA Astrophysics Data System (ADS)

    Ivancevic, Vladimir G.; Reid, Darryn J.

    2015-11-01

    The following sections are included: * Complex Plane Dynamics of Crowds and Groups * Introduction * Complex-Valued Dynamics of Crowd and Group Behaviors * Kähler Geometry of Crowd and Group Dynamics * Computer Simulations of Crowds and Croups Dynamics * Braids of Agents' Behaviors in the Complex Plane * Hilbert-Space Control of Crowds and Groups Dynamics * Quantum Random Fields: A Unique Framework for Simulation, Optimization, Control and Learning * Introduction * Adaptive Quantum Oscillator * Optimization and Learning on Banach and Hilbert Spaces * Appendix * Complex-Valued Image Processing * Linear Integral Equations * Riemann-Liouville Fractional Calculus * Rigorous Geometric Quantization * Supervised Machine-Learning Methods * First-Order Logic and Quantum Random Fields

  7. Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes

    NASA Astrophysics Data System (ADS)

    Mostame, Sarah; Rebentrost, Patrick; Eisfeld, Alexander; Kerman, Andrew J.; Tsomokos, Dimitris I.; Aspuru-Guzik, Alan

    2012-02-01

    In the initial stage of photosynthesis, light-harvested energy is transferred with remarkably high efficiency to a reaction center, with the vibrational environment assisting the transport mechanism. It is of great interest to mimic this process with present-day technologies. Here we propose an analog quantum simulator of open system dynamics, where noise engineering of the environment has a central role. In particular, we propose the use of superconducting qubits for the simulation of exciton transport in the Fenna-Matthew-Olson protein, a prototypical photosynthetic complex. Our method allows for a single-molecule implementation and the investigation of energy transfer pathways as well as non-Markovian and spatiotemporal noise-correlation effects.

  8. Jammed Clusters and Non-locality in Dense Granular Flows

    NASA Astrophysics Data System (ADS)

    Kharel, Prashidha; Rognon, Pierre

    We investigate the micro-mechanisms underpinning dense granular flow behaviour from a series of DEM simulations of pure shear flows of dry grains. We observe the development of transient clusters of jammed particles within the flow. Typical size of such clusters is found to scale with the inertial number with a power law that is similar to the scaling of shear-rate profile relaxation lengths observed previously. Based on the simple argument that transient clusters of size l exist in the dense flow regime, the formulation of steady state condition for non-homogeneous shear flow results in a general non-local relation, which is similar in form to the non-local relation conjectured for soft glassy flows. These findings suggest the formation of jammed clusters to be the key micro-mechanism underpinning non-local behaviour in dense granular flows. Particles and Grains Laboratory, School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia.

  9. Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes

    PubMed Central

    2013-01-01

    Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed. PMID:24172215

  10. To the non-local theory of cold nuclear fusion.

    PubMed

    Alexeev, Boris V

    2014-10-01

    In this paper, we revisit the cold fusion (CF) phenomenon using the generalized Bolzmann kinetics theory which can represent the non-local physics of this CF phenomenon. This approach can identify the conditions when the CF can take place as the soliton creation under the influence of the intensive sound waves. The vast mathematical modelling leads to affirmation that all parts of soliton move with the same velocity and with the small internal change of the pressure. The zone of the high density is shaped on the soliton's front. It means that the regime of the 'acoustic CF' could be realized from the position of the non-local hydrodynamics.

  11. Cellular uptake and photosensitizing properties of quantum dot-chlorin e6 complex: in vitro study.

    PubMed

    Steponkiene, Simona; Valanciunaite, Jurga; Skripka, Artiom; Rotomskis, Ricardas

    2014-04-01

    Recently it has been suggested that quantum dots could be used in the photodynamic therapy of cancer as resonant energy donors for conventional porphyrin type photosensitizers. Here we summarize our results obtained by studying a non-covalent complex formed between quantum dots and a second generation photosensitizer, chlorin e6, in aqueous medium and in live pancreatic MiaPaCa2 cancer cells. Spectral changes in the absorption and photoluminescence of quantum dots and chlorin e6, as well as changes in the photoluminescence lifetime of quantum dots, revealed the formation of quantum dot-chlorin e6 complex. Fluorescence confocal microscopy with spectral imaging unit showed uptake of quantum dot-chlorin e6 complex in live cancer cells: the complex localized in plasma membrane and endocytic vesicles. Fluorescence lifetime imaging revealed Forster resonance energy transfer from quantum dots to chlorin e6 within live cells. Finally, a light-induced damage to cancer cells by the quantum dot-chlorin e6 complex was achieved.

  12. Two flavor superconductivity in non-local models

    SciTech Connect

    Duhau, R.; Grunfeld, A.G.; Scoccola, N.N.

    2004-12-02

    In the present work we study a relativistic quark model at finite temperature and density with non-local quark-antiquark and quark-quark interactions with SU(2) flavour and SU(3) color symmetries. After proper bosonization, we analyze the structure of the corresponding phase diagram and discuss the competition between the chiral and 2SC phases.

  13. Non-local rheology for dense granular flows in avalanches

    NASA Astrophysics Data System (ADS)

    Izzet, Adrien; Clement, Eric; Andreotti, Bruno

    A local constitutive relation was proposed to describe dense granular flows (GDR MiDi, EPJE 2004). It provides a rather good prediction of the flowing regime but does not foresee the existence of a ``creep regime'' as observed by Komatsu et al. (PRL 2001). In the context of a 2D shear cell, a relaxation length for the velocity profile was measured (Bouzid et al., PRL 2013) which confirmed the existence of a flow below the standard Coulomb yield threshold. A correction for the local rheology was proposed. To test further this non-local constitutive relation, we built an inclined narrow channel within which we monitor the flow from the side. We managed to observe the ``creep regime'' over five orders of magnitude in velocity and fit the velocity profiles in the depth with an asymptotic solution of the non-local equation. However, the boundary condition at the free surface needs to be selected in order to calibrate the non-local rheology over the whole range of stresses in the system. In this perspective, we complement the experimental results with 2D simulations of hard and frictional discs on an inclined plane in which we introduce a surface friction force proportional to the effective pressure in the granular. We analyze these results in the light of the non-local rheology.

  14. Non-local correlation interference with pseudo-thermal light

    NASA Astrophysics Data System (ADS)

    Dou, Ling-Yu; Gao, Lu; Song, Xin-Bing

    2016-12-01

    We report an experimental demonstration of non-local correlation interference with a pseudo-thermal light source. The experimental results show denser and sparser interference effects compared to classical interference. Our experimental result suggests that denser lithography and imaging can also be achieved with correlation method.

  15. Quantum computational complexity of the N-representability problem: QMA complete.

    PubMed

    Liu, Yi-Kai; Christandl, Matthias; Verstraete, F

    2007-03-16

    We study the computational complexity of the N-representability problem in quantum chemistry. We show that this problem is quantum Merlin-Arthur complete, which is the quantum generalization of nondeterministic polynomial time complete. Our proof uses a simple mapping from spin systems to fermionic systems, as well as a convex optimization technique that reduces the problem of finding ground states to N representability.

  16. Ultracold Molecules in Crystals of Light: A Highly Tunable System for Exploring Novel Materials, Quantum Dynamics, and Quantum Complexity

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln; Maeda, Kenji; Wall, Michael L.

    2015-03-01

    Ultracold molecules trapped in optical lattices present a new regime of physical chemistry and a new state of matter: complex dipolar matter. Such systems open up the prospect of tunable quantum complexity. We present models for the quantum many-body statics and dynamics of present experiments on polar bi-alkali dimer molecules. We are developing Hamiltonians and simulations for upcoming experiments on dimers beyond the alkali metals, including biologically and chemically important naturally occurring free radicals like the hydroxyl free radical (OH), as well as symmetric top polyatomic molecules like methyl fluoride (CH3F). These systems offer surprising opportunities in modeling and design of new materials. For example, symmetric top polyatomics can be used to study quantum molecular magnets and quantum liquid crystals. We use matrix-product-state (MPS) algorithms, supplemented by exact diagonalization, variational, perturbative, and other approaches. MPS algorithms not only produce experimentally measurable quantum phase diagrams but also explore the dynamical interplay between internal and external degrees of freedom inherent in complex dipolar matter. We maintain open source code (openTEBD and openMPS) available freely and used widely. Funded by NSF and AFOSR.

  17. Quantum Tomography via Compressed Sensing: Error Bounds, Sample Complexity and Efficient Estimators

    DTIC Science & Technology

    2012-09-27

    REPORT Quantum tomography via compressed sensing : error bounds, sample complexity and efficient estimators 14. ABSTRACT 16. SECURITY CLASSIFICATION OF...Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS quantum tomography, compressed sensing Steven T Flammia, David Gross, Yi-Kai Liu... compressed sensing : error bounds, sample complexity and efficient estimators Report Title ABSTRACT Intuitively, if a density operator has small rank, then

  18. Dynamical symmetries in Kondo tunneling through complex quantum dots.

    PubMed

    Kuzmenko, T; Kikoin, K; Avishai, Y

    2002-10-07

    Kondo tunneling reveals hidden SO(n) dynamical symmetries of evenly occupied quantum dots. As is exemplified for an experimentally realizable triple quantum dot in parallel geometry, the possible values n=3,4,5,7 can be easily tuned by gate voltages. Following construction of the corresponding o(n) algebras, scaling equations are derived and Kondo temperatures are calculated. The symmetry group for a magnetic field induced anisotropic Kondo tunneling is SU(2) or SO(4).

  19. Cosmological perturbations in non-local higher-derivative gravity

    SciTech Connect

    Craps, Ben; Jonckheere, Tim De; Koshelev, Alexey S. E-mail: Tim.De.Jonckheere@vub.ac.be

    2014-11-01

    We study cosmological perturbations in a non-local higher-derivative model of gravity introduced by Biswas, Mazumdar and Siegel. We extend previous work, which had focused on classical scalar perturbations around a cosine hyperbolic bounce solution, in three ways. First, we point out the existence of a Starobinsky solution in this model, which is more attractive from a phenomenological point of view (even though it has no bounce). Second, we study classical vector and tensor pertuxsxrbations. Third, we show how to quantize scalar and tensor perturbations in a de Sitter phase (for choices of parameters such that the model is ghost-free). Our results show that the model is well-behaved at this level, and are very similar to corresponding results in local f(R) models. In particular, for the Starobinsky solution of non-local higher-derivative gravity, we find the same tensor-to-scalar ratio as for the conventional Starobinsky model.

  20. MRI noise estimation and denoising using non-local PCA.

    PubMed

    Manjón, José V; Coupé, Pierrick; Buades, Antonio

    2015-05-01

    This paper proposes a novel method for MRI denoising that exploits both the sparseness and self-similarity properties of the MR images. The proposed method is a two-stage approach that first filters the noisy image using a non local PCA thresholding strategy by automatically estimating the local noise level present in the image and second uses this filtered image as a guide image within a rotationally invariant non-local means filter. The proposed method internally estimates the amount of local noise presents in the images that enables applying it automatically to images with spatially varying noise levels and also corrects the Rician noise induced bias locally. The proposed approach has been compared with related state-of-the-art methods showing competitive results in all the studied cases.

  1. To the non-local theory of cold nuclear fusion

    PubMed Central

    Alexeev, Boris V.

    2014-01-01

    In this paper, we revisit the cold fusion (CF) phenomenon using the generalized Bolzmann kinetics theory which can represent the non-local physics of this CF phenomenon. This approach can identify the conditions when the CF can take place as the soliton creation under the influence of the intensive sound waves. The vast mathematical modelling leads to affirmation that all parts of soliton move with the same velocity and with the small internal change of the pressure. The zone of the high density is shaped on the soliton's front. It means that the regime of the ‘acoustic CF’ could be realized from the position of the non-local hydrodynamics. PMID:26064528

  2. Non-local crime density estimation incorporating housing information

    PubMed Central

    Woodworth, J. T.; Mohler, G. O.; Bertozzi, A. L.; Brantingham, P. J.

    2014-01-01

    Given a discrete sample of event locations, we wish to produce a probability density that models the relative probability of events occurring in a spatial domain. Standard density estimation techniques do not incorporate priors informed by spatial data. Such methods can result in assigning significant positive probability to locations where events cannot realistically occur. In particular, when modelling residential burglaries, standard density estimation can predict residential burglaries occurring where there are no residences. Incorporating the spatial data can inform the valid region for the density. When modelling very few events, additional priors can help to correctly fill in the gaps. Learning and enforcing correlation between spatial data and event data can yield better estimates from fewer events. We propose a non-local version of maximum penalized likelihood estimation based on the H1 Sobolev seminorm regularizer that computes non-local weights from spatial data to obtain more spatially accurate density estimates. We evaluate this method in application to a residential burglary dataset from San Fernando Valley with the non-local weights informed by housing data or a satellite image. PMID:25288817

  3. Critical thresholds in flocking hydrodynamics with non-local alignment.

    PubMed

    Tadmor, Eitan; Tan, Changhui

    2014-11-13

    We study the large-time behaviour of Eulerian systems augmented with non-local alignment. Such systems arise as hydrodynamic descriptions of agent-based models for self-organized dynamics, e.g. Cucker & Smale (2007 IEEE Trans. Autom. Control 52, 852-862. (doi:10.1109/TAC.2007.895842)) and Motsch & Tadmor (2011 J. Stat. Phys. 144, 923-947. (doi:10.1007/s10955-011-0285-9)) models. We prove that, in analogy with the agent-based models, the presence of non-local alignment enforces strong solutions to self-organize into a macroscopic flock. This then raises the question of existence of such strong solutions. We address this question in one- and two-dimensional set-ups, proving global regularity for subcritical initial data. Indeed, we show that there exist critical thresholds in the phase space of the initial configuration which dictate the global regularity versus a finite-time blow-up. In particular, we explore the regularity of non-local alignment in the presence of vacuum.

  4. Positive cosmological constant, non-local gravity and horizon entropy

    NASA Astrophysics Data System (ADS)

    Solodukhin, Sergey N.

    2012-08-01

    We discuss a class of (local and non-local) theories of gravity that share same properties: (i) they admit the Einstein spacetime with arbitrary cosmological constant as a solution; (ii) the on-shell action of such a theory vanishes and (iii) any (cosmological or black hole) horizon in the Einstein spacetime with a positive cosmological constant does not have a non-trivial entropy. The main focus is made on a recently proposed non-local model. This model has two phases: with a positive cosmological constant Λ>0 and with zero Λ. The effective gravitational coupling differs essentially in these two phases. Generalizing the previous result of Barvinsky we show that the non-local theory in question is free of ghosts on the background of any Einstein spacetime and that it propagates a standard spin-2 particle. Contrary to the phase with a positive Λ, where the entropy vanishes for any type of horizon, in an Einstein spacetime with zero cosmological constant the horizons have the ordinary entropy proportional to the area. We conclude that, somewhat surprisingly, the presence of any, even extremely tiny, positive cosmological constant should be important for the proper resolution of the entropy problem and, possibly, the information puzzle.

  5. Non-local crime density estimation incorporating housing information.

    PubMed

    Woodworth, J T; Mohler, G O; Bertozzi, A L; Brantingham, P J

    2014-11-13

    Given a discrete sample of event locations, we wish to produce a probability density that models the relative probability of events occurring in a spatial domain. Standard density estimation techniques do not incorporate priors informed by spatial data. Such methods can result in assigning significant positive probability to locations where events cannot realistically occur. In particular, when modelling residential burglaries, standard density estimation can predict residential burglaries occurring where there are no residences. Incorporating the spatial data can inform the valid region for the density. When modelling very few events, additional priors can help to correctly fill in the gaps. Learning and enforcing correlation between spatial data and event data can yield better estimates from fewer events. We propose a non-local version of maximum penalized likelihood estimation based on the H(1) Sobolev seminorm regularizer that computes non-local weights from spatial data to obtain more spatially accurate density estimates. We evaluate this method in application to a residential burglary dataset from San Fernando Valley with the non-local weights informed by housing data or a satellite image.

  6. Complex quantum transport in a modulation doped strained Ge quantum well heterostructure with a high mobility 2D hole gas

    NASA Astrophysics Data System (ADS)

    Morrison, C.; Casteleiro, C.; Leadley, D. R.; Myronov, M.

    2016-09-01

    The complex quantum transport of a strained Ge quantum well (QW) modulation doped heterostructure with two types of mobile carriers has been observed. The two dimensional hole gas (2DHG) in the Ge QW exhibits an exceptionally high mobility of 780 000 cm2/Vs at temperatures below 10 K. Through analysis of Shubnikov de-Haas oscillations in the magnetoresistance of this 2DHG below 2 K, the hole effective mass is found to be 0.065 m0. Anomalous conductance peaks are observed at higher fields which deviate from standard Shubnikov de-Haas and quantum Hall effect behaviour due to conduction via multiple carrier types. Despite this complex behaviour, analysis using a transport model with two conductive channels explains this behaviour and allows key physical parameters such as the carrier effective mass, transport, and quantum lifetimes and conductivity of the electrically active layers to be extracted. This finding is important for electronic device applications, since inclusion of highly doped interlayers which are electrically active, for enhancement of, for example, room temperature carrier mobility, does not prevent analysis of quantum transport in a QW.

  7. Electrostatic streaming instability modes in complex viscoelastic quantum plasmas

    NASA Astrophysics Data System (ADS)

    Karmakar, P. K.; Goutam, H. P.

    2016-11-01

    A generalized quantum hydrodynamic model is procedurally developed to investigate the electrostatic streaming instability modes in viscoelastic quantum electron-ion-dust plasma. Compositionally, inertialess electrons are anticipated to be degenerate quantum particles owing to their large de Broglie wavelengths. In contrast, inertial ions and dust particulates are treated in the same classical framework of linear viscoelastic fluids (non-Newtonian). It considers a dimensionality-dependent Bohmian quantum correction prefactor, γ = [(D - 2)/3D], in electron quantum dynamics, with D symbolizing the problem dimensionality. Applying a regular Fourier-formulaic plane-wave analysis around the quasi-neutral hydrodynamic equilibrium, two distinct instabilities are explored to exist. They stem in ion-streaming (relative to electrons and dust) and dust-streaming (relative to electrons and ions). Their stability is numerically illustrated in judicious parametric windows in both the hydrodynamic and kinetic regimes. The non-trivial influential roles by the relative streams, viscoelasticities, and correction prefactor are analyzed. It is seen that γ acts as a stabilizer for the ion-stream case only. The findings alongside new entailments, as special cases of realistic interest, corroborate well with the earlier predictions in plasma situations. Applicability of the analysis relevant in cosmic and astronomical environments of compact dwarf stars is concisely indicated.

  8. Quantum mechanics can reduce the complexity of classical models.

    PubMed

    Gu, Mile; Wiesner, Karoline; Rieper, Elisabeth; Vedral, Vlatko

    2012-03-27

    Mathematical models are an essential component of quantitative science. They generate predictions about the future, based on information available in the present. In the spirit of simpler is better; should two models make identical predictions, the one that requires less input is preferred. Yet, for almost all stochastic processes, even the provably optimal classical models waste information. The amount of input information they demand exceeds the amount of predictive information they output. Here we show how to systematically construct quantum models that break this classical bound, and that the system of minimal entropy that simulates such processes must necessarily feature quantum dynamics. This indicates that many observed phenomena could be significantly simpler than classically possible should quantum effects be involved.

  9. Optimal control-based efficient synthesis of building blocks of quantum algorithms: A perspective from network complexity towards time complexity

    SciTech Connect

    Schulte-Herbrueggen, T.; Spoerl, A.; Glaser, S.J.; Khaneja, N.

    2005-10-15

    In this paper, we demonstrate how optimal control methods can be used to speed up the implementation of modules of quantum algorithms or quantum simulations in networks of coupled qubits. The gain is most prominent in realistic cases, where the qubits are not all mutually coupled. Thus the shortest times obtained depend on the coupling topology as well as on the characteristic ratio of the time scales for local controls vs nonlocal (i.e., coupling) evolutions in the specific experimental setting. Relating these minimal times to the number of qubits gives the tightest known upper bounds to the actual time complexity of the quantum modules. As will be shown, time complexity is a more realistic measure of the experimental cost than the usual gate complexity. In the limit of fast local controls (as, e.g., in NMR), time-optimized realizations are shown for the quantum Fourier transform (QFT) and the multiply controlled NOT gate (C{sup n-1}NOT) in various coupling topologies of n qubits. The speed-ups are substantial: in a chain of six qubits the quantum Fourier transform so far obtained by optimal control is more than eight times faster than the standard decomposition into controlled phase, Hadamard and SWAP gates, while the C{sup n-1}NOT gate for a completely coupled network of six qubits is nearly seven times faster.

  10. Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free

    PubMed Central

    Bianconi, Ginestra; Rahmede, Christoph

    2015-01-01

    In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension . We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the -faces of the -dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the -faces. PMID:26356079

  11. Complex Quantum Network Manifolds in Dimension d > 2 are Scale-Free.

    PubMed

    Bianconi, Ginestra; Rahmede, Christoph

    2015-09-10

    In quantum gravity, several approaches have been proposed until now for the quantum description of discrete geometries. These theoretical frameworks include loop quantum gravity, causal dynamical triangulations, causal sets, quantum graphity, and energetic spin networks. Most of these approaches describe discrete spaces as homogeneous network manifolds. Here we define Complex Quantum Network Manifolds (CQNM) describing the evolution of quantum network states, and constructed from growing simplicial complexes of dimension d. We show that in d = 2 CQNM are homogeneous networks while for d > 2 they are scale-free i.e. they are characterized by large inhomogeneities of degrees like most complex networks. From the self-organized evolution of CQNM quantum statistics emerge spontaneously. Here we define the generalized degrees associated with the δ-faces of the d-dimensional CQNMs, and we show that the statistics of these generalized degrees can either follow Fermi-Dirac, Boltzmann or Bose-Einstein distributions depending on the dimension of the δ-faces.

  12. Complex quantum Hamilton-Jacobi equation with Bohmian trajectories: application to the photodissociation dynamics of NOCl.

    PubMed

    Chou, Chia-Chun

    2014-03-14

    The complex quantum Hamilton-Jacobi equation-Bohmian trajectories (CQHJE-BT) method is introduced as a synthetic trajectory method for integrating the complex quantum Hamilton-Jacobi equation for the complex action function by propagating an ensemble of real-valued correlated Bohmian trajectories. Substituting the wave function expressed in exponential form in terms of the complex action into the time-dependent Schrödinger equation yields the complex quantum Hamilton-Jacobi equation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation describing the rate of change in the complex action transported along Bohmian trajectories is simultaneously integrated with the guidance equation for Bohmian trajectories, and the time-dependent wave function is readily synthesized. The spatial derivatives of the complex action required for the integration scheme are obtained by solving one moving least squares matrix equation. In addition, the method is applied to the photodissociation of NOCl. The photodissociation dynamics of NOCl can be accurately described by propagating a small ensemble of trajectories. This study demonstrates that the CQHJE-BT method combines the considerable advantages of both the real and the complex quantum trajectory methods previously developed for wave packet dynamics.

  13. Complex quantum Hamilton-Jacobi equation with Bohmian trajectories: Application to the photodissociation dynamics of NOCl

    SciTech Connect

    Chou, Chia-Chun

    2014-03-14

    The complex quantum Hamilton-Jacobi equation-Bohmian trajectories (CQHJE-BT) method is introduced as a synthetic trajectory method for integrating the complex quantum Hamilton-Jacobi equation for the complex action function by propagating an ensemble of real-valued correlated Bohmian trajectories. Substituting the wave function expressed in exponential form in terms of the complex action into the time-dependent Schrödinger equation yields the complex quantum Hamilton-Jacobi equation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation describing the rate of change in the complex action transported along Bohmian trajectories is simultaneously integrated with the guidance equation for Bohmian trajectories, and the time-dependent wave function is readily synthesized. The spatial derivatives of the complex action required for the integration scheme are obtained by solving one moving least squares matrix equation. In addition, the method is applied to the photodissociation of NOCl. The photodissociation dynamics of NOCl can be accurately described by propagating a small ensemble of trajectories. This study demonstrates that the CQHJE-BT method combines the considerable advantages of both the real and the complex quantum trajectory methods previously developed for wave packet dynamics.

  14. Quantum coherent energy transfer over varying pathways in single light-harvesting complexes.

    PubMed

    Hildner, Richard; Brinks, Daan; Nieder, Jana B; Cogdell, Richard J; van Hulst, Niek F

    2013-06-21

    The initial steps of photosynthesis comprise the absorption of sunlight by pigment-protein antenna complexes followed by rapid and highly efficient funneling of excitation energy to a reaction center. In these transport processes, signatures of unexpectedly long-lived coherences have emerged in two-dimensional ensemble spectra of various light-harvesting complexes. Here, we demonstrate ultrafast quantum coherent energy transfer within individual antenna complexes of a purple bacterium under physiological conditions. We find that quantum coherences between electronically coupled energy eigenstates persist at least 400 femtoseconds and that distinct energy-transfer pathways that change with time can be identified in each complex. Our data suggest that long-lived quantum coherence renders energy transfer in photosynthetic systems robust in the presence of disorder, which is a prerequisite for efficient light harvesting.

  15. Integro-differential equation of non-local wave interaction

    SciTech Connect

    Engibaryan, N B; Khachatryan, Aghavard Kh

    2007-06-30

    The integro-differential equation d{sup 2}f/dx{sup 2} + Af = {integral}{sub 0}{sup {infinity}}K(x-t)f(t)dt + g(x) with kernel K(x)={lambda}{integral}{sub a}{sup {infinity}}e{sup -|x|p}G(p)dp, a{>=}0, is considered, in which A>0, {lambda} element of 9-{infinity},{infinity}), G(p){>=}0, 2{integral}{sub a}{sup {infinity}}1/p g(p)dp=1. These equations arise, in particular, in the theory of non-local wave interaction. A factorization method of their analysis and solution is developed. Bibliography: 9 titles.

  16. Fairy circles and their non-local stochastic instability

    NASA Astrophysics Data System (ADS)

    Fuentes, Miguel Angel; Cáceres, Manuel O.

    2017-02-01

    We study analytically a non local stochastic partial differential equation describing a fundamental mechanism for patterns formation, as the one responsible for the so called fairy circles appearing in two different bio-physical scenarios; one on the African continent and another in Australia. Using a stochastic multiscale perturbation expansion, and a minimum coupling approximation we are able to describe the life-times associated to the stochastic evolution from an unstable uniform state to a patterned one. In this way we discuss how two different biological mechanisms can be collapsed in one analytical framework.

  17. Functional Lagrange formalism for time-non-local Lagrangians

    NASA Astrophysics Data System (ADS)

    Ferialdi, L.; Bassi, A.

    2012-05-01

    We develop a time-non-local (TNL) formalism based on variational calculus, which allows for the analysis of TNL Lagrangians. We derive the generalized Euler-Lagrange equations starting from the Hamilton's principle and, by defining a generalized momentum, we introduce the corresponding Hamiltonian formalism. We apply the formalism to second order TNL Lagrangians and we show that it reproduces standard results in the time-local limit. An example will show how the formalism works, and will provide an interesting insight on the non-standard features of TNL equations.

  18. Temperature chaos is a non-local effect

    NASA Astrophysics Data System (ADS)

    Fernandez, L. A.; Marinari, E.; Martin-Mayor, V.; Parisi, G.; Yllanes, D.

    2016-12-01

    Temperature chaos plays a role in important effects, for example memory and rejuvenation, in spin glasses, colloids, polymers. We numerically investigate temperature chaos in spin glasses, exploiting its recent characterization as a rare-event driven phenomenon. The peculiarities of the transformation from periodic to anti-periodic boundary conditions in spin glasses allow us to conclude that temperature chaos is non-local: no bounded region of the system causes it. We precisely show the statistical relationship between temperature chaos and the free-energy changes upon varying boundary conditions.

  19. Occurrence of exact R 2 inflation in non-local UV-complete gravity

    NASA Astrophysics Data System (ADS)

    Koshelev, Alexey S.; Modesto, Leonardo; Rachwal, Leslaw; Starobinsky, Alexei A.

    2016-11-01

    The R + R 2, shortly named " R 2" ("Starobinsky") inflationary model, represents a fully consistent example of a one-parameter inflationary scenario. This model has a "graceful exit" from inflation and provides a mechanism for subsequent creation and final thermalization of the standard matter. Moreover, it produces a very good fit of the observed spectrum of primordial perturbations. In the present paper we show explicitly that the R 2 inflationary spacetime is an exact solution of a range of weakly non-local (quasi-polynomial) gravitational theories, which provide an ultraviolet completion of the R 2 theory. These theories are ghost-free, super-renormalizable or finite at quantum level, and perturbatively unitary. Their spectrum consists of the graviton and the scalaron that is responsible for driving the inflation. Notably, any further extension of the spectrum leads to propagating ghost degrees of freedom. We are aimed at presenting a detailed construction of such theories in the so called Weyl basis. Further, we give a special account to the cosmological implications of this theory by considering perturbations during inflation. The highlight of the non-local model is the prediction of a modified, in comparison to a local R 2 model, value for the ratio of tensor and scalar power spectra r, depending on the parameters of the theory. The relevant parameters are under control to be successfully confronted with existing observational data. Furthermore, the modified r can surely meet future observational constraints.

  20. From First Principles: The Application of Quantum Mechanics to Complex Molecules and Solvated Systems

    SciTech Connect

    Freitag, Mark A.

    2001-12-31

    The major title of this dissertation, 'From first principles,' is a phase often heard in the study of thermodynamics and quantum mechanics. These words embody a powerful idea in the physical sciences; namely, that it is possible to distill the complexities of nature into a set of simple, well defined mathematical laws from which specific relations can then be derived . In thermodynamics, these fundamental laws are immediately familiar to the physical scientist by their numerical order: the First, Second and Third Laws. However, the subject of the present volume is quantum mechanics-specifically, non-relativistic quantum mechanics, which is appropriate for most systems of chemical interest.

  1. A non-local computational boundary condition for duct acoustics

    NASA Technical Reports Server (NTRS)

    Zorumski, William E.; Watson, Willie R.; Hodge, Steve L.

    1994-01-01

    A non-local boundary condition is formulated for acoustic waves in ducts without flow. The ducts are two dimensional with constant area, but with variable impedance wall lining. Extension of the formulation to three dimensional and variable area ducts is straightforward in principle, but requires significantly more computation. The boundary condition simulates a nonreflecting wave field in an infinite duct. It is implemented by a constant matrix operator which is applied at the boundary of the computational domain. An efficient computational solution scheme is developed which allows calculations for high frequencies and long duct lengths. This computational solution utilizes the boundary condition to limit the computational space while preserving the radiation boundary condition. The boundary condition is tested for several sources. It is demonstrated that the boundary condition can be applied close to the sound sources, rendering the computational domain small. Computational solutions with the new non-local boundary condition are shown to be consistent with the known solutions for nonreflecting wavefields in an infinite uniform duct.

  2. Quantum effects in energy and charge transfer in an artificial photosynthetic complex

    NASA Astrophysics Data System (ADS)

    Ghosh, Pulak Kumar; Smirnov, Anatoly Yu.; Nori, Franco

    2011-06-01

    We investigate the quantum dynamics of energy and charge transfer in a wheel-shaped artificial photosynthetic antenna-reaction center complex. This complex consists of six light-harvesting chromophores and an electron-acceptor fullerene. To describe quantum effects on a femtosecond time scale, we derive the set of exact non-Markovian equations for the Heisenberg operators of this photosynthetic complex in contact with a Gaussian heat bath. With these equations we can analyze the regime of strong system-bath interactions, where reorganization energies are of the order of the intersite exciton couplings. We show that the energy of the initially excited antenna chromophores is efficiently funneled to the porphyrin-fullerene reaction center, where a charge-separated state is set up in a few picoseconds, with a quantum yield of the order of 95%. In the single-exciton regime, with one antenna chromophore being initially excited, we observe quantum beatings of energy between two resonant antenna chromophores with a decoherence time of ˜100 fs. We also analyze the double-exciton regime, when two porphyrin molecules involved in the reaction center are initially excited. In this regime we obtain pronounced quantum oscillations of the charge on the fullerene molecule with a decoherence time of about 20 fs (at liquid nitrogen temperatures). These results show a way to directly detect quantum effects in artificial photosynthetic systems.

  3. Sequential generation of polynomial invariants and N-body non-local correlations

    NASA Astrophysics Data System (ADS)

    Sharma, S. Shelly; Sharma, N. K.

    2016-12-01

    We report an inductive process that allows for sequential construction of local unitary invariant polynomials of state coefficients for multipartite quantum states. The starting point can be a physically meaningful invariant of a smaller part of the system. The process is applied to construct a chain of invariants that quantify non-local N-way correlations in an N-qubit pure state. It also yields the invariants to quantify the sum of N-way and ( N-1)-way correlations. Analytic expressions for four-way and three-way correlation quantifiers for four-qubit states, as well as, five-way and four-way correlation quantifiers for five-qubit pure states are given.

  4. Non-local features of a hydrodynamic pilot-wave system

    NASA Astrophysics Data System (ADS)

    Nachbin, Andre; Couchman, Miles; Bush, John

    2016-11-01

    A droplet walking on the surface of a vibrating fluid bath constitutes a pilot-wave system of the form envisaged for quantum dynamics by Louis de Broglie: a particle moves in resonance with its guiding wave field. We here present an examination of pilot-wave hydrodynamics in a confined domain. Specifically, we present a one-dimensional water wave model that describes droplets walking in single and multiple cavities. The cavities are separated by a submerged barrier, and so allow for the study of tunneling. They also highlight the non-local dynamical features arising due to the spatially-extended wave field. Results from computational simulations are complemented by laboratory experiments.

  5. New insights on emergence from the perspective of weak values and dynamical non-locality

    NASA Astrophysics Data System (ADS)

    Tollaksen, Jeff

    2014-04-01

    In this article, we will examine new fundamental aspects of "emergence" and "information" using novel approaches to quantum mechanics which originated from the group around Aharonov. The two-state vector formalism provides a complete description of pre- and post-selected quantum systems and has uncovered a host of new quantum phenomena which were previously hidden. The most important feature is that any weak coupling to a pre- and post-selected system is effectively a coupling to a "weak value" which is given by a simple expression depending on the two-state vector. In particular, weak values, are the outcomes of so called "weak measurements" which have recently become a very powerful tool for ultra-sensitive measurements. Using weak values, we will show how to separate a particle from its properties, not unlike the Cheshire cat story: "Well! I've often seen a cat without a grin," thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!" Next, we address the question whether the physics on different scales "emerges" from quantum mechanics or whether the laws of physics at those scales are fundamental. We show that the classical limit of quantum mechanics is a far more complicated issue; it is in fact dramatically more involved and it requires a complete revision of all our intuitions. The revised intuitions can then serve as a guide to finding novel quantum effects. Next we show that novel experimental aspects of contextuality can be demonstrated with weak measurements and these suggest new restrictions on hidden variable approaches. Next we emphasize that the most important implication of the Aharonov-Bohm effect is the existence of non-local interactions which do not violate causality. Finally, we review some generalizations of quantum mechanics and their implications for "emergence" and "information." First, we review an alternative approach to quantum evolution in which each moment of time is viewed as a new "universe

  6. Vibronic enhancement of excitation energy transport: Interplay between local and non-local exciton-phonon interactions

    NASA Astrophysics Data System (ADS)

    Lee, Myeong H.; Troisi, Alessandro

    2017-02-01

    It has been reported in recent years that vibronic resonance between vibrational energy of the intramolecular nuclear mode and excitation-energy difference is crucial to enhance excitation energy transport in light harvesting proteins. Here we investigate how vibronic enhancement induced by vibronic resonance is influenced by the details of local and non-local exciton-phonon interactions. We study a heterodimer model with parameters relevant to the light-harvesting proteins with the surrogate Hamiltonian quantum dynamics method in a vibronic basis. In addition, the impact of field-driven excitation on the efficiency of population transfer is compared with the instantaneous excitation, and the effect of multi-mode vibronic coupling is presented in comparison with the coupling to a single effective vibrational mode. We find that vibronic enhancement of site population transfer is strongly suppressed with the increase of non-local exciton-phonon interaction and increasing the number of strongly coupled high-frequency vibrational modes leads to a further decrease in vibronic enhancement. Our results indicate that vibronic enhancement is present but may be much smaller than previously thought and therefore care needs to be taken when interpreting its role in excitation energy transport. Our results also suggest that non-local exciton-phonon coupling, which is related to the fluctuation of the excitonic coupling, may be as important as local exciton-phonon coupling and should be included in any quantum dynamics model.

  7. Bridging quantum and classical plasmonics with a quantum-corrected model.

    PubMed

    Esteban, Ruben; Borisov, Andrei G; Nordlander, Peter; Aizpurua, Javier

    2012-05-08

    Electromagnetic coupling between plasmonic resonances in metallic nanoparticles allows for engineering of the optical response and generation of strong localized near-fields. Classical electrodynamics fails to describe this coupling across sub-nanometer gaps, where quantum effects become important owing to non-local screening and the spill-out of electrons. However, full quantum simulations are not presently feasible for realistically sized systems. Here we present a novel approach, the quantum-corrected model (QCM), that incorporates quantum-mechanical effects within a classical electrodynamic framework. The QCM approach models the junction between adjacent nanoparticles by means of a local dielectric response that includes electron tunnelling and tunnelling resistivity at the gap and can be integrated within a classical electrodynamical description of large and complex structures. The QCM predicts optical properties in excellent agreement with fully quantum mechanical calculations for small interacting systems, opening a new venue for addressing quantum effects in realistic plasmonic systems.

  8. Non-local mind from the perspective of social cognition

    PubMed Central

    Chatel-Goldman, Jonas; Schwartz, Jean-Luc; Jutten, Christian; Congedo, Marco

    2012-01-01

    Two main conceptual approaches have been employed to study the mechanisms of social cognition, whether one considers isolated or interacting minds. Using neuro-imaging of subjects in isolation, the former approach has provided knowledge on the neural underpinning of a variety of social processes. However, it has been argued that considering one brain alone cannot account for all mechanisms subtending online social interaction. This challenge has been tackled recently by using neuro-imaging of multiple interacting subjects in more ecological settings. The present short review aims at offering a comprehensive view on various advances done in the last decade. We provide a taxonomy of existing research in neuroscience of social interaction, situating them in the frame of general organization principles of social cognition. Finally, we discuss the putative enabling role of emerging non-local social mechanisms—such as interpersonal brain and body coupling—in processes underlying our ability to create a shared world. PMID:23565084

  9. Non-local mind from the perspective of social cognition.

    PubMed

    Chatel-Goldman, Jonas; Schwartz, Jean-Luc; Jutten, Christian; Congedo, Marco

    2013-01-01

    Two main conceptual approaches have been employed to study the mechanisms of social cognition, whether one considers isolated or interacting minds. Using neuro-imaging of subjects in isolation, the former approach has provided knowledge on the neural underpinning of a variety of social processes. However, it has been argued that considering one brain alone cannot account for all mechanisms subtending online social interaction. This challenge has been tackled recently by using neuro-imaging of multiple interacting subjects in more ecological settings. The present short review aims at offering a comprehensive view on various advances done in the last decade. We provide a taxonomy of existing research in neuroscience of social interaction, situating them in the frame of general organization principles of social cognition. Finally, we discuss the putative enabling role of emerging non-local social mechanisms-such as interpersonal brain and body coupling-in processes underlying our ability to create a shared world.

  10. Inflationary magnetogenesis and non-local actions: the conformal anomaly

    SciTech Connect

    El-Menoufi, Basem Kamal

    2016-02-01

    We discuss the possibility of successful magnetogenesis during inflation by employing the one-loop effective action of massless QED. The action is strictly non-local and results from the long distance fluctuations of massless charged particles present at the inflationary scale. Most importantly, it encodes the conformal anomaly of QED which is crucial to avoid the vacuum preservation in classical electromagnetism. In particular, we find a blue spectrum for the magnetic field with spectral index n{sub B} ≅ 2 − α{sub e} where α{sub e} depends on both the number of e-folds during inflation as well as the coefficient of the one-loop beta function. In particular, the sign of the beta function has important bearing on the final result. A low reheating temperature is required for the present day magnetic field to be consistent with the lower bound inferred on the field in the intergalactic medium.

  11. Exact solutions for semirelativistic problems with non-local potentials

    NASA Astrophysics Data System (ADS)

    Hall, Richard L.

    2006-01-01

    It is shown that exact solutions may be found for the energy eigenvalue problem generated by the class of semirelativistic Hamiltonians of the form H = \\sqrt{m^2+p^2} + \\hat{V} , where \\hat{V} is a non-local potential with a separable kernel of the form {\\cal V}(r,r^{\\prime}) = - \\sum_{i=1}^n v_i f_i(r)g_i(r^{\\prime}) . Explicit examples in one and three dimensions are discussed, including the Yamaguchi and Gauss potentials. The results are used to obtain lower bounds for the energy of the corresponding N-boson problem, with upper bounds provided by the use of a Gaussian trial function.

  12. Fast non local means denoising for 3D MR images.

    PubMed

    Coupé, Pierrick; Yger, Pierre; Barillot, Christian

    2006-01-01

    One critical issue in the context of image restoration is the problem of noise removal while keeping the integrity of relevant image information. Denoising is a crucial step to increase image conspicuity and to improve the performances of all the processings needed for quantitative imaging analysis. The method proposed in this paper is based on an optimized version of the Non Local (NL) Means algorithm. This approach uses the natural redundancy of information in image to remove the noise. Tests were carried out on synthetic datasets and on real 3T MR images. The results show that the NL-means approach outperforms other classical denoising methods, such as Anisotropic Diffusion Filter and Total Variation.

  13. Synthesis and characterization of chitosan-based polyelectrolyte complexes, doped by quantum dots

    NASA Astrophysics Data System (ADS)

    Abuzova, N. V.; Gerasimova, M. A.; Slabko, V. V.; Slyusareva, E. A.

    2015-12-01

    Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.

  14. Effective descriptions of complex quantum systems: path integrals and operator ordering problems

    NASA Astrophysics Data System (ADS)

    Eckern, U.; Gruber, M. J.; Schwab, P.

    2005-09-01

    [Dedicated to Bernhard Mühlschlegel on the occasion ofhis 80th birthday]We study certain aspects of the effective, occasionally called collective, description of complex quantum systems within the framework of the path integral formalism, in which the environment is integrated out. Generalising the standard Feynman-Vernon Caldeira-Leggett model to include a non-linear coupling between particle and environment, and considering a particular spectral density of the coupling, a coordinate-dependent mass (or velocity-dependent potential) is obtained. The related effective quantum theory, which depends on the proper discretisation of the path integral, is derived and discussed. As a result, we find that in general a simple effective low-energy Hamiltonian, in which only the coordinate-dependent mass enters, cannot be formulated. The quantum theory of weakly coupled superconductors and the quantum dynamics of vortices in Josephson junction arrays are physical examples where these considerations, in principle, are of relevance.

  15. Quantum chemical study of the O 3-HONO complex

    NASA Astrophysics Data System (ADS)

    Roohi, Hossein; Ashuri, Masomeh

    2009-07-01

    Gas phase hydrogen-bonded isomers of the O 3-HONO complex have been investigated by means of DFT(B3LYP), MP2, MP4(SDTQ), CCSD(T) and QCISD(T) methods in conjunction with the 6-311++G(2d,2p), 6-311++G(df,pd), AUG-cc-pVDZ and AUG-cc-pVTZ basis sets. Ten isomers were found for the O 3-HONO complex. The O⋯H and O⋯O interactions are predicted that participate in the formation of non-planar ring structure of the most stable isomer. The AIM calculations reveal that the O⋯H interaction in the most stable complex is stronger than others. In addition, both O⋯H and O⋯O interactions in O 3-HONO complexes are electrostatic in nature.

  16. Lanthanide macrocyclic complexes, 'quantum dyes': optical properties and significance

    NASA Astrophysics Data System (ADS)

    Vallarino, Lidia M.; Harlow, Patrick M.; Leif, Robert C.

    1993-05-01

    Macrocylic complexes of the lanthanide (III) ions were functionalized to permit their attachment to antibodies, nucleic acid probes, and any other species capable of specific binding. The Eu(III) complex was found to possess a combination of properties (water solubility, inertness to metal release, ligand-sensitized luminescence, reactive peripheral functionalities) that make it suitable as a luminescent marker for bio-substrates. Its coupling to avidin was achieved, and the properties of the resulting conjugate were investigated.

  17. Quantum transport in networks and photosynthetic complexes at the steady state.

    PubMed

    Manzano, Daniel

    2013-01-01

    Recently, several works have analysed the efficiency of photosynthetic complexes in a transient scenario and how that efficiency is affected by environmental noise. Here, following a quantum master equation approach, we study the energy and excitation transport in fully connected networks both in general and in the particular case of the Fenna-Matthew-Olson complex. The analysis is carried out for the steady state of the system where the excitation energy is constantly "flowing" through the system. Steady state transport scenarios are particularly relevant if the evolution of the quantum system is not conditioned on the arrival of individual excitations. By adding dephasing to the system, we analyse the possibility of noise-enhancement of the quantum transport.

  18. Probing indirect exciton complexes in a quantum dot molecule via capacitance-voltage spectroscopy

    NASA Astrophysics Data System (ADS)

    Pal, Shovon; Junggebauer, Clara; Valentin, Sascha R.; Eickelmann, Pia; Scholz, Sven; Ludwig, Arne; Wieck, Andreas D.

    2016-12-01

    Capacitance-voltage spectroscopy has proved to be a very powerful experimental technique towards the investigation of carrier-carrier interactions both qualitatively and quantitatively in complex coupled nanostructures. Here, we exploit this method to observe indirect exciton complexes in a quantum dot molecule and to quantify the electron-hole interactions between two dots in a quantum dot molecule, formed by vertical stacking of self-assembled quantum dot layers. While frequency-dependent measurements distinguish between the s - and p -charging behavior, under perpendicular magnetic fields, reordering of the quantized states charging sequence is observed along with the formation of a Landau fan in the wetting layer that is used to reconstruct the Fermi energy level.

  19. Average-Case Complexity Versus Approximate Simulation of Commuting Quantum Computations

    NASA Astrophysics Data System (ADS)

    Bremner, Michael J.; Montanaro, Ashley; Shepherd, Dan J.

    2016-08-01

    We use the class of commuting quantum computations known as IQP (instantaneous quantum polynomial time) to strengthen the conjecture that quantum computers are hard to simulate classically. We show that, if either of two plausible average-case hardness conjectures holds, then IQP computations are hard to simulate classically up to constant additive error. One conjecture relates to the hardness of estimating the complex-temperature partition function for random instances of the Ising model; the other concerns approximating the number of zeroes of random low-degree polynomials. We observe that both conjectures can be shown to be valid in the setting of worst-case complexity. We arrive at these conjectures by deriving spin-based generalizations of the boson sampling problem that avoid the so-called permanent anticoncentration conjecture.

  20. One-time pad, complexity of verification of keys, and practical security of quantum cryptography

    NASA Astrophysics Data System (ADS)

    Molotkov, S. N.

    2016-11-01

    A direct relation between the complexity of the complete verification of keys, which is one of the main criteria of security in classical systems, and a trace distance used in quantum cryptography is demonstrated. Bounds for the minimum and maximum numbers of verification steps required to determine the actual key are obtained.

  1. Towards a Social Theory of School Administrative Practice in a Complex, Chaotic, Quantum World.

    ERIC Educational Resources Information Center

    Beavis, Allan K.

    Educational administration, like many other social sciences, has traditionally followed the rubrics of classical science with its emphasis on prediction and control and attempts to understand the whole by understanding in ever finer detail how the parts fit together. However, the "new" science (especially quantum mechanics, complexity,…

  2. Solution of coupled integral equations for quantum scattering in the presence of complex potentials

    SciTech Connect

    Franz, Jan

    2015-01-15

    In this paper, we present a method to compute solutions of coupled integral equations for quantum scattering problems in the presence of a complex potential. We show how the elastic and absorption cross sections can be obtained from the numerical solution of these equations in the asymptotic region at large radial distances.

  3. Quantum mechanics of excitation transport in photosynthetic complexes: a key issues review.

    PubMed

    Levi, Federico; Mostarda, Stefano; Rao, Francesco; Mintert, Florian

    2015-07-01

    For a long time microscopic physical descriptions of biological processes have been based on quantum mechanical concepts and tools, and routinely employed by chemical physicists and quantum chemists. However, the last ten years have witnessed new developments on these studies from a different perspective, rooted in the framework of quantum information theory. The process that more, than others, has been subject of intense research is the transfer of excitation energy in photosynthetic light-harvesting complexes, a consequence of the unexpected experimental discovery of oscillating signals in such highly noisy systems. The fundamental interdisciplinary nature of this research makes it extremely fascinating, but can also constitute an obstacle to its advance. Here in this review our objective is to provide an essential summary of the progress made in the theoretical description of excitation energy dynamics in photosynthetic systems from a quantum mechanical perspective, with the goal of unifying the language employed by the different communities. This is initially realized through a stepwise presentation of the fundamental building blocks used to model excitation transfer, including protein dynamics and the theory of open quantum system. Afterwards, we shall review how these models have evolved as a consequence of experimental discoveries; this will lead us to present the numerical techniques that have been introduced to quantitatively describe photo-absorbed energy dynamics. Finally, we shall discuss which mechanisms have been proposed to explain the unusual coherent nature of excitation transport and what insights have been gathered so far on the potential functional role of such quantum features.

  4. Quantum mechanics of excitation transport in photosynthetic complexes: a key issues review

    NASA Astrophysics Data System (ADS)

    Levi, Federico; Mostarda, Stefano; Rao, Francesco; Mintert, Florian

    2015-07-01

    For a long time microscopic physical descriptions of biological processes have been based on quantum mechanical concepts and tools, and routinely employed by chemical physicists and quantum chemists. However, the last ten years have witnessed new developments on these studies from a different perspective, rooted in the framework of quantum information theory. The process that more, than others, has been subject of intense research is the transfer of excitation energy in photosynthetic light-harvesting complexes, a consequence of the unexpected experimental discovery of oscillating signals in such highly noisy systems. The fundamental interdisciplinary nature of this research makes it extremely fascinating, but can also constitute an obstacle to its advance. Here in this review our objective is to provide an essential summary of the progress made in the theoretical description of excitation energy dynamics in photosynthetic systems from a quantum mechanical perspective, with the goal of unifying the language employed by the different communities. This is initially realized through a stepwise presentation of the fundamental building blocks used to model excitation transfer, including protein dynamics and the theory of open quantum system. Afterwards, we shall review how these models have evolved as a consequence of experimental discoveries; this will lead us to present the numerical techniques that have been introduced to quantitatively describe photo-absorbed energy dynamics. Finally, we shall discuss which mechanisms have been proposed to explain the unusual coherent nature of excitation transport and what insights have been gathered so far on the potential functional role of such quantum features.

  5. An optimized locally adaptive non-local means denoising filter for cryo-electron microscopy data.

    PubMed

    Wei, Dai-Yu; Yin, Chang-Cheng

    2010-12-01

    Cryo-electron microscopy (cryo-EM) now plays an important role in structural analysis of macromolecular complexes, organelles and cells. However, the cryo-EM images obtained close to focus and under low dose conditions have a very high level of noise and a very low contrast, which hinders high-resolution structural analysis. Here, an optimized locally adaptive non-local (LANL) means filter, which can preserve signal details and simultaneously significantly suppress noise for cryo-EM data, is presented. This filter takes advantage of a wide range of pixels to estimate the denoised pixel values instead of the traditional filter that only uses pixels in the local neighborhood. The filter performed well on simulated data and showed promising results on raw cryo-EM images and tomograms. The predominant advantage of this optimized LANL-means filter is the structural signal and the background are clearly distinguishable. This locally adaptive non-local means filter may become a useful tool in the analysis of cryo-EM data, such as automatic particle picking, extracting structural features and segmentation of tomograms.

  6. An optimal parametrization framework for infrasonic tomography of the stratospheric winds using non-local sources

    NASA Astrophysics Data System (ADS)

    Blom, Philip S.; Marcillo, Omar E.

    2017-03-01

    A method is developed to apply acoustic tomography methods to a localized network of infrasound arrays with intention of monitoring the atmosphere state in the region around the network using non-local sources without requiring knowledge of the precise source location or non-local atmosphere state. Closely spaced arrays provide a means to estimate phase velocities of signals that can provide limiting bounds on certain characteristics of the atmosphere. Larger spacing between such clusters provide a means to estimate celerity from propagation times along multiple unique stratospherically or thermospherically ducted propagation paths and compute more precise estimates of the atmosphere state. In order to avoid the commonly encountered complex, multimodal distributions for parametric atmosphere descriptions and to maximize the computational efficiency of the method, an optimal parametrization framework is constructed. This framework identifies the ideal combination of parameters for tomography studies in specific regions of the atmosphere and statistical model selection analysis shows that high quality corrections to the middle atmosphere winds can be obtained using as few as three parameters. Comparison of the resulting estimates for synthetic data sets shows qualitative agreement between the middle atmosphere winds and those estimated from infrasonic traveltime observations.

  7. An Optimal Parameterization Framework for Infrasonic Tomography of the Stratospheric Winds Using Non-Local Sources

    NASA Astrophysics Data System (ADS)

    Blom, Philip S.; Marcillo, Omar

    2016-12-01

    A method is developed to apply acoustic tomography methods to a localized network of infrasound arrays with intention of monitoring the atmosphere state in the region around the network using non-local sources without requiring knowledge of the precise source location or non-local atmosphere state. Closely spaced arrays provide a means to estimate phase velocities of signals that can provide limiting bounds on certain characteristics of the atmosphere. Larger spacing between such clusters provide a means to estimate celerity from propagation times along multiple unique stratospherically or thermospherically ducted propagation paths and compute more precise estimates of the atmosphere state. In order to avoid the commonly encountered complex, multi-modal distributions for parametric atmosphere descriptions and to maximize the computational efficiency of the method, an optimal parameterization framework is constructed. This framework identifies the ideal combination of parameters for tomography studies in specific regions of the atmosphere and statistical model selection analysis shows that high quality corrections to the middle atmosphere winds can be obtained using as few as three parameters. Comparison of the resulting estimates for synthetic datasets shows qualitative agreement between the middle atmosphere winds and those estimated from infrasonic travel time observations.

  8. An Optimal Parameterization Framework for Infrasonic Tomography of the Stratospheric Winds Using Non-Local Sources

    DOE PAGES

    Blom, Philip Stephen; Marcillo, Omar Eduardo

    2016-12-05

    A method is developed to apply acoustic tomography methods to a localized network of infrasound arrays with intention of monitoring the atmosphere state in the region around the network using non-local sources without requiring knowledge of the precise source location or non-local atmosphere state. Closely spaced arrays provide a means to estimate phase velocities of signals that can provide limiting bounds on certain characteristics of the atmosphere. Larger spacing between such clusters provide a means to estimate celerity from propagation times along multiple unique stratospherically or thermospherically ducted propagation paths and compute more precise estimates of the atmosphere state. Inmore » order to avoid the commonly encountered complex, multimodal distributions for parametric atmosphere descriptions and to maximize the computational efficiency of the method, an optimal parametrization framework is constructed. This framework identifies the ideal combination of parameters for tomography studies in specific regions of the atmosphere and statistical model selection analysis shows that high quality corrections to the middle atmosphere winds can be obtained using as few as three parameters. Lastly, comparison of the resulting estimates for synthetic data sets shows qualitative agreement between the middle atmosphere winds and those estimated from infrasonic traveltime observations.« less

  9. An Optimal Parameterization Framework for Infrasonic Tomography of the Stratospheric Winds Using Non-Local Sources

    SciTech Connect

    Blom, Philip Stephen; Marcillo, Omar Eduardo

    2016-12-05

    A method is developed to apply acoustic tomography methods to a localized network of infrasound arrays with intention of monitoring the atmosphere state in the region around the network using non-local sources without requiring knowledge of the precise source location or non-local atmosphere state. Closely spaced arrays provide a means to estimate phase velocities of signals that can provide limiting bounds on certain characteristics of the atmosphere. Larger spacing between such clusters provide a means to estimate celerity from propagation times along multiple unique stratospherically or thermospherically ducted propagation paths and compute more precise estimates of the atmosphere state. In order to avoid the commonly encountered complex, multimodal distributions for parametric atmosphere descriptions and to maximize the computational efficiency of the method, an optimal parametrization framework is constructed. This framework identifies the ideal combination of parameters for tomography studies in specific regions of the atmosphere and statistical model selection analysis shows that high quality corrections to the middle atmosphere winds can be obtained using as few as three parameters. Lastly, comparison of the resulting estimates for synthetic data sets shows qualitative agreement between the middle atmosphere winds and those estimated from infrasonic traveltime observations.

  10. Cosmological evolution of generalized non-local gravity

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Wu, Ya-Bo; Li, Song; Liu, Yu-Chen; Chen, Bo-Hai; Chai, Yun-Tian; Shu, Shuang

    2016-07-01

    We construct a class of generalized non-local gravity (GNLG) model which is the modified theory of general relativity (GR) obtained by adding a term m2n-2 R□-nR to the Einstein-Hilbert action. Concretely, we not only study the gravitational equation for the GNLG model by introducing auxiliary scalar fields, but also analyse the classical stability and examine the cosmological consequences of the model for different exponent n. We find that the half of the scalar fields are always ghost-like and the exponent n must be taken even number for a stable GNLG model. Meanwhile, the model spontaneously generates three dominant phases of the evolution of the universe, and the equation of state parameters turn out to be phantom-like. Furthermore, we clarify in another way that exponent n should be even numbers by the spherically symmetric static solutions in Newtonian gauge. It is worth stressing that the results given by us can include ones in refs. [28, 34] as the special case of n=2.

  11. NABS: non-local automatic brain hemisphere segmentation.

    PubMed

    Romero, José E; Manjón, José V; Tohka, Jussi; Coupé, Pierrick; Robles, Montserrat

    2015-05-01

    In this paper, we propose an automatic method to segment the five main brain sub-regions (i.e. left/right hemispheres, left/right cerebellum and brainstem) from magnetic resonance images. The proposed method uses a library of pre-labeled brain images in a stereotactic space in combination with a non-local label fusion scheme for segmentation. The main novelty of the proposed method is the use of a multi-label block-wise label fusion strategy specifically designed to deal with the classification of main brain sub-volumes that process only specific parts of the brain images significantly reducing the computational burden. The proposed method has been quantitatively evaluated against manual segmentations. The evaluation showed that the proposed method was faster while producing more accurate segmentations than a current state-of-the-art method. We also present evidences suggesting that the proposed method was more robust against brain pathologies than the compared method. Finally, we demonstrate the clinical value of our method compared to the state-of-the-art approach in terms of the asymmetry quantification in Alzheimer's disease.

  12. EDITORIAL: How to control decoherence and entanglement in quantum complex systems?

    NASA Astrophysics Data System (ADS)

    Akulin, V. M.; Kurizki, G.; Lidar, D. A.

    2007-05-01

    Theory and experiment have not fully resolved the apparent dichotomy, which has agonized physics for the past eighty years: on the one hand, the description of microsystems by quantum mechanics and, on the other, the description of macrosystems by classical dynamics or statistical mechanics. Derivations of the time-irreversible Liouville equation for an open quantum system, based on projecting out its environment, have narrowed the gap between the quantum and classical descriptions. Yet our `classical' intuition continues to be confronted by quantum-mechanical results like the Einstein--Podolsky--Rosen paradox that challenges the classical notion of locality, or the quantum Zeno effect which suggests that the isolation of a system is not the only way to preserve its quantum state. There are two key concepts in any discussion of such issues. The first, which is responsible for the most salient nonclassical properties, is entanglement, that is partial or complete correlation or, more generally, inseparability of the elements comprising a quantum ensemble. Even after their interaction has ceased, this inseparability, originating from their past interaction, can affect the state of one element when another element is subject to a nonunitary action, such as its measurement, tracing- out, or thermalization. The second key concept is decoherence of open quantum systems, which is the consequence of their entanglement with their environment, a `meter' or a thermal `reservoir', followed by the tracing-out of the latter. Despite new insights into entanglement and decoherence, there are still no complete, unequivocal answers to the fundamental questions of the transition from quantal to classical behaviour: how do irreversibility and classicality emerge from unitarity as systems and their environments become increasingly complex? At what stage does system--meter entanglement give rise to a classical readout of the meter? Is there an upper limit on the size or complexity of

  13. Diagrammatic quantum mechanics

    NASA Astrophysics Data System (ADS)

    Kauffman, Louis H.; Lomonaco, Samuel J.

    2015-05-01

    This paper explores how diagrams of quantum processes can be used for modeling and for quantum epistemology. The paper is a continuation of the discussion where we began this formulation. Here we give examples of quantum networks that represent unitary transformations by dint of coherence conditions that constitute a new form of non-locality. Local quantum devices interconnected in space can form a global quantum system when appropriate coherence conditions are maintained.

  14. Energy transfer in complexes of water-soluble quantum dots and chlorin e6 molecules in different environments

    PubMed Central

    Martynenko, Irina V; Maslov, Vladimir G; Baranov, Alexander V; Fedorov, Anatoly V; Artemyev, Mikhail

    2013-01-01

    Summary The photoexcitation energy transfer is found and investigated in complexes of CdSe/ZnS cationic quantum dots and chlorin e6 molecules formed by covalent bonding and electrostatic interaction in aqueous solution and in porous track membranes. The quantum dots and chlorin e6 molecules form stable complexes that exhibit Förster resonance energy transfer (FRET) from quantum dots to chlorin e6 regardless of complex formation conditions. Competitive channels of photoexcitation energy dissipation in the complexes, which hamper the FRET process, were found and discussed. PMID:24367759

  15. Energy transfer in complexes of water-soluble quantum dots and chlorin e6 molecules in different environments.

    PubMed

    Martynenko, Irina V; Orlova, Anna O; Maslov, Vladimir G; Baranov, Alexander V; Fedorov, Anatoly V; Artemyev, Mikhail

    2013-01-01

    The photoexcitation energy transfer is found and investigated in complexes of CdSe/ZnS cationic quantum dots and chlorin e6 molecules formed by covalent bonding and electrostatic interaction in aqueous solution and in porous track membranes. The quantum dots and chlorin e6 molecules form stable complexes that exhibit Förster resonance energy transfer (FRET) from quantum dots to chlorin e6 regardless of complex formation conditions. Competitive channels of photoexcitation energy dissipation in the complexes, which hamper the FRET process, were found and discussed.

  16. Dissipative quantum dynamics in low-energy collisions of complex nuclei

    SciTech Connect

    Diaz-Torres, A.; Hinde, D. J.; Dasgupta, M.; Milburn, G. J.; Tostevin, J. A.

    2008-12-15

    Model calculations that include the effects of irreversible, environmental couplings on top of a coupled-channels dynamical description of the collision of two complex nuclei are presented. The Liouville-von Neumann equation for the time evolution of the density matrix of a dissipative system is solved numerically providing a consistent transition from coherent to decoherent (and dissipative) dynamics during the collision. Quantum decoherence and dissipation are clearly manifested in the model calculations. Energy dissipation, due to the irreversible decay of giant-dipole vibrational states of the colliding nuclei, is shown to result in a hindrance of quantum tunneling and fusion.

  17. Resonant raman scattering in complexes of nc-Si/SiO2 quantum dots and oligonucleotides

    NASA Astrophysics Data System (ADS)

    Bairamov, F. B.; Poloskin, E. D.; Kornev, A. A.; Chernev, A. L.; Toporov, V. V.; Dubina, M. V.; Röder, C.; Sprung, C.; Lipsanen, H.; Bairamov, B. Kh.

    2014-11-01

    We report on the functionalization of nanocrystalline nc-Si/SiO2 semiconductor quantum dots (QDs) by short d(20G, 20T) oligonucleotides. The obtained complexes have been studied by Raman spectroscopy techniques with high spectral and spatial resolution. A new phenomenon of multiband resonant light scattering on single oligonucleotide molecules has been discovered, and peculiarities of this effect related to the nonradiative transfer of photoexcitation from nc-Si/SiO2 quantum dots to d(20G, 20T) oligonucleotide molecules have been revealed.

  18. Real-Time Quantum Dynamics Reveals Complex, Many-Body Interactions in Solvated Nanodroplets.

    PubMed

    Oviedo, M Belén; Wong, Bryan M

    2016-04-12

    Electronic excitations in the liquid phase are surprisingly rich and considerably more complex than either gas-phase or solid-state systems. While the majority of physical and biological processes take place in solvent, our understanding of nonequilibrium excited-state processes in these condensed phase environments remains far from complete. A central and long-standing issue in these solvated environments is the assessment of many-body interactions, particularly when the entire system is out of equilibrium and many quantum states participate in the overall process. Here we present a microscopic picture of solute-solvent electron dynamics and solvatochromic effects, which we uncover using a new real-time quantum dynamics approach for extremely large solvated nanodroplets. In particular, we find that a complex interplay of quantum interactions underlies our observations of solute-solvent effects, and simple macroscopic solvatochromic shifts can even be qualitatively different at the microscopic molecular level in these systems. By treating both the solvent and the solute on the same footing at a quantum-mechanical level, we demonstrate that the electron dynamics in these systems are surprisingly complex, and the emergence of many-body interactions underlies the dynamics in these solvated systems.

  19. Long-lived quantum coherence in photosynthetic complexes at physiological temperature

    PubMed Central

    Panitchayangkoon, Gitt; Hayes, Dugan; Fransted, Kelly A.; Caram, Justin R.; Harel, Elad; Wen, Jianzhong; Blankenship, Robert E.; Engel, Gregory S.

    2010-01-01

    Photosynthetic antenna complexes capture and concentrate solar radiation by transferring the excitation to the reaction center that stores energy from the photon in chemical bonds. This process occurs with near-perfect quantum efficiency. Recent experiments at cryogenic temperatures have revealed that coherent energy transfer—a wave-like transfer mechanism—occurs in many photosynthetic pigment-protein complexes. Using the Fenna–Matthews–Olson antenna complex (FMO) as a model system, theoretical studies incorporating both incoherent and coherent transfer as well as thermal dephasing predict that environmentally assisted quantum transfer efficiency peaks near physiological temperature; these studies also show that this mechanism simultaneously improves the robustness of the energy transfer process. This theory requires long-lived quantum coherence at room temperature, which never has been observed in FMO. Here we present evidence that quantum coherence survives in FMO at physiological temperature for at least 300 fs, long enough to impact biological energy transport. These data prove that the wave-like energy transfer process discovered at 77 K is directly relevant to biological function. Microscopically, we attribute this long coherence lifetime to correlated motions within the protein matrix encapsulating the chromophores, and we find that the degree of protection afforded by the protein appears constant between 77 K and 277 K. The protein shapes the energy landscape and mediates an efficient energy transfer despite thermal fluctuations. PMID:20615985

  20. A Study of Complex Deep Learning Networks on High Performance, Neuromorphic, and Quantum Computers

    SciTech Connect

    Potok, Thomas E; Schuman, Catherine D; Young, Steven R; Patton, Robert M; Spedalieri, Federico; Liu, Jeremy; Yao, Ke-Thia; Rose, Garrett; Chakma, Gangotree

    2016-01-01

    Current Deep Learning models use highly optimized convolutional neural networks (CNN) trained on large graphical processing units (GPU)-based computers with a fairly simple layered network topology, i.e., highly connected layers, without intra-layer connections. Complex topologies have been proposed, but are intractable to train on current systems. Building the topologies of the deep learning network requires hand tuning, and implementing the network in hardware is expensive in both cost and power. In this paper, we evaluate deep learning models using three different computing architectures to address these problems: quantum computing to train complex topologies, high performance computing (HPC) to automatically determine network topology, and neuromorphic computing for a low-power hardware implementation. Due to input size limitations of current quantum computers we use the MNIST dataset for our evaluation. The results show the possibility of using the three architectures in tandem to explore complex deep learning networks that are untrainable using a von Neumann architecture. We show that a quantum computer can find high quality values of intra-layer connections and weights, while yielding a tractable time result as the complexity of the network increases; a high performance computer can find optimal layer-based topologies; and a neuromorphic computer can represent the complex topology and weights derived from the other architectures in low power memristive hardware. This represents a new capability that is not feasible with current von Neumann architecture. It potentially enables the ability to solve very complicated problems unsolvable with current computing technologies.

  1. Optimal control of many-body quantum dynamics: Chaos and complexity

    NASA Astrophysics Data System (ADS)

    Poggi, P. M.; Wisniacki, D. A.

    2016-09-01

    Achieving full control of the time-evolution of a many-body quantum system is currently a major goal in physics. In this work we investigate the different ways in which the controllability of a quantum system can be influenced by its complexity, or even its chaotic properties. By using optimal control theory, we are able to derive the control fields necessary to drive various physical processes in a spin chain. Then, we study the spectral properties of such fields and how they relate to different aspects of the system complexity. We find that the spectral bandwidth of the fields is, quite generally, independent of the system dimension. Conversely, the spectral complexity of such fields does increase with the number of particles. Nevertheless, we find that the regular or chaotic nature of the system does not affect significantly its controllability.

  2. What the complex joint probabilities observed in weak measurements can tell us about quantum physics

    SciTech Connect

    Hofmann, Holger F.

    2014-12-04

    Quantummechanics does not permit joint measurements of non-commuting observables. However, it is possible to measure the weak value of a projection operator, followed by the precise measurement of a different property. The results can be interpreted as complex joint probabilities of the two non-commuting measurement outcomes. Significantly, it is possible to predict the outcome of completely different measurements by combining the joint probabilities of the initial state with complex conditional probabilities relating the new measurement to the possible combinations of measurement outcomes used in the characterization of the quantum state. We can therefore conclude that the complex conditional probabilities observed in weak measurements describe fundamental state-independent relations between non-commuting properties that represent the most fundamental form of universal laws in quantum physics.

  3. Spintronic characteristics of self-assembled neurotransmitter acetylcholine molecular complexes enable quantum information processing in neural networks and brain

    NASA Astrophysics Data System (ADS)

    Tamulis, Arvydas; Majauskaite, Kristina; Kairys, Visvaldas; Zborowski, Krzysztof; Adhikari, Kapil; Krisciukaitis, Sarunas

    2016-09-01

    Implementation of liquid state quantum information processing based on spatially localized electronic spin in the neurotransmitter stable acetylcholine (ACh) neutral molecular radical is discussed. Using DFT quantum calculations we proved that this molecule possesses stable localized electron spin, which may represent a qubit in quantum information processing. The necessary operating conditions for ACh molecule are formulated in self-assembled dimer and more complex systems. The main quantum mechanical research result of this paper is that the neurotransmitter ACh systems, which were proposed, include the use of quantum molecular spintronics arrays to control the neurotransmission in neural networks.

  4. Uncertainty quantification for quantum chemical models of complex reaction networks.

    PubMed

    Proppe, Jonny; Husch, Tamara; Simm, Gregor N; Reiher, Markus

    2016-12-22

    For the quantitative understanding of complex chemical reaction mechanisms, it is, in general, necessary to accurately determine the corresponding free energy surface and to solve the resulting continuous-time reaction rate equations for a continuous state space. For a general (complex) reaction network, it is computationally hard to fulfill these two requirements. However, it is possible to approximately address these challenges in a physically consistent way. On the one hand, it may be sufficient to consider approximate free energies if a reliable uncertainty measure can be provided. On the other hand, a highly resolved time evolution may not be necessary to still determine quantitative fluxes in a reaction network if one is interested in specific time scales. In this paper, we present discrete-time kinetic simulations in discrete state space taking free energy uncertainties into account. The method builds upon thermo-chemical data obtained from electronic structure calculations in a condensed-phase model. Our kinetic approach supports the analysis of general reaction networks spanning multiple time scales, which is here demonstrated for the example of the formose reaction. An important application of our approach is the detection of regions in a reaction network which require further investigation, given the uncertainties introduced by both approximate electronic structure methods and kinetic models. Such cases can then be studied in greater detail with more sophisticated first-principles calculations and kinetic simulations.

  5. Quantum Effects in Cosmochemistry: Complexation Energy and Van Der Waals Radii

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Wilson, T. L.

    2007-01-01

    The subject of quantum effects in cosmochemistry was recently addressed with the goal of understanding how they contribute to Q-phase noble gas abundances found in meteorites. It was the pursuit of the Q-phase carrier of noble gases and their anomalous abundances that ultimately led to the identification, isolation, and discovery of presolar grains. In spite of its importance, Q-phase investigations have led a number of authors to reach conclusions that do not seem to be supported by quantum chemistry. In view of the subject's fundamental significance, additional study is called for. Two quantum properties of Q-phase candidates known as endohedral carbon-cage clathrates such as fullerenes will be addressed here. These are complexation energy and instability induced by Pauli blocking (exclusion principle).

  6. A fast non-local image denoising algorithm

    NASA Astrophysics Data System (ADS)

    Dauwe, A.; Goossens, B.; Luong, H. Q.; Philips, W.

    2008-02-01

    In this paper we propose several improvements to the original non-local means algorithm introduced by Buades et al. which obtains state-of-the-art denoising results. The strength of this algorithm is to exploit the repetitive character of the image in order to denoise the image unlike conventional denoising algorithms, which typically operate in a local neighbourhood. Due to the enormous amount of weight computations, the original algorithm has a high computational cost. An improvement of image quality towards the original algorithm is to ignore the contributions from dissimilar windows. Even though their weights are very small at first sight, the new estimated pixel value can be severely biased due to the many small contributions. This bad influence of dissimilar windows can be eliminated by setting their corresponding weights to zero. Using the preclassification based on the first three statistical moments, only contributions from similar neighborhoods are computed. To decide whether a window is similar or dissimilar, we will derive thresholds for images corrupted with additive white Gaussian noise. Our accelerated approach is further optimized by taking advantage of the symmetry in the weights, which roughly halves the computation time, and by using a lookup table to speed up the weight computations. Compared to the original algorithm, our proposed method produces images with increased PSNR and better visual performance in less computation time. Our proposed method even outperforms state-of-the-art wavelet denoising techniques in both visual quality and PSNR values for images containing a lot of repetitive structures such as textures: the denoised images are much sharper and contain less artifacts. The proposed optimizations can also be applied in other image processing tasks which employ the concept of repetitive structures such as intra-frame super-resolution or detection of digital image forgery.

  7. Minimally complex ion traps as modules for quantum communication and computing

    NASA Astrophysics Data System (ADS)

    Nigmatullin, Ramil; Ballance, Christopher J.; de Beaudrap, Niel; Benjamin, Simon C.

    2016-10-01

    Optically linked ion traps are promising as components of network-based quantum technologies, including communication systems and modular computers. Experimental results achieved to date indicate that the fidelity of operations within each ion trap module will be far higher than the fidelity of operations involving the links; fortunately internal storage and processing can effectively upgrade the links through the process of purification. Here we perform the most detailed analysis to date on this purification task, using a protocol which is balanced to maximise fidelity while minimising the device complexity and the time cost of the process. Moreover we ‘compile down’ the quantum circuit to device-level operations including cooling and shuttling events. We find that a linear trap with only five ions (two of one species, three of another) can support our protocol while incorporating desirable features such as global control, i.e. laser control pulses need only target an entire zone rather than differentiating one ion from its neighbour. To evaluate the capabilities of such a module we consider its use both as a universal communications node for quantum key distribution, and as the basic repeating unit of a quantum computer. For the latter case we evaluate the threshold for fault tolerant quantum computing using the surface code, finding acceptable fidelities for the ‘raw’ entangling link as low as 83% (or under 75% if an additional ion is available).

  8. Quantum entanglement and the communication complexity of the inner product function

    SciTech Connect

    Cleve, R.; Dam, W. van |; Nielsen, M. |; Tapp, A.

    1998-08-01

    The authors consider the communication complexity of the binary inner product function in a variation of the two-party scenario where the parties have an a priori supply of particles in an entangled quantum state. They prove linear lower bounds for both exact protocols, as well as for protocols that determine the answer with bounded-error probability. The proofs employ a novel kind of quantum reduction from multibit communication problems to the problem of computing the inner product. The communication required for the former problem can then be bounded by an application of Holevo`s theorem. They also give a specific example of a probabilistic scenario where entanglement reduces the communication complexity of the inner product function by one bit.

  9. Quantum-confined emission and fluorescence blinking of individual exciton complexes in CdSe nanowires.

    PubMed

    Franz, Dennis; Reich, Aina; Strelow, Christian; Wang, Zhe; Kornowski, Andreas; Kipp, Tobias; Mews, Alf

    2014-11-12

    One-dimensional semiconductor nanostructures combine electron mobility in length direction with the possibility of tailoring the physical properties by confinement effects in radial direction. Here we show that thin CdSe quantum nanowires exhibit low-temperature fluorescence spectra with a specific universal structure of several sharp lines. The structure strongly resembles the pattern of bulk spectra but show a diameter-dependent shift due to confinement effects. Also the fluorescence shows a pronounced complex blinking behavior with very different blinking dynamics of different emission lines in one and the same spectrum. Time- and space-resolved optical spectroscopy are combined with high-resolution transmission electron microscopy of the very same quantum nanowires to establish a detailed structure-property relationship. Extensive numerical simulations strongly suggest that excitonic complexes involving donor and acceptor sites are the origin of the feature-rich spectra.

  10. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    SciTech Connect

    Zamstein, Noa; Tannor, David J.

    2012-12-14

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  11. Quantum-classical transition for an analog of the double-slit experiment in complex collisions: Dynamical decoherence in quantum many-body systems

    SciTech Connect

    Benet, L.; Chadderton, L. T.; Kun, S. Yu.; Qi Wang

    2007-06-15

    We study coherent superpositions of clockwise and anticlockwise rotating intermediate complexes with overlapping resonances formed in bimolecular chemical reactions. Disintegration of such complexes represents an analog of a famous double-slit experiment. The time for disappearance of the interference fringes is estimated from heuristic arguments related to fingerprints of chaotic dynamics of a classical counterpart of the coherently rotating complex. Validity of this estimate is confirmed numerically for the H+D{sub 2} chemical reaction. Thus we demonstrate the quantum-classical transition in temporal behavior of highly excited quantum many-body systems in the absence of external noise and coupling to an environment.

  12. Equivalent dynamical complexity in a many-body quantum and collective human system

    NASA Astrophysics Data System (ADS)

    Johnson, Neil F.; Ashkenazi, Josef; Zhao, Zhenyuan; Quiroga, Luis

    2011-03-01

    Proponents of Complexity Science believe that the huge variety of emergent phenomena observed throughout nature, are generated by relatively few microscopic mechanisms. Skeptics however point to the lack of concrete examples in which a single mechanistic model manages to capture relevant macroscopic and microscopic properties for two or more distinct systems operating across radically different length and time scales. Here we show how a single complexity model built around cluster coalescence and fragmentation, can cross the fundamental divide between many-body quantum physics and social science. It simultaneously (i) explains a mysterious recent finding of Fratini et al. concerning quantum many-body effects in cuprate superconductors (i.e. scale of 10-9 - 10-4 meters and 10-12 - 10-6 seconds), (ii) explains the apparent universality of the casualty distributions in distinct human insurgencies and terrorism (i.e. scale of 103 - 106 meters and 104 - 108 seconds), (iii) shows consistency with various established empirical facts for financial markets, neurons and human gangs and (iv) makes microscopic sense for each application. Our findings also suggest that a potentially productive shift can be made in Complexity research toward the identification of equivalent many-body dynamics in both classical and quantum regimes.

  13. Time-evolution of quantum systems via a complex nonlinear Riccati equation. I. Conservative systems with time-independent Hamiltonian

    SciTech Connect

    Cruz, Hans; Schuch, Dieter; Castaños, Octavio; Rosas-Ortiz, Oscar

    2015-09-15

    The sensitivity of the evolution of quantum uncertainties to the choice of the initial conditions is shown via a complex nonlinear Riccati equation leading to a reformulation of quantum dynamics. This sensitivity is demonstrated for systems with exact analytic solutions with the form of Gaussian wave packets. In particular, one-dimensional conservative systems with at most quadratic Hamiltonians are studied.

  14. Local and non-local correlations in nanoscopic systems

    NASA Astrophysics Data System (ADS)

    Sangiovanni, Giorgio; Valli, A.; Rohringer, G.; Toschi, A.; Held, K.; Das, H.; Saha-Dasgupta, T.

    2012-02-01

    Tools for reliably treating nanoscopic systems, like coupled quantum-dots, ad-atoms on surfaces, macromolecules, etc., in the presence of electronic correlations are either missing or prohibitively expensive. We have implemented a new computational scheme based on a self-consistently defined set of local problems [1]. Our method scales linearly with the number of sites and allows us to perform large-scale sign-problem free Quantum Monte-Carlo simulations. We have studied the behavior of a single-atom junction formed upon stretching a metallic wire and found that a metal-insulator crossover is induced when the wire is about to break up. The combination with ab-initio techniques allowed us to study size-dependent properties of Manganite nano-clusters [2]. The simplest implementation of our method includes only local self-energy effects. We recently went beyond this and applied the resulting more sophisticated version of our method to an exactly solvable model finding results in remarkable agreement with the exact solution. [1] A. Valli, G. Sangiovanni, O. Gunnarsson, A. Toschi and K. Held, PRL 104, 246402 (2010) [2] H. Das, G. Sangiovanni, A. Valli, K. Held and T. Saha-Dasgupta, PRL 107, 197202 (2011)

  15. Complex-time singularity and locality estimates for quantum lattice systems

    NASA Astrophysics Data System (ADS)

    Bouch, Gabriel

    2015-12-01

    We present and prove a well-known locality bound for the complex-time dynamics of a general class of one-dimensional quantum spin systems. Then we discuss how one might hope to extend this same procedure to higher dimensions using ideas related to the Eden growth process and lattice trees. Finally, we demonstrate with a specific family of lattice trees in the plane why this approach breaks down in dimensions greater than one and prove that there exist interactions for which the complex-time dynamics blows-up in finite imaginary time.

  16. Long-lived quantum coherence and non-Markovianity of photosynthetic complexes

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Bin; Lien, Jiun-Yi; Hwang, Chi-Chuan; Chen, Yueh-Nan

    2014-04-01

    Long-lived quantum coherence in photosynthetic pigment-protein complexes has recently been reported at physiological temperature. It has been pointed out that the discrete vibrational modes may be responsible for the long-lived coherence. Here, we propose an analytical non-Markovian model to explain the origin of the long-lived coherence in pigment-protein complexes. We show that the memory effect of the discrete vibrational modes produces a long oscillating tail in the coherence. We further use the recently proposed measure to quantify the non-Markovianity of the system and find out the prolonged coherence is highly correlated to it.

  17. Complex-time singularity and locality estimates for quantum lattice systems

    SciTech Connect

    Bouch, Gabriel

    2015-12-15

    We present and prove a well-known locality bound for the complex-time dynamics of a general class of one-dimensional quantum spin systems. Then we discuss how one might hope to extend this same procedure to higher dimensions using ideas related to the Eden growth process and lattice trees. Finally, we demonstrate with a specific family of lattice trees in the plane why this approach breaks down in dimensions greater than one and prove that there exist interactions for which the complex-time dynamics blows-up in finite imaginary time. .

  18. Photosynthetic protein complexes as bio-photovoltaic building blocks retaining a high internal quantum efficiency.

    PubMed

    Kamran, Muhammad; Delgado, Juan D; Friebe, Vincent; Aartsma, Thijs J; Frese, Raoul N

    2014-08-11

    Photosynthetic compounds have been a paradigm for biosolar cells and biosensors and for application in photovoltaic and photocatalytic devices. However, the interconnection of proteins and protein complexes with electrodes, in terms of electronic contact, structure, alignment and orientation, remains a challenge. Here we report on a deposition method that relies on the self-organizing properties of these biological protein complexes to produce a densely packed monolayer by using Langmuir-Blodgett technology. The monolayer is deposited onto a gold electrode with defined orientation and produces the highest light-induced photocurrents per protein complex to date, 45 μA/cm(2) (with illumination power of 23 mW/cm(2) at 880 nm), under ambient conditions. Our work shows for the first time that a significant portion of the intrinsic quantum efficiency of primary photosynthesis can be retained outside the biological cell, leading to an internal quantum efficiency (absorbed photon to electron injected into the electrode) of the metal electrode-protein complex system of 32%.

  19. Non-adiabatic molecular dynamics with complex quantum trajectories. I. The diabatic representation.

    PubMed

    Zamstein, Noa; Tannor, David J

    2012-12-14

    We extend a recently developed quantum trajectory method [Y. Goldfarb, I. Degani, and D. J. Tannor, J. Chem. Phys. 125, 231103 (2006)] to treat non-adiabatic transitions. Each trajectory evolves on a single surface according to Newton's laws with complex positions and momenta. The transfer of amplitude between surfaces stems naturally from the equations of motion, without the need for surface hopping. In this paper we derive the equations of motion and show results in the diabatic representation, which is rarely used in trajectory methods for calculating non-adiabatic dynamics. We apply our method to the first two benchmark models introduced by Tully [J. Chem. Phys. 93, 1061 (1990)]. Besides giving the probability branching ratios between the surfaces, the method also allows the reconstruction of the time-dependent wavepacket. Our results are in quantitative agreement with converged quantum mechanical calculations.

  20. Probabilities in quantum cosmological models: A decoherent histories analysis using a complex potential

    SciTech Connect

    Halliwell, J. J.

    2009-12-15

    In the quantization of simple cosmological models (minisuperspace models) described by the Wheeler-DeWitt equation, an important step is the construction, from the wave function, of a probability distribution answering various questions of physical interest, such as the probability of the system entering a given region of configuration space at any stage in its entire history. A standard but heuristic procedure is to use the flux of (components of) the wave function in a WKB approximation. This gives sensible semiclassical results but lacks an underlying operator formalism. In this paper, we address the issue of constructing probability distributions linked to the Wheeler-DeWitt equation using the decoherent histories approach to quantum theory. The key step is the construction of class operators characterizing questions of physical interest. Taking advantage of a recent decoherent histories analysis of the arrival time problem in nonrelativistic quantum mechanics, we show that the appropriate class operators in quantum cosmology are readily constructed using a complex potential. The class operator for not entering a region of configuration space is given by the S matrix for scattering off a complex potential localized in that region. We thus derive the class operators for entering one or more regions in configuration space. The class operators commute with the Hamiltonian, have a sensible classical limit, and are closely related to an intersection number operator. The definitions of class operators given here handle the key case in which the underlying classical system has multiple crossings of the boundaries of the regions of interest. We show that oscillatory WKB solutions to the Wheeler-DeWitt equation give approximate decoherence of histories, as do superpositions of WKB solutions, as long as the regions of configuration space are sufficiently large. The corresponding probabilities coincide, in a semiclassical approximation, with standard heuristic procedures

  1. Semiconductor quantum dot/albumin complex is a long-life and highly photostable endosome marker.

    PubMed

    Hanaki, Ken-ichi; Momo, Asami; Oku, Taisuke; Komoto, Atsushi; Maenosono, Shinya; Yamaguchi, Yukio; Yamamoto, Kenji

    2003-03-14

    For the purpose of selecting the efficient dispersion condition of hydrophilic semiconductor quantum dots (QDs) in biological buffers, the dispersion of the QDs mixed with a serum albumin from 9 different species or an ovalbumin was compared by a fluorescence intensity analysis. The QDs mixed with sheep serum albumin (SSA) showed the highest fluorescence of all when the mixtures were dissolved in Dulbecco's MEM. QD/SSA complexes were accumulated in the endosome/lysosome of Vero cells and the fluorescence could be detected over a 5-day post-incubation period. The photostability of QD/SSA complexes associated with the endosomes was detectable, at least, 30 times as long as that of fluorescein-labeled dextran involved in endosomes. QD/SSA complex, therefore, can be used as a long-life and highly photostable endosome marker.

  2. Barrier scattering with complex-valued quantum trajectories: Taxonomy and analysis of isochrones

    SciTech Connect

    David, Julianne K.; Wyatt, Robert E.

    2008-03-07

    To facilitate the search for isochrones when using complex-valued trajectory methods for quantum barrier scattering calculations, the structure and shape of isochrones in the complex plane were studied. Isochrone segments were categorized based on their distinguishing features, which are shared by each situation studied: High and low energy wave packets, scattering from both thick and thin Gaussian and Eckart barriers of varying height. The characteristic shape of the isochrone is a trifurcated system: Trajectories that transmit the barrier are launched from the lower branch (T), while the middle and upper branches form the segments for reflected trajectories (F and B). In addition, a model is presented for the curved section of the lower branch (from which transmitted trajectories are launched), and important features of the complex extension of the initial wave packet are identified.

  3. Probing the nature of chemical bonding in uranyl(VI) complexes with quantum chemical methods.

    PubMed

    Vallet, Valérie; Wahlgren, Ulf; Grenthe, Ingmar

    2012-12-20

    To assess the nature of chemical bonds in uranyl(VI) complexes with Lewis base ligands, such as F(-), Cl(-), OH(-), CO(3)(2-), and O(2)(2-), we have used quantum chemical observables, such as the bond distances, the internal symmetric/asymmetric uranyl stretch frequencies, and the electron density with its topology analyzed using the quantum theory of atoms-in-molecules. This analysis confirms that complex formation induces a weakening of the uranium-axial oxygen bond, reflected by the longer U-O(yl) bond distance and reduced uranyl-stretching frequencies. The strength of the ligand-induced effect increases in the order H(2)O < Cl(-) < F(-) < OH(-) < CO(3)(2-) < O(2)(2-). In-depth analysis reveals that the trend across the series does not always reflect an increasing covalent character of the uranyl-ligand bond. By using a point-charge model for the uranyl tetra-fluoride and tetra-chloride complexes, we show that a significant part of the uranyl bond destabilization arises from purely electrostatic interactions, the remaining part corresponding either to charge-transfer from the negatively charged ligands to the uranyl unit or a covalent interaction. The charge-transfer and the covalent interaction are qualitatively different due to the absence of a charge build up in the uranyl-halide bond region in the latter case. In all the charged complexes, the uranyl-ligand bond is best described as an ionic interaction. However, there are covalent contributions in the very stable peroxide complex and, to some extent, also in the carbonate complex. This study demonstrates that it is possible to describe the nature of chemical bond by observables rather than by ad hoc quantities such as atomic populations or molecular orbitals.

  4. Intrusion Detection With Quantum Mechanics: A Photonic Quantum Fence

    DTIC Science & Technology

    2008-12-01

    computing and quantum key distribution (QKD). Some of the most remarkable examples include quantum teleportation for the non-local transfer of...1 INTRUSION DETECTION WITH QUANTUM MECHANICS: A PHOTONIC QUANTUM FENCE T. S. Humble*, R. S. Bennink, and W. P. Grice Oak Ridge National...use of quantum -mechanically entangled photons for sensing intrusions across a physical perimeter. Our approach to intrusion detection uses the no

  5. When do perturbative approaches accurately capture the dynamics of complex quantum systems?

    PubMed Central

    Fruchtman, Amir; Lambert, Neill; Gauger, Erik M.

    2016-01-01

    Understanding the dynamics of higher-dimensional quantum systems embedded in a complex environment remains a significant theoretical challenge. While several approaches yielding numerically converged solutions exist, these are computationally expensive and often provide only limited physical insight. Here we address the question: when do more intuitive and simpler-to-compute second-order perturbative approaches provide adequate accuracy? We develop a simple analytical criterion and verify its validity for the case of the much-studied FMO dynamics as well as the canonical spin-boson model. PMID:27335176

  6. Quantum-chemical investigation of the structure and electronic absorption spectra of electroluminescent zinc complexes

    NASA Astrophysics Data System (ADS)

    Minaev, B. F.; Baryshnikov, G. V.; Korop, A. A.; Minaeva, V. A.; Kaplunov, M. G.

    2013-01-01

    Using the quantum chemical methods of the density functional theory and of the electron density topological analysis, we have studied the structure of two recently synthesized electroluminescent zinc complexes, one with aminoquinoline ligands and the other with a Schiff base (N,O-donor). The energies and intensities of vertical excitations for the molecules under study have been calculated in terms of the PM3 semiempirical approximation taking into account the configurational interaction between singly excited singlet excited states. Good agreement between calculation results and experimental data on the electron density topological characteristics and on the visible and UV absorption spectra has been obtained.

  7. Including Quantum Effects in the Dynamics of Complex (i.e., Large)Molecular Systems

    SciTech Connect

    Miller, William H.

    2006-04-27

    The development in the 1950's and 60's of crossed molecular beam methods for studying chemical reactions at the single-collision molecular level stimulated the need and desire for theoretical methods to describe these and other dynamical processes in molecular systems. Chemical dynamics theory has made great strides in the ensuing decades, so that methods are now available for treating the quantum dynamics of small molecular systems essentially completely. For the large molecular systems that are of so much interest nowadays (e.g. chemical reactions in solution, in clusters, in nano-structures, in biological systems, etc.), however, the only generally available theoretical approach is classical molecular dynamics (MD) simulations. Much effort is currently being devoted to the development of approaches for describing the quantum dynamics of these complex systems. This paper reviews some of these approaches, especially the use of semiclassical approximations for adding quantum effects to classical MD simulations, also showing some new versions that should make these semiclassical approaches even more practical and accurate.

  8. Stability of Complex Biomolecular Structures: van der Waals, Hydrogen Bond Cooperativity, and Nuclear Quantum Effects.

    PubMed

    Rossi, Mariana; Fang, Wei; Michaelides, Angelos

    2015-11-05

    Biomolecules are complex systems stabilized by a delicate balance of weak interactions, making it important to assess all energetic contributions in an accurate manner. However, it is a priori unclear which contributions make more of an impact. Here, we examine stacked polyglutamine (polyQ) strands, a peptide repeat often found in amyloid aggregates. We investigate the role of hydrogen bond (HB) cooperativity, van der Waals (vdW) dispersion interactions, and quantum contributions to free energies, including anharmonicities through density functional theory and ab initio path integral simulations. Of these various factors, we find that the largest impact on structural stabilization comes from vdW interactions. HB cooperativity is the second largest contribution as the size of the stacked chain grows. Competing nuclear quantum effects make the net quantum contribution small but very sensitive to anharmonicities, vdW, and the number of HBs. Our results suggest that a reliable treatment of these systems can only be attained by considering all of these components.

  9. Unsupervised Discriminant Analysis Based on the Local and Non-local Mean

    NASA Astrophysics Data System (ADS)

    Chen, Caikou; Shi, Jun; Huang, Pu

    Considering the performance of unsupervised discriminant projections (UDP) is gravely influenced by outliers, especially in small training sample size situation, a novel method called unsupervised discriminant analysis (UDA) based on the local and non-local mean for feature extraction is proposed in this paper, which is robust to outliers. It utilizes the local and non-local mean to construct the local and non-local scatter, to some extent, overcomes the discriminant difficulty caused by outliers. Besides, LUDA is computationally more efficient than UDP. Experimental results on ORL, YALE and AR face image databases show that the proposed UDA is more efficient and effective than UDP.

  10. Unexpected non-local effects in dual-probe-sideband BOTDA

    NASA Astrophysics Data System (ADS)

    Dominguez-Lopez, Alejandro; Angulo-Vinuesa, Xabier; Lopez-Gil, Alexia; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2015-09-01

    Until now, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems have been considered negligible if the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. In this paper, we show the appearance of non-local effects even below the SBS threshold. The pump pulse experiences a frequency dependent spectral deformation that affects the readout process differently in the gain and loss configurations. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. These results are of particular interest for manufacturers of long-range BOTDA systems.

  11. Quantum statistical vibrational entropy and enthalpy of formation of helium-vacancy complex in BCC W

    NASA Astrophysics Data System (ADS)

    Wen, Haohua; Woo, C. H.

    2016-12-01

    High-temperature advance-reactor design and operation require knowledge of in-reactor materials properties far from the thermal ground state. Temperature-dependence due to the effects of lattice vibrations is important to the understanding and formulation of atomic processes involved in irradiation-damage accumulation. In this paper, we concentrate on the formation of He-V complex. The free-energy change in this regard is derived via thermodynamic integration from the phase-space trajectories generated from MD simulations based on the quantum fluctuation-dissipation relation. The change of frequency distribution of vibration modes during the complex formation is properly accounted for, and the corresponding entropy change avoids the classical ln(T) divergence that violates the third law. The vibrational enthalpy and entropy of formation calculated this way have significant effects on the He kinetics during irradiation.

  12. Excitonic complexes in GaN/(Al,Ga)N quantum dots

    NASA Astrophysics Data System (ADS)

    Elmaghraoui, D.; Triki, M.; Jaziri, S.; Muñoz-Matutano, G.; Leroux, M.; Martinez-Pastor, J.

    2017-03-01

    Here we report a theoretical investigation of excitonic complexes in polar GaN/(Al,Ga)N quantum dots (QDs). A sum rule between the binding energies of charged excitons is used to calculate the biexciton binding energy. The binding energies of excitonic complexes in GaN/AlN are shown to be strongly correlated to the QD size. Due to the large hole localization, the positively charged exciton energy is found to be always blueshifted compared to the exciton one. The negatively charged exciton and the biexciton energy can be blueshifted or redshifted according to the QD size. Increasing the size of GaN/AlN QDs makes the identification of charged excitons difficult, and the use of an Al0.5Ga0.5N barrier can be advantageous for clear identification. Our theoretical results for the binding energy of exciton complexes are also confronted with values deduced experimentally for InAs/GaAs QDs, confirming our theoretical prediction for charged excitonic complexes in GaN/(Al,Ga)N QDs. Finally, we realize that the trends of excitonic complexes in QDs are significantly related to competition between the local charge separation (whatever its origin) and the correlation effect. Following our findings, entangled photons pairs can be produced in QDs with careful control of their size in order to obtain zero exciton–biexciton energy separation.

  13. Physical realization of a quantum spin liquid based on a complex frustration mechanism

    NASA Astrophysics Data System (ADS)

    Balz, Christian; Lake, Bella; Reuther, Johannes; Luetkens, Hubertus; Schönemann, Rico; Herrmannsdörfer, Thomas; Singh, Yogesh; Nazmul Islam, A. T. M.; Wheeler, Elisa M.; Rodriguez-Rivera, Jose A.; Guidi, Tatiana; Simeoni, Giovanna G.; Baines, Chris; Ryll, Hanjo

    2016-10-01

    Unlike conventional magnets where the magnetic moments are partially or completely static in the ground state, in a quantum spin liquid they remain in collective motion down to the lowest temperatures. The importance of this state is that it is coherent and highly entangled without breaking local symmetries. In the case of magnets with isotropic interactions, spin-liquid behaviour is sought in simple lattices with antiferromagnetic interactions that favour antiparallel alignments of the magnetic moments and are incompatible with the lattice geometries. Despite an extensive search, experimental realizations remain very few. Here we investigate the novel, unexplored magnet Ca10Cr7O28, which has a complex Hamiltonian consisting of several different isotropic interactions and where the ferromagnetic couplings are stronger than the antiferromagnetic ones. We show both experimentally and theoretically that it displays all the features expected of a quantum spin liquid. Thus spin-liquid behaviour in isotropic magnets is not restricted to the simple idealized models currently investigated, but can be compatible with complex structures and ferromagnetic interactions.

  14. Non-local residue-residue contacts in proteins are more conserved than local ones.

    PubMed

    Noivirt-Brik, Orly; Hazan, Gershon; Unger, Ron; Ofran, Yanay

    2013-02-01

    Non-covalent residue-residue contacts drive the folding of proteins and stabilize them. They may be local-i.e. involve residues that are close in sequence, or non-local. It has been suggested that, in most proteins, local contacts drive protein folding by providing crucial constraints of the conformational space, thus allowing proteins to fold. We compared residues that are involved in local contacts to residues that are involved in non-local contacts and found that, in most proteins, residues in non-local contacts are significantly more conserved evolutionarily than residues in local contacts. Moreover, non-local contacts are more structurally conserved: a contact between positions that are distant in sequence is more likely to exist in many structural homologues compared with a contact between positions that are close in sequence. These results provide new insights into the mechanisms of protein folding and may allow for better prediction of critical intra-chain contacts.

  15. Single image super-resolution with non-local means and steering kernel regression.

    PubMed

    Zhang, Kaibing; Gao, Xinbo; Tao, Dacheng; Li, Xuelong

    2012-11-01

    Image super-resolution (SR) reconstruction is essentially an ill-posed problem, so it is important to design an effective prior. For this purpose, we propose a novel image SR method by learning both non-local and local regularization priors from a given low-resolution image. The non-local prior takes advantage of the redundancy of similar patches in natural images, while the local prior assumes that a target pixel can be estimated by a weighted average of its neighbors. Based on the above considerations, we utilize the non-local means filter to learn a non-local prior and the steering kernel regression to learn a local prior. By assembling the two complementary regularization terms, we propose a maximum a posteriori probability framework for SR recovery. Thorough experimental results suggest that the proposed SR method can reconstruct higher quality results both quantitatively and perceptually.

  16. Stability of Large-Scale Oceanic Flows and the Importance of Non-Local Effects

    DTIC Science & Technology

    2009-06-01

    2009-09 DOCTORAL DISSERTATION by Hristina G. Hristova June 2009 Stability of Large -Scale Oceanic Flows and the Importance of Non-Local Effects MIT...MITIWHOI 2009-09 Stability of Large -Scale Oceanic Flows and the Importance of Non-Local Effects by Hristina G. Hristova Massachusetts Institute of...part is permitted for any purpose of the United States Government. This thesis should be cited as: Hristina G. Hristova, 2009. Stability of Large -Scale

  17. Ultrasensitive fluorescence detection of heparin based on quantum dots and a functional ruthenium polypyridyl complex.

    PubMed

    Cao, Yanlin; Shi, Shuo; Wang, Linlin; Yao, Junliang; Yao, Tianming

    2014-05-15

    A new strategy for the detection of heparin is developed by utilizing quantum dots (QDs) and a functional ruthenium polypyridyl complex [Ru(phen)2(dppz-idzo)](2+) (phen=1,10-phenanthroline, dppz-idzo=dipyrido-[3,2-a:2',3'-c] phenazine-imidazolone). The emission of CdTe QDs is found to be quenched by Ru complex due to electron transfer. Upon addition of the polyanionic heparin, it could remove the quencher (Ru complex) from the surface of QDs owing to the electrostatic and/or hydrogen bonding interactions between heparin and Ru complex, which led to significant fluorescence recovery of CdTe QDs. The fluorescence intensity enhanced with the increase of heparin and a linear relationship was observed in the range of 21-77 nM for heparin detection in buffer solution and the limit of detection (LOD) is 0.38 nM. Moreover, the strategy was successfully applied to detect heparin as low as 0.68 nM with a linear range of 35-98 nM in fetal bovine serum samples. The selectivity results of the fluorescence assay revealed that our system displayed excellent fluorescence selectivity towards heparin over its analogues, such as chondroitin 4-sulfate (Chs) or hyaluronic acid (Hya). This fluorescence "switch on" assay for heparin is label-free, convenient, sensitive and selective, which can be used to detect heparin in biological systems even with the naked eyes.

  18. Circular dichroism spectroscopy of chlorin e6 and its complexes with quantum dots in different media

    NASA Astrophysics Data System (ADS)

    Kundelev, E. V.; Orlova, A. O.; Maslov, V. G.; Baranov, A. V.; Fedorov, A. V.

    2017-01-01

    The circular dichroism (CD) spectra of chlorin e6 and its complexes with ZnS:Mn/ZnS and CdSe/ZnS quantum dots (QDs) in aqueous solutions with different pH, in methanol, and in dimethyl sulfoxide (DMSO) have been experimentally investigated. The changes in the CD spectra of free chlorin e6 caused by its complexing with semiconductor QDs are analyzed. The application of CD spectroscopy made it possible to record for the first time the CD spectrum of luminescent dimer of chlorin e6 and reveal a nonluminescent aggregate of chlorin e6 (interpreted preliminary as a "tetramer"), the anisotropy factor of which exceeds that of its monomer by a factor of 40. An analysis of the experimental data shows that chlorin e6 in a complex with QDs can be either in the monomeric form or in the form of a nonluminescent "tetramer." The interaction with a relatively low-stable luminescent dimer of chlorin e6 with QDs leads to its partial monomerization and formation of complexes where chlorin e6 is in the monomeric form.

  19. Characteristics of the complexing of chitosan with sodium dodecyl sulfate, according to IR spectroscopy data and quantum-chemical calculations

    NASA Astrophysics Data System (ADS)

    Shilova, S. V.; Romanova, K. A.; Galyametdinov, Yu. G.; Tret'yakova, A. Ya.; Barabanov, V. P.

    2016-06-01

    The complexing of protonated chitosan with dodecyl sulfate ions in water solutions is studied using IR spectroscopy data and quantum-chemical calculations. It is established that the electrostatic interaction between the protonated amino groups of chitosan and dodecyl sulfate ions is apparent in the IR spectrum as a band at 833 cm-1. The need to consider the effect the solvent has on the formation of hydrogen-bound ion pairs [CTS+ ṡ C12H25O 3 - ] is shown via a quantum-chemical simulation of the equilibrium geometry and the energy characteristics of complexing and hydration.

  20. Droplet etching of deep nanoholes for filling with self-aligned complex quantum structures

    NASA Astrophysics Data System (ADS)

    Küster, Achim; Heyn, Christian; Ungeheuer, Arne; Juska, Gediminas; Tommaso Moroni, Stefano; Pelucchi, Emanuele; Hansen, Wolfgang

    2016-06-01

    Strain-free epitaxial quantum dots (QDs) are fabricated by a combination of Al local droplet etching (LDE) of nanoholes in AlGaAs surfaces and subsequent hole filling with GaAs. The whole process is performed in a conventional molecular beam epitaxy (MBE) chamber. Autocorrelation measurements establish single-photon emission from LDE QDs with a very small correlation function g (2)(0)≃ 0.01 of the exciton emission. Here, we focus on the influence of the initial hole depth on the QD optical properties with the goal to create deep holes suited for filling with more complex nanostructures like quantum dot molecules (QDM). The depth of droplet etched nanoholes is controlled by the droplet material coverage and the process temperature, where a higher coverage or temperature yields deeper holes. The requirements of high quantum dot uniformity and narrow luminescence linewidth, which are often found in applications, set limits to the process temperature. At high temperatures, the hole depths become inhomogeneous and the linewidth rapidly increases beyond 640 °C. With the present process technique, we identify an upper limit of 40-nm hole depth if the linewidth has to remain below 100 μeV. Furthermore, we study the exciton fine-structure splitting which is increased from 4.6 μeV in 15-nm-deep to 7.9 μeV in 35-nm-deep holes. As an example for the functionalization of deep nanoholes, self-aligned vertically stacked GaAs QD pairs are fabricated by filling of holes with 35 nm depth. Exciton peaks from stacked dots show linewidths below 100 μeV which is close to that from single QDs.

  1. Droplet etching of deep nanoholes for filling with self-aligned complex quantum structures.

    PubMed

    Küster, Achim; Heyn, Christian; Ungeheuer, Arne; Juska, Gediminas; Tommaso Moroni, Stefano; Pelucchi, Emanuele; Hansen, Wolfgang

    2016-12-01

    Strain-free epitaxial quantum dots (QDs) are fabricated by a combination of Al local droplet etching (LDE) of nanoholes in AlGaAs surfaces and subsequent hole filling with GaAs. The whole process is performed in a conventional molecular beam epitaxy (MBE) chamber. Autocorrelation measurements establish single-photon emission from LDE QDs with a very small correlation function g ((2))(0)≃ 0.01 of the exciton emission. Here, we focus on the influence of the initial hole depth on the QD optical properties with the goal to create deep holes suited for filling with more complex nanostructures like quantum dot molecules (QDM). The depth of droplet etched nanoholes is controlled by the droplet material coverage and the process temperature, where a higher coverage or temperature yields deeper holes. The requirements of high quantum dot uniformity and narrow luminescence linewidth, which are often found in applications, set limits to the process temperature. At high temperatures, the hole depths become inhomogeneous and the linewidth rapidly increases beyond 640 °C. With the present process technique, we identify an upper limit of 40-nm hole depth if the linewidth has to remain below 100 μeV. Furthermore, we study the exciton fine-structure splitting which is increased from 4.6 μeV in 15-nm-deep to 7.9 μeV in 35-nm-deep holes. As an example for the functionalization of deep nanoholes, self-aligned vertically stacked GaAs QD pairs are fabricated by filling of holes with 35 nm depth. Exciton peaks from stacked dots show linewidths below 100 μeV which is close to that from single QDs.

  2. Complexes of photosensitizer and CdSe/ZnS quantum dots passivated with BSA: optical properties and intracomplex energy transfer

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Vera; Orlova, Anna; Martynenko, Irina; Kundelev, Evgeny; Maslov, Vladimir; Fedorov, Anatoly; Baranov, Alexander; Gun'ko, Yurii

    2016-04-01

    Here we report our investigations of the formation conditions and photophysical properties of complexes between luminescent semiconducting nanoparticles (quantum dots, QDs) and the photosensitizer chlorin e6, which is widely used for the photodynamic therapy. In our complexes, bovine serum albumin (BSA), the most abundant protein in blood serum, was used as a linker between QDs and chlorin e6 molecules. The influence of BSA on the optical properties of Ce6 and QDs in complexes was properly examined using spectral-luminescent methods. It was found that BSA passivated QD surface and substantially QD quantum yield of luminescence was increased. In addition, BSA prevented the aggregation of chlorin e6 molecules in complexes with QDs. We demonstrated that the use of BSA as a linker allows to create functional QD-chlorin e6 complexes with effective photoexcitation energy transfer from QDs to the molecules.

  3. Toward extending photosynthetic biosignatures: quantum dynamics calculation of light harvesting complexes

    NASA Astrophysics Data System (ADS)

    Komatsu, Yu; Umemura, Masayuki; Shoji, Mitsuo; Kayanuma, Megumi; Yabana, Kazuhiro; Shiraishi, Kenji

    For detecting life from reflectance spectra on extrasolar planets, several indicators called surface biosignatures have been proposed. One of them is the vegetation red edge (VRE) which derives from surface vegetation. VRE is observed in 700-750 nm on the Earth, but there is no guarantee that exovegetation show the red edge in this wavelength. Therefore it is necessary to check the validity of current standards of VRE as the signatures. In facts, M stars (cooler than Sun) will be the main targets in future missions, it is significantly important to know on the fundamental mechanisms in photosynthetic organism such as purple bacteria which absorb longer wavelength radiation. We investigated light absorptions and excitation energy transfers (EETs) in light harvesting complexes in purple bacteria (LH2s) by using quantum dynamics simulations. In LH2, effective EET is accomplished by corporative electronic excitation of the pigments. In our theoretical model, a dipole-dipole approximation was used for the electronic interactions between pigment excitations. Quantum dynamics simulations were performed according to Liouville equation to examine the EET process. The calculated oscillator strength and the transfer time between LH2 were good agreement with the experimental values. As the system size increases, the absorption bands shifted longer and the transfer velocities became larger. When two pigments in a LHC were exchanged to another pigments with lower excitation energy, faster and intensive light collection were observed.

  4. Non-local dynamics governing the self-induced motion of a planar vortex filament

    NASA Astrophysics Data System (ADS)

    Van Gorder, Robert A.

    2015-06-01

    While the Hasimoto planar vortex filament is one of the few exact solutions to the local induction approximation (LIA) approximating the self-induced motion of a vortex filament, it is natural to wonder whether such a vortex filament solution would exist for the non-local Biot-Savart dynamics exactly governing the filament motion, and if so, whether the non-local effects would drastically modify the solution properties. Both helical vortex filaments and vortex rings are known to exist under both the LIA and non-local Biot-Savart dynamics; however, the planar filament is a bit more complicated. In the present paper, we demonstrate that a planar vortex filament solution does exist for the non-local Biot-Savart formulation, provided that a specific non-linear integral equation (governing the spatial structure of such a filament) has a non-trivial solution. By using the Poincaré-Lindstedt method, we are able to obtain an accurate analytical approximation to the solution of this integral equation under physically reasonable assumptions. To obtain these solutions, we approximate local effects near the singularity of the integral equation using the LIA and non-local effects using the Biot-Savart formulation. Mathematically, the results constitute an analytical solution to an interesting nonlinear singular integro-differential equation in space and time variables. Physically, these results show that planar vortex filaments exist and maintain their forms under the non-local Biot-Savart formulation, as one would hope. Due to the regularization approach utilized, we are able to compare the structure of the planar filaments obtained under both LIA and Biot-Savart formulations in a rather straightforward manner, in order to determine the role of the non-locality on the structure of the planar filament.

  5. Non-local bias contribution to third-order galaxy correlations

    NASA Astrophysics Data System (ADS)

    Bel, J.; Hoffmann, K.; Gaztañaga, E.

    2015-10-01

    We study halo clustering bias with second- and third-order statistics of halo and matter density fields in the Marenostrum Institut de Ciències de l'Espai (MICE) Grand Challenge simulation. We verify that two-point correlations deliver reliable estimates of the linear bias parameters at large scales, while estimations from the variance can be significantly affected by non-linear and possibly non-local contributions to the bias function. Combining three-point auto- and cross-correlations we find, for the first time in configuration space, evidence for the presence of such non-local contributions. These contributions are consistent with predicted second-order non-local effects on the bias functions originating from the dark matter tidal field. Samples of massive haloes show indications of bias (local or non-local) beyond second order. Ignoring non-local bias causes 20-30 and 5-10 per cent overestimation of the linear bias from three-point auto- and cross-correlations, respectively. We study two third-order bias estimators that are not affected by second-order non-local contributions. One is a combination of three-point auto- and cross-correlations. The other is a combination of third-order one- and two-point cumulants. Both methods deliver accurate estimations of the linear bias. Ignoring non-local bias causes higher values of the second-order bias from three-point correlations. Our results demonstrate that third-order statistics can be employed for breaking the growth-bias degeneracy.

  6. Origin of long-lived quantum coherence and excitation dynamics in pigment-protein complexes

    NASA Astrophysics Data System (ADS)

    Zhang, Zhedong; Wang, Jin

    2016-11-01

    We explore the mechanism for the long-lived quantum coherence by considering the discrete phonon modes: these vibrational modes effectively weaken the exciton-environment interaction, due to the new composite (polaron) formed by excitons and vibrons. This subsequently demonstrates the role of vibrational coherence which greatly contributes to long-lived feature of the excitonic coherence that has been observed in femtosecond experiments. The estimation of the timescale of coherence elongated by vibrational modes is given in an analytical manner. To test the validity of our theory, we study the pigment-protein complex in detail by exploring the energy transfer and coherence dynamics. The ground-state vibrational coherence generated by incoherent radiations is shown to be long-survived and is demonstrated to be significant in promoting the excitation energy transfer. This is attributed to the nonequilibriumness of the system caused by the detailed-balance-breaking, which funnels the downhill migration of excitons.

  7. Origin of long-lived quantum coherence and excitation dynamics in pigment-protein complexes

    PubMed Central

    Zhang, Zhedong; Wang, Jin

    2016-01-01

    We explore the mechanism for the long-lived quantum coherence by considering the discrete phonon modes: these vibrational modes effectively weaken the exciton-environment interaction, due to the new composite (polaron) formed by excitons and vibrons. This subsequently demonstrates the role of vibrational coherence which greatly contributes to long-lived feature of the excitonic coherence that has been observed in femtosecond experiments. The estimation of the timescale of coherence elongated by vibrational modes is given in an analytical manner. To test the validity of our theory, we study the pigment-protein complex in detail by exploring the energy transfer and coherence dynamics. The ground-state vibrational coherence generated by incoherent radiations is shown to be long-survived and is demonstrated to be significant in promoting the excitation energy transfer. This is attributed to the nonequilibriumness of the system caused by the detailed-balance-breaking, which funnels the downhill migration of excitons. PMID:27876861

  8. Optical properties in complex-structured nanometric quantum wells: Photoluminescence, photoluminescence excitation, and Stokes shift

    NASA Astrophysics Data System (ADS)

    Silva, A. A. P.; Vasconcellos, Áurea. R.; Luzzi, Roberto; Meneses, E. A.; Laureto, E.

    2009-10-01

    Systems in which one or more directions are in the nanometric space scale exhibit significantly some peculiar phenomena and processes. We consider here the case of nanometric quantum wells with complex structure, displaying fractal-like characteristics, which are part of semiconductor heterostructures. An extensive theoretical study of the optical properties of photoluminescence and excited photoluminescence, and then involving absorption and the question of emergence of the so-called Stokes shift that is observed in some cases are performed. The results are compared with some experimental data. This is of relevance for opening up the possibility to use optical measurements to perform a (nondestructive) quality control of samples grown under different methods and protocols.

  9. Probing degradation in complex engineering silicones by 1H multiple quantum NMR

    SciTech Connect

    Maxwell, R S; Chinn, S C; Giuliani, J; Herberg, J L

    2007-09-05

    Static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR) has recently been shown to provide detailed insight into the network structure of pristine silicon based polymer systems. The MQ NMR method characterizes the residual dipolar couplings of the silicon chains that depend on the average molecular weight between physical or chemical constraints. Recently, we have employed MQ NMR methods to characterize the changes in network structure in a series of complex silicone materials subject to numerous degradation mechanisms, including thermal, radiative, and desiccative. For thermal degradation, MQ NMR shows that a combination of crosslinking due to post-curing reactions as well as random chain scissioning reactions occurs. For radiative degradation, the primary mechanisms are via crosslinking both in the network and at the interface between the polymer and the inorganic filler. For samples stored in highly desiccating environments, MQ NMR shows that the average segmental dynamics are slowed due to increased interactions between the filler and the network polymer chains.

  10. Energy-scales convergence for optimal and robust quantum transport in photosynthetic complexes.

    PubMed

    Mohseni, M; Shabani, A; Lloyd, S; Rabitz, H

    2014-01-21

    Underlying physical principles for the high efficiency of excitation energy transfer in light-harvesting complexes are not fully understood. Notably, the degree of robustness of these systems for transporting energy is not known considering their realistic interactions with vibrational and radiative environments within the surrounding solvent and scaffold proteins. In this work, we employ an efficient technique to estimate energy transfer efficiency of such complex excitonic systems. We observe that the dynamics of the Fenna-Matthews-Olson (FMO) complex leads to optimal and robust energy transport due to a convergence of energy scales among all important internal and external parameters. In particular, we show that the FMO energy transfer efficiency is optimum and stable with respect to important parameters of environmental interactions including reorganization energy λ, bath frequency cutoff γ, temperature T, and bath spatial correlations. We identify the ratio of kBλT/ℏγ⁢g as a single key parameter governing quantum transport efficiency, where g is the average excitonic energy gap.

  11. Energy-scales convergence for optimal and robust quantum transport in photosynthetic complexes

    SciTech Connect

    Mohseni, M.; Shabani, A.; Lloyd, S.; Rabitz, H.

    2014-01-21

    Underlying physical principles for the high efficiency of excitation energy transfer in light-harvesting complexes are not fully understood. Notably, the degree of robustness of these systems for transporting energy is not known considering their realistic interactions with vibrational and radiative environments within the surrounding solvent and scaffold proteins. In this work, we employ an efficient technique to estimate energy transfer efficiency of such complex excitonic systems. We observe that the dynamics of the Fenna-Matthews-Olson (FMO) complex leads to optimal and robust energy transport due to a convergence of energy scales among all important internal and external parameters. In particular, we show that the FMO energy transfer efficiency is optimum and stable with respect to important parameters of environmental interactions including reorganization energy λ, bath frequency cutoff γ, temperature T, and bath spatial correlations. We identify the ratio of k{sub B}λT/ℏγ⁢g as a single key parameter governing quantum transport efficiency, where g is the average excitonic energy gap.

  12. Characterization of citrate capped gold nanoparticle-quercetin complex: Experimental and quantum chemical approach

    NASA Astrophysics Data System (ADS)

    Pal, Rajat; Panigrahi, Swati; Bhattacharyya, Dhananjay; Chakraborti, Abhay Sankar

    2013-08-01

    Quercetin and several other bioflavonoids possess antioxidant property. These biomolecules can reduce the diabetic complications, but metabolize very easily in the body. Nanoparticle-mediated delivery of a flavonoid may further increase its efficacy. Gold nanoparticle is used by different groups as vehicle for drug delivery, as it is least toxic to human body. Prior to search for the enhanced efficacy, the gold nanoparticle-flavonoid complex should be prepared and well characterized. In this article, we report the interaction of gold nanoparticle with quercetin. The interaction is confirmed by different biophysical techniques, such as Scanning Electron Microscope (SEM), Circular Dichroism (CD), Fourier-Transform InfraRed (FT-IR) spectroscopy and Thermal Gravimetric Analysis (TGA) and cross checked by quantum chemical calculations. These studies indicate that gold clusters are covered by citrate groups, which are hydrogen bonded to the quercetin molecules in the complex. We have also provided evidences how capping is important in stabilizing the gold nanoparticle and further enhances its interaction with other molecules, such as drugs. Our finding also suggests that gold nanoparticle-quercetin complex can pass through the membranes of human red blood cells.

  13. Bio serves nano: biological light-harvesting complex as energy donor for semiconductor quantum dots.

    PubMed

    Werwie, Mara; Xu, Xiangxing; Haase, Mathias; Basché, Thomas; Paulsen, Harald

    2012-04-03

    Light-harvesting complex (LHCII) of the photosynthetic apparatus in plants is attached to type-II core-shell CdTe/CdSe/ZnS nanocrystals (quantum dots, QD) exhibiting an absorption band at 710 nm and carrying a dihydrolipoic acid coating for water solubility. LHCII stays functional upon binding to the QD surface and enhances the light utilization of the QDs significantly, similar to its light-harvesting function in photosynthesis. Electronic excitation energy transfer of about 50% efficiency is shown by donor (LHCII) fluorescence quenching as well as sensitized acceptor (QD) emission and corroborated by time-resolved fluorescence measurements. The energy transfer efficiency is commensurable with the expected efficiency calculated according to Förster theory on the basis of the estimated donor-acceptor separation. Light harvesting is particularly efficient in the red spectral domain where QD absorption is relatively low. Excitation over the entire visible spectrum is further improved by complementing the biological pigments in LHCII with a dye attached to the apoprotein; the dye has been chosen to absorb in the "green gap" of the LHCII absorption spectrum and transfers its excitation energy ultimately to QD. This is the first report of a biological light-harvesting complex serving an inorganic semiconductor nanocrystal. Due to the charge separation between the core and the shell in type-II QDs the presented LHCII-QD hybrid complexes are potentially interesting for sensitized charge-transfer and photovoltaic applications.

  14. A mixed quantum-classical description of excitation energy transfer in supramolecular complexes: Förster theory and beyond.

    PubMed

    Megow, Jörg; Röder, Beate; Kulesza, Alexander; Bonačić-Koutecký, Vlasta; May, Volkhard

    2011-02-25

    Electronic excitation energy transfer (EET) is described theoretically for the chromophore complex P(4) formed by a butanediamine dendrimer to which four pheophorbide-a molecules are covalently linked. To achieve a description with atomic resolution, and to account for the effect of an ethanol solvent, a mixed quantum-classical methodology is utilized. Room-temperature molecular dynamics simulations are used to describe the nuclear dynamics, and EET is accounted for in utilizing a mixed quantum-classical formulation of the transition rates. Therefore, the full quantum expression of the EET rates is given and the change to a mixed quantum-classical version is briefly explained. The description results in the calculation of transition rates which coincide rather satisfactory with available experimental data on P(4). It is also shown that different assumptions of classical Förster theory are not valid for P(4). The temporal behavior of EET deduced from the rate equations is confronted with that following from the solution of the time-dependent Schrödinger equation entering the mixed quantum-classical description of EET. From this we can conclude that EET in flexible chromophore complexes such as P(4) can be rather satisfactory estimated by single transition rates. A correct description, however, is only achievable by using a sufficiently large set of rates that correspond to the various possible equilibrium configurations of the complex.

  15. Crossed Andreev Reflection and Spin-Resolved Non-local Electron Transport

    NASA Astrophysics Data System (ADS)

    Kalenkov, Mikhail S.; Zaikin, Andrei D.

    The phenomenon of crossed Andreev reflection (CAR) is known to play a key role in non-local electron transport across three-terminal normal-superconducting-normal (NSN) devices. Here, we review our general theory of non-local charge transport in three-terminal disordered ferromagnet-superconductor-ferromagnet (FSF) structures. We demonstrate that CAR is highly sensitive to electron spins and yields a rich variety of properties of non-local conductance, which we describe non-perturbatively at arbitrary voltages, temperature, degree of disorder, spin-dependent interface transmissions and their polarizations. We demonstrate that magnetic effects have different implications: While strong exchange field suppresses disorder-induced electron interference in ferromagnetic electrodes, spin-sensitive electron scattering at SF interfaces can drive the total non-local conductance negative at sufficiently low energies. At higher energies, magnetic effects become less important and the non-local resistance behaves similarly to the non-magnetic case. Our results can be applied to multi-terminal hybrid structures with normal, ferromagnetic and half-metallic electrodes and can be directly tested in future experiments.

  16. PREFACE: DICE 2008 - From Quantum Mechanics through Complexity to Spacetime: the role of emergent dynamical structures

    NASA Astrophysics Data System (ADS)

    Diósi, Lajos; Elze, Hans-Thomas; Fronzoni, Leone; Halliwell, Jonathan; Vitiello, Giuseppe

    2009-07-01

    These proceedings present the Invited Lectures and Contributed Papers of the Fourth International Workshop on Decoherence, Information, Complexity and Entropy - DICE 2008, held at Castello Pasquini, Castiglioncello (Tuscany), 22-26 September 2008. We deliver these proceedings as a means to document to the interested public, to the wider scientific community, and to the participants themselves the stimulating exchange of ideas at this conference. The steadily growing number of participants, among them acclaimed scientists in their respective fields, show its increasing attraction and a fruitful concept, based on bringing leading researchers together and in contact with a mix of advanced students and scholars. Thus, this series of meetings successfully continued from the beginning with DICE 2002, (Decoherence and Entropy in Complex Systems ed H-T Elze Lecture Notes in Physics 633 (Berlin: Springer, 2004)) followed by DICE 2004 (Proceedings of the Second International Workshop on Decoherence, Information, Complexity and Entropy - DICE 2004 ed H-T Elze Braz. Journ. Phys. 35, 2A & 2B (2005) pp 205-529 free access at: www.sbfisica.org.br/bjp) and by DICE 2006, (Proceedings of the Third International Workshop on Decoherence, Information, Complexity and Entropy - DICE 2006 eds H-T Elze, L Diósi and G Vitiello Journal of Physics: Conference Series 67 (2007); free access at: http://www.iop.org/EJ/toc/1742-6596/67/1) uniting about one hundred participants from more than twenty different countries worldwide this time. It has been a great honour and inspiration for all of us to have Professor Sir Roger Penrose from the Mathematical Institute at the University of Oxford with us, who presented the lecture ``Black holes, quantum theory and cosmology'' (included in this volume). Discussions under the wider theme ``From Quantum Mechanics through Complexity to Spacetime: the role of emergent dynamical structures'' took place in the very pleasant and inspiring atmosphere of Castello

  17. Parameters for the RM1 Quantum Chemical Calculation of Complexes of the Trications of Thulium, Ytterbium and Lutetium.

    PubMed

    Filho, Manoel A M; Dutra, José Diogo L; Rocha, Gerd B; Simas, Alfredo M; Freire, Ricardo O

    2016-01-01

    The RM1 quantum chemical model for the calculation of complexes of Tm(III), Yb(III) and Lu(III) is advanced. Subsequently, we tested the models by fully optimizing the geometries of 126 complexes. We then compared the optimized structures with known crystallographic ones from the Cambridge Structural Database. Results indicate that, for thulium complexes, the accuracy in terms of the distances between the lanthanide ion and its directly coordinated atoms is about 2%. Corresponding results for ytterbium and lutetium are both 3%, levels of accuracy useful for the design of lanthanide complexes, targeting their countless applications.

  18. Parameters for the RM1 Quantum Chemical Calculation of Complexes of the Trications of Thulium, Ytterbium and Lutetium

    PubMed Central

    Filho, Manoel A. M.; Dutra, José Diogo L.; Rocha, Gerd B.; Simas, Alfredo M.

    2016-01-01

    The RM1 quantum chemical model for the calculation of complexes of Tm(III), Yb(III) and Lu(III) is advanced. Subsequently, we tested the models by fully optimizing the geometries of 126 complexes. We then compared the optimized structures with known crystallographic ones from the Cambridge Structural Database. Results indicate that, for thulium complexes, the accuracy in terms of the distances between the lanthanide ion and its directly coordinated atoms is about 2%. Corresponding results for ytterbium and lutetium are both 3%, levels of accuracy useful for the design of lanthanide complexes, targeting their countless applications. PMID:27223475

  19. AIScore chemically diverse empirical scoring function employing quantum chemical binding energies of hydrogen-bonded complexes.

    PubMed

    Raub, Stephan; Steffen, Andreas; Kämper, Andreas; Marian, Christel M

    2008-07-01

    In this work we report on a novel scoring function that is based on the LUDI model and focuses on the prediction of binding affinities. AIScore extends the original FlexX scoring function using a chemically diverse set of hydrogen-bonded interactions derived from extensive quantum chemical ab initio calculations. Furthermore, we introduce an algorithmic extension for the treatment of multifurcated hydrogen bonds (XFurcate). Charged and resonance-assisted hydrogen bond energies and hydrophobic interactions as well as a scaling factor for implicit solvation were fitted to experimental data. To this end, we assembled a set of 101 protein-ligand complexes with known experimental binding affinities. Tightly bound water molecules in the active site were considered to be an integral part of the binding pocket. Compared to the original FlexX scoring function, AIScore significantly improves the prediction of the binding free energies of the complexes in their native crystal structures. In combination with XFurcate, AIScore yields a Pearson correlation coefficient of R P = 0.87 on the training set. In a validation run on the PDBbind test set we achieved an R P value of 0.46 for 799 attractively scored complexes, compared to a value of R P = 0.17 and 739 bound complexes obtained with the FlexX original scoring function. The redocking capability of AIScore, on the other hand, does not fully reach the good performance of the original FlexX scoring function. This finding suggests that AIScore should rather be used for postscoring in combination with the standard FlexX incremental ligand construction scheme.

  20. Human development VIII: a theory of "deep" quantum chemistry and cell consciousness: quantum chemistry controls genes and biochemistry to give cells and higher organisms consciousness and complex behavior.

    PubMed

    Ventegodt, Søren; Hermansen, Tyge Dahl; Flensborg-Madsen, Trine; Nielsen, Maj Lyck; Merrick, Joav

    2006-11-14

    Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it "sees", and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occam's razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules' orbitals make one huge "cell-orbital", which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants) and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness.

  1. A new model for the prediction of turbofan noise with the effect of locally and non-locally reacting liners

    NASA Astrophysics Data System (ADS)

    Sun, Xiaofeng; Wang, Xiaoyu; Du, Lin; Jing, Xiaodong

    2008-09-01

    This paper presents a unified model to study the effect of both locally and non-locally reacting liners on the sound radiation generated by fan blade rotating sources. This model is set up by the following steps. First, the spinning mode eigenfunction expansions are used to obtain the solution of sound field inside the duct, while the effect of duct liner is modeled by distributed monopole sources, thus effectively avoiding the solution of a difficult complex eigenvalue problem. Secondly, in order to avoid the estimation of the generalized impedances at the inlet and exhaust planes, a boundary element method is used to give the solution outside the duct. With the suitable boundary conditions imposed on the inlet and exhaust planes, a matrix equation is obtained, and the relevant numerical calculation shows this model can not only give a good agreement with existing results for locally reacting liner but also has a capability to predict the sound radiation from fan rotating blade sources with an arbitrary combination of locally and non-locally reacting liners.

  2. Probing the structural and dynamical properties of liquid water with models including non-local electron correlation

    SciTech Connect

    Del Ben, Mauro Hutter, Jürg; VandeVondele, Joost

    2015-08-07

    Water is a ubiquitous liquid that displays a wide range of anomalous properties and has a delicate structure that challenges experiment and simulation alike. The various intermolecular interactions that play an important role, such as repulsion, polarization, hydrogen bonding, and van der Waals interactions, are often difficult to reproduce faithfully in atomistic models. Here, electronic structure theories including all these interactions at equal footing, which requires the inclusion of non-local electron correlation, are used to describe structure and dynamics of bulk liquid water. Isobaric-isothermal (NpT) ensemble simulations based on the Random Phase Approximation (RPA) yield excellent density (0.994 g/ml) and fair radial distribution functions, while various other density functional approximations produce scattered results (0.8-1.2 g/ml). Molecular dynamics simulation in the microcanonical (NVE) ensemble based on Møller-Plesset perturbation theory (MP2) yields dynamical properties in the condensed phase, namely, the infrared spectrum and diffusion constant. At the MP2 and RPA levels of theory, ice is correctly predicted to float on water, resolving one of the anomalies as resulting from a delicate balance between van der Waals and hydrogen bonding interactions. For several properties, obtaining quantitative agreement with experiment requires correction for nuclear quantum effects (NQEs), highlighting their importance, for structure, dynamics, and electronic properties. A computed NQE shift of 0.6 eV for the band gap and absorption spectrum illustrates the latter. Giving access to both structure and dynamics of condensed phase systems, non-local electron correlation will increasingly be used to study systems where weak interactions are of paramount importance.

  3. A Transport Model for Non-Local Heating of Electrons in ICP Reactors

    NASA Technical Reports Server (NTRS)

    Chang, C. H.; Bose, Deepak; Arnold, James O. (Technical Monitor)

    1998-01-01

    A new model has been developed for non-local heating of electrons in ICP reactors, based on a hydrodynamic approach. The model has been derived using the electron momentum conservation in azimuthal direction with electromagnetic and frictional forces respectively as driving force and damper of harmonic oscillatory motion of electrons. The resulting transport equations include the convection of azimuthal electron momentum in radial and axial directions, thereby accounting for the non-local effects. The azimuthal velocity of electrons and the resulting electrical current are coupled to the Maxwell's relations, thus forming a self-consistent model for non-local heating. This model is being implemented along with a set of Navier-Stokes equations for plasma dynamics and gas flow to simulate low-pressure (few mTorr's) ICP discharges. Characteristics of nitrogen plasma in a TCP 300mm etch reactor is being studied. The results will be compared against the available Langmuir probe measurements.

  4. Pion-to-Photon Transition Distribution Amplitudes in the Non-Local Chiral Quark Model

    NASA Astrophysics Data System (ADS)

    Kotko, P.; Praszałowicz, M.

    2009-01-01

    We apply the non-local chiral quark model to study vector and axial pion-to-photon transition amplitudes that are needed as a nonperturbative input to estimate the cross-section of pion annihilation into the real and virtual photon. We use a simple form of the non-locality that allows to perform all calculations in the Minkowski space and guaranties polynomiality of the TDAs. We note only residual dependence on the precise form of the cut-off function, however vector TDA that is symmetric in skewedness parameter in the local quark model is no longer symmetric in the non-local case. We calculate also the transition form-factors and compare them with existing experimental parametrizations.

  5. A shifted Jacobi collocation algorithm for wave type equations with non-local conservation conditions

    NASA Astrophysics Data System (ADS)

    Doha, Eid H.; Bhrawy, Ali H.; Abdelkawy, Mohammed A.

    2014-09-01

    In this paper, we propose an efficient spectral collocation algorithm to solve numerically wave type equations subject to initial, boundary and non-local conservation conditions. The shifted Jacobi pseudospectral approximation is investigated for the discretization of the spatial variable of such equations. It possesses spectral accuracy in the spatial variable. The shifted Jacobi-Gauss-Lobatto (SJ-GL) quadrature rule is established for treating the non-local conservation conditions, and then the problem with its initial and non-local boundary conditions are reduced to a system of second-order ordinary differential equations in temporal variable. This system is solved by two-stage forth-order A-stable implicit RK scheme. Five numerical examples with comparisons are given. The computational results demonstrate that the proposed algorithm is more accurate than finite difference method, method of lines and spline collocation approach

  6. Hepatic vessel segmentation using variational level set combined with non-local robust statistics.

    PubMed

    Lu, Siyu; Huang, Hui; Liang, Ping; Chen, Gang; Xiao, Liang

    2017-02-01

    Hepatic vessel segmentation is a challenging step in therapy guided by magnetic resonance imaging (MRI). This paper presents an improved variational level set method, which uses non-local robust statistics to suppress the influence of noise in MR images. The non-local robust statistics, which represent vascular features, are learned adaptively from seeds provided by users. K-means clustering in neighborhoods of seeds is utilized to exclude inappropriate seeds, which are obviously corrupted by noise. The neighborhoods of appropriate seeds are placed in an array to calculate the non-local robust statistics, and the variational level set formulation can be constructed. Bias correction is utilized in the level set formulation to reduce the influence of intensity inhomogeneity of MRI. Experiments were conducted over real MR images, and showed that the proposed method performed better on small hepatic vessel segmentation compared with other segmentation methods.

  7. Synthesis, vibrational and quantum chemical investigations of hydrogen bonded complex betaine dihydrogen selenite

    NASA Astrophysics Data System (ADS)

    Arjunan, V.; Marchewka, Mariusz K.; Kalaivani, M.

    2012-10-01

    The molecular complex of betaine with selenious acid namely, betaine dihydrogen selenite (C5H13NO5Se, BDHSe) was synthesised by the reaction of betaine and SeO2 in a 1:1:1 solution of isopropanol, methanol and water. Crystals were grown from this solution by cooling to 253 K for few days. The complex was formed without accompanying proton transfer from selenious acid molecule to betaine. The complete vibrational assignments and analysis of BDHSe have been performed by FTIR, FT-Raman and far-infrared spectral studies. More support on the experimental findings was added from the quantum chemical studies performed with DFT (B3LYP) method using 6-311++G∗∗, 6-31G∗∗, cc-pVDZ and 3-21G basis sets. The structural parameters, energies, thermodynamic parameters and the NBO charges of BDHSe were determined by the DFT method. The 1H and 13C isotropic chemical shifts (δ ppm) of BDHSe with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. SHG experiment was carried out using Kurtz-Perry powder technique. The efficiency of second harmonic generation for BDHSe was estimated relatively to KDP: deff = 0.97 deff (KDP).

  8. New Insights To Simulate the Luminescence Properties of Pt(II) Complexes Using Quantum Calculations.

    PubMed

    Massuyeau, Florian; Faulques, Eric; Latouche, Camille

    2017-03-24

    The present manuscript reports a thorough quantum investigation on the luminescence properties of three monoplatinum(II) complexes. First, the simulated bond lengths at the ground state are compared to the observed ones, and the simulated electronic transitions are compared to the reported ones in the literature in order to assess our methodology. In a second time we show that geometries from the first triplet excited state are similar to the ground state ones. Simulations of the phosphorescence spectra from the first triplet excited states have been performed taking into account the vibronic coupling effects together with mode-mixing (Dushinsky) and solvent effects. Our simulations are compared with the observed ones already reported in the literature and are in good agreement. The calculations demonstrate that the normal modes of low energy are of great importance on the phosphorescence signature. When temperature effects are taken into account, the simulated phosphorescence spectra are drastically improved. An analysis of the computational time shows that the vibronic coupling simulation is cost-effective and thus can be extended to treat large transition metal complexes. In addition to the intrinsic importance of the investigated targets, this work provides a robust method to simulate phosphorescence spectra and to increase the duality experiment-theory.

  9. [A fast non-local means algorithm for denoising of computed tomography images].

    PubMed

    Kang, Changqing; Cao, Wenping; Fang, Lei; Hua, Li; Cheng, Hong

    2012-11-01

    A fast non-local means image denoising algorithm is presented based on the single motif of existing computed tomography images in medical archiving systems. The algorithm is carried out in two steps of prepossessing and actual possessing. The sample neighborhood database is created via the data structure of locality sensitive hashing in the prepossessing stage. The CT image noise is removed by non-local means algorithm based on the sample neighborhoods accessed fast by locality sensitive hashing. The experimental results showed that the proposed algorithm could greatly reduce the execution time, as compared to NLM, and effectively preserved the image edges and details.

  10. Reaching the ultimate performance limit given by non-local effects in BOTDA sensors

    NASA Astrophysics Data System (ADS)

    Dominguez-Lopez, Alejandro; Yang, Zhisheng; Soto, Marcelo A.; Angulo-Vinuesa, Xabier; Martin-Lopez, S.; Thevenaz, Luc; Gonzalez-Herraez, Miguel

    2015-09-01

    Non-local effects have been traditionally identified as one of the most limiting factors of the performance of Brillouin optical time-domain analyzers. These phenomena, directly linked with the energy gained/lost by the pump pulse, limit the probe power and ultimately the SNR of the system. Several solutions have been proposed, although none offers the possibility to increase the probe power until its limit, the onset of amplified spontaneous Brillouin scattering. In this work, we propose a technique that avoids non-local effects and permits to set the probe power at its maximum, reaching a 100 km sensing distance with 2 meter resolution.

  11. Quantum Chemistry Meets Spectroscopy for Astrochemistry: Increasing Complexity toward Prebiotic Molecules.

    PubMed

    Barone, Vincenzo; Biczysko, Malgorzata; Puzzarini, Cristina

    2015-05-19

    For many years, scientists suspected that the interstellar medium was too hostile for organic species and that only a few simple molecules could be formed under such extreme conditions. However, the detection of approximately 180 molecules in interstellar or circumstellar environments in recent decades has changed this view dramatically. A rich chemistry has emerged, and relatively complex molecules such as C60 and C70 are formed. Recently, researchers have also detected complex organic and potentially prebiotic molecules, such as amino acids, in meteorites and in other space environments. Those discoveries have further stimulated the debate on the origin of the building blocks of life in the universe. Many efforts continue to focus on the physical, chemical, and astrophysical processes by which prebiotic molecules can be formed in the interstellar dust and dispersed to Earth or to other planets.Spectroscopic techniques, which are widely used to infer information about molecular structure and dynamics, play a crucial role in the investigation of planetary atmosphere and the interstellar medium. Increasingly these astrochemical investigations are assisted by quantum-mechanical calculations of structures as well as spectroscopic and thermodynamic properties, such as transition frequencies and reaction enthalpies, to guide and support observations, line assignments, and data analysis in these new and chemically complicated situations. However, it has proved challenging to extend accurate quantum-chemical computational approaches to larger systems because of the unfavorable scaling with the number of degrees of freedom (both electronic and nuclear).In this Account, we show that it is now possible to compute physicochemical properties of building blocks of biomolecules with an accuracy rivaling that of the most sophisticated experimental techniques, and we summarize specific contributions from our groups. As a test case, we present the underlying computational machinery

  12. The influence of phthalocyanine aggregation in complexes with CdSe/ZnS quantum dots on the photophysical properties of the complexes

    PubMed Central

    Martynenko, Irina V; Maslov, Vladimir G; Fedorov, Anatoly V; Berwick, Kevin; Baranov, Alexander V

    2016-01-01

    Summary The formation of nonluminescent aggregates of aluminium sulfonated phthalocyanine in complexes with CdSe/ZnS quantum dots causes a decrease of the intracomplex energy transfer efficiency with increasing phthalocyanine concentration. This was confirmed by steady-state absorption and photoluminescent spectroscopy. A corresponding physical model was developed that describes well the experimental data. The results can be used at designing of QD/molecule systems with the desired spatial arrangement for photodynamic therapy. PMID:27547619

  13. Hölder estimates for non-local parabolic equations with critical drift

    NASA Astrophysics Data System (ADS)

    Chang-Lara, Héctor A.; Dávila, Gonzalo

    2016-03-01

    In this paper we extend previous results on the regularity of solutions of integro-differential parabolic equations. The kernels are non-necessarily symmetric which could be interpreted as a non-local drift with the same order as the diffusion. We provide a growth lemma and a Harnack inequality which can be used to prove higher regularity estimates.

  14. Small and Medium-Sized Information Technology Firms: Assessment of Non-Local Partnership Facilitators

    ERIC Educational Resources Information Center

    Findikoglu, Melike Nur

    2012-01-01

    A two-phased qualitative study was conducted to explore the facilitators of non-local (i.e. domestic or international) partnerships formed by small- and medium-sized firms (SME). Rooted in trust, proximity and dynamic capabilities lenses, the study focused on behaviors of SMEs performing in dynamic, competitive and highly interlinked industry, the…

  15. Quality Assurance of Non-Local Accounting Programs Conducted in Hong Kong

    ERIC Educational Resources Information Center

    Cheng, Mei-Ai; Leung, Noel W.

    2014-01-01

    This study examines the current government policy and institutional practice on quality assurance of non-local accounting programs conducted in Hong Kong. Both international guidelines, national regulations and institutional frameworks in higher education and transnational higher education, and professional practice in accounting education are…

  16. A NEW COMBINED LOCAL AND NON-LOCAL PBL MODEL FOR METEOROLOGY AND AIR QUALITY MODELING

    EPA Science Inventory

    A new version of the Asymmetric Convective Model (ACM) has been developed to describe sub-grid vertical turbulent transport in both meteorology models and air quality models. The new version (ACM2) combines the non-local convective mixing of the original ACM with local eddy diff...

  17. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    SciTech Connect

    Cao, Duc; Moses, Gregory; Delettrez, Jacques

    2015-08-15

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester.

  18. Quantum-chemical, NMR, FT IR, and ESI MS studies of complexes of colchicine with Zn(II).

    PubMed

    Jankowski, Wojciech; Kurek, Joanna; Barczyński, Piotr; Hoffmann, Marcin

    2017-04-01

    Colchicine is a tropolone alkaloid from Colchicinum autumnale. It shows antifibrotic, antimitotic, and anti-inflammatory activities, and is used to treat gout and Mediterranean fever. In this work, complexes of colchicine with zinc(II) nitrate were synthesized and investigated using DFT, (1)H and (13)C NMR, FT IR, and ESI MS. The counterpoise-corrected and uncorrected interaction energies of these complexes were calculated. We also calculated their (1)H, (13)C NMR, and IR spectra and compared them with the corresponding experimentally obtained data. According to the ESI MS mass spectra, colchicine forms stable complexes with zinc(II) nitrate that have various stoichiometries: 2:1, 1:1:1, and 2:1:1 with respect to colchichine, Zn(II), and nitrate ion. All of the complexes were investigated using the quantum theory of atoms in molecules (QTAIM). The calculated and the measured spectra showed differences before and after the complexation process. Calculated electron densities and bond critical points indicated the presence of bonds between the ligands and the central cation in the investigated complexes that satisfied the quantum theory of atoms in molecules. Graphical Abstract DFT, NMR, FT IR, ESI MS, QTAIM and puckering studies of complexes of colchicine with Zn(II).

  19. Specific non-local interactions are not necessary for recovering native protein dynamics.

    PubMed

    Dasgupta, Bhaskar; Kasahara, Kota; Kamiya, Narutoshi; Nakamura, Haruki; Kinjo, Akira R

    2014-01-01

    The elastic network model (ENM) is a widely used method to study native protein dynamics by normal mode analysis (NMA). In ENM we need information about all pairwise distances, and the distance between contacting atoms is restrained to the native value. Therefore ENM requires O(N2) information to realize its dynamics for a protein consisting of N amino acid residues. To see if (or to what extent) such a large amount of specific structural information is required to realize native protein dynamics, here we introduce a novel model based on only O(N) restraints. This model, named the 'contact number diffusion' model (CND), includes specific distance restraints for only local (along the amino acid sequence) atom pairs, and semi-specific non-local restraints imposed on each atom, rather than atom pairs. The semi-specific non-local restraints are defined in terms of the non-local contact numbers of atoms. The CND model exhibits the dynamic characteristics comparable to ENM and more correlated with the explicit-solvent molecular dynamics simulation than ENM. Moreover, unrealistic surface fluctuations often observed in ENM were suppressed in CND. On the other hand, in some ligand-bound structures CND showed larger fluctuations of buried protein atoms interacting with the ligand compared to ENM. In addition, fluctuations from CND and ENM show comparable correlations with the experimental B-factor. Although there are some indications of the importance of some specific non-local interactions, the semi-specific non-local interactions are mostly sufficient for reproducing the native protein dynamics.

  20. Does Model Development Ahead of Data Collection Have Merit? A Case for Advancing Non-Local Fluvial Transport Theories

    NASA Astrophysics Data System (ADS)

    Voller, V. R.; Falcini, F.; Foufoula-Georgiou, E.; Ganti, V.; Paola, C.; Hill, K. M.; Swenson, J. B.; Longjas, A.

    2013-12-01

    The purpose of this work is to suggest how experiments might be constructed to provide data to test recently proposed phenomenological non-local model of depositional transport; formulated on the basis of morphological arguments but with limited data. A sound methodology for developing models of geological systems is to first collect significant data and then carefully identify an appropriate model form and parameters. An alternative approach is to construct what might be referred to as a phenomenological model, where limited observation of the system is used to suggest an appropriate mathematical form that matches the critical nature of the physical system behavior. By their nature, phenomenological models are often developed within a fairly narrow range of observations. In this way, interesting findings can occur when the models are modified and exercised across wider physical domains, in particular in domains where there is an absence of hard data to corroborate or invalidate the model predictions. Although this approach might be frown on my some, it is important to recognize the stellar and proven track record of phenomenological models, which despite the original scarcity of data, often pave the way to new perspectives and important findings. The poster child example is the Higgs boson. In the early 60's manipulation of the quantum field equations revealed a critical inconsistency related to the masses of fundamental particles that could only be mathematically resolved by assuming that they operated within a field that would exert drag; this conjecture took almost fifty years and the vast experimental operation of the Large Hadron Collider to physically confirm. In this work we examine a current phenomenological model used to describe non-local transport in fluvial sediment domains. This model has its genesis in attempting to describe the shapes of hill slope profiles, while acknowledging the fact that two points of the landscape with the same local slope are

  1. Resonant transfer of one- and two-photon excitations in quantum dot-bacteriorhodopsin complexes

    NASA Astrophysics Data System (ADS)

    Krivenkov, V. A.; Samokhvalov, P. S.; Bilan, R. S.; Chistyakov, A. A.; Nabiev, I. R.

    2017-01-01

    Light-sensitive protein bacteriorhodopsin (BR), which is capable of electrical response upon exposure to light, is a promising material for photovoltaics and optoelectronics. However, the rather narrow absorption spectrum of BR does not allow achieving efficient conversion of the light energy in the blue and infrared spectral regions. This paper summarizes the results of studies showing the possibility of extending the spectral region of the BR function by means of the Förster resonance energy transfer (FRET) from CdSe/ZnS quantum dots (QDs), which have a broad spectrum of one-photon absorption and a large twophoton absorption cross section (TPACS), to BR upon one- and two-photon excitation. In particular, it is shown that, on the basis of QDs and BR-containing purple membranes, it is possible to create electrostatically associated bio-nano hybrid systems in which FRET is implemented. In addition, the large TPACS of QDs, which is two orders of magnitude larger than those of BR and organic dyes, opens up a means for selective two-photon excitation of synthesized bio-nano hybrid complexes. On the basis of the results of this work, the spectral region in which BR converts the light energy into electrical energy can be extended from the UV to near-IR region, creating new opportunities for the use of this material in photovoltaics and optoelectronics.

  2. Quantum chemical insights in energy dissipation and carotenoid radical cation formation in light harvesting complexes.

    PubMed

    Wormit, Michael; Dreuw, Andreas

    2007-06-21

    Light harvesting complexes (LHCs) have been identified in all photosynthetic organisms. To understand their function in light harvesting and energy dissipation, detailed knowledge about possible excitation energy transfer (EET) and electron transfer (ET) processes in these pigment proteins is of prime importance. This again requires the study of electronically excited states of the involved pigment molecules, in LHCs of chlorophylls and carotenoids. This paper represents a critical review of recent quantum chemical calculations on EET and ET processes between pigment pairs relevant for the major LHCs of green plants (LHC-II) and of purple bacteria (LH2). The theoretical methodology for a meaningful investigation of such processes is described in detail, and benefits and limitations of standard methods are discussed. The current status of excited state calculations on chlorophylls and carotenoids is outlined. It is focused on the possibility of EET and ET in the context of chlorophyll fluorescence quenching in LHC-II and carotenoid radical cation formation in LH2. In the context of non-photochemical quenching of green plants, it is shown that replacement of the carotenoid violaxanthin by zeaxanthin in its binding pocket of LHC-II can not result in efficient quenching. In LH2, our computational results give strong evidence that the S(1) states of the carotenoids are involved in carotenoid cation formation. By comparison of theoretical findings with recent experimental data, a general mechanism for carotenoid radical cation formation is suggested.

  3. Observation of quantum interference as a function of Berry's phase in a complex Hadamard optical network.

    PubMed

    Laing, Anthony; Lawson, Thomas; López, Enrique Martín; O'Brien, Jeremy L

    2012-06-29

    Emerging models of quantum computation driven by multiphoton quantum interference, while not universal, may offer an exponential advantage over classical computers for certain problems. Implementing these circuits via geometric phase gates could mitigate requirements for error correction to achieve fault tolerance while retaining their relative physical simplicity. We report an experiment in which a geometric phase is embedded in an optical network with no closed loops, enabling quantum interference between two photons as a function of the phase.

  4. Quantum Mechanics, Path Integrals and Option Pricing:. Reducing the Complexity of Finance

    NASA Astrophysics Data System (ADS)

    Baaquie, Belal E.; Corianò, Claudio; Srikant, Marakani

    2003-04-01

    Quantum Finance represents the synthesis of the techniques of quantum theory (quantum mechanics and quantum field theory) to theoretical and applied finance. After a brief overview of the connection between these fields, we illustrate some of the methods of lattice simulations of path integrals for the pricing of options. The ideas are sketched out for simple models, such as the Black-Scholes model, where analytical and numerical results are compared. Application of the method to nonlinear systems is also briefly overviewed. More general models, for exotic or path-dependent options are discussed.

  5. Minimal Model of Quantum Kinetic Clusters for the Energy-Transfer Network of a Light-Harvesting Protein Complex.

    PubMed

    Wu, Jianlan; Tang, Zhoufei; Gong, Zhihao; Cao, Jianshu; Mukamel, Shaul

    2015-04-02

    The energy absorbed in a light-harvesting protein complex is often transferred collectively through aggregated chromophore clusters. For population evolution of chromophores, the time-integrated effective rate matrix allows us to construct quantum kinetic clusters quantitatively and determine the reduced cluster-cluster transfer rates systematically, thus defining a minimal model of energy-transfer kinetics. For Fenna-Matthews-Olson (FMO) and light-havrvesting complex II (LCHII) monomers, quantum Markovian kinetics of clusters can accurately reproduce the overall energy-transfer process in the long-time scale. The dominant energy-transfer pathways are identified in the picture of aggregated clusters. The chromophores distributed extensively in various clusters can assist a fast and long-range energy transfer.

  6. Non-local Effects in a Stratified Glow Discharge With Dusty Particles

    SciTech Connect

    Sukhinin, G. I.; Fedoseev, A. V.; Ramazanov, T. S.; Amangaliyeva, R. Zh.; Dosbolayev, M. K.; Jumabekov, A. N.

    2008-09-07

    The work is aimed to describe non-local effects in the positive column of a low pressure stratified DC glow discharge in argon with dusty particles in a vertical cylindrical discharge tube. The numerical calculations of plasma parameters in the axis of the discharge tube were performed with the help of hybrid model based on the solution of non-local Boltzmann equation for EEDF. Distributions of optical emission from striations were measured experimentally. It is shown that in a stratified positive column the EEDF is not Maxwellian and even non-monotonous. Also, the effect of displacing of optical emission distribution relative to the electric field is shown both by numerical simulation and experimental measurements.

  7. Non-linear non-local molecular electrodynamics with nano-optical fields.

    PubMed

    Chernyak, Vladimir Y; Saurabh, Prasoon; Mukamel, Shaul

    2015-10-28

    The interaction of optical fields sculpted on the nano-scale with matter may not be described by the dipole approximation since the fields may vary appreciably across the molecular length scale. Rather than incrementally adding higher multipoles, it is advantageous and more physically transparent to describe the optical process using non-local response functions that intrinsically include all multipoles. We present a semi-classical approach for calculating non-local response functions based on the minimal coupling Hamiltonian. The first, second, and third order response functions are expressed in terms of correlation functions of the charge and the current densities. This approach is based on the gauge invariant current rather than the polarization, and on the vector potential rather than the electric and magnetic fields.

  8. Saturation of SRS-LDI with Non-local Growth of SRS Driven Electron Plasma Wave

    NASA Astrophysics Data System (ADS)

    Salcedo, A.; Bers, A.; Ram, A. K.

    2000-10-01

    Experimental observations have shown the coupling of SRS and Langmuir decay interaction (LDI), in ICF experiments where the SRS backscattering is dependent on the damping of ion acoustic waves.(Juan P. Fernandez, et al., Phys. Rev. Lett.) 77, 2702 (1996); R. K. Kirkwood, et al., Phys. Rev. Lett. 77, 13, (1996). A model 3-wave interaction equations for LDI with a growing EPW (driven by SRS) and its non-local Landau damping, gives a simple description of the effect of LDI on the saturation of SRS and its dependence on IAW damping. ( A. Salcedo, A. Bers, A. K. Ram, in Proc. 1st IFSA), Bordeaux, France (1999), pp. 343-348. We present results on the extension of this model to include the non-local growth of the SRS driven EPW, and a comparison with simulations of the full five-wave interaction equations for SRS coupled to LDI. (J. A. Heikkinen, J. Karttunen, Phys. Fluids) 29 (4), (1986).

  9. Stable bounce and inflation in non-local higher derivative cosmology

    SciTech Connect

    Biswas, Tirthabir; Koshelev, Alexey S.; Mazumdar, Anupam; Vernov, Sergey Yu. E-mail: alexey.koshelev@vub.ac.be E-mail: svernov@theory.sinp.msu.ru

    2012-08-01

    One of the greatest problems of primordial inflation is that the inflationary space-time is past-incomplete. This is mainly because Einstein's GR suffers from a space-like Big Bang singularity. It has recently been shown that ghost-free, non-local higher-derivative ultra-violet modifications of Einstein's gravity may be able to resolve the cosmological Big Bang singularity via a non-singular bounce. Within the framework of such non-local cosmological models, we are going to study both sub- and super-Hubble perturbations around an inflationary trajectory which is preceded by the Big Bounce in the past, and demonstrate that the inflationary trajectory has an ultra-violet completion and that perturbations do not suffer from any pathologies.

  10. Rotational effects in complex-forming bimolecular substitution reactions: A quantum-mechanical approach

    NASA Astrophysics Data System (ADS)

    Hennig, Carsten; Schmatz, Stefan

    2009-12-01

    The quantum dynamics of the complex-forming SN2 reaction Cl-+CH3Br→ClCH3+Br- is studied with emphasis on rotational effects. The pseudotriatomic system Cl-Me-Br is treated with a corresponding three-dimensional (3D) potential energy surface as a function of the two scattering coordinates and the enclosed angle where the geometry of the methyl group Me is optimized at each point. The 3D space is divided into three different parts, the interaction region, an intermediate region, and the asymptotic region. In line with simple classical-mechanical arguments and previous classical trajectory calculations, initial rotational motion of CH3Br seemingly decreases the reaction probability. However, the dynamical inclusion of the rotational degree of freedom and the presence of the many rovibrational product states overall lead to a large increase in reactivity compared to our previous collinear study on this reaction. If the reactant is rotationally excited, the higher vibrational product states are depleted in favor of lower-lying levels. Starting the reaction with rotationless reactants may end up in significant rotational excitation in the product molecules (translation-to-rotation energy transfer). On the other hand, initial rotational energy in rotationally highly excited reactants is to a large amount converted into translational and vibrational energy. The average amount of rotational energy in the products shows a twofold vibrational excitation-independent saturation (i.e., memorylessness), with respect to both initial rotational excitation and translational energy. Since only about one-half of all reactant states end in rotationless products, the reaction probability should be increased by a factor of 2; the actually larger reactivity points to other dynamical effects that play an important role in the reaction.

  11. Mixed-spin [2 × 2] Fe4 grid complex optimized for quantum cellular automata.

    PubMed

    Schneider, Benjamin; Demeshko, Serhiy; Neudeck, Sven; Dechert, Sebastian; Meyer, Franc

    2013-11-18

    The new pyrazolate-bridged proligand 4-methyl-3,5-bis{6-(2,2'-bipyridyl)}pyrazole ((Me)LH) has been synthesized. Similar to its congener that lacks the backbone methyl substituent ((H)LH) it forms a robust Fe(II)4 grid complex, [(Me)L4Fe(II)4](BF4)4. The molecular structure of [(Me)L4Fe(II)4](BF4)4·2MeCN has been elucidated by X-ray diffraction, revealing two high-spin (HS) and two low-spin (LS) ferrous ions at opposite corners of the rhombic metal ion arrangement. SQUID and (57)Fe Mössbauer data for solid material showed that this [HS-LS-HS-LS] configuration persists over a wide temperature range, between 7 and 250 K, while spin-crossover sets in only above 250 K. According to Mössbauer spectroscopy a [1HS-3LS] configuration is present in solution at 80 K. Thus, the methyl substituent in [(Me)L](-) leads to a stronger ligand field compared to parent [(H)L](-) and hence to a higher LS fraction both in the solid state and in solution. Cyclic voltammetry of [(Me)L4Fe(II)4](BF4)4 reveals four sequential oxidations coming in two pairs with pronounced stability of the di-mixed-valence species [(Me)L4Fe(II)2Fe(III)2](6+) (K(C) = 3.35 × 10(8)). The particular [HS-LS-HS-LS] configuration as well as the di-mixed-valence configuration, both with identical spin or redox states at diagonally opposed vertices of the grid, make this system attractive as a molecular component for quantum cellular automata.

  12. Synthesis of a quantum nanocrystal-gold nanoshell complex for near-infrared generated fluorescence and photothermal decay of luminescence.

    PubMed

    Lin, Adam Y; Young, Joseph K; Nixon, Ariel V; Drezek, Rebekah A

    2014-09-21

    Multifunction nanoparticle complexes have previously been developed to aid physicians in both diagnosis and treatment of cancerous tissue. Here, we designed a nanoparticle complex structure that consists of a plasmonically active hollow gold nanoshell core surrounded by photoluminescent quantum nanocrystals (QNs) in the form of PbS encapsulated by a silica layer. There are three main design variables including HGN synthesis and optical tuning, formation of the silica layer on the hollow gold nanoshell surface, and fabrication and photoluminescence tuning of PbS quantum nanocrystals. The hollow gold nanoshells were deliberately designed to function in the optical regimes that maximize tissue transmissivity (800 nm) and minimize tissue absorption (1100 nm). Secondly, several chemical ligands were tested such as (3-mercaptopropyl)trimethoxysilane and mercaptoundecanoic acid for controlled growth of the silica layer. Last, PbS QNs were synthesized and optimized with various capping agents, where the nanocrystals excited at the same wavelength were used to activate the photothermal properties of the hollow gold nanoshells. Upon irradiation of the complex with a lower power 800 nm laser, the nanocrystals luminesce at 1100 nm. At ablative temperatures the intrinsic luminescent properties of the QNs are altered and the luminescent output is significantly reduced (>70%). While this paper focuses on synthesis and optimization of the QN-HGN complex, in the future we believe that this novel particle complex design may have the potential to serve as a triple theranostic agent, which will aid satellite tumor localization, photothermal treatment, and ablative confirmation.

  13. The Blocking Moving Window Sampler. Conditioning Stochastic Multiple Point Simulations to non-local Hydrogeological Data.

    NASA Astrophysics Data System (ADS)

    Alcolea, A.; Renard, P.

    2008-12-01

    Geological scenarios often present well connected lithofacies distributions. Multiple Point statistical techniques have been traditionally used to delineate connectivity patterns from local lithofacies data in such scenarios. Yet, little attention has been paid to the conditioning to non-local connectivity data and dependent state variables (e.g., heads). These data sets contain valuable information on the connectivity patterns and must be accounted for in meaningful models. This work is a step in that direction. A novel direct iterative sampler, termed Blocking Moving Window (BMW) is presented. The BMW algorithm couples an MP simulator with a fast groundwater flow simulator. First, an MP simulation of lithofacies is delineated from training images, local lithofacies from available well logs and non-local connectivity data sets. Only a random portion of the domain (the Moving Window) is simulated at a given iteration. This makes the search less random and therefore, more efficient. Second, values of hydraulic properties at the intrafacies are assigned. Next, state variables are simulated. The MP simulation is rejected if the fit of measured state variables is poor. We analyze the performance of the BMW algorithm on a 2D toy example mimicking the groundwater flow to a well in a channel-type geological setting. We explore the sensitivity to the size of the Moving Window and the role of the state variable and non-local connectivity data sets. Results show that, (1) the size of the Moving Window must be optimum; (2) conditioning to state variables enhances dramatically the initial MP characterization (i.e., conditioned to raw geological data only) and (3) the use of non-local connectivity data increases the reliability of the characterization and speeds up the convergence of the algorithm.

  14. New Exact Solutions of the CDGSK Equation Related to a Non-local Symmetry

    NASA Astrophysics Data System (ADS)

    Lou, Senyue; Ruan, Hangyu; Chen, Weizhong; Wang, Zhenli; Chen, Lili

    1994-10-01

    A non-local symmetry of the Caudrey-Dodd-Gibbon-Sawada-Kotera (CDGSK) equation has been used for finding exact solution in two different ways. Firstly, using the standard prolongation approach, we obtain the finite Lie Bäcklund transformation and the single soliton solution. Secondly, combining some local symmetries and the nonlocal symmetry, we get the group invariant solution which is described by the Weierstrass elliptic function and is deduced to the so-called interacting soliton for a special parameter.

  15. Quantum Nonlocality and Reality

    NASA Astrophysics Data System (ADS)

    Bell, Mary; Gao, Shan

    2016-09-01

    Preface; Part I. John Stewart Bell: The Physicist: 1. John Bell: the Irish connection Andrew Whitaker; 2. Recollections of John Bell Michael Nauenberg; 3. John Bell: recollections of a great scientist and a great man Gian-Carlo Ghirardi; Part II. Bell's Theorem: 4. What did Bell really prove? Jean Bricmont; 5. The assumptions of Bell's proof Roderich Tumulka; 6. Bell on Bell's theorem: the changing face of nonlocality Harvey R. Brown and Christopher G. Timpson; 7. Experimental tests of Bell inequalities Marco Genovese; 8. Bell's theorem without inequalities: on the inception and scope of the GHZ theorem Olival Freire, Jr and Osvaldo Pessoa, Jr; 9. Strengthening Bell's theorem: removing the hidden-variable assumption Henry P. Stapp; Part III. Nonlocality: Illusions or Reality?: 10. Is any theory compatible with the quantum predictions necessarily nonlocal? Bernard d'Espagnat; 11. Local causality, probability and explanation Richard A. Healey; 12. Bell inequality and many-worlds interpretation Lev Vaidman; 13. Quantum solipsism and non-locality Travis Norsen; 14. Lessons of Bell's theorem: nonlocality, yes; action at a distance, not necessarily Wayne C. Myrvold; 15. Bell non-locality, Hardy's paradox and hyperplane dependence Gordon N. Fleming; 16. Some thoughts on quantum nonlocality and its apparent incompatibility with relativity Shan Gao; 17. A reasonable thing that just might work Daniel Rohrlich; 18. Weak values and quantum nonlocality Yakir Aharonov and Eliahu Cohen; Part IV. Nonlocal Realistic Theories: 19. Local beables and the foundations of physics Tim Maudlin; 20. John Bell's varying interpretations of quantum mechanics: memories and comments H. Dieter Zeh; 21. Some personal reflections on quantum non-locality and the contributions of John Bell Basil J. Hiley; 22. Bell on Bohm Sheldon Goldstein; 23. Interactions and inequality Philip Pearle; 24. Gravitation and the noise needed in objective reduction models Stephen L. Adler; 25. Towards an objective

  16. Numerical implementation of non-local polycrystal plasticity using fast Fourier transforms

    NASA Astrophysics Data System (ADS)

    Lebensohn, Ricardo A.; Needleman, Alan

    2016-12-01

    We present the numerical implementation of a non-local polycrystal plasticity theory using the FFT-based formulation of Suquet and co-workers. Gurtin (2002) non-local formulation, with geometry changes neglected, has been incorporated in the EVP-FFT algorithm of Lebensohn et al. (2012). Numerical procedures for the accurate estimation of higher order derivatives of micromechanical fields, required for feedback into single crystal constitutive relations, are identified and applied. A simple case of a periodic laminate made of two fcc crystals with different plastic properties is first used to assess the soundness and numerical stability of the proposed algorithm and to study the influence of different model parameters on the predictions of the non-local model. Different behaviors at grain boundaries are explored, and the one consistent with the micro-clamped condition gives the most pronounced size effect. The formulation is applied next to 3-D fcc polycrystals, illustrating the possibilities offered by the proposed numerical scheme to analyze the mechanical response of polycrystalline aggregates in three dimensions accounting for size dependence arising from plastic strain gradients with reasonable computing times.

  17. Non-Local Signal in Quasi-2DEG of LAO/STO

    NASA Astrophysics Data System (ADS)

    Jin, Mi-Jin; Moon, Seon Young; Modepalli, Vijayakumar; Jo, Junhyeon; Park, Jungmin; Baek, Seung-Hyub; Yoo, Jung-Woo

    2015-03-01

    Electron gas arizen at the insulating oxide interfaces exhibits high electron mobility, tunable carrier densities and related unique behaviors such as coexistence of superconductivity and ferromagnetism, Kondo resistance, etc. Itinerant electrons at the oxide hetero-interface are predicted to have long spin diffusion length, while they are under the relatively strong Rashba-type spin orbit coupling due to inversion symmetry breaking. We studied non-local spin signal induced by spin orbit coupling with additional gate-controlled Rashba field in quasi-2DEG of LaAlO3/SrTiO (LAO/STO) interface. We fabricated simple hall-bar like geometry to measure non-local signal with the variation of channel length (2 ~ 10 μm). Cleaned sample was patterned using e-beam lithography and reactive ion etching followed by oxygen treatment to anneal out oxygen vacancies. When an electric current flows one line of the hall bar structure, spin orbit coupling will induce the current flow away from the source current channel via spin hall and inverse spin hall effects. The non-local signals were studied under different angles of magnetic field and the variation of applied gate voltage. This work was supported by a grant from (No. 1.140092.01) funded by the Ulsan National Institute of Science and Technology.

  18. Spin-Hall Non-Local Transport Mediated by a Magnetic Insulator

    NASA Astrophysics Data System (ADS)

    Ramezani Masir, Massoud; Chen, Hua; Sodemann, Inti; MacDonald, Allan. H.

    Magnetic systems with easy-plane order support dissipationless spin supercurrents that can lead to non-local coupling between electrically separated conductors. Recently the electrical properties of a system containing two magnetic multilayer stacks with perpendicular magnetic anisotropy electrodes and a shared easy-plane magnetic layer have been discussed. In this research we discuss a closely related system in which the two conducting channels that are coupled by the easy-plane magnetic layer are co-planar thin film metals with large spin Hall effects. We theoretically explained the non-local relationship between the current-voltage relationships of two thin film metallic conductors. Coupling occurs because both conductors inject spins into the magnetic insulator and because this information is communicated between conductors via exchange interactions within the magnetic system. We investigate the non-local transport properties of the system in the macrospin and long thin nanomagnet limits, deriving conditions for the critical currents and using solutions to the Landau-Liftshitz-Gilbert equation to characterize the dynamic steady state case. This work was supported by as part of SHINES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # SC0012670.

  19. An Adaptive Non-Local-Means Filter for Real-Time MR-Thermometry.

    PubMed

    Zachiu, Cornel; Ries, Mario; Moonen, Chrit; de Senneville, Baudouin Denis

    2017-04-01

    Proton resonance frequency shift-based magnetic resonance thermometry is a currently used technique for monitoring temperature during targeted thermal therapies. However, in order to provide temperature updates with very short latency times, fast MR acquisition schemes are usually employed, which in turn might lead to noisy temperature measurements. This will, in general, have a direct impact on therapy control and endpoint detection. In this paper, we address this problem through an improved non-local filtering technique applied on the temperature images. Compared with previous non-local filtering methods, the proposed approach considers not only spatial information but also exploits temporal redundancies. The method is fully automatic and designed to improve the precision of the temperature measurements while at the same time maintaining output accuracy. In addition, the implementation was optimized in order to ensure real-time availability of the temperature measurements while having a minimal impact on latency. The method was validated in three complementary experiments: a simulation, an ex-vivo and an in-vivo study. Compared to the original non-local means filter and two other previously employed temperature filtering methods, the proposed approach shows considerable improvement in both accuracy and precision of the filtered data. Together with the low computational demands of the numerical scheme, the proposed filtering technique shows great potential for improving temperature measurements during real-time MR thermometry dedicated to targeted thermal therapies.

  20. Numerical implementation of non-local polycrystal plasticity using fast Fourier transforms

    SciTech Connect

    Lebensohn, Ricardo A.; Needleman, Alan

    2016-03-28

    Here, we present the numerical implementation of a non-local polycrystal plasticity theory using the FFT-based formulation of Suquet and co-workers. Gurtin (2002) non-local formulation, with geometry changes neglected, has been incorporated in the EVP-FFT algorithm of Lebensohn et al. (2012). Numerical procedures for the accurate estimation of higher order derivatives of micromechanical fields, required for feedback into single crystal constitutive relations, are identified and applied. A simple case of a periodic laminate made of two fcc crystals with different plastic properties is first used to assess the soundness and numerical stability of the proposed algorithm and to study the influence of different model parameters on the predictions of the non-local model. Different behaviors at grain boundaries are explored, and the one consistent with the micro-clamped condition gives the most pronounced size effect. The formulation is applied next to 3-D fcc polycrystals, illustrating the possibilities offered by the proposed numerical scheme to analyze the mechanical response of polycrystalline aggregates in three dimensions accounting for size dependence arising from plastic strain gradients with reasonable computing times.

  1. Numerical implementation of non-local polycrystal plasticity using fast Fourier transforms

    DOE PAGES

    Lebensohn, Ricardo A.; Needleman, Alan

    2016-03-28

    Here, we present the numerical implementation of a non-local polycrystal plasticity theory using the FFT-based formulation of Suquet and co-workers. Gurtin (2002) non-local formulation, with geometry changes neglected, has been incorporated in the EVP-FFT algorithm of Lebensohn et al. (2012). Numerical procedures for the accurate estimation of higher order derivatives of micromechanical fields, required for feedback into single crystal constitutive relations, are identified and applied. A simple case of a periodic laminate made of two fcc crystals with different plastic properties is first used to assess the soundness and numerical stability of the proposed algorithm and to study the influencemore » of different model parameters on the predictions of the non-local model. Different behaviors at grain boundaries are explored, and the one consistent with the micro-clamped condition gives the most pronounced size effect. The formulation is applied next to 3-D fcc polycrystals, illustrating the possibilities offered by the proposed numerical scheme to analyze the mechanical response of polycrystalline aggregates in three dimensions accounting for size dependence arising from plastic strain gradients with reasonable computing times.« less

  2. Non-local magnetoelectric effects via Coulomb interaction in TI-FMI heterostructures

    NASA Astrophysics Data System (ADS)

    Rex, Stefan; Nogueira, Flavio S.; Sudbø, Asle

    Magnetic order on the surface of a 3 D topological insulator (TI) has been predicted to evoke a topological magnetoelectric effect (TME) by the breaking of time-reversal invariance. In the TME, an electric field leads to a magnetic polarization in the same direction as the field and vice versa. Here, we consider heterostructures of TI and ferromagnetic insulator (FMI) layers. We show that in the presence of long-range Coulomb interactions the magnetization couples non-locally to the fluctuating electric field (non-local TME) by performing a field-theoretic calculation of the vacuum polarization. In addition, we obtain a Landau-Lifshitz equation for the magnetization dynamics, and find that charged magnetic textures lead to a net magnetization even at a large distance. Such textures can be induced by an external electric field with nonzero in-plane divergence. We apply this effect to a FMI-TI-FMI trilayer heterostructure with two parallel interfaces being well-separated by the bulk TI, where we propose to non-locally control the magnetic texture at one interface by proper gating of the other interface. A preprint can be found at arXiv:1510.04285 Supported by the Norwegian Research Council, Grants 205591/V20 and 216700/F20, and the Collaborative Research Center SFB 1143 ''Correlated Magnetism: From Frustration to Topology''.

  3. [Multispectral remote sensing image denoising based on non-local means].

    PubMed

    Liu, Peng; Liu, Ding-Sheng; Li, Guo-Qing; Liu, Zhi-Wen

    2011-11-01

    The non-local mean denoising (NLM) exploits the fact that similar neighborhoods can occur anywhere in the image and can contribute to denoising. However, these current NLM methods do not aim at multichannel remote sensing image. Smoothing every band image separately will seriously damage the spectral information of the multispectral image. Then the authors promote the NLM from two aspects. Firstly, for multispectral image denoising, a weight value should be related to all channels but not only one channel. So for the kth band image, the authors use sum of smoothing kernel in all bands instead of one band. Secondly, for the patch whose spectral feature is similar to the spectral feature of the central patch, its weight should be larger. Bringing the two changes into the traditional non-local mean, a new multispectral non-local mean denoising method is proposed. In the experiments, different satellite images containing both urban and rural parts are used. For better evaluating the performance of the different method, ERGAS and SAM as quality index are used. And some other methods are compared with the proposed method. The proposed method shows better performance not only in ERGAS but also in SAM. Especially the spectral feature is better reserved in proposed NLM denoising.

  4. Non-local effects in dual-probe-sideband Brillouin optical time domain analysis.

    PubMed

    Dominguez-Lopez, Alejandro; Angulo-Vinuesa, Xabier; Lopez-Gil, Alexia; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2015-04-20

    According to recent models, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems should be essentially negligible whenever the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. This paper shows that actually there appear non-local effects in this type of systems before the SBS threshold. To explain these effects it is necessary to take into account a full spectral description of the SBS process. The pump pulse experiences a frequency-dependent spectral deformation that affects the readout process differently in the gain and loss configurations. This paper provides a simple analytical model of this phenomenon, which is validated against compelling experimental data, showing good agreement. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. Experimental and theoretical results show that, for a total probe wave power of ~1 mW (500 μW on each sideband), there is an up-shifting of ~1 MHz in the Brillouin Frequency Shift (BFS) retrieved from the Brillouin Loss Spectrum, whereas the BFS extracted from the measured Brillouin Gain Spectrum is up-shifted only ~0.6 MHz. These results are of particular interest for manufacturers of long-range BOTDA systems.

  5. Quantum computation for quantum chemistry

    NASA Astrophysics Data System (ADS)

    Aspuru-Guzik, Alan

    2010-03-01

    Numerically exact simulation of quantum systems on classical computers is in general, an intractable computational problem. Computational chemists have made progress in the development of approximate methods to tackle complex chemical problems. The downside of these approximate methods is that their failure for certain important cases such as long-range charge transfer states in the case of traditional density functional theory. In 1982, Richard Feynman suggested that a quantum device should be able to simulate quantum systems (in our case, molecules) exactly using quantum computers in a tractable fashion. Our group has been working in the development of quantum chemistry algorithms for quantum devices. In this talk, I will describe how quantum computers can be employed to carry out numerically exact quantum chemistry and chemical reaction dynamics calculations, as well as molecular properties. Finally, I will describe our recent experimental quantum computation of the energy of the hydrogen molecule using an optical quantum computer.

  6. Structure and dynamics of the uranyl tricarbonate complex in aqueous solution: insights from quantum mechanical charge field molecular dynamics.

    PubMed

    Tirler, Andreas O; Hofer, Thomas S

    2014-11-13

    This investigation presents the characterization of structural and dynamical properties of uranyl tricarbonate in aqueous solution employing an extended hybrid quantum mechanical/molecular mechanical (QM/MM) approach. It is shown that the inclusion of explicit solvent molecules in the quantum chemical treatment is essential to mimic the complex interaction occurring in an aqueous environment. Thus, in contrast to gas phase cluster calculations on a quantum chemical level proposing a 6-fold coordination of the three carbonates, the QMCF MD simulation proposes a 5-fold coordination. An extensive comparison of the simulation results to structural and dynamical data available in the literature was found to be in excellent agreement. Furthermore, this work is the first theoretical study on a quantum chemical level of theory able to observe the conversion of carbonate (CO₃²⁻) to bicarbonate (HCO₃⁻) in the equatorial coordination sphere of the uranyl ion. From a comparison of the free energy ΔG values for the unprotonated educt [UO₂(CO₃)₃]⁴⁻ and the protonated [UO₂(CO₃)₂(HCO₃)]³⁻, it could be concluded that the reaction equilibrium is strongly shifted toward the product state confirming the benignity for the observed protonation reaction. Structural properties and the three-dimensional arrangement of carbonate ligands were analyzed via pair-, three-body, and angular distributions, the dynamical properties were evaluated by hydrogen-bond correlation functions and vibrational power spectra.

  7. Heterodimetallic [LnLn′] Lanthanide Complexes: Toward a Chemical Design of Two-Qubit Molecular Spin Quantum Gates

    PubMed Central

    2015-01-01

    A major challenge for realizing quantum computation is finding suitable systems to embody quantum bits (qubits) and quantum gates (qugates) in a robust and scalable architecture. An emerging bottom-up approach uses the electronic spins of lanthanides. Universal qugates may then be engineered by arranging in a molecule two interacting and different lanthanide ions. Preparing heterometallic lanthanide species is, however, extremely challenging. We have discovered a method to obtain [LnLn′] complexes with the appropriate requirements. Compound [CeEr] is deemed to represent an ideal situation. Both ions have a doubly degenerate magnetic ground state and can be addressed individually. Their isotopes have mainly zero nuclear spin, which enhances the electronic spin coherence. The analogues [Ce2], [Er2], [CeY], and [LaEr] have also been prepared to assist in showing that [CeEr] meets the qugate requirements, as revealed through magnetic susceptibility, specific heat, and EPR. Molecules could now be used for quantum information processing. PMID:25203521

  8. A Semiclassical Theory on Complex Manifolds with Applications in Statistical Physics and Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Gulden, Tobias

    Increased interest in non-Hermitian quantum systems calls for the development of efficient methods to treat these. This interest was sparked by the introduction of PT-symmetry and the study of mathematical mappings which map conventional statistical or quantum mechanics onto non-Hermitian quantum operators. One of the most common methods in quantum mechanics is the semiclassial approximation which requires integration along trajectories that solve classical equations of motion. However in non-Hermitian systems these solutions are rarely attainable. We borrow concepts from algebraic topology to develop methods to avoid solving the equations of motion and avoid straightforward integration altogether. We apply these methods to solve the semiclassical problem for three largely dierent systems and demonstrate their usefulness for Hermitian and non-Hermitian systems alike.

  9. Frame functions in finite-dimensional quantum mechanics and its Hamiltonian formulation on complex projective spaces

    NASA Astrophysics Data System (ADS)

    Moretti, Valter; Pastorello, Davide

    2016-12-01

    This work concerns some issues about the interplay of standard and geometric (Hamiltonian) approaches to finite-dimensional quantum mechanics, formulated in the projective space. Our analysis relies upon the notion and the properties of so-called frame functions, introduced by Gleason to prove his celebrated theorem. In particular, the problem of associating quantum states with positive Liouville densities is tackled from an axiomatic point of view, proving a theorem classifying all possible correspondences. A similar result is established for classical-like observables (i.e. real scalar functions on the projective space) representing quantum ones. These correspondences turn out to be encoded in a one-parameter class and, in both cases, the classical-like objects representing quantum ones result to be frame functions. The requirements of U(n) covariance and (convex) linearity play a central role in the proof of those theorems. A new characterization of classical-like observables describing quantum observables is presented, together with a geometric description of the C∗-algebra structure of the set of quantum observables in terms of classical-like ones.

  10. Plasmon enhanced molecular absorption: A mixed quantum-classical description of supramolecular complexes attached to a metal nanoparticle

    NASA Astrophysics Data System (ADS)

    Megow, Jörg; May, Volkhard

    2014-01-01

    The application of a mixed quantum-classical methodology for an investigation of single pheophorbide-a molecules (Pheos) and respective supramolecular complexes is continued to effects caused by a nearby placed metal nanoparticle (MNP). Therefore, the classical simulation of the molecular nuclear degrees of freedom is combined with a uniform quantum description of the molecular electronic excitations coupled to those of the MNP. To account for the short MNP plasmon life time the quantum dynamics of the electronic degrees of freedom is formulated in the framework of a system-bath theory. Linear absorption spectra are calculated for a spherical 14 nm diameter Au-MNP decorated with isolated Pheos or with P16 complexes formed by 16 Pheos. The spectra are analyzed with respect to the molecular orientation at the MNP surface. While all studies on P16 only account for the Pheo Qy-transition we also present data on the MNP induced change of the single Pheo Qx-absorption.

  11. Response to 'Comment on 'Bohmian mechanics with complex action: A new trajectory-based formulation of quantum mechanics'' [J. Chem. Phys. 127, 197101 (2007)

    SciTech Connect

    Goldfarb, Yair; Degani, Ilan; Tannor, David J.

    2007-11-21

    In their comment, Sanz and Miret-Artes (SMA) describe previous trajectory-based formalisms based on the quantum Hamilton-Jacobi (QHJ) formalism. In this reply, we highlight our unique contributions: the identification of the smallness of the quantum force in the complex QHJ and its solution using complex trajectories. SMA also raise the question of how the term locality should be used in quantum mechanics. We suggest that at least certain aspects of nonlocality can depend on the method used to solve the problem.

  12. Kinetically Stable Lanthanide Complexes Displaying Exceptionally High Quantum Yields upon Long-Wavelength Excitation: Synthesis, Photophysical Properties, and Solution Speciation.

    PubMed

    Routledge, Jack D; Jones, Michael W; Faulkner, Stephen; Tropiano, Manuel

    2015-04-06

    We demonstrate how highly emissive, kinetically stable complexes can be prepared using the macrocyclic scaffold of DO3A bearing coordinating aryl ketones as highly effective sensitizing chromophores. In the europium complexes, high quantum yields (up to 18% in water) can be combined with long-wavelength excitation (370 nm). The behavior in solution upon variation of pH, studied by means of UV-vis absorption, emission, and NMR spectroscopies, reveals that the nature of the chromophore can give rise to pH-dependent behavior as a consequence of deprotonation adjacent to the carbonyl group. Knowledge of the molecular speciation in solution is therefore critical when assessing the luminescence properties of such complexes.

  13. Direct evidence of quantum transport in photosynthetic light-harvesting complexes.

    PubMed

    Panitchayangkoon, Gitt; Voronine, Dmitri V; Abramavicius, Darius; Caram, Justin R; Lewis, Nicholas H C; Mukamel, Shaul; Engel, Gregory S

    2011-12-27

    The photosynthetic light-harvesting apparatus moves energy from absorbed photons to the reaction center with remarkable quantum efficiency. Recently, long-lived quantum coherence has been proposed to influence efficiency and robustness of photosynthetic energy transfer in light-harvesting antennae. The quantum aspect of these dynamics has generated great interest both because of the possibility for efficient long-range energy transfer and because biology is typically considered to operate entirely in the classical regime. Yet, experiments to date show only that coherence persists long enough that it can influence dynamics, but they have not directly shown that coherence does influence energy transfer. Here, we provide experimental evidence that interaction between the bacteriochlorophyll chromophores and the protein environment surrounding them not only prolongs quantum coherence, but also spawns reversible, oscillatory energy transfer among excited states. Using two-dimensional electronic spectroscopy, we observe oscillatory excited-state populations demonstrating that quantum transport of energy occurs in biological systems. The observed population oscillation suggests that these light-harvesting antennae trade energy reversibly between the protein and the chromophores. Resolving design principles evident in this biological antenna could provide inspiration for new solar energy applications.

  14. Direct evidence of quantum transport in photosynthetic light-harvesting complexes

    PubMed Central

    Panitchayangkoon, Gitt; Voronine, Dmitri V.; Abramavicius, Darius; Caram, Justin R.; Lewis, Nicholas H. C.; Mukamel, Shaul; Engel, Gregory S.

    2011-01-01

    The photosynthetic light-harvesting apparatus moves energy from absorbed photons to the reaction center with remarkable quantum efficiency. Recently, long-lived quantum coherence has been proposed to influence efficiency and robustness of photosynthetic energy transfer in light-harvesting antennae. The quantum aspect of these dynamics has generated great interest both because of the possibility for efficient long-range energy transfer and because biology is typically considered to operate entirely in the classical regime. Yet, experiments to date show only that coherence persists long enough that it can influence dynamics, but they have not directly shown that coherence does influence energy transfer. Here, we provide experimental evidence that interaction between the bacteriochlorophyll chromophores and the protein environment surrounding them not only prolongs quantum coherence, but also spawns reversible, oscillatory energy transfer among excited states. Using two-dimensional electronic spectroscopy, we observe oscillatory excited-state populations demonstrating that quantum transport of energy occurs in biological systems. The observed population oscillation suggests that these light-harvesting antennae trade energy reversibly between the protein and the chromophores. Resolving design principles evident in this biological antenna could provide inspiration for new solar energy applications. PMID:22167798

  15. Decoherence induced by a chaotic enviroment: A quantum walker with a complex coin

    SciTech Connect

    Ermann, Leonardo; Paz, Juan Pablo; Saraceno, Marcos

    2006-01-15

    We study the differences between the processes of decoherence induced by chaotic and regular environments. For this we analyze a family of simple models that contain both regular and chaotic environments. In all cases the system of interest is a ''quantum walker,'' i.e., a quantum particle that can move on a lattice with a finite number of sites. The walker interacts with an environment which has a D-dimensional Hilbert space. The results we obtain suggest that regular and chaotic environments are not distinguishable from each other in a (short) time scale t*, which scales with the dimensionality of the environment as t*{proportional_to}log{sub 2}(D). However, chaotic environments continue to be effective over exponentially longer time scales while regular environments tend to reach saturation much sooner. We present both numerical and analytical results supporting this conclusion. The family of chaotic evolutions we consider includes the so-called quantum multibaker map as a particular case.

  16. Overcoming non-local effects and Brillouin threshold limitations in Brillouin distributed sensors

    NASA Astrophysics Data System (ADS)

    Urricelqui, Javier; Ruiz-Lombera, Rubén.; Sagues, Mikel; Mirapeix, Jesús; López-Higuera, José M.; Loayssa, Alayn

    2015-09-01

    We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber and that is free from detrimental non-local effects. The technique is based on a dual-probe-sideband setup in which a frequency modulation of the probes waves along the fiber is introduced. This makes the frequency of maximum interaction between pump and probes to vary along the fiber, thus mitigating the pump pulse depletion and making it possible to use very large probe power, which brings an improved signal-to-noise ratio in detection.

  17. Non-local dynamics of weakly nonlinear spin excitations in thin ferromagnetic films

    NASA Astrophysics Data System (ADS)

    Kiseliev, V. V.; Tankeyev, A. P.

    1996-12-01

    Effective integro-differential equations of weakly nonlinear dynamics describing the interaction of quasi-one-dimensional exchange-dipole spin-waves are derived for a thin ferromagnetic slab (film). The non-local part of the magnetostatic dispersion of these waves has been taken into account. Algebraic soliton-like states have been predicted. The conditions of their existence and their dynamic properties are investigated depending on the film thickness and on the magnitude and orientation of the external magnetic field. The role of crystallographic magnetic anisotropy in the formation of these states is analysed.

  18. Coherence-incoherence patterns in a ring of non-locally coupled phase oscillators

    NASA Astrophysics Data System (ADS)

    Omel'chenko, O. E.

    2013-09-01

    We consider a paradigmatic spatially extended model of non-locally coupled phase oscillators which are uniformly distributed within a one-dimensional interval and interact depending on the distance between their sites' modulo periodic boundary conditions. This model can display peculiar spatio-temporal patterns consisting of alternating patches with synchronized (coherent) or irregular (incoherent) oscillator dynamics, hence the name coherence-incoherence pattern, or chimera state. For such patterns we formulate a general bifurcation analysis scheme based on a hierarchy of continuum limit equations. This provides the possibility of classifying known coherence-incoherence patterns and of suggesting directions for the search for new ones.

  19. Non-local Optical Topological Transitions and Critical States in Electromagnetic Metamaterials

    PubMed Central

    Ishii, Satoshi; Narimanov, Evgenii

    2015-01-01

    Just as the topology of the Fermi surface defines the properties of the free electrons in metals and semiconductors, the geometry of the iso-frequency surface in the phase space of the propagating electromagnetic waves, determines the optical properties of the corresponding optical materials. Furthermore, in the direct analog to the Lifshitz transition in condensed matter physics, a change in the topology of iso-frequency surface has a dramatic effect on the emission, propagation and scattering of the electromagnetic waves. Here, we uncover a new class of such optical topological transitions in metamaterials, induced by the non-locality of the electromagnetic response inherent to these composites. PMID:26670600

  20. An Algorithm for Improving Non-Local Means Operators via Low-Rank Approximation.

    PubMed

    May, Victor; Keller, Yosi; Sharon, Nir; Shkolnisky, Yoel

    2016-03-01

    We present a method for improving a non-local means (NLM) operator by computing its low-rank approximation. The low-rank operator is constructed by applying a filter to the spectrum of the original NLM operator. This results in an operator, which is less sensitive to noise while preserving important properties of the original operator. The method is efficiently implemented based on Chebyshev polynomials and is demonstrated on the application of natural images denoising. For this application, we provide a comparison of our method with other denoising methods.

  1. Phase-shift based BOTDA measurements tolerant to non-local effects

    NASA Astrophysics Data System (ADS)

    Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2013-05-01

    We demonstrate a BOTDA sensor based on the use of the Brillouin phase-shift that performs measurements tolerant to non-local effects. This technique raises opportunities to increase the distance covered by these sensors and the maximum optical power of the probe wave injected to the fiber. As a result, the system has the potential to increase the SNR achieved at the last meters of the fiber. Proof-of-concept experiments demonstrate unaltered measurements of the phase-shift spectrum in a 20Km long fiber for large frequency-dependent distortions of the pump pulse.

  2. Modern or post-modern? Local or non-local? A response to Leick.

    PubMed

    Walach, Harald

    2008-04-01

    Most debates in science and the humanities that cannot be settled are not about truth, nor about data, but about beliefs and world views. Philippe Leick's comment on entanglement models of homeopathy are a good example. Because of this, no argument, however, convincing to some, will settle that debate. The only thing that can resolve it is a large cultural shift. My own ideas about non-local models, for a whole category of possibly similar events of which homeopathy is but one example.

  3. Phosphorescent Iridium(III) Complexes Bearing Fluorinated Aromatic Sulfonyl Group with Nearly Unity Phosphorescent Quantum Yields and Outstanding Electroluminescent Properties.

    PubMed

    Zhao, Jiang; Yu, Yue; Yang, Xiaolong; Yan, Xiaogang; Zhang, Huiming; Xu, Xianbin; Zhou, Guijiang; Wu, Zhaoxin; Ren, Yixia; Wong, Wai-Yeung

    2015-11-11

    A series of heteroleptic functional Ir(III) complexes bearing different fluorinated aromatic sulfonyl groups has been synthesized. Their photophysical features, electrochemical behaviors, and electroluminescent (EL) properties have been characterized in detail. These complexes emit intense yellow phosphorescence with exceptionally high quantum yields (ΦP > 0.9) at room temperature, and the emission maxima of these complexes can be finely tuned depending upon the number of the fluorine substituents on the pendant phenyl ring of the sulfonyl group. Furthermore, the electrochemical properties and electron injection/transporting (EI/ET) abilities of these Ir(III) phosphors can also be effectively tuned by the fluorinated aromatic sulfonyl group to furnish some desired characters for enhancing the EL performance. Hence, the maximum luminance efficiency (ηL) of 81.2 cd A(-1), corresponding to power efficiency (ηP) of 64.5 lm W(-1) and external quantum efficiency (ηext) of 19.3%, has been achieved, indicating the great potential of these novel phosphors in the field of organic light-emitting diodes (OLEDs). Furthermore, a clear picture has been drawn for the relationship between their optoelectronic properties and chemical structures. These results should provide important information for developing highly efficient phosphors.

  4. Interplay among electrostatic, dispersion and steric interactions: Spectroscopy and quantum chemical calculations of π-hydrogen bonded complexes.

    PubMed

    Kumar, Sumit; Singh, Santosh Kumar; Vaishnav, Jamuna Kanaram; Hill, J Grant; Das, Aloke

    2017-01-26

    π-hydrogen bonding interactions are ubiquitous in both materials and biology. Despite their relatively weak nature great progress has been made in their investigation by experimental and theoretical methods, but this becomes significantly more complicated when secondary intermolecular interactions are present. In this study the effect of successive methyl substitution on the supramolecular structure and interaction energy of indole⋯methylated benzene (ind⋯n-mb, n = 1-6) complexes is probed through a combination of supersonic jet experiment and benchmark quality quantum chemical calculations. It is demonstrated that additional secondary interactions introduce a subtle interplay among electrostatic and dispersion forces, as well as steric repulsion, which fine-tunes the overall structural motif. Resonant Two-Photon Ionization (R2PI) and IR-UV double resonance spectroscopy techniques were used to probe jet-cooled ind⋯n-mb (n = 2, 3, 6) complexes, with red-shifting of the N-H IR stretching frequency showing that increasing the degree of methyl substitution increases the strength of the primary N-H⋯π interaction. Ab initio harmonic frequency and binding energy calculations confirm this trend for all six complexes. Electronic spectra of the three dimers are broad and structureless, with quantum chemical calculations revealing that this is likely due to multiple tilted conformations of each dimer possessing similar stabilization energies.

  5. Four-mode quantum calculations of resonance states in complex-forming bimolecular reactions: Cl-+CH3Br

    NASA Astrophysics Data System (ADS)

    Schmatz, Stefan

    2005-06-01

    The vibrational resonance states of the complexes formed in the nucleophilic bimolecular substitution (SN2) reaction Cl-+CH3Br→ClCH3+Br- were calculated by means of the filter diagonalization method employing a coupled-cluster potential-energy surface and a Hamiltonian that incorporates an optical potential and is formulated in Radau coordinates for the carbon-halogen stretching modes. The four-dimensional model also includes the totally symmetric vibrations of the methyl group (C-H stretch and umbrella bend). The vast majority of bound states and many resonance states up to the first overtone of the symmetric stretching vibration in the exit channel complex have been calculated, analyzed, and assigned four quantum numbers. The resonances are classified into entrance channel, exit channel, and delocalized states. The resonance widths fluctuate over six orders of magnitude. In addition to a majority of Feshbach-type resonances there are also exceedingly long-lived shape resonances, which are associated with the entrance channel and can only decay by tunneling. The state-selective decay of the resonances was studied in detail. The linewidths of the resonances, and thus the coupling to the energetic continuum, increase with excitation in any mode. Due to the strong mixing of the many progressions in the intermolecular stretching modes of the intermediate complexes, this increase as a function of the corresponding quantum numbers is not monotonic, but exhibits pronounced fluctuations.

  6. Quantum transport behavior of Ni-based dinuclear complexes in presence of zigzag graphene nanoribbon as electrode

    NASA Astrophysics Data System (ADS)

    Sarkar, Sunandan; Pramanik, Anup; Sarkar, Pranab

    2016-10-01

    Quantum transport properties of some Ni-based dinuclear complexes with different polydentate organic ligands have been studied by applying abinitio density functional theory along with nonequilibrium Green's function formulations. It is demonstrated that these materials are capable of showing multifunctional spin dependent properties by the influence of edge states of zigzag edged graphene nanoribbons. The current-voltage characteristics of these materials show spin dependent negative differential resistance behavior, spin filtering effect, and also voltage rectifying property. Proper tuning of these materials can alter these effects which may be utilized in various spintronic devices.

  7. Direct calculation of the reactive transition matrix by L-squared quantum mechanical variational methods with complex boundary conditions

    NASA Technical Reports Server (NTRS)

    Sun, Yan; Yu, Chin-Hui; Kouri, Donald J.; Schwenke, David W.; Halvick, Philippe

    1989-01-01

    A new formalism of the generalized Newton variational principle for the calculation of quantum mechanical state-to-state reaction probabilities is presented. The reformulation involves solving directly for the transition matrix rather than the reactance mtrix so that calculations may be carried out for individual columns of the transition matrix without obtaining solutions for all possible initial channels. The convergence of calculations with real and complex boundary conditions are compared for H + H2 - H2 + H, O + H2 - OH + H, and O + HD - OH + D and OD + H.

  8. Synthesis of a quantum nanocrystal-gold nanoshell complex for near-infrared generated fluorescence and photothermal decay of luminescence

    NASA Astrophysics Data System (ADS)

    Lin, Adam Y.; Young, Joseph K.; Nixon, Ariel V.; Drezek, Rebekah A.

    2014-08-01

    Multifunction nanoparticle complexes have previously been developed to aid physicians in both diagnosis and treatment of cancerous tissue. Here, we designed a nanoparticle complex structure that consists of a plasmonically active hollow gold nanoshell core surrounded by photoluminescent quantum nanocrystals (QNs) in the form of PbS encapsulated by a silica layer. There are three main design variables including HGN synthesis and optical tuning, formation of the silica layer on the hollow gold nanoshell surface, and fabrication and photoluminescence tuning of PbS quantum nanocrystals. The hollow gold nanoshells were deliberately designed to function in the optical regimes that maximize tissue transmissivity (800 nm) and minimize tissue absorption (1100 nm). Secondly, several chemical ligands were tested such as (3-mercaptopropyl)trimethoxysilane and mercaptoundecanoic acid for controlled growth of the silica layer. Last, PbS QNs were synthesized and optimized with various capping agents, where the nanocrystals excited at the same wavelength were used to activate the photothermal properties of the hollow gold nanoshells. Upon irradiation of the complex with a lower power 800 nm laser, the nanocrystals luminesce at 1100 nm. At ablative temperatures the intrinsic luminescent properties of the QNs are altered and the luminescent output is significantly reduced (>70%). While this paper focuses on synthesis and optimization of the QN-HGN complex, in the future we believe that this novel particle complex design may have the potential to serve as a triple theranostic agent, which will aid satellite tumor localization, photothermal treatment, and ablative confirmation.Multifunction nanoparticle complexes have previously been developed to aid physicians in both diagnosis and treatment of cancerous tissue. Here, we designed a nanoparticle complex structure that consists of a plasmonically active hollow gold nanoshell core surrounded by photoluminescent quantum nanocrystals (QNs

  9. Probability-based non-local means filter for speckle noise suppression in optical coherence tomography images.

    PubMed

    Yu, Hancheng; Gao, Jianlin; Li, Aiting

    2016-03-01

    In this Letter, a probability-based non-local means filter is proposed for speckle reduction in optical coherence tomography (OCT). Originally developed for additive white Gaussian noise, the non-local means filter is not suitable for multiplicative speckle noise suppression. This Letter presents a two-stage non-local means algorithm using the uncorrupted probability of each pixel to effectively reduce speckle noise in OCT. Experiments on real OCT images demonstrate that the proposed filter is competitive with other state-of-the-art speckle removal techniques and able to accurately preserve edges and structural details with small computational cost.

  10. Numerically Exact Dynamics of Functional Quantum Systems - Applications to GaAs Quantum Dot Qubits and 2-DIMENSIONAL Spectra of Very Large Photosyntheitc Complexes

    NASA Astrophysics Data System (ADS)

    Dattani, Nikesh S.

    2013-06-01

    Functional quantum systems is an emerging research field which includes quantum engineering (the design of technologies that make use of quantum mechanics to outperform their classical counterparts, such as quantum computers, quantum communication devices, quantum thermometers, quantum telescopes, etc.) and the study of natural processes where quantum mechanics provides some improvement that cannot be realized with classical mechanics (possible examples are photosynthesis, animal navigation, the sense of smell, etc.). Being able to predict how a quantum mechanical system changes (ie, how its density matrix changes), given its hamiltonian, is paramount in quantum engineering as one needs to know which hamiltonian will give the desired outcome. Likewise, being able to predict density matrix dynamics in natural systems can help in understanding the system's mechanism, in controlling the system's processes, and can be helpful if designing a technology which attempts to mimic a natural process. State of the art techniques for calculating density matrix dynamics of functional quantum systems in real-time, and with numerically exact accuracy, have been developed over the last year. These techniques will be presented, followed by applications for quantum dot based quantum computing, and for calculating the 2D spectra of large biological systems.

  11. Local and Non-local Regularization Techniques in Emission (PET/SPECT) Tomographic Image Reconstruction Methods.

    PubMed

    Ahmad, Munir; Shahzad, Tasawar; Masood, Khalid; Rashid, Khalid; Tanveer, Muhammad; Iqbal, Rabail; Hussain, Nasir; Shahid, Abubakar; Fazal-E-Aleem

    2016-06-01

    Emission tomographic image reconstruction is an ill-posed problem due to limited and noisy data and various image-degrading effects affecting the data and leads to noisy reconstructions. Explicit regularization, through iterative reconstruction methods, is considered better to compensate for reconstruction-based noise. Local smoothing and edge-preserving regularization methods can reduce reconstruction-based noise. However, these methods produce overly smoothed images or blocky artefacts in the final image because they can only exploit local image properties. Recently, non-local regularization techniques have been introduced, to overcome these problems, by incorporating geometrical global continuity and connectivity present in the objective image. These techniques can overcome drawbacks of local regularization methods; however, they also have certain limitations, such as choice of the regularization function, neighbourhood size or calibration of several empirical parameters involved. This work compares different local and non-local regularization techniques used in emission tomographic imaging in general and emission computed tomography in specific for improved quality of the resultant images.

  12. Robust GM/WM segmentation of the spinal cord with iterative non-local statistical fusion.

    PubMed

    Asman, Andrew J; Smith, Seth A; Reich, Daniel S; Landman, Bennett A

    2013-01-01

    New magnetic resonance imaging (MRI) sequences are enabling clinical study of the in vivo spinal cord's internal structure. Yet, low contrast-to-noise ratio, artifacts, and imaging distortions have limited the applicability of tissue segmentation techniques pioneered elsewhere in the central nervous system. Recently, methods have been presented for cord/non-cord segmentation on MRI and the feasibility of gray matter/white matter tissue segmentation has been evaluated. To date, no automated algorithms have been presented. Herein, we present a non-local multi-atlas framework that robustly identifies the spinal cord and segments its internal structure with submillimetric accuracy. The proposed algorithm couples non-local fusion with a large number of slice-based atlases (as opposed to typical volumetric ones). To improve performance, the fusion process is interwoven with registration so that segmentation information guides registration and vice versa. We demonstrate statistically significant improvement over state-of-the-art benchmarks in a study of 67 patients. The primary contributions of this work are (1) innovation in non-volumetric atlas information, (2) advancement of label fusion theory to include iterative registration/segmentation, and (3) the first fully automated segmentation algorithm for spinal cord internal structure on MRI.

  13. Quantitative universality and non-local interactions in neural pattern formation

    NASA Astrophysics Data System (ADS)

    Kaschube, Matthias; Schnabel, Michael; Loewel, Siegrid; Coppola, David; White, Leonard; Wolf, Fred

    2008-03-01

    The occurrence of universal quantitative laws in a strongly interacting multi-component system indicates that its behavior can be elucidated through the identification of general mathematical principles rather than by the detailed characterization of its individual components. Here we demonstrate that universal quantitative laws govern the spatial layout of orientation selective neurons in the visual cortex in three mammalian species separated in evolution by more than 50 million years. Most suggestive of a mathematical structure underlying this universality, the average number of pinwheel centers per orientation hyper-column in all three species is statistically indistinguishable from the constant π. Mathematical models of neural pattern formation can reproduce all observed universal quantitative laws if non-local interactions are dominant, indicating that non-local interactions are constitutive in visual cortical development. The spatial layout adheres to these laws even if visual cortical organization exhibits marked overall inhomogeneities and when neuronal response properties are experimentally altered. These results demonstrate that mathematical principles can shape the organization of the brain as powerfully as an organism's genetic make-up.

  14. Finite-element modeling of thermal gradients during non-local thermal spin injection

    NASA Astrophysics Data System (ADS)

    Yang, Zihao; Giles, Brandon; Jamison, John; Myers, Roberto

    A new spin Seebeck experiment has been demonstrated, in which a laser is focused on an electrically isolated Pt absorbing pad on yttrium iron garnet (YIG), thermally generating a spin current in YIG. The spins diffuse laterally and are detected non-locally on a remote Pt detector via the inverse spin Hall effect (VISHEnon - local) . This geometry is expected to remove parasitic thermal transport voltages unrelated to the magnonic spin current that could contaminate VISHEnon - local . To validate this, 3D steady-state heat conduction equations are solved to determine the stray temperature gradient at the Pt detector as a function of distance from the laser heating source. We find that the temperature gradient beneath the Pt detector vanishes when the laser is laterally displaced (along x) by 50 μm. The gradient along the interface normal follows ∇Tz (x) ~e - 1 . 76 x and the gradient parallel to the interface follows ∇Tx (x) ~e - 0 . 08 x . Both gradients decay much faster than the measured VISHEnon - local (x) ~e - 0 . 025 x demonstrating the validity of the non-local geometry in probing laterally diffused spin. This work is supported by ARO-MURI W911NF-14-1-0016.

  15. Spectral non-uniform temperature and non-local heat transfer in the spin Seebeck effect.

    PubMed

    Tikhonov, Konstantin S; Sinova, Jairo; Finkel'stein, Alexander M

    2013-01-01

    Recently discovered spin-dependent thermoelectric effects have merged spin, charge, and thermal physics, known as spin caloritronics, of which the spin Seebeck effect is its most puzzling. Here we present a theory of this effect driven by subthermal non-local phonon heat transfer and spectral non-uniform temperature. The theory explains its non-local behaviour from the fact that phonons that store the energy (thermal) and the phonons that transfer it (subthermal) are located in different parts of the spectrum and have different kinetics. This gives rise to a spectral phonon distribution that deviates from local equilibrium along the substrate and is sensitive to boundary conditions. The theory also predicts a non-magnon origin of the effect in ferromagnetic metals in agreement with observations in recent experiments. Equilibration of the heat flow from the substrate to the Pt probe and backwards leads to a vertical spin current produced by the spin-polarized electrons dragged by the thermal phonons.

  16. Rotation-invariant multi-contrast non-local means for MS lesion segmentation.

    PubMed

    Guizard, Nicolas; Coupé, Pierrick; Fonov, Vladimir S; Manjón, Jose V; Arnold, Douglas L; Collins, D Louis

    2015-01-01

    Multiple sclerosis (MS) lesion segmentation is crucial for evaluating disease burden, determining disease progression and measuring the impact of new clinical treatments. MS lesions can vary in size, location and intensity, making automatic segmentation challenging. In this paper, we propose a new supervised method to segment MS lesions from 3D magnetic resonance (MR) images using non-local means (NLM). The method uses a multi-channel and rotation-invariant distance measure to account for the diversity of MS lesions. The proposed segmentation method, rotation-invariant multi-contrast non-local means segmentation (RMNMS), captures the MS lesion spatial distribution and can accurately and robustly identify lesions regardless of their orientation, shape or size. An internal validation on a large clinical magnetic resonance imaging (MRI) dataset of MS patients demonstrated a good similarity measure result (Dice similarity = 60.1% and sensitivity = 75.4%), a strong correlation between expert and automatic lesion load volumes (R(2) = 0.91), and a strong ability to detect lesions of different sizes and in varying spatial locations (lesion detection rate = 79.8%). On the independent MS Grand Challenge (MSGC) dataset validation, our method provided competitive results with state-of-the-art supervised and unsupervised methods. Qualitative visual and quantitative voxel- and lesion-wise evaluations demonstrated the accuracy of RMNMS method.

  17. Image-Guided Non-Local Dense Matching with Three-Steps Optimization

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Zhang, Yongjun; Yue, Zhaoxi

    2016-06-01

    This paper introduces a new image-guided non-local dense matching algorithm that focuses on how to solve the following problems: 1) mitigating the influence of vertical parallax to the cost computation in stereo pairs; 2) guaranteeing the performance of dense matching in homogeneous intensity regions with significant disparity changes; 3) limiting the inaccurate cost propagated from depth discontinuity regions; 4) guaranteeing that the path between two pixels in the same region is connected; and 5) defining the cost propagation function between the reliable pixel and the unreliable pixel during disparity interpolation. This paper combines the Census histogram and an improved histogram of oriented gradient (HOG) feature together as the cost metrics, which are then aggregated based on a new iterative non-local matching method and the semi-global matching method. Finally, new rules of cost propagation between the valid pixels and the invalid pixels are defined to improve the disparity interpolation results. The results of our experiments using the benchmarks and the Toronto aerial images from the International Society for Photogrammetry and Remote Sensing (ISPRS) show that the proposed new method can outperform most of the current state-of-the-art stereo dense matching methods.

  18. Bonding in diborane-metal complexes: a quantum-chemical and experimental study of complexes featuring early and late transition metals.

    PubMed

    Wagner, Arne; Kaifer, Elisabeth; Himmel, Hans-Jörg

    2013-06-03

    The coordination chemistry of the doubly base-stabilised diborane(4), [HB(hpp)]2 (hpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido-[1,2-a]pyrimidinate), was extended by the synthesis of new late transition-metal complexes containing Cu(I) and Rh(I) fragments. A detailed experimental study was conducted and quantum-chemical calculations on the metal-ligand bonding interactions for [HB(hpp)]2 complexes of Group 6, 9, 11 and 12 metals revealed the dominant B-H-M interactions in the case of early transition-metal fragments, whereas the B-B-M bonding prevails in the case of the late d-block compounds. These findings support the experimental results as reflected by the IR and NMR spectroscopic parameters of the investigated compounds. DFT calculations on [MeB(hpp)]2 and model reactions between [B2H4⋅2NMe3] and [Rh(μ-Cl)(C2H4)2] showed that the bicyclic guanidinate allows in principle for an oxidative addition of the B-B bond. However, the formation of σ-complexes is thermodynamically favoured. The results point to the selective B-H or B-B bond-activation of diborane compounds by complexation, depending on the chosen transition-metal fragment.

  19. Quantum Computing for Quantum Chemistry

    DTIC Science & Technology

    2010-09-01

    random walks as the decoherence became strong. Recent experiments on photosynthetic light -harvesting complexes observed long-lived excitonic coherences...by the light -harvesting complex. In Environment-assisted quantum walks in energy transfer of photosynthetic complexes, J. Chem. Phys. 129 (2008...a decohered quantum walk. Motivated by the experiments on the Fenna-Matthews-Olson (FMO) light -harvesting complex of green sulfur bacteria, we

  20. The Foundations of Quantum Mechanics: Historical Analysis and Open Questions -- Cesena, 2004

    NASA Astrophysics Data System (ADS)

    Garola, Claudio; Rossi, Arcangelo; Sozzo, Sandro

    Introduction / C. Garola, A. Rossi and S. Sozzo -- If Bertlmann had three feet / A. Afriat -- Macroscopic interpretability of quantum component systems / R. Ascoli -- Premeasurement versus measurement: a basic form of complementarity / G. Auletta and G. Tarozzi -- Remarks on conditioning / E. G. Beltrametti -- Entangled state preparation in experiments on quantum non-locality / V. Berardi and A. Garuccio -- The first steps of quantum electrodynamics: what is it that's being quantized? / S. Bergia -- On the meaning of element in the science of italic tradition, the question of physical objectivity (and/or physical meaning) and quantum mechanics / G. Boscarino -- Mathematics and epistemology in Planck's theoretical work (1898-1915) / P. Campogalliani -- On the free motion with noise / B. Carazza and R. Tedeschi -- Field quantization and wave/particle duality / M. Cini -- Parastatistics in econophysics? / D. Costantini and U. Garibaldi -- Theory-laden instruments and quantum mechanics / S. D'Agostino -- Quantum non-locality and the mathematical representation of experience / V. Fano -- On the notion of proposition in classical and quantum mechanics / C. Garola and S. Sozzo -- The electromagnetic conception of nature and the origins of quantum physics / E. A. Giannetto -- What we talk about when we talk about universe computability / S. Guccione -- Bohm and Bohmian mechanics / G. Introzzi and M. Rossetti -- An objective background for quantum theory relying on thermodynamic concepts / L. Lanz and B. Vacchini -- The entrance of quantum mechanics in Italy: from Garbasso to Fermi / M. Leone and N. Robotti -- The measure of momentum in quantum mechanics / F. Logiurato and C. Tarsitani -- On the two-slit interference experiment: a statistical discussion / M. Minozzo -- Why the reactivity of the elements is a relational property, and why it matters / V. Mosini -- Detecting non compatible properties in double-slit experiment without erasure / G. Nisticò -- If you can

  1. Quantum chemical characterization of zwitterionic structures: Supramolecular complexes for modifying the wettability of oil-water-limestone system.

    PubMed

    Lopez-Chavez, Ernesto; Garcia-Quiroz, Alberto; Gonzalez-Garcia, Gerardo; Orozco-Duran, Gabriela E; Zamudio-Rivera, Luis S; Martinez-Magadan, José M; Buenrostro-Gonzalez, Eduardo; Hernandez-Altamirano, Raul

    2014-06-01

    In this work, we present a quantum chemical study pertaining to some supramolecular complexes acting as wettability modifiers of oil-water-limestone system. The complexes studied are derived from zwitterionic liquids of the types N'-alkyl-bis, N-alquenil, N-cycloalkyl, N-amyl-bis-beta amino acid or salts acting as sparkling agents. We studied two molecules of zwitterionic liquids (ZL10 and ZL13), HOMO and LUMO levels, and the energy gap between them, were calculated, as well as the electron affinity (EA) and ionization potential (IP), chemical potential, chemical hardness, chemical electrophilicity index and selectivity descriptors such Fukui indices. In this work, electrochemical comparison was realized with cocamidopropyl betaine (CPB), which is a structure zwitterionic liquid type, nowadays widely applied in enhanced recovery processes.

  2. ESR, spectroscopic, and quantum-chemical studies on the electronic structures of complexes formed by Cu(I) with radicals

    SciTech Connect

    Gritsan, N.P.; Usov, O.M.; Shokhirev, N.V.; Khmelinskii, I.V.; Plyusnin, V.F.; Bazhin, N.M.

    1986-07-01

    The optical and ESR spectra have been examined for complexes of Cu(I) with various radicals, which contain various numbers of Cl/sup -/ ions in the central-atom coordination sphere. The spin-Hamiltonian parameters have been determined for all these radical complexes, and the observed ESR spectra have been compared with those calculated with allowance for second-order effects. The observed values for the isotropic and anisotropic components of the HFI constant from the central ion have been used to estimate the contributions from the 4s and 3d/sup 2//sub z/ orbitals of the copper ion to the unpaired-electron MO. Quantum-chemical calculations have been performed by the INDO method on the electronic structures and geometries of complexes formed by CH/sub 2/OH with Cu(I) for various Cl/sup -/ contents in the coordination sphere. The radical is coordinated by the ..pi.. orbital on the carbon atom, and the stabilities of the radical complexes decrease as the number of Cl/sup -/ ions in the coordination sphere increases. A geometry close to planar for the CuCl/sub 4//sup 3 -/ fragment in a complex containing four Cl/sup -/ ions.

  3. Improving Signal-to-Noise Ratio in Susceptibility Weighted Imaging: A Novel Multicomponent Non-Local Approach

    PubMed Central

    Borrelli, Pasquale; Palma, Giuseppe; Tedeschi, Enrico; Cocozza, Sirio; Comerci, Marco; Alfano, Bruno; Haacke, E. Mark; Salvatore, Marco

    2015-01-01

    In susceptibility-weighted imaging (SWI), the high resolution required to obtain a proper contrast generation leads to a reduced signal-to-noise ratio (SNR). The application of a denoising filter to produce images with higher SNR and still preserve small structures from excessive blurring is therefore extremely desirable. However, as the distributions of magnitude and phase noise may introduce biases during image restoration, the application of a denoising filter is non-trivial. Taking advantage of the potential multispectral nature of MR images, a multicomponent approach using a Non-Local Means (MNLM) denoising filter may perform better than a component-by-component image restoration method. Here we present a new MNLM-based method (Multicomponent-Imaginary-Real-SWI, hereafter MIR-SWI) to produce SWI images with high SNR and improved conspicuity. Both qualitative and quantitative comparisons of MIR-SWI with the original SWI scheme and previously proposed SWI restoring pipelines showed that MIR-SWI fared consistently better than the other approaches. Noise removal with MIR-SWI also provided improvement in contrast-to-noise ratio (CNR) and vessel conspicuity at higher factors of phase mask multiplications than the one suggested in the literature for SWI vessel imaging. We conclude that a proper handling of noise in the complex MR dataset may lead to improved image quality for SWI data. PMID:26030293

  4. Temporal Non-Local Means Filtering Reveals Real-Time Whole-Brain Cortical Interactions in Resting fMRI

    PubMed Central

    Bhushan, Chitresh; Chong, Minqi; Choi, Soyoung; Joshi, Anand A.; Haldar, Justin P.; Damasio, Hanna; Leahy, Richard M.

    2016-01-01

    Intensity variations over time in resting BOLD fMRI exhibit spatial correlation patterns consistent with a set of large scale cortical networks. However, visualizations of this data on the brain surface, even after extensive preprocessing, are dominated by local intensity fluctuations that obscure larger scale behavior. Our novel adaptation of non-local means (NLM) filtering, which we refer to as temporal NLM or tNLM, reduces these local fluctuations without the spatial blurring that occurs when using standard linear filtering methods. We show examples of tNLM filtering that allow direct visualization of spatio-temporal behavior on the cortical surface. These results reveal patterns of activity consistent with known networks as well as more complex dynamic changes within and between these networks. This ability to directly visualize brain activity may facilitate new insights into spontaneous brain dynamics. Further, temporal NLM can also be used as a preprocessor for resting fMRI for exploration of dynamic brain networks. We demonstrate its utility through application to graph-based functional cortical parcellation. Simulations with known ground truth functional regions demonstrate that tNLM filtering prior to parcellation avoids the formation of false parcels that can arise when using linear filtering. Application to resting fMRI data from the Human Connectome Project shows significant improvement, in comparison to linear filtering, in quantitative agreement with functional regions identified independently using task-based experiments as well as in test-retest reliability. PMID:27391481

  5. Temporal Non-Local Means Filtering Reveals Real-Time Whole-Brain Cortical Interactions in Resting fMRI.

    PubMed

    Bhushan, Chitresh; Chong, Minqi; Choi, Soyoung; Joshi, Anand A; Haldar, Justin P; Damasio, Hanna; Leahy, Richard M

    2016-01-01

    Intensity variations over time in resting BOLD fMRI exhibit spatial correlation patterns consistent with a set of large scale cortical networks. However, visualizations of this data on the brain surface, even after extensive preprocessing, are dominated by local intensity fluctuations that obscure larger scale behavior. Our novel adaptation of non-local means (NLM) filtering, which we refer to as temporal NLM or tNLM, reduces these local fluctuations without the spatial blurring that occurs when using standard linear filtering methods. We show examples of tNLM filtering that allow direct visualization of spatio-temporal behavior on the cortical surface. These results reveal patterns of activity consistent with known networks as well as more complex dynamic changes within and between these networks. This ability to directly visualize brain activity may facilitate new insights into spontaneous brain dynamics. Further, temporal NLM can also be used as a preprocessor for resting fMRI for exploration of dynamic brain networks. We demonstrate its utility through application to graph-based functional cortical parcellation. Simulations with known ground truth functional regions demonstrate that tNLM filtering prior to parcellation avoids the formation of false parcels that can arise when using linear filtering. Application to resting fMRI data from the Human Connectome Project shows significant improvement, in comparison to linear filtering, in quantitative agreement with functional regions identified independently using task-based experiments as well as in test-retest reliability.

  6. The effects of local and non-local traffic on child pedestrian safety: a spatial displacement of risk.

    PubMed

    Yiannakoulias, Nikolaos; Scott, Darren M

    2013-03-01

    In most places, motor-vehicle traffic volume is associated with increased risk of child pedestrian injury; however, the burden of risk is geographically complex. In some neighbourhoods, proportionally fewer drivers may be local, meaning that the moral and practical responsibility of risk to children is displaced from one place (e.g., the suburbs) to another (e.g., downtown). Using the City of Toronto, Canada, as a case study, this research asks two related questions: 1) what is the variation in traffic volume by neighbourhood of origin and socioeconomic status and 2) what is the relationship between the geographical origin of traffic and the risk of collisions involving child pedestrians and motor-vehicles? We find that low-income downtown neighbourhoods have the highest proportion of non-local traffic. We also find that while higher local traffic activity is associated with lower risk of collision, higher flow-through traffic activity (excluding traffic from major thoroughfares) is associated with higher risk of collision. We interpret the former as very likely a proxy of parents' frequency of chauffeuring children to school, and the latter an illustration of the spatial displacement of risk between Toronto neighbourhoods. Our results suggest that more attention needs to be paid to account for the externalization of harm experienced by children, particularly in low-income downtown neighbourhoods.

  7. Quantum dynamics studies of gas-surface reactions and use of complex absorbing potentials in wave-packet calculations

    NASA Astrophysics Data System (ADS)

    Ge, Jiuyuan

    1999-11-01

    In this thesis, quantum dynamics studies are conducted on gas-surface reactions and complex absorbing potentials. Through a three-dimensional model, dissociation probabilities for O2 on both (110) and (100) surfaces of copper are calculated for ground state as well as rovibrationally excited oxygen molecules. Specifically, the reason for the difference in calculated dissociation probabilities of oxygen on two surfaces is explained. Then the thermal effect of the surface on the dissociation probability is studied by a one dimensional fluctuating barrier. It is observed that the quantum mechanical tunneling probability exhibits a maximum as a function of the oscillating frequency between the low and the high frequency limits. The physical origin and process underlying this resonantlike phenomenon are proposed. In the second part of this thesis, the complex absorbing potential (CAP) is introduced and studied. Exact numerical calculation shows that use of optimized CAP significantly improves the efficiency of wavefunction absorption over that of negative imaginary potential (NIP) in scattering applications. The CAP is optimized by an efficient time-dependent propagation approach. Application to the prototype inelastic scattering of He + H2 demonstrates the accuracy and efficiency of the channel-dependent CAP for extracting state-to-state scattering information.

  8. Complex transport behaviors of rectangular graphene quantum dots subject to mechanical vibrations

    NASA Astrophysics Data System (ADS)

    Xu, Mengke; Wang, Yisen; Bao, Rui; Huang, Liang; Lai, Ying-Cheng

    2016-05-01

    Graphene-based mechanical resonators have attracted much attention due to their superior elastic properties and extremely low mass density. We investigate the effects of mechanical vibrations on electronic transport through graphene quantum dots, under the physically reasonable assumption that the time scale associated with electronic transport is much shorter than that with mechanical vibration so that, at any given time, an electron “sees” a static but deformed graphene sheet. We find that, besides periodic oscillation in the quantum transmission at the same frequency as that of mechanical vibrations, structures at finer scales can emerge as an intermediate state, which may lead to spurious higher-frequency components in the current through the device.

  9. Effect of Rasbha spin-orbit interaction on the ground state energy of a hydrogenic D{sup 0} complex in a Gaussian quantum dot

    SciTech Connect

    Boda, Aalu Kumar, D. Sanjeev; Chatterjee, Ashok; Mukhopadhyay, Soma

    2015-06-24

    The ground state energy of a hydrogenic D{sup 0} complex trapped in a three-dimensional GaAs quantum dot with Gaussian confinement is calculated variationally incorporating the effect of Rashba spin-orbit interaction. The results are obtained as a function of the quantum dot size and the Rashba spin-orbit interaction. The results show that the Rashba interaction reduces the ground state energy of the system.

  10. Geometrically Constructed Markov Chain Monte Carlo Study of Quantum Spin-phonon Complex Systems

    NASA Astrophysics Data System (ADS)

    Suwa, Hidemaro

    2013-03-01

    We have developed novel Monte Carlo methods for precisely calculating quantum spin-boson models and investigated the critical phenomena of the spin-Peierls systems. Three significant methods are presented. The first is a new optimization algorithm of the Markov chain transition kernel based on the geometric weight allocation. This algorithm, for the first time, satisfies the total balance generally without imposing the detailed balance and always minimizes the average rejection rate, being better than the Metropolis algorithm. The second is the extension of the worm (directed-loop) algorithm to non-conserved particles, which cannot be treated efficiently by the conventional methods. The third is the combination with the level spectroscopy. Proposing a new gap estimator, we are successful in eliminating the systematic error of the conventional moment method. Then we have elucidated the phase diagram and the universality class of the one-dimensional XXZ spin-Peierls system. The criticality is totally consistent with the J1 -J2 model, an effective model in the antiadiabatic limit. Through this research, we have succeeded in investigating the critical phenomena of the effectively frustrated quantum spin system by the quantum Monte Carlo method without the negative sign. JSPS Postdoctoral Fellow for Research Abroad

  11. What might rice piles tell us about non-local sediment transport?

    NASA Astrophysics Data System (ADS)

    Longjas, A.; Voller, V. R.; Paola, C.; Filipovitch, N.

    2014-12-01

    Our research objective is to identify sediment transport systems that exhibit non local signals, such as those seen in the long-profile of fluvial surfaces. In previous work we have shown that appropriate nonlocal models of sediment transport under various tectonic forcing, can lead to fluvial surface shapes that are distinct from those obtained with local models. For example, in the study of a sediment bypass system, a nonlocal model for the sediment flux predicts a concave down fluvial surface in contrast to the linear surface predicted with a local flux model. It is well known that hold ups and fast paths in transport systems lead to non-local behaviors. And we think that the mechanism that creates the unexpected curvatures in fluvial profiles is one of "storage and release". Perhaps the classic storage and release system is that seen in rice pile experiments. One set up for this experiment involves the formation of a rice pile in the gap (~25mm) between two vertical glass plates resting on a solid surface. In this system rice is added at a constant rate at the left and allowed to freely exit a distance (~0.5m) downstream; the system is run until a steady state is approached. Of course, an exact steady state is not reached because the rice does not move steadily down the pile surface but rather advances in a series of avalanches, with multiple length scales, separated by waiting times; in other words is transported via storage and release. The naive expectancy is that at the steady state the surface of the rice pile will exhibit a constant angle of repose. Our experiments with the system, however, indicate that while the storage and release mechanism invokes large temporal fluctuations in the pile its surface exhibits a persistent concave down shape. In this paper, we present the main findings of our rice pile experiment, explore models that might explain the persistence of the curved surface, and uncover the behavioral links between the rice pile model and non-local

  12. A remark on the role of indeterminism and non-locality in the violation of Bell’s inequalities

    SciTech Connect

    Sassoli de Bianchi, Massimiliano

    2014-03-15

    Diederik Aerts was the first in the eighties to develop a concrete example of a macroscopic “classical” entity violating Bell’s inequalities (BI). In more recent years, he also developed a macroscopic model in which the amount of non-locality and indeterminism can be continuously varied, and used it to show that by increasing non-locality one increases the degree of violation of BI, whereas by increasing indeterminism one decreases the degree of violation of BI. In this article we introduce and analyze a different macroscopic model in which the amount of non-locality and indeterminism can also be parameterized, and therefore varied, and find that, in accordance with the model of Aerts, an increase of non-locality does produce a stronger violation of BI. However, differently from his model, we also find that, depending on the initial state in which the system is prepared, an increase of indeterminism can either strengthen or weaken the degree of violation of BI. -- Highlights: •There are macroscopic models that can violate Bell’s inequalities (BI). •We describe a model in which non-locality and indeterminism can be continuously varied. •An increase of non-locality produces a stronger violation of BI. •An increase of indeterminism can either produce a stronger or weaker violation of BI, depending on the initial state.

  13. A non-local free boundary problem arising in a theory of financial bubbles

    PubMed Central

    Berestycki, Henri; Monneau, Regis; Scheinkman, José A.

    2014-01-01

    We consider an evolution non-local free boundary problem that arises in the modelling of speculative bubbles. The solution of the model is the speculative component in the price of an asset. In the framework of viscosity solutions, we show the existence and uniqueness of the solution. We also show that the solution is convex in space, and establish several monotonicity properties of the solution and of the free boundary with respect to parameters of the problem. To study the free boundary, we use, in particular, the fact that the odd part of the solution solves a more standard obstacle problem. We show that the free boundary is and describe the asymptotics of the free boundary as c, the cost of transacting the asset, goes to zero. PMID:25288815

  14. Non-local sub-characteristic zones of influence in unsteady interactive boundary-layers

    NASA Technical Reports Server (NTRS)

    Rothmayer, A. P.

    1992-01-01

    The properties of incompressible, unsteady, interactive, boundary layers are examined for a model hypersonic boundary layer and internal flow past humps or, equivalently, external flow past short-scaled humps. Using a linear high frequency analysis, it is shown that the domains of dependence within the viscous sublayer may be a strong function of position within the sublayer and may be strongly influenced by the pressure displacement interaction, or the prescribed displacement condition. Detailed calculations are presented for the hypersonic boundary layer. This effect is found to carry over directly to the fully viscous problem as well as the nonlinear problem. In the fully viscous problem, the non-local character of the domains of dependence manifests itself in the sub-characteristics. Potential implications of the domain of dependence structure on finite difference computations of unsteady boundary layers are briefly discussed.

  15. A Non-Local Fuzzy Segmentation Method: Application to Brain MRI

    NASA Astrophysics Data System (ADS)

    Caldairou, Benoît; Rousseau, François; Passat, Nicolas; Habas, Piotr; Studholme, Colin; Heinrich, Christian

    The Fuzzy C-Means algorithm is a widely used and flexible approach for brain tissue segmentation from 3D MRI. Despite its recent enrichment by addition of a spatial dependency to its formulation, it remains quite sensitive to noise. In order to improve its reliability in noisy contexts, we propose a way to select the most suitable example regions for regularisation. This approach inspired by the Non-Local Mean strategy used in image restoration is based on the computation of weights modelling the grey-level similarity between the neighbourhoods being compared. Experiments were performed on MRI data and results illustrate the usefulness of the approach in the context of brain tissue classification.

  16. Non-local neighbor embedding image denoising algorithm in sparse domain

    NASA Astrophysics Data System (ADS)

    Shi, Guo-chuan; Xia, Liang; Liu, Shuang-qing; Xu, Guo-ming

    2013-12-01

    To get better denoising results, the prior knowledge of nature images should be taken into account to regularize the ill-posed inverse problem. In this paper, we propose an image denoising algorithm via non-local similar neighbor embedding in sparse domain. Firstly, a local statistical feature, namely histograms of oriented gradients of image patches is used to perform the clustering, and then the whole training data set is partitioned into a set of subsets which have similar local geometric structures and the centroid of each subset is also obtained. Secondly, we apply the principal component analysis (PCA) to learn the compact sub-dictionary for each cluster. Next, through sparse coding over the sub-dictionary and neighborhood selecting, the image patch to be synthesized can be approximated by its top k neighbors. The extensive experimental results validate the effective of the proposed method both in PSNR and visual perception.

  17. Effect of non-local electron conduction in compression of solid ball target for fast ignition

    NASA Astrophysics Data System (ADS)

    Nagatomo, Hideo; Asahina, Takashi; Nicolai, Philippe; Sunahara, Atsushi; Johzaki, Tomoyuki

    2016-10-01

    In the first phase of the fast ignition scheme, fuel target is compressed by the implosion laser, where only achievement of high dense fuel is required because the increment of the temperature to ignite the fuel is given by heating lasers. The ideal compression method for solid target is isentropic compression with tailored pulse shape. However, it requires the high laser intensity >1015 W/cm2 which cause the hot electrons. Numerical simulation for these conditions non-local electron transport model is necessary. Recently, we have installed SNB model to a 2-D radiation hydrodynamic simulation code. In this presentation, effect of hot electron in isentropic compression and optimum method are discussed, which may be also significant for shock ignition scheme. Also effect of external magnetic field to the hot electron will be considered. This study was supported by JSPS KAKENHI Grant No. 26400532.

  18. Thermal engineering of non-local resistance in lateral spin valves

    NASA Astrophysics Data System (ADS)

    Kasai, S.; Hirayama, S.; Takahashi, Y. K.; Mitani, S.; Hono, K.; Adachi, H.; Ieda, J.; Maekawa, S.

    2014-04-01

    We study the non-local spin transport in Permalloy/Cu lateral spin valves (LSVs) fabricated on thermally oxidized Si and MgO substrates. While these LSVs show the same magnitude of spin signals, significant substrate dependence of the baseline resistance was observed. The baseline resistance shows much weaker dependence on the inter-electrode distance than that of the spin transport observed in the Cu wires. A simple analysis of voltage-current characteristics in the baseline resistance indicates the observed result can be explained by a combination of the Peltier and Seebeck effects at the injector and detector junctions, suggesting the usage of high thermal conductivity substrate (or under-layer) is effective to reduce the baseline resistance.

  19. Non-local meta-conformal invariance in diffusion-limited erosion

    NASA Astrophysics Data System (ADS)

    Henkel, Malte

    2016-12-01

    The non-stationary relaxation and physical ageing in the diffusion-limited erosion process (dle) is studied through the exact solution of its Langevin equation, in d spatial dimensions. The dynamical exponent z = 1, the growth exponent β =\\max (0,(1-d)/2) and the ageing exponents a=b=d-1 and {λ }C={λ }R=d are found. In d = 1 spatial dimension, a new representation of the meta-conformal Lie algebra, isomorphic to {sl}(2,{{R}})\\oplus {sl}(2,{{R}}), acts as a dynamical symmetry of the noise-averaged dle Langevin equation. Its infinitesimal generators are non-local in space. The exact form of the full time-space dependence of the two-time response function of dle is reproduced for d = 1 from this symmetry. The relationship to the terrace-step-kink model of vicinal surfaces is discussed.

  20. Thermal engineering of non-local resistance in lateral spin valves

    SciTech Connect

    Kasai, S. Takahashi, Y. K.; Hirayama, S.; Mitani, S.; Hono, K.; Adachi, H.; Ieda, J.; Maekawa, S.

    2014-04-21

    We study the non-local spin transport in Permalloy/Cu lateral spin valves (LSVs) fabricated on thermally oxidized Si and MgO substrates. While these LSVs show the same magnitude of spin signals, significant substrate dependence of the baseline resistance was observed. The baseline resistance shows much weaker dependence on the inter-electrode distance than that of the spin transport observed in the Cu wires. A simple analysis of voltage-current characteristics in the baseline resistance indicates the observed result can be explained by a combination of the Peltier and Seebeck effects at the injector and detector junctions, suggesting the usage of high thermal conductivity substrate (or under-layer) is effective to reduce the baseline resistance.

  1. Can non-local or higher derivative theories provide alternatives to inflation?

    SciTech Connect

    Geshnizjani, Ghazal; Ahmadi, Nahid E-mail: nahmadi@ut.ac.ir

    2013-11-01

    The standard mechanism for producing the observed scale-invariant power spectrum from adiabatic vacuum fluctuations relies on first order derivative of fields in the action for curvature perturbations. It has been proven [1] that, under this ansatz, any theory of early universe that matches cosmological observations should include a phase of accelerated expansion (i.e. inflation) or it has to break at least one of the following tenets of classical general relativity: Null Energy Conditions (NEC), subluminal signal propagation, or sub-Planckian energy densities. We extend this proof to a large class of theories with higher (spatial) derivative or non-local terms in the action. Interestingly, only theories in the neighborhood of Lifshitz points with ω{sub k}∝k{sup 0} and k{sup 3} remain viable.

  2. Improving dimensional measurement from noisy atomic force microscopy images by non-local means filtering.

    PubMed

    Chen, Yuhang

    2016-01-01

    Quantitative evaluation of dimensional parameters from noisy atomic force microscopy (AFM) images was investigated. Non-local means (NLM) denoising was adopted to reduce noise and maintain fine image structures. Major tuning parameters in NLM filtering, such as the patch size and the window size, were optimized on simulated surface structures. The ability of dimensional evaluation from noisy data was demonstrated to be improved by almost 15 times. Finally, NLM filtering with optimal settings was applied on experimental AFM images, which were scanned on a patterned few-layer graphene specimen. Evaluations of the step height and the pattern size were verified to be much more accurate and robust. Such a data processing method can enhance the AFM dimensional measurements, particularly when the noise-level is reached.

  3. Impact of Rician adapted Non-Local Means filtering on HARDI.

    PubMed

    Descoteaux, Maxime; Wiest-Daesslé, Nicolas; Prima, Sylvain; Barillot, Christian; Deriche, Rachid

    2008-01-01

    In this paper we study the impact of denoising the raw high angular resolution diffusion imaging (HARDI) data with the Non-Local Means filter adapted to Rician noise (NLMr). We first show that NLMr filtering improves robustness of apparent diffusion coefficient (ADC) and orientation distribution function (ODF) reconstructions from synthetic HARDI datasets. Our results suggest that the NLMr filtering improve the quality of anisotropy maps computed from ADC and ODF and improve the coherence of q-ball ODFs with the underlying anatomy while not degrading angular resolution. These results are shown on a biological phantom with known ground truth and on a real human brain dataset. Most importantly, we show that multiple measurements of diffusion-weighted (DW) images and averaging these images along each direction can be avoided because NLMr filtering of the individual DW images produces better quality generalized fractional anisotropy maps and more accurate ODF fields than when computed from the averaged DW datasets.

  4. Sparse angular CT reconstruction using non-local means based iterative-correction POCS.

    PubMed

    Huang, Jing; Ma, Jianhua; Liu, Nan; Zhang, Hua; Bian, Zhaoying; Feng, Yanqiu; Feng, Qianjin; Chen, Wufan

    2011-04-01

    In divergent-beam computed tomography (CT), sparse angular sampling frequently leads to conspicuous streak artifacts. In this paper, we propose a novel non-local means (NL-means) based iterative-correction projection onto convex sets (POCS) algorithm, named as NLMIC-POCS, for effective and robust sparse angular CT reconstruction. The motivation for using NLMIC-POCS is that NL-means filtered image can produce an acceptable priori solution for sequential POCS iterative reconstruction. The NLMIC-POCS algorithm has been tested on simulated and real phantom data. The experimental results show that the presented NLMIC-POCS algorithm can significantly improve the image quality of the sparse angular CT reconstruction in suppressing streak artifacts and preserving the edges of the image.

  5. Iterative image reconstruction using non-local means with total variation from insufficient projection data.

    PubMed

    Ertas, Metin; Yildirim, Isa; Kamasak, Mustafa; Akan, Aydin

    2016-01-01

    In this work, algebraic reconstruction technique (ART) is extended by using non-local means (NLM) and total variation (TV) for reduction of artifacts that are due to insufficient projection data. TV and NLM algorithms use different image models and their application in tandem becomes a powerful denoising method that reduces erroneous variations in the image while preserving edges and details. Simulations were performed on a widely used 2D Shepp-Logan phantom to demonstrate performance of the introduced method (ART + TV) NLM and compare it to TV based ART (ART + TV) and ART. The results indicate that (ART + TV) NLM achieves better reconstructions compared to (ART + TV) and ART.

  6. Denoising MR images using non-local means filter with combined patch and pixel similarity.

    PubMed

    Zhang, Xinyuan; Hou, Guirong; Ma, Jianhua; Yang, Wei; Lin, Bingquan; Xu, Yikai; Chen, Wufan; Feng, Yanqiu

    2014-01-01

    Denoising is critical for improving visual quality and reliability of associative quantitative analysis when magnetic resonance (MR) images are acquired with low signal-to-noise ratios. The classical non-local means (NLM) filter, which averages pixels weighted by the similarity of their neighborhoods, is adapted and demonstrated to effectively reduce Rician noise without affecting edge details in MR magnitude images. However, the Rician NLM (RNLM) filter usually blurs small high-contrast particle details which might be clinically relevant information. In this paper, we investigated the reason of this particle blurring problem and proposed a novel particle-preserving RNLM filter with combined patch and pixel (RNLM-CPP) similarity. The results of experiments on both synthetic and real MR data demonstrate that the proposed RNLM-CPP filter can preserve small high-contrast particle details better than the original RNLM filter while denoising MR images.

  7. Phasorial DPP-BOTDA sensor tolerant to non-local effects

    NASA Astrophysics Data System (ADS)

    Urricelqui, Javier; Mariñelarena, Jon; Sagues, Mikel; Loayssa, Alayn

    2014-05-01

    We introduce a modification of the differential pulse-width pair technique in a BOTDA sensor based on a phase-modulated probe wave and RF demodulation. This provides a differential Brillouin phasorial signal with high spatial and spectral resolution in both components (magnitude and phase-shift). Moreover, the use of a phase-modulated probe wave provides RF phase-shift measurements tolerant to the emergence of non-local effects. The combination of both techniques can lead to the development of long-range BOTDA sensors. Proof-of-concept experiments demonstrate RF phase-shift measurements with 1m spatial resolution over 50km and an uncertainty of 1.3ºC at the worst contrast position.

  8. Bounded Self-Weights Estimation Method for Non-Local Means Image Denoising Using Minimax Estimators.

    PubMed

    Nguyen, Minh Phuong; Chun, Se Young

    2017-04-01

    A non-local means (NLM) filter is a weighted average of a large number of non-local pixels with various image intensity values. The NLM filters have been shown to have powerful denoising performance, excellent detail preservation by averaging many noisy pixels, and using appropriate values for the weights, respectively. The NLM weights between two different pixels are determined based on the similarities between two patches that surround these pixels and a smoothing parameter. Another important factor that influences the denoising performance is the self-weight values for the same pixel. The recently introduced local James-Stein type center pixel weight estimation method (LJS) outperforms other existing methods when determining the contribution of the center pixels in the NLM filter. However, the LJS method may result in excessively large self-weight estimates since no upper bound is assumed, and the method uses a relatively large local area for estimating the self-weights, which may lead to a strong bias. In this paper, we investigated these issues in the LJS method, and then propose a novel local self-weight estimation methods using direct bounds (LMM-DB) and reparametrization (LMM-RP) based on the Baranchik's minimax estimator. Both the LMM-DB and LMM-RP methods were evaluated using a wide range of natural images and a clinical MRI image together with the various levels of additive Gaussian noise. Our proposed parameter selection methods yielded an improved bias-variance trade-off, a higher peak signal-to-noise (PSNR) ratio, and fewer visual artifacts when compared with the results of the classical NLM and LJS methods. Our proposed methods also provide a heuristic way to select a suitable global smoothing parameters that can yield PSNR values that are close to the optimal values.

  9. Cortical Organization of Language Pathways in Children with Non-Localized Cryptogenic Epilepsy

    PubMed Central

    Frye, Richard Eugene; Liederman, Jacqueline

    2014-01-01

    Children with a history of epilepsy are almost six times more likely than their unaffected siblings to be referred for speech or language therapy. However, the abnormalities in neural pathway that cause these delays are poorly understood. We recorded evoked fields using whole-head magnetoencephalography during real and non-word visual and auditory rhyme tasks in 15 children with non-localized cryptogenic epilepsy. Basic phonological and orthographic language skills were assessed using Woodcock–Johnson Test of Achievement subtests. Dynamic statistical parameter mapping was used with individual participant magnetic resonance images. Significant cortical activity was visualized on average and performance weighted maps. For the auditory rhyme tasks, bilateral primary and secondary auditory cortices, the superior temporal sulcus, and insular cortex were activated early with later increases in left hemisphere activity. Visual rhyme tasks evoked early bilateral primary and secondary occipital cortical and angular gyri activity followed by later activation of the planum temporale and supramarginal gyri and the left ventral occipitotemporal area. For the auditory rhyme tasks, performance weighted maps demonstrated that early right hemisphere activation was associated with poorer reading skills while later activity was associated with better reading skills; for the left hemisphere, greater early activation of the secondary auditory cortex, including the planum temporale, was related to better reading skills while relatively later activation of these areas was associated with poorer reading skills. For the visual rhyme tasks, greater activity in the bilateral ventral occipitotemporal and insular areas and angular and supramarginal gyri were associated with better performance. These data suggest that spatiotemporal cortical activation patterns are associated with variations in language performance in non-localized cryptogenic epilepsy. PMID:25346681

  10. Non-local order in Mott insulators, duality and Wilson loops

    SciTech Connect

    Rath, Steffen Patrick; Simeth, Wolfgang; Endres, Manuel; Zwerger, Wilhelm

    2013-07-15

    It is shown that the Mott insulating and superfluid phases of bosons in an optical lattice may be distinguished by a non-local ‘parity order parameter’ which is directly accessible via single site resolution imaging. In one dimension, the lattice Bose model is dual to a classical interface roughening problem. We use known exact results from the latter to prove that the parity order parameter exhibits long range order in the Mott insulating phase, consistent with recent experiments by Endres et al. [M. Endres, M. Cheneau, T. Fukuhara, C. Weitenberg, P. Schauß, C. Gross, L. Mazza, M.C. Bañuls, L. Pollet, I. Bloch, et al., Science 334 (2011) 200]. In two spatial dimensions, the parity order parameter can be expressed in terms of an equal time Wilson loop of a non-trivial U(1) gauge theory in 2+1 dimensions which exhibits a transition between a Coulomb and a confining phase. The negative logarithm of the parity order parameter obeys a perimeter law in the Mott insulator and is enhanced by a logarithmic factor in the superfluid. -- Highlights: •Number statistics of cold atoms in optical lattices show non-local correlations. •These correlations are measurable via single site resolution imaging. •Incompressible phases exhibit an area law in particle number fluctuations. •This leads to long-range parity order of Mott-insulators in one dimension. •Parity order in 2d is connected with a Wilson-loop in a lattice gauge theory.

  11. Filtering of high noise breast thermal images using fast non-local means.

    PubMed

    Suganthi, S S; Ramakrishnan, S

    2014-01-01

    Analyses of breast thermograms are still a challenging task primarily due to the limitations such as low contrast, low signal to noise ratio and absence of clear edges. Therefore, always there is a requirement for preprocessing techniques before performing any quantitative analysis. In this work, a noise removal framework using fast non-local means algorithm, method noise and median filter was used to denoise breast thermograms. The images considered were subjected to Anscombe transformation to convert the distribution from Poisson to Gaussian. The pre-denoised image was obtained by subjecting the transformed image to fast non-local means filtering. The method noise which is the difference between the original and pre-denoised image was observed with the noise component merged in few structures and fine detail of the image. The image details presented in the method noise was extracted by smoothing the noise part using the median filter. The retrieved image part was added to the pre-denoised image to obtain the final denoised image. The performance of this technique was compared with that of Wiener and SUSAN filters. The results show that all the filters considered are able to remove the noise component. The performance of the proposed denoising framework is found to be good in preserving detail and removing noise. Further, the method noise is observed with negligible image details. Similarly, denoised image with no noise and smoothed edges are observed using Wiener filter and its method noise is contained with few structures and image details. The performance results of SUSAN filter is found to be blurred denoised image with little noise and also method noise with extensive structure and image details. Hence, it appears that the proposed denoising framework is able to preserve the edge information and generate clear image that could help in enhancing the diagnostic relevance of breast thermograms. In this paper, the introduction, objectives, materials and methods

  12. Manipulating Nonlinear Emission and Cooperative Effect of CdSe/ZnS Quantum Dots by Coupling to a Silver Nanorod Complex Cavity

    PubMed Central

    Nan, Fan; Cheng, Zi-Qiang; Wang, Ya-Lan; Zhang, Qing; Zhou, Li; Yang, Zhong-Jian; Zhong, Yu-Ting; Liang, Shan; Xiong, Qihua; Wang, Qu-Quan

    2014-01-01

    Colloidal semiconductor quantum dots have three-dimensional confined excitons with large optical oscillator strength and gain. The surface plasmons of metallic nanostructures offer an efficient tool to enhance exciton-exciton coupling and excitation energy transfer at appropriate geometric arrangement. Here, we report plasmon-mediated cooperative emissions of approximately one monolayer of ensemble CdSe/ZnS quantum dots coupled with silver nanorod complex cavities at room temperature. Power-dependent spectral shifting, narrowing, modulation, and amplification are demonstrated by adjusting longitudinal surface plasmon resonance of silver nanorods, reflectivity and phase shift of silver nanostructured film, and mode spacing of the complex cavity. The underlying physical mechanism of the nonlinear excitation energy transfer and nonlinear emissions are further investigated and discussed by using time-resolved photoluminescence and finite-difference time-domain numerical simulations. Our results suggest effective strategies to design active plasmonic complex cavities for cooperative emission nanodevices based on semiconductor quantum dots. PMID:24787617

  13. Generalization of the Activated Complex Theory of Reaction Rates. I. Quantum Mechanical Treatment

    DOE R&D Accomplishments Database

    Marcus, R. A.

    1964-01-01

    In its usual form activated complex theory assumes a quasi-equilibrium between reactants and activated complex, a separable reaction coordinate, a Cartesian reaction coordinate, and an absence of interaction of rotation with internal motion in the complex. In the present paper a rate expression is derived without introducing the Cartesian assumption. The expression bears a formal resemblance to the usual one and reduces to it when the added assumptions of the latter are introduced.

  14. Deep-blue phosphorescent organic light-emitting diode with external quantum efficiency over 30% using novel Ir complex

    NASA Astrophysics Data System (ADS)

    Inoue, Hideko; Yamada, Yui; Ohsawa, Nobuharu; Seo, Satoshi; Hosoumi, Shunsuke; Watabe, Takeyoshi; Mitsumori, Satomi; Kido, Hiromitsu

    2016-09-01

    We report a newly developed deep-blue phosphorescent iridium complex exhibiting a narrow emission spectrum. The use of this complex resulted in a deep-blue organic light-emitting diode (OLED) with an external quantum efficiency (EQE) exceeding 30%. Two iridium complexes with a 4H-1,2,4-triazole ligand which has an adamantyl group at the 4-position were synthesized, with the resulting effects of the adamantyl group on photoluminescence (PL) behavior investigated. [Ir(Adm1)3] having a 1-adamantyl group did not exhibit any emissions at room temperature, whereas [Ir(Adm2)3] having a 2-adamantyl group exhibited a blue emission with a peak wavelength of 459 nm and a high PL quantum yield of 0.94. Structural transformations between the ground state and excited state were estimated by molecular orbital calculations, which suggests that [Ir(Adm1)3] undergoes a considerably more extensive change than [Ir(Adm2)3]. It is therefore probable that [Ir(Adm1)3] ultimately experiences thermal deactivation owing to structural relaxation. Furthermore, an OLED was fabricated using [Ir(Adm2)3] as a dopant. The associated electroluminescence spectrum had an emission peak at 457 nm and a relatively small shoulder peak at 485 nm, which are consistent with the PL spectrum. A narrowed emission spectrum with a full width at half maximum of 58 nm was obtained, leading to a deep-blue emission with high color purity (CIE, x = 0.15, y = 0.22). This device ultimately exhibited an extremely high EQE of 32% at 2 mA/cm2, which was likely attributable to an increase in outcoupling efficiency via molecular orientation.

  15. Complex Förster energy transfer interactions between semiconductor quantum dots and a redox-active osmium assembly.

    PubMed

    Stewart, Michael H; Huston, Alan L; Scott, Amy M; Efros, Alexander L; Melinger, Joseph S; Gemmill, Kelly Boeneman; Trammell, Scott A; Blanco-Canosa, Juan B; Dawson, Philip E; Medintz, Igor L

    2012-06-26

    The ability of luminescent semiconductor quantum dots (QDs) to engage in diverse energy transfer processes with organic dyes, light-harvesting proteins, metal complexes, and redox-active labels continues to stimulate interest in developing them for biosensing and light-harvesting applications. Within biosensing configurations, changes in the rate of energy transfer between the QD and the proximal donor, or acceptor, based upon some external (biological) event form the principle basis for signal transduction. However, designing QD sensors to function optimally is predicated on a full understanding of all relevant energy transfer mechanisms. In this report, we examine energy transfer between a range of CdSe-ZnS core-shell QDs and a redox-active osmium(II) polypyridyl complex. To facilitate this, the Os complex was synthesized as a reactive isothiocyanate and used to label a hexahistidine-terminated peptide. The Os-labeled peptide was ratiometrically self-assembled to the QDs via metal affinity coordination, bringing the Os complex into close proximity of the nanocrystal surface. QDs displaying different emission maxima were assembled with increasing ratios of Os-peptide complex and subjected to detailed steady-state, ultrafast transient absorption, and luminescence lifetime decay analyses. Although the possibility exists for charge transfer quenching interactions, we find that the QD donors engage in relatively efficient Förster resonance energy transfer with the Os complex acceptor despite relatively low overall spectral overlap. These results are in contrast to other similar QD donor-redox-active acceptor systems with similar separation distances, but displaying far higher spectral overlap, where charge transfer processes were reported to be the dominant QD quenching mechanism.

  16. Spectroscopy of highly luminescent 1,3,5-triazapentadiene complexes of platinum(II) in solution and in the adsorbed and solid states and quantum-chemical interpretation

    NASA Astrophysics Data System (ADS)

    Lyalin, G. N.; Litke, S. V.; Gushchin, P. V.; Maslov, V. G.

    2012-02-01

    We have measured the absorption, luminescence, and luminescence excitation spectra, as well as the excited-state lifetimes and luminescence quantum yields, of 1,3,5-triazapentadiene complexes of platinum(II) in a solution, in the solid state, in an adsorbed state on a SiO2 surface, and in a polystyrene matrix at room temperature and at 77 K. We also have performed quantum-chemical calculations of the equilibrium geometry of the ground and excited states of the complexes and of the nature and structure of molecular orbitals.

  17. Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function.

    PubMed

    Rota, R; Casulleras, J; Mazzanti, F; Boronat, J

    2015-03-21

    We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order approximations for the quantum propagator, it is possible to obtain Monte Carlo data all the way from purely imaginary time to δ values near the limit of real time. As a consequence, it is possible to infer accurately the spectral functions using simple inversion algorithms. We test this approach in the calculation of the dynamic structure function S(q, ω) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, ω) can be exactly calculated. We notice a clear improvement in the calculation of the dynamic response with respect to the common approach based on the inverse Laplace transform of the imaginary-time correlation function.

  18. Structure and excited state relaxation dynamics in nanoscale self-assembled arrays: multiporphyrin complexes, porphyrin-quantum dot composites

    NASA Astrophysics Data System (ADS)

    Zenkevich, E. I.; von Borczyskowski, C.

    2005-06-01

    Self-assembled nanoscale arrays of controllable geometry and composition (up to 8 tetrapyrroles) have been formed via non-covalent binding interactions of the meso-phenyl bridged Zn-octaethylporphyrin chemical dimers or trimers with di- /tetrapyridyl substituted porphyrin extra-ligands. In these complexes using steady-state and time-resolved (ps fluorescence and fs pump-probe) measurements pathways and efficiencies of the energy transfer photoinduced charge separation as well as exchange d-π effects have been studied in solutions of variable polarity at 77-293 K. The same principles of aggregation via the key-hole scheme "Zn-pyridyl" have been used also for the surface passivation of pyridylsubstituted tetrapyrroles on the coreshell semiconductor CdSe/ZnS quantum dots (QD) showing quantum confinement effects. Picosecond time-resolved and steady-state data reveal that CdSe/ZnS QD emission is multiexponential and the efficiency of its quenching by attached porphyrins (due to energy transfer and photoinduced charge separation) depends strongly on the number of anchoring groups their arrangement in the porphyrin molecule as well as on QD size and number of ZnS monolayers. The analysis of spectroscopic and kinetic findings reveals that on average only ~l/5 porphyrin molecules are assembled on the QD and a limited number of "vacancies" accessible for porphyrin attachment is available on the QD surface.

  19. Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function

    NASA Astrophysics Data System (ADS)

    Rota, R.; Casulleras, J.; Mazzanti, F.; Boronat, J.

    2015-03-01

    We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order approximations for the quantum propagator, it is possible to obtain Monte Carlo data all the way from purely imaginary time to δ values near the limit of real time. As a consequence, it is possible to infer accurately the spectral functions using simple inversion algorithms. We test this approach in the calculation of the dynamic structure function S(q, ω) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, ω) can be exactly calculated. We notice a clear improvement in the calculation of the dynamic response with respect to the common approach based on the inverse Laplace transform of the imaginary-time correlation function.

  20. Charge Transfer as a Probe for the Interfacial Properties of Quantum Dot-Ligand Complexes

    NASA Astrophysics Data System (ADS)

    Weinberg, David Joseph

    This dissertation describes the study of charge transfer interactions between colloidal quantum dots (QDs) and molecular redox partners in the context of both fundamental investigations of charge recombination mechanisms in nanocrystal-molecule systems, and as a technique to probe the properties of the QD ligand shell. Charge separation in a system of CdS nanocrystals and organic hole acceptors results in the formation of a spin-correlated radical ion pair. Interrogating this photogenerated species with EPR and magnetic field effect transient absorption techniques reveals that the charge recombination dynamics of this donor-acceptor system are dictated by the radical pair intersystem crossing mechanism on the nanosecond timescale. These experiments also indicate that the photoinjected electron localizes at a CdS QD surface trap state, and the coupling between the electron and hole in this spin-correlated system is low. Additional studies involving the CdS QDs and organic hole acceptors are proposed which would investigate the exchange of charge and energy within the nanocrystal organic adlayer. Collisional charge transfer interactions between substituted benzoquinone molecules and PbS QDs coated with mixed monolayers of oleic acid and perfluorodecanethiol are monitored via photoluminescence and transient absorption spectroscopies. These experiments reveal that partially fluorinated ligand shells are less permeable to solution phase molecules and offer greater protection of the nanocrystal surface than their aliphatic counterparts. Only a small amount of fluorinated surfactant ( 20% surface coverage) is necessary to profoundly change the permeability of the ligand shell, and the protective nature of these fluorinated molecules is likely a combination of the molecular volume and oleophobicity of these ligands. Follow up work is discussed which would elucidate the influence of solvent and extent of surfactant fluorination on the permeability of these ligand shells, as

  1. Synthesis, Spectroscopic, Structural and Quantum Chemical Studies of a New Imine Oxime and Its Palladium(II) Complex: Hydrolysis Mechanism.

    PubMed

    Kaya, Yunus; Yilmaz, Veysel T; Buyukgungor, Orhan

    2016-01-21

    In this work, we report synthesis, crystallographic, spectroscopic and quantum chemical studies of a new imine oxime, namely (4-nitro-phenyl)-(1-phenyl-ethylimino)-acetaldehyde oxime (nppeieoH). Spectroscopic and X-ray diffraction studies showed that nppeieoH is hydrolyzed in aqueous solution, forming nitroisonitrosoacetophenone (ninap) and the hydrolysis product binds to Pd(II) to yield [Pd(nppeieo)(ninap)]. The mechanism of the hydrolysis reaction has been theoretically investigated in detail, using density functional theory (DFT) with the B3LYP method. The vibrational and the electronic spectra of nppeieoH and its Pd(II) complex, the HOMO and LUMO analysis, Mulliken atomic charges and molecular electrostatic potential were also performed. The predicted nonlinear optical properties of both compounds are higher than those of urea.

  2. A Possible Approach to Inclusion of Space and Time in Frame Fields of Quantum Representations of Real and Complex Numbers

    DOE PAGES

    Benioff, Paul

    2009-01-01

    Tmore » his work is based on the field of reference frames based on quantum representations of real and complex numbers described in other work. Here frame domains are expanded to include space and time lattices. Strings of qukits are described as hybrid systems as they are both mathematical and physical systems. As mathematical systems they represent numbers. As physical systems in each frame the strings have a discrete Schrodinger dynamics on the lattices.he frame field has an iterative structure such that the contents of a stage j frame have images in a stage j - 1 (parent) frame. A discussion of parent frame images includes the proposal that points of stage j frame lattices have images as hybrid systems in parent frames.he resulting association of energy with images of lattice point locations, as hybrid systems states, is discussed. Representations and images of other physical systems in the different frames are also described.« less

  3. Porphyrin-cobaloxime complexes for hydrogen production, a photo- and electrochemical study, coupled with quantum chemical calculations.

    PubMed

    Manton, Jennifer C; Long, Conor; Vos, Johannes G; Pryce, Mary T

    2014-03-07

    Two porphyrin-cobaloxime complexes; [{Co(dmgH)2Cl}{MPyTPP}] () and [{Co(dmgH)2Cl}{ZnMPyTPP}] () (dmgH = dimethylglyoxime, MPyTPP = 5-(4-pyridyl)-10,15,20-triphenylporphyrin) have been synthesised as model systems for the generation of hydrogen from water. Although initially envisaged as photocatalytic systems neither complex catalysed the reduction of water to hydrogen following irradiation. However, both complexes are molecular precursors for hydrogen evolution under electrochemical conditions. Turnover numbers for hydrogen production of 1.8 × 10(3) and 5.1 × 10(3) were obtained for and respectively following potentiostatic electrolysis at -1.2 V vs. Ag/AgCl while cobaloxime alone produced a turnover-number of 8.0 × 10(3). The photophysical properties of and were examined to provide an explanation for the lack of photochemical activity. These results, coupled with quantum chemical calculations, confirm that porphyrins fail to act as light-harvesting units for these systems and that the lowest energy excited states are in fact cobaloxime-based rather than porphyrin based.

  4. A photo- and electrochemical investigation of BODIPY-cobaloxime complexes for hydrogen production, coupled with quantum chemical calculations.

    PubMed

    Manton, Jennifer C; Long, Conor; Vos, Johannes G; Pryce, Mary T

    2014-03-21

    Two BODIPY-cobaloxime complexes; [{Co(dmgH)2Cl}{3-[bis-(4-ethyl-3,5-dimethyl-1H-pyrrol-2-yl)-methyl]-pyridine-borondiflouride}] (1a) and [{Co(dmgH)2Cl}{4-[bis-(4-ethyl-3,5-dimethyl-1H-pyrrol-2-yl)-methyl]-pyridine-borondiflouride}] (2a) (BODIPY = boron dipyrromethene), (dmgH = dimethylglyoxime) have been synthesised and studied as model catalytic systems for the generation of hydrogen gas in aqueous media. Under photochemical conditions, neither complex catalysed the reduction of water to hydrogen. However, both complexes showed considerable activity under electrochemical conditions. Turn-over-numbers for hydrogen production of 1.65 × 10(4) and 1.08 × 10(4) were obtained for 1a and 2a respectively following potentiostatic electrolysis at -1.2 V vs. Ag/AgCl after 1 hour. Quantum chemical calculations were performed to provide an explanation for the lack of photochemical activity.

  5. Quantum-mechanical study of energies, structures, and vibrational spectra of the H(D)Cl complexed with dimethyl ether

    SciTech Connect

    Boda, Łukasz Boczar, Marek; Gług, Maciej; Wójcik, Marek J.

    2015-11-28

    Interaction energies, molecular structure and vibrational frequencies of the binary complex formed between H(D)Cl and dimethyl ether have been obtained using quantum-chemical methods. Equilibrium and vibrationally averaged structures, harmonic and anharmonic wavenumbers of the complex and its deuterated isotopomer were calculated using harmonic and anharmonic second-order perturbation theory procedures with Density Functional Theory B3LYP and B2PLYP-D and ab initio Møller-Plesset second-order methods, and a 6-311++G(3d,3p) basis set. A phenomenological model describing anharmonic-type vibrational couplings within hydrogen bonds was developed to explain the unique broadening and fine structure, as well as the isotope effect of the Cl–H and Cl–D stretching IR absorption bands in the gaseous complexes with dimethyl ether, as an effect of hydrogen bond formation. Simulations of the rovibrational structure of the Cl–H and Cl–D stretching bands were performed and the results were compared with experimental spectra.

  6. Quantum-dot-based quantitative identification of pathogens in complex mixture

    NASA Astrophysics Data System (ADS)

    Lim, Sun Hee; Bestwater, Felix; Buchy, Philippe; Mardy, Sek; Yu, Alexey Dan Chin

    2010-02-01

    In the present study we describe sandwich design hybridization probes consisting of magnetic particles (MP) and quantum dots (QD) with target DNA, and their application in the detection of avian influenza virus (H5N1) sequences. Hybridization of 25-, 40-, and 100-mer target DNA with both probes was analyzed and quantified by flow cytometry and fluorescence microscopy on the scale of single particles. The following steps were used in the assay: (i) target selection by MP probes and (ii) target detection by QD probes. Hybridization efficiency between MP conjugated probes and target DNA hybrids was controlled by a fluorescent dye specific for nucleic acids. Fluorescence was detected by flow cytometry to distinguish differences in oligo sequences as short as 25-mer capturing in target DNA and by gel-electrophoresis in the case of QD probes. This report shows that effective manipulation and control of micro- and nanoparticles in hybridization assays is possible.

  7. Kondo Physics at Interfaces in Metallic Non-Local Spin Transport Devices

    NASA Astrophysics Data System (ADS)

    Leighton, Chris

    2015-03-01

    Despite the maturity of metallic spintronics there remain large gaps in our understanding of spin transport in metals, particularly with injection of spins across ferromagnetic/non-magnetic (FM/NM) interfaces, and their subsequent diffusion and relaxation. Unresolved issues include the limits of applicability of Elliott-Yafet spin relaxation, quantification of the influence of defects, surfaces, and interfaces on spin relaxation at nanoscopic dimensions, and the importance of magnetic and spin-orbit scattering. The non-local spin-valve is an enabling device in this context as, in addition to offering potentially disruptive applications, it allows for the separation of charge and spin currents. One particularly perplexing issue in metallic non-local spin valves is the widely observed non-monotonicity in the T-dependent spin accumulation, where the spin signal actually decreases at low T, in contrast to simple expectations. In this work, by studying an expanded range of FM/NM combinations (encompassing Ni80Fe20, Ni, Fe, Co, Cu, and Al), we demonstrate that this effect is not a property of a given FM or NM, but rather of the FM/NM pair. The non-monotonicity is in fact strongly correlated with the ability of the FM to form a dilute local magnetic moment in the NM. We show that local moments, resulting in this case from the ppm-level tail of the FM/NM interdiffusion profile, suppress the injected spin polarization and diffusion length via a novel manifestation of the Kondo effect, explaining all observations associated with the low T downturn in spin accumulation. We further show: (a) that this effect can be promoted by thermal annealing, at which point the conventional charge transport Kondo effect is simultaneously detected in the NM, and (b) that this suppression in spin accumulation can be quenched, even at interfaces that are highly susceptible to the effect, by insertion of a thin non-moment-supporting interlayer. Important implications for room temperature

  8. Extracting quantum coherence via steering

    PubMed Central

    Hu, Xueyuan; Fan, Heng

    2016-01-01

    As the precious resource for quantum information processing, quantum coherence can be created remotely if the involved two sites are quantum correlated. It can be expected that the amount of coherence created should depend on the quantity of the shared quantum correlation, which is also a resource. Here, we establish an operational connection between coherence induced by steering and the quantum correlation. We find that the steering-induced coherence quantified by such as relative entropy of coherence and trace-norm of coherence is bounded from above by a known quantum correlation measure defined as the one-side measurement-induced disturbance. The condition that the upper bound saturated by the induced coherence varies for different measures of coherence. The tripartite scenario is also studied and similar conclusion can be obtained. Our results provide the operational connections between local and non-local resources in quantum information processing. PMID:27682450

  9. Extracting quantum coherence via steering

    NASA Astrophysics Data System (ADS)

    Hu, Xueyuan; Fan, Heng

    2016-09-01

    As the precious resource for quantum information processing, quantum coherence can be created remotely if the involved two sites are quantum correlated. It can be expected that the amount of coherence created should depend on the quantity of the shared quantum correlation, which is also a resource. Here, we establish an operational connection between coherence induced by steering and the quantum correlation. We find that the steering-induced coherence quantified by such as relative entropy of coherence and trace-norm of coherence is bounded from above by a known quantum correlation measure defined as the one-side measurement-induced disturbance. The condition that the upper bound saturated by the induced coherence varies for different measures of coherence. The tripartite scenario is also studied and similar conclusion can be obtained. Our results provide the operational connections between local and non-local resources in quantum information processing.

  10. Assessment of Quantum Mechanical Methods for Copper and Iron Complexes by Photoelectron Spectroscopy

    PubMed Central

    2015-01-01

    Broken-symmetry density functional theory (BS-DFT) calculations are assessed for redox energetics [Cu(SCH3)2]1–/0, [Cu(NCS)2]1–/0, [FeCl4]1–/0, and [Fe(SCH3)4]1–/0 against vertical detachment energies (VDE) from valence photoelectron spectroscopy (PES), as a prelude to studies of metalloprotein analogs. The M06 and B3LYP hybrid functionals give VDE that agree with the PES VDE for the Fe complexes, but both underestimate it by ∼400 meV for the Cu complexes; other hybrid functionals give VDEs that are an increasing function of the amount of Hartree–Fock (HF) exchange and so cannot show good agreement for both Cu and Fe complexes. Range-separated (RS) functionals appear to give a better distribution of HF exchange since the negative HOMO energy is approximately equal to the VDEs but also give VDEs dependent on the amount of HF exchange, sometimes leading to ground states with incorrect electron configurations; the LRC-ωPBEh functional reduced to 10% HF exchange at short-range give somewhat better values for both, although still ∼150 meV too low for the Cu complexes and ∼50 meV too high for the Fe complexes. Overall, the results indicate that while HF exchange compensates for self-interaction error in DFT calculations of both Cu and Fe complexes, too much may lead to more sensitivity to nondynamical correlation in the spin-polarized Fe complexes. PMID:24803858

  11. Efficient quantum walk on a quantum processor

    NASA Astrophysics Data System (ADS)

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.

    2016-05-01

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.

  12. Efficient quantum walk on a quantum processor

    PubMed Central

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L.; Wang, Jingbo B.; Matthews, Jonathan C. F.

    2016-01-01

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor. PMID:27146471

  13. Efficient quantum walk on a quantum processor.

    PubMed

    Qiang, Xiaogang; Loke, Thomas; Montanaro, Ashley; Aungskunsiri, Kanin; Zhou, Xiaoqi; O'Brien, Jeremy L; Wang, Jingbo B; Matthews, Jonathan C F

    2016-05-05

    The random walk formalism is used across a wide range of applications, from modelling share prices to predicting population genetics. Likewise, quantum walks have shown much potential as a framework for developing new quantum algorithms. Here we present explicit efficient quantum circuits for implementing continuous-time quantum walks on the circulant class of graphs. These circuits allow us to sample from the output probability distributions of quantum walks on circulant graphs efficiently. We also show that solving the same sampling problem for arbitrary circulant quantum circuits is intractable for a classical computer, assuming conjectures from computational complexity theory. This is a new link between continuous-time quantum walks and computational complexity theory and it indicates a family of tasks that could ultimately demonstrate quantum supremacy over classical computers. As a proof of principle, we experimentally implement the proposed quantum circuit on an example circulant graph using a two-qubit photonics quantum processor.

  14. Predicting local and non-local effects of resources on animal space use using a mechanistic step selection model

    PubMed Central

    Potts, Jonathan R; Bastille-Rousseau, Guillaume; Murray, Dennis L; Schaefer, James A; Lewis, Mark A

    2014-01-01

    Predicting space use patterns of animals from their interactions with the environment is fundamental for understanding the effect of habitat changes on ecosystem functioning. Recent attempts to address this problem have sought to unify resource selection analysis, where animal space use is derived from available habitat quality, and mechanistic movement models, where detailed movement processes of an animal are used to predict its emergent utilization distribution. Such models bias the animal's movement towards patches that are easily available and resource-rich, and the result is a predicted probability density at a given position being a function of the habitat quality at that position. However, in reality, the probability that an animal will use a patch of the terrain tends to be a function of the resource quality in both that patch and the surrounding habitat. We propose a mechanistic model where this non-local effect of resources naturally emerges from the local movement processes, by taking into account the relative utility of both the habitat where the animal currently resides and that of where it is moving. We give statistical techniques to parametrize the model from location data and demonstrate application of these techniques to GPS location data of caribou (Rangifer tarandus) in Newfoundland. Steady-state animal probability distributions arising from the model have complex patterns that cannot be expressed simply as a function of the local quality of the habitat. In particular, large areas of good habitat are used more intensively than smaller patches of equal quality habitat, whereas isolated patches are used less frequently. Both of these are real aspects of animal space use missing from previous mechanistic resource selection models. Whilst we focus on habitats in this study, our modelling framework can be readily used with any environmental covariates and therefore represents a unification of mechanistic modelling and step selection approaches to

  15. Predicting local and non-local effects of resources on animal space use using a mechanistic step selection model.

    PubMed

    Potts, Jonathan R; Bastille-Rousseau, Guillaume; Murray, Dennis L; Schaefer, James A; Lewis, Mark A

    2014-03-01

    Predicting space use patterns of animals from their interactions with the environment is fundamental for understanding the effect of habitat changes on ecosystem functioning. Recent attempts to address this problem have sought to unify resource selection analysis, where animal space use is derived from available habitat quality, and mechanistic movement models, where detailed movement processes of an animal are used to predict its emergent utilization distribution. Such models bias the animal's movement towards patches that are easily available and resource-rich, and the result is a predicted probability density at a given position being a function of the habitat quality at that position. However, in reality, the probability that an animal will use a patch of the terrain tends to be a function of the resource quality in both that patch and the surrounding habitat.We propose a mechanistic model where this non-local effect of resources naturally emerges from the local movement processes, by taking into account the relative utility of both the habitat where the animal currently resides and that of where it is moving. We give statistical techniques to parametrize the model from location data and demonstrate application of these techniques to GPS location data of caribou (Rangifer tarandus) in Newfoundland.Steady-state animal probability distributions arising from the model have complex patterns that cannot be expressed simply as a function of the local quality of the habitat. In particular, large areas of good habitat are used more intensively than smaller patches of equal quality habitat, whereas isolated patches are used less frequently. Both of these are real aspects of animal space use missing from previous mechanistic resource selection models.Whilst we focus on habitats in this study, our modelling framework can be readily used with any environmental covariates and therefore represents a unification of mechanistic modelling and step selection approaches to

  16. Chapter 10 Quantum Mechanics and the Special and General Theory of Relativity

    NASA Astrophysics Data System (ADS)

    Brändas, Erkki J.

    The old dilemma of quantum mechanics versus the theory of relativity is reconsidered. A first principles relativistically invariant theory will be provided through a model, which is basically quantum mechanical. Moreover, by analytically extending quantum mechanics into the complex plane, it is possible to include dynamical features such as time-, length-, and temperature-scales into the theory. The flexibility of including complex symmetric interactions will in the same way support a transition from firmly quantum mechanical non-local behaviour to a decidedly classical-local appearance. Furthermore, the extended formulation gives rise to so-called Jordan blocks. They will be shown to appear logically in the present generalized dynamical picture and a compelling interpretation is microscopic self-organization (MSO). Not only have the manifestation of quantum-thermal correlations, and the emergence of generic time scales been established, but the present viewpoint also appears to throw new light on the age-old problem of quantum mechanics versus relativity. To bring all these ideas together, we will demonstrate that our model (i) displays the simple occurrence of such a degenerate unit, (ii) demonstrates the link with the Klein-Gordon-Dirac relativistic theory and (iii) provides dynamical features of both special and general relativity theory.

  17. Classification of 4-qubit Entangled Graph States According to Bipartite Entanglement, Multipartite Entanglement and Non-local Properties

    NASA Astrophysics Data System (ADS)

    Assadi, Leila; Jafarpour, Mojtaba

    2016-11-01

    We use concurrence to study bipartite entanglement, Meyer-Wallach measure and its generalizations to study multi-partite entanglement and MABK and SASA inequalities to study the non-local properties of the 4-qubit entangled graph states, quantitatively. Then, we present 3 classifications, each one in accordance with one of the aforementioned properties. We also observe that the classification according to multipartite entanglement does exactly coincide with that according to nonlocal properties, but does not match with that according to bipartite entanglement. This observation signifies the fact that non-locality and multipartite entanglement enjoy the same basic underlying principles, while bipartite entanglement may not reveal the non-locality issue in its entirety.

  18. Rician noise reduction in magnetic resonance images using adaptive non-local mean and guided image filtering

    NASA Astrophysics Data System (ADS)

    Mahmood, Muhammad Tariq; Chu, Yeon-Ho; Choi, Young-Kyu

    2016-06-01

    This paper proposes a Rician noise reduction method for magnetic resonance (MR) images. The proposed method is based on adaptive non-local mean and guided image filtering techniques. In the first phase, a guidance image is obtained from the noisy image through an adaptive non-local mean filter. Sobel operators are applied to compute the strength of edges which is further used to control the spread of the kernel in non-local mean filtering. In the second phase, the noisy and the guidance images are provided to the guided image filter as input to restore the noise-free image. The improved performance of the proposed method is investigated using the simulated and real data sets of MR images. Its performance is also compared with the previously proposed state-of-the art methods. Comparative analysis demonstrates the superiority of the proposed scheme over the existing approaches.

  19. Non-rigid registration and non-local principle component analysis to improve electron microscopy spectrum images

    NASA Astrophysics Data System (ADS)

    Yankovich, Andrew B.; Zhang, Chenyu; Oh, Albert; Slater, Thomas J. A.; Azough, Feridoon; Freer, Robert; Haigh, Sarah J.; Willett, Rebecca; Voyles, Paul M.

    2016-09-01

    Image registration and non-local Poisson principal component analysis (PCA) denoising improve the quality of characteristic x-ray (EDS) spectrum imaging of Ca-stabilized Nd2/3TiO3 acquired at atomic resolution in a scanning transmission electron microscope. Image registration based on the simultaneously acquired high angle annular dark field image significantly outperforms acquisition with a long pixel dwell time or drift correction using a reference image. Non-local Poisson PCA denoising reduces noise more strongly than conventional weighted PCA while preserving atomic structure more faithfully. The reliability of and optimal internal parameters for non-local Poisson PCA denoising of EDS spectrum images is assessed using tests on phantom data.

  20. Locally optimized non-local means denoising for low-dose X-ray backscatter imagery.

    PubMed

    Tracey, Brian H; Miller, Eric L; Wu, Yue; Alvino, Christopher; Schiefele, Markus; Al-Kofahi, Omar

    2014-01-01

    While recent years have seen considerable progress in image denoising, the leading techniques have been developed for digital photographs or other images that can have very different characteristics than those encountered in X-ray applications. In particular here we examine X-ray backscatter (XBS) images collected by airport security systems, where images are piecewise smooth and edge information is typically more correlated with objects while texture is dominated by statistical noise in the detected signal. In this paper, we show how multiple estimates for a denoised XBS image can be combined using a variational approach, giving a solution that enhances edge contrast by trading off gradient penalties against data fidelity terms. We demonstrate the approach by combining several estimates made using the non-local means (NLM) algorithm, a widely used patch-based denoising method. The resulting improvements hold the potential for improving automated analysis of low-SNR X-ray imagery and can be applied in other applications where edge information is of interest.

  1. A non-local approach for image super-resolution using intermodality priors ☆

    PubMed Central

    Rousseau, François

    2010-01-01

    Image enhancement is of great importance in medical imaging where image resolution remains a crucial point in many image analysis algorithms. In this paper, we investigate brain hallucination (Rousseau, 2008), or generating a high-resolution brain image from an input low-resolution image, with the help of another high-resolution brain image. We propose an approach for image super-resolution by using anatomical intermodality priors from a reference image. Contrary to interpolation techniques, in order to be able to recover fine details in images, the reconstruction process is based on a physical model of image acquisition. Another contribution to this inverse problem is a new regularization approach that uses an example-based framework integrating non-local similarity constraints to handle in a better way repetitive structures and texture. The effectiveness of our approach is demonstrated by experiments on realistic Brainweb Magnetic Resonance images and on clinical images from ADNI, generating automatically high-quality brain images from low-resolution input. PMID:20580893

  2. A non-local, ordinary-state-based viscoelasticity model for peridynamics.

    SciTech Connect

    Mitchell, John Anthony

    2011-10-01

    A non-local, ordinary-state-based, peridynamics viscoelasticity model is developed. In this model, viscous effects are added to deviatoric deformations and the bulk response remains elastic. The model uses internal state variables and is conceptually similar to linearized isotropic viscolelasticity in the local theory. The modulus state, which is used to form the Jacobian matrix in Newton-Raphson algorithms, is presented. The model is shown to satisfy the 2nd law of thermodynamics and is applicable to problems in solid continuum mechanics where fracture and rate effects are important; it inherits all the advantages for modeling fracture associated with peridynamics. By combining this work with the previously published ordinary-state-based plasticity model, the model may be amenable to viscoplasticity problems where plasticity and rate effects are simultaneously important. Also, the model may be extended to include viscous effects for spherical deformations as well. The later two extensions are not presented and may be the subject of further work.

  3. Correlations and non-local transport in a critical-gradient fluctuation model

    NASA Astrophysics Data System (ADS)

    Nicolau, J. H.; García, L.; Carreras, B. A.

    2016-11-01

    A one-dimensional model based on critical-gradient fluctuation dynamics is used to study turbulent transport in magnetically confined plasmas. The model exhibits the selforganized criticality (SOC) dynamics. At the steady state, two regions are found: the outer one is close to critical state and the inner one remaining at the subcritical gradient. The gradient- flux relation exhibits a parabola-like profile centered in the most probable gradient following experimental studies. This is a signature of the non-locality of particle transport driven by avalanches: at the given position transport is due to gradients situated into closer but different positions. The R/S analysis, applied to the fluxes dynamics reveals memory and correlation. Different H exponents corresponding to different dynamical behavior are obtained. The flux at the edge exhibits long time correlations, which can be suppressed if the external drive or the system size is modified. On the other hand, we found that in the sub-critical region the quasiperiodicity is present in the avalanches.

  4. A non-local approach for image super-resolution using intermodality priors.

    PubMed

    Rousseau, François

    2010-08-01

    Image enhancement is of great importance in medical imaging where image resolution remains a crucial point in many image analysis algorithms. In this paper, we investigate brain hallucination (Rousseau, 2008), or generating a high-resolution brain image from an input low-resolution image, with the help of another high-resolution brain image. We propose an approach for image super-resolution by using anatomical intermodality priors from a reference image. Contrary to interpolation techniques, in order to be able to recover fine details in images, the reconstruction process is based on a physical model of image acquisition. Another contribution to this inverse problem is a new regularization approach that uses an example-based framework integrating non-local similarity constraints to handle in a better way repetitive structures and texture. The effectiveness of our approach is demonstrated by experiments on realistic Brainweb Magnetic Resonance images and on clinical images from ADNI, generating automatically high-quality brain images from low-resolution input.

  5. Momentum transport and non-local transport in heat-flux-driven magnetic reconnection in HEDP

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Fox, Will; Bhattacharjee, Amitava

    2016-10-01

    Strong magnetic fields are readily generated in high-energy-density plasmas and can affect the heat confinement properties of the plasma. Magnetic reconnection can in turn be important as an inverse process, which destroys or reconfigures the magnetic field. Recent theory has demonstrated a novel physics regime for reconnection in high-energy-density plasmas where the magnetic field is advected into the reconnection layer by plasma heat flux via the Nernst effect. In this work we elucidate the physics of the electron dissipation layer in this heat-flux-driven regime. Through fully kinetic simulation and a new generalized Ohm's law, we show that momentum transport due to the heat-flux-viscosity effect provides the dissipation mechanism to allow magnetic field line reconnection. Scaling analysis and simulations show that the characteristic width of the current sheet in this regime is several electron mean-free-paths. These results additionally show a coupling between non-local transport and momentum transport, which in turn affects the dynamics of the magnetic field. This work was supported by the U.S. Department of Energy under Contract No. DE-SC0008655.

  6. A non-local evolution equation model of cell–cell adhesion in higher dimensional space

    PubMed Central

    Dyson, Janet; Gourley, Stephen A.; Webb, Glenn F.

    2013-01-01

    A model for cell–cell adhesion, based on an equation originally proposed by Armstrong et al. [A continuum approach to modelling cell–cell adhesion, J. Theor. Biol. 243 (2006), pp. 98–113], is considered. The model consists of a nonlinear partial differential equation for the cell density in an N-dimensional infinite domain. It has a non-local flux term which models the component of cell motion attributable to cells having formed bonds with other nearby cells. Using the theory of fractional powers of analytic semigroup generators and working in spaces with bounded uniformly continuous derivatives, the local existence of classical solutions is proved. Positivity and boundedness of solutions is then established, leading to global existence of solutions. Finally, the asymptotic behaviour of solutions about the spatially uniform state is considered. The model is illustrated by simulations that can be applied to in vitro wound closure experiments. AMS Classifications: 35A01; 35B09; 35B40; 35K57; 92C17 PMID:23289870

  7. Denoising 3D MR images by the enhanced non-local means filter for Rician noise.

    PubMed

    Liu, Hong; Yang, Cihui; Pan, Ning; Song, Enmin; Green, Richard

    2010-12-01

    The non-local means (NLM) filter removes noise by calculating the weighted average of the pixels in the global area and shows superiority over existing local filter methods that only consider local neighbor pixels. This filter has been successfully extended from 2D images to 3D images and has been applied to denoising 3D magnetic resonance (MR) images. In this article, a novel filter based on the NLM filter is proposed to improve the denoising effect. Considering the characteristics of Rician noise in the MR images, denoising by the NLM filter is first performed on the squared magnitude images. Then, unbiased correcting is carried out to eliminate the biased deviation. When performing the NLM filter, the weight is calculated based on the Gaussian-filtered image to reduce the disturbance of the noise. The performance of this filter is evaluated by carrying out a qualitative and quantitative comparison of this method with three other filters, namely, the original NLM filter, the unbiased NLM (UNLM) filter and the Rician NLM (RNLM) filter. Experimental results demonstrate that the proposed filter achieves better denoising performance over the other filters being compared.

  8. Medical image denoising via optimal implementation of non-local means on hybrid parallel architecture.

    PubMed

    Nguyen, Tuan-Anh; Nakib, Amir; Nguyen, Huy-Nam

    2016-06-01

    The Non-local means denoising filter has been established as gold standard for image denoising problem in general and particularly in medical imaging due to its efficiency. However, its computation time limited its applications in real world application, especially in medical imaging. In this paper, a distributed version on parallel hybrid architecture is proposed to solve the computation time problem and a new method to compute the filters' coefficients is also proposed, where we focused on the implementation and the enhancement of filters' parameters via taking the neighborhood of the current voxel more accurately into account. In terms of implementation, our key contribution consists in reducing the number of shared memory accesses. The different tests of the proposed method were performed on the brain-web database for different levels of noise. Performances and the sensitivity were quantified in terms of speedup, peak signal to noise ratio, execution time, the number of floating point operations. The obtained results demonstrate the efficiency of the proposed method. Moreover, the implementation is compared to that of other techniques, recently published in the literature.

  9. Multimodal Image Analysis in Alzheimer's Disease via Statistical Modelling of Non-local Intensity Correlations.

    PubMed

    Lorenzi, Marco; Simpson, Ivor J; Mendelson, Alex F; Vos, Sjoerd B; Cardoso, M Jorge; Modat, Marc; Schott, Jonathan M; Ourselin, Sebastien

    2016-04-11

    The joint analysis of brain atrophy measured with magnetic resonance imaging (MRI) and hypometabolism measured with positron emission tomography with fluorodeoxyglucose (FDG-PET) is of primary importance in developing models of pathological changes in Alzheimer's disease (AD). Most of the current multimodal analyses in AD assume a local (spatially overlapping) relationship between MR and FDG-PET intensities. However, it is well known that atrophy and hypometabolism are prominent in different anatomical areas. The aim of this work is to describe the relationship between atrophy and hypometabolism by means of a data-driven statistical model of non-overlapping intensity correlations. For this purpose, FDG-PET and MRI signals are jointly analyzed through a computationally tractable formulation of partial least squares regression (PLSR). The PLSR model is estimated and validated on a large clinical cohort of 1049 individuals from the ADNI dataset. Results show that the proposed non-local analysis outperforms classical local approaches in terms of predictive accuracy while providing a plausible description of disease dynamics: early AD is characterised by non-overlapping temporal atrophy and temporo-parietal hypometabolism, while the later disease stages show overlapping brain atrophy and hypometabolism spread in temporal, parietal and cortical areas.

  10. Non-local means variants for denoising of diffusion-weighted and diffusion tensor MRI.

    PubMed

    Wiest-Daesslé, Nicolas; Prima, Sylvain; Coupé, Pierrick; Morrissey, Sean Patrick; Barillot, Christian

    2007-01-01

    Diffusion tensor imaging (DT-MRI) is very sensitive to corrupting noise due to the non linear relationship between the diffusion-weighted image intensities (DW-MRI) and the resulting diffusion tensor. Denoising is a crucial step to increase the quality of the estimated tensor field. This enhanced quality allows for a better quantification and a better image interpretation. The methods proposed in this paper are based on the Non-Local (NL) means algorithm. This approach uses the natural redundancy of information in images to remove the noise. We introduce three variations of the NL-means algorithms adapted to DW-MRI and to DT-MRI. Experiments were carried out on a set of 12 diffusion-weighted images (DW-MRI) of the same subject. The results show that the intensity based NL-means approaches give better results in the context of DT-MRI than other classical denoising methods, such as Gaussian Smoothing, Anisotropic Diffusion and Total Variation.

  11. Majorana Fermion Induced Non-local Current Correlations in Spin-orbit Coupled Superconducting Wires

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Zhang, Fu-Chun; Law, K. T.

    2014-03-01

    The observation of zero bias conductance peaks in semiconductor wire-superconductor heterostructures has generated great interest, and there is a hot debate on whether the observation is associated with Majorana Fermions (MFs) or other effects which enhance local Andreev reflections. In this work, we study the transport of a normal lead/semiconductor wire-superconductor heterostructure /normal lead junction. We show that when MF end states from the two ends of the wire are strongly coupled, the MF end states can suppress local Andreev reflections and strongly enhance crossed Andreev reflections (CARs), in which an electron from one lead is reflected as a hole in a different lead. In the CAR dominated regime, the current-current correlations between the two leads are strongly enhanced. Moreover, the Fano factor of a normal lead, which is the ratio of the shot noise to the average current, is reduced from 2e to e. Since the CAR associated effects are non-local effects and they cannot be induced by processes which enhance local Andreev reflections, therefore, the measurement of Fano factors and current-current correlations of the normal leads can be used to identify MFs.

  12. Rapid computation of spectrally integrated non-local thermodynamic equilibrium limb emission

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Olander, Daphne S.; Lopez-Puertas, Manuel

    1994-01-01

    The interpretation of infrared radiance measurements made by satellite-borne limb-scanning broadband radiometers requires accurate and computationally fast techniques with which to evaluate the equation of radiative transfer. This requirement is made even more stringent when analyzing measurements of non-local thermodynamic equilibrium (non-LTE) emission from the terrestrial mesosphere and lower thermosphere. In principle, line-by-line calculations which explicitly account for the departure from thermodynamic equilibrium in both the source functions and the transmittances are necessary. In this paper we extend the emissivity growth approximation (EGA) technique developed for local thermodynamic equilibrium (LTE) limb radiance for the molecular oxygen dayglow (1.27 micrometers and 762 nm), ozone and carbon dioxide in the 9- to 11-micrometer spectral interval, carbon monoxide (4.6 micrometers), nitric oxide (5.3 micrometers), and the carbon dioxide bands (15 micrometers) are presented. Using the non-LTE form of the EGA, the spectrally integrated limb emission is calculated for 35 tangent heights in the mesosphere and lower thermosphere (a total of 1200 atmospheric layers) with line-by-line accuracy in approximately 0.35 s of CPU time on readily available desktop computer hardware, while the corresponding line-by-line calculations may require several minutes. The non-LTE EGA technique will allow kinetic temperature and minor constituend retrieval algorithms to readily include non-LTE efects limited only by the a priori knowledge of the departure from LTE in the observed bands.

  13. Multicolor imaging and the anticancer effect of a bifunctional silica nanosystem based on the complex of graphene quantum dots and hypocrellin A.

    PubMed

    Zhou, Lin; Zhou, Lin; Ge, Xuefeng; Zhou, Jiahong; Wei, Shaohua; Shen, Jian

    2015-01-01

    An effective theranostic platform based on porous silica nanoparticles encapsulated with the complex of a photodynamic anticancer drug and graphene quantum dots (GQDs), with the bifunction of multicolor imaging and satisfactory photo-induced anticancer activity, was successfully designed and prepared for in vitro photodynamic therapy (PDT) of superficial cancer.

  14. Circular dichroism spectroscopy of complexes of semiconductor quantum dots with chlorin e6

    NASA Astrophysics Data System (ADS)

    Kundelev, Evgeny V.; Orlova, Anna O.; Maslov, Vladimir G.; Baranov, Alexsander V.; Fedorov, Anatoly V.

    2016-04-01

    Experimental investigation of circular dichroism (CD) spectra of complexes based on ZnS:Mn/ZnS and CdSe/ZnS QDs and chlorin e6 (Ce6) molecules in aqua solutions at different pH level, in methanol and in DMSO were carried out. The changes in CD spectra of Ce6 upon its bonding in complex with semiconductor QDs were analyzed. Application of CD spectroscopy allowed to obtain the CD spectrum of luminescent Ce6 dimer for the first time, and to discover a nonluminescent Ce6 aggregate, preliminary identified as a "tetramer", dissymmetry factor of which is 40 times larger than that for its monomer. The analysis of obtained data showed that in complexes with QDs Ce6 can be either in the monomeric form or in the form of non-luminescent tetramer. The interaction of relatively unstable luminescent Ce6 dimerwith QDs leads to its partial monomerization and formation complexes with chlorin e6 in monomeric form.

  15. Complex responses to Si quantum dots accumulation in carp liver tissue: Beyond oxidative stress.

    PubMed

    Serban, Andreea Iren; Stanca, Loredana; Sima, Cornelia; Staicu, Andrea Cristina; Zarnescu, Otilia; Dinischiotu, Anca

    2015-09-05

    The use of quantum dots (QDs) in biomedical applications is limited due to their inherent toxicity caused by the heavy metal core of the particles. Consequently, silicon-based QDs are expected to display diminished toxicity. We investigated the in vivo effects induced by Si/SiO2 QDs intraperitoneally injected in crucian carp liver. The QDs contained a crystalline Si core encased in a SiO2 shell, with a size between 2.75 and 11.25nm and possess intrinsic fluorescence (Ex 325nm/Em ∼690nm). Tissue fluorescence microscopy analysis revealed the presence of QDs in the liver for at least 2weeks after injection. Although protein and lipid oxidative stress markers showed the onset of oxidative stress, the hepatic tissue exhibited significant antioxidant adaptations (increase of antioxidant enzymes, recovery of glutathione levels), sustained by the activation of Hsp30 and Hsp70 chaperoning proteins. The increased activity of cyclooxigenase-2 (COX-2) and matrix metalloproteinases (MMPs) support the idea that Si/SiO2 QDs have a potential to induce inflammatory response, a scenario also indicated by the profile of Hsp60 and Hsp90 heat shock proteins. MMPs profile and the recovery of oxidative stress markers suggested a tissue remodelation phase after 3weeks from QDs administration.

  16. Large photocurrent response and external quantum efficiency in biophotoelectrochemical cells incorporating reaction center plus light harvesting complexes.

    PubMed

    Yaghoubi, Houman; Lafalce, Evan; Jun, Daniel; Jiang, Xiaomei; Beatty, J Thomas; Takshi, Arash

    2015-04-13

    Bacterial photosynthetic reaction centers (RCs) are promising materials for solar energy harvesting, due to their high ratio of photogenerated electrons to absorbed photons and long recombination time of generated charges. In this work, photoactive electrodes were prepared from a bacterial RC-light-harvesting 1 (LH1) core complex, where the RC is encircled by the LH1 antenna, to increase light capture. A simple immobilization method was used to prepare RC-LH1 photoactive layer. Herein, we demonstrate that the combination of pretreatment of the RC-LH1 protein complexes with quinone and the immobilization method results in biophotoelectrochemical cells with a large peak transient photocurrent density and photocurrent response of 7.1 and 3.5 μA cm(-2), respectively. The current study with monochromatic excitation showed maximum external quantum efficiency (EQE) and photocurrent density of 0.21% and 2 μA cm(-2), respectively, with illumination power of ∼6 mW cm(-2) at ∼875 nm, under ambient conditions. This work provides new directions to higher performance biophotoelectrochemical cells as well as possibly other applications of this broadly functional photoactive material.

  17. Multi-level quantum Monte Carlo wave functions for complex reactions: the decomposition of α-hydroxy-dimethylnitrosamine.

    PubMed

    Fracchia, Francesco; Filippi, Claudia; Amovilli, Claudio

    2014-01-05

    We present here several novel features of our recently proposed Jastrow linear generalized valence bond (J-LGVB) wave functions, which allow a consistently accurate description of complex potential energy surfaces (PES) of medium-large systems within quantum Monte Carlo (QMC). In particular, we develop a multilevel scheme to treat different regions of the molecule at different levels of the theory. As prototypical study case, we investigate the decomposition of α-hydroxy-dimethylnitrosamine, a carcinogenic metabolite of dimethylnitrosamine (NDMA), through a two-step mechanism of isomerization followed by a retro-ene reaction. We compute a reliable reaction path with the quadratic configuration interaction method and employ QMC for the calculation of the electronic energies. We show that the use of multideterminantal wave functions is very important to correctly describe the critical points of this PES within QMC, and that our multilevel J-LGVB approach is an effective tool to significantly reduce the cost of QMC calculations without loss of accuracy. As regards the complex PES of α-hydroxy-dimethylnitrosamine, the accurate energies computed with our approach allows us to confirm the validity of the two-step reaction mechanism of decomposition originally proposed within density functional theory, but with some important differences in the barrier heights of the individual steps.

  18. Complex generalized minimal residual algorithm for iterative solution of quantum-mechanical reactive scattering equations

    NASA Technical Reports Server (NTRS)

    Chatfield, David C.; Reeves, Melissa S.; Truhlar, Donald G.; Duneczky, Csilla; Schwenke, David W.

    1992-01-01

    Complex dense matrices corresponding to the D + H2 and O + HD reactions were solved using a complex generalized minimal residual (GMRes) algorithm described by Saad and Schultz (1986) and Saad (1990). To provide a test case with a different structure, the H + H2 system was also considered. It is shown that the computational effort for solutions with the GMRes algorithm depends on the dimension of the linear system, the total energy of the scattering problem, and the accuracy criterion. In several cases with dimensions in the range 1110-5632, the GMRes algorithm outperformed the LAPACK direct solver, with speedups for the linear equation solution as large as a factor of 23.

  19. Classical and Quantum Complexity of the Sturm-Liouville Eigenvalue Problem

    DTIC Science & Technology

    2005-03-03

    study of a nonlin- ear continuous problem was done in [20] for ordinary differential equations with polynomial speedups over the classical settings. The...multivariate approximation, and ordinary differential equations . Tight bit query complexity bounds are known for a number of such problems, see [14, 15, 16...Linear Algebra, SIAM, Philadelphia. [12] Gary, H. (1965), Computing Eigenvalues of Ordinary Differential Equations with Finite Differences, Mathematics

  20. Integrated photonic quantum walks

    NASA Astrophysics Data System (ADS)

    Gräfe, Markus; Heilmann, René; Lebugle, Maxime; Guzman-Silva, Diego; Perez-Leija, Armando; Szameit, Alexander

    2016-10-01

    Over the last 20 years quantum walks (QWs) have gained increasing interest in the field of quantum information science and processing. In contrast to classical walkers, quantum objects exhibit intrinsic properties like non-locality and non-classical many-particle correlations, which renders QWs a versatile tool for quantum simulation and computation as well as for a deeper understanding of genuine quantum mechanics. Since they are highly controllable and hardly interact with their environment, photons seem to be ideally suited quantum walkers. In order to study and exploit photonic QWs, lattice structures that allow low loss coherent evolution of quantum states are demanded. Such requirements are perfectly met by integrated optical waveguide devices that additionally allow a substantial miniaturization of experimental settings. Moreover, by utilizing the femtosecond direct laser writing technique three-dimensional waveguide structures are capable of analyzing QWs also on higher dimensional geometries. In this context, advances and findings of photonic QWs are discussed in this review. Various concepts and experimental results are presented covering, such as different quantum transport regimes, the Boson sampling problem, and the discrete fractional quantum Fourier transform.

  1. A complex guided spectral transform Lanczos method for studying quantum resonance states

    DOE PAGES

    Yu, Hua-Gen

    2014-12-28

    A complex guided spectral transform Lanczos (cGSTL) algorithm is proposed to compute both bound and resonance states including energies, widths and wavefunctions. The algorithm comprises of two layers of complex-symmetric Lanczos iterations. A short inner layer iteration produces a set of complex formally orthogonal Lanczos (cFOL) polynomials. They are used to span the guided spectral transform function determined by a retarded Green operator. An outer layer iteration is then carried out with the transform function to compute the eigen-pairs of the system. The guided spectral transform function is designed to have the same wavefunctions as the eigenstates of the originalmore » Hamiltonian in the spectral range of interest. Therefore the energies and/or widths of bound or resonance states can be easily computed with their wavefunctions or by using a root-searching method from the guided spectral transform surface. The new cGSTL algorithm is applied to bound and resonance states of HO₂, and compared to previous calculations.« less

  2. A complex guided spectral transform Lanczos method for studying quantum resonance states

    SciTech Connect

    Yu, Hua-Gen

    2014-12-28

    A complex guided spectral transform Lanczos (cGSTL) algorithm is proposed to compute both bound and resonance states including energies, widths and wavefunctions. The algorithm comprises of two layers of complex-symmetric Lanczos iterations. A short inner layer iteration produces a set of complex formally orthogonal Lanczos (cFOL) polynomials. They are used to span the guided spectral transform function determined by a retarded Green operator. An outer layer iteration is then carried out with the transform function to compute the eigen-pairs of the system. The guided spectral transform function is designed to have the same wavefunctions as the eigenstates of the original Hamiltonian in the spectral range of interest. Therefore the energies and/or widths of bound or resonance states can be easily computed with their wavefunctions or by using a root-searching method from the guided spectral transform surface. The new cGSTL algorithm is applied to bound and resonance states of HO₂, and compared to previous calculations.

  3. Thermal effects on spin currents in non-local metallic spin valves

    NASA Astrophysics Data System (ADS)

    Hojem, Alex

    The study of non-local spin valves (NLSVs) has recently proven to be a fertile area for both applied and fundamental research in nanomagnetism due to the unique ability to separate charge currents and spin currents. NLSVs may also prove essential for a new class of high-density hard disk read heads due to their favorable scalability. Recent studies have shown thermal effects created by high current densities play a significant role in the response of NLSVs. These thermal effects also provide the opportunity to create a pure spin current from thermal gradients via a mechanism call the spin dependent Seebeck effect (SDSE). Due to the challenges in control and measurement of thermal gradients in nanoscale structures, both the fundamental physics and materials dependencies of thermally-driven spin transport in nanoscale structures remains largely unexplored. In the dissertation I present measurements of thermal and electrical spin injection in nanoscale metallic non-local spin valve (NLSV) structures. Informed by measurements of the Seebeck coefficient and thermal conductivity of representative films made using a micromachined Si-N thermal isolation platform, we use simple analytical and finite element thermal models to determine limits on the thermal gradient driving thermal spin injection and calculate the spin-dependent Seebeck coefficient that is comparable in terms of the fraction of the absolute Seebeck coefficient to previous results, despite dramatically smaller electrical spin injection signals. Since the small electrical spin signals are likely caused by interfacial effects, we conclude that thermal spin injection is less sensitive to the FM/NM interface, and possibly benefits from the presence of oxidized ferromagnet, which further stimulates interest in thermal spin injection for applications in sensors and pure spin current sources. To investigate contact resistance further we also present work comparing NLSVs with permalloy oxide contacts and devices with

  4. Contextuality supplies the 'magic' for quantum computation.

    PubMed

    Howard, Mark; Wallman, Joel; Veitch, Victor; Emerson, Joseph

    2014-06-19

    Quantum computers promise dramatic advantages over their classical counterparts, but the source of the power in quantum computing has remained elusive. Here we prove a remarkable equivalence between the onset of contextuality and the possibility of universal quantum computation via 'magic state' distillation, which is the leading model for experimentally realizing a fault-tolerant quantum computer. This is a conceptually satisfying link, because contextuality, which precludes a simple 'hidden variable' model of quantum mechanics, provides one of the fundamental characterizations of uniquely quantum phenomena. Furthermore, this connection suggests a unifying paradigm for the resources of quantum information: the non-locality of quantum theory is a particular kind of contextuality, and non-locality is already known to be a critical resource for achieving advantages with quantum communication. In addition to clarifying these fundamental issues, this work advances the resource framework for quantum computation, which has a number of practical applications, such as characterizing the efficiency and trade-offs between distinct theoretical and experimental schemes for achieving robust quantum computation, and putting bounds on the overhead cost for the classical simulation of quantum algorithms.

  5. Non-Local Means Inpainting of MS Lesions in Longitudinal Image Processing

    PubMed Central

    Guizard, Nicolas; Nakamura, Kunio; Coupé, Pierrick; Fonov, Vladimir S.; Arnold, Douglas L.; Collins, D. Louis

    2015-01-01

    In medical imaging, multiple sclerosis (MS) lesions can lead to confounding effects in automatic morphometric processing tools such as registration, segmentation and cortical extraction, and subsequently alter individual longitudinal measurements. Multiple magnetic resonance imaging (MRI) inpainting techniques have been proposed to decrease the impact of MS lesions in medical image processing, however, most of these methods make the assumption that lesions only affect white matter. Here, we propose a method to fill lesion regions using the patch-based non-local mean (NLM) strategy. The method consists of a hierarchical concentric filling strategy after identification of the lesion region. The lesion is filled iteratively, based on the surrounding tissue intensity, using an onion peel strategy. This concentric technique presents the advantage of preserving the local information and therefore the continuity of the anatomy and does not require identification of any a priori normal brain tissues. The method is first evaluated on 20 healthy subjects with simulated artificial MS lesions where we assessed our technique by measuring the peak signal-to-noise ratio (PSNR) of the images with inpainted lesion and the original healthy images. Second, in order to assess the impact of lesion filling on longitudinal image analyses, we performed a power analysis with sample size estimation to evaluate brain atrophy and ventricular growth in patients with MS. The method was compared to two different publicly available methods (FSL lesion fill and Lesion LEAP) and a more classic method, which fills the region with intensities similar to that of the surrounding healthy white matter tissue or mask the lesions. The proposed method was shown to exceed the other methods in reproducing the fidelity of healthy subject images where the lesions were inpainted. The method also improved the power to detect brain atrophy or ventricular growth by decreasing the sample size by 25% in the presence

  6. Non-local thermodynamic equilibrium 1.5D modeling of red giant stars

    SciTech Connect

    Young, Mitchell E.; Short, C. Ian

    2014-05-20

    Spectra for two-dimensional (2D) stars in the 1.5D approximation are created from synthetic spectra of one-dimensional (1D) non-local thermodynamic equilibrium (NLTE) spherical model atmospheres produced by the PHOENIX code. The 1.5D stars have the spatially averaged Rayleigh-Jeans flux of a K3-4 III star while varying the temperature difference between the two 1D component models (ΔT {sub 1.5D}) and the relative surface area covered. Synthetic observable quantities from the 1.5D stars are fitted with quantities from NLTE and local thermodynamic equilibrium (LTE) 1D models to assess the errors in inferred T {sub eff} values from assuming horizontal homogeneity and LTE. Five different quantities are fit to determine the T {sub eff} of the 1.5D stars: UBVRI photometric colors, absolute surface flux spectral energy distributions (SEDs), relative SEDs, continuum normalized spectra, and TiO band profiles. In all cases except the TiO band profiles, the inferred T {sub eff} value increases with increasing ΔT {sub 1.5D}. In all cases, the inferred T {sub eff} value from fitting 1D LTE quantities is higher than from fitting 1D NLTE quantities and is approximately constant as a function of ΔT {sub 1.5D} within each case. The difference between LTE and NLTE for the TiO bands is caused indirectly by the NLTE temperature structure of the upper atmosphere, as the bands are computed in LTE. We conclude that the difference between T {sub eff} values derived from NLTE and LTE modeling is relatively insensitive to the degree of the horizontal inhomogeneity of the star being modeled and largely depends on the observable quantity being fit.

  7. Non-Local Means Inpainting of MS Lesions in Longitudinal Image Processing.

    PubMed

    Guizard, Nicolas; Nakamura, Kunio; Coupé, Pierrick; Fonov, Vladimir S; Arnold, Douglas L; Collins, D Louis

    2015-01-01

    In medical imaging, multiple sclerosis (MS) lesions can lead to confounding effects in automatic morphometric processing tools such as registration, segmentation and cortical extraction, and subsequently alter individual longitudinal measurements. Multiple magnetic resonance imaging (MRI) inpainting techniques have been proposed to decrease the impact of MS lesions in medical image processing, however, most of these methods make the assumption that lesions only affect white matter. Here, we propose a method to fill lesion regions using the patch-based non-local mean (NLM) strategy. The method consists of a hierarchical concentric filling strategy after identification of the lesion region. The lesion is filled iteratively, based on the surrounding tissue intensity, using an onion peel strategy. This concentric technique presents the advantage of preserving the local information and therefore the continuity of the anatomy and does not require identification of any a priori normal brain tissues. The method is first evaluated on 20 healthy subjects with simulated artificial MS lesions where we assessed our technique by measuring the peak signal-to-noise ratio (PSNR) of the images with inpainted lesion and the original healthy images. Second, in order to assess the impact of lesion filling on longitudinal image analyses, we performed a power analysis with sample size estimation to evaluate brain atrophy and ventricular growth in patients with MS. The method was compared to two different publicly available methods (FSL lesion fill and Lesion LEAP) and a more classic method, which fills the region with intensities similar to that of the surrounding healthy white matter tissue or mask the lesions. The proposed method was shown to exceed the other methods in reproducing the fidelity of healthy subject images where the lesions were inpainted. The method also improved the power to detect brain atrophy or ventricular growth by decreasing the sample size by 25% in the presence

  8. Coherent scatter radar instabilities observed over Arecibo and proposed non-local linear gradient drift theory

    NASA Astrophysics Data System (ADS)

    Rosado-Roman, J. M.; Farley, D. T.; Swartz, W. E.; Seyler, C. E.

    2001-05-01

    Common volume observations with the Cornell University Portable Radar Interferometer (CUPRI) coherent scatter radar and the Arecibo Observatory incoherent scatter radar (AO-ISR) obtained during the NASA El Coquí campaign of 1992, are used to study the causes of coherent radar backscatter at mid-latitudes. The common volume data reveal that coherent scatter echoes are obtained from sporadic E (Es) layers that exhibit little or no gravity wave altitude modulation and possess high densities and sharp gradients. The echoes are associated with larger than typical F-region south-perpendicular electric fields. The echoes appear to come from the linearly unstable side of the Es layers even though the usual local linear theory is invalid at mid-latitudes. Non-local shorting effects along magnetic field lines play a crucial role at mid-latitudes, and we have developed a theory that takes this into account. The unstable eigen modes are a sum of plane waves with k vectors varying vertically about pure perpendicular propagation by a few degrees (allowing for the spatial localization of the modes on the top or bottom of the layer). The k vectors are also approximately aligned with the E x B drift. While both density and potential modes peak in amplitude on the unstable side of the layer, the density mode peaks closer to the maximum of the layer than does the potential mode. The separation and shape of the modes is determined by the profile of the vertical scale length, Lz = Ne / (d)/(dz) Ne; convergent growing solutions are found when the scale length profile exhibits a deep local minimum (steep gradient). We used a narrow Gaussian layer superimposed on a constant background density. Perhaps surprisingly, the constant background is essential for the numerical calculations. It can be small but not zero.

  9. Photochemical Studies on Chromium(III) Cyclam Complexes: Photosensitization with Semiconductor Quantum Dots and Nitric Oxide Release

    NASA Astrophysics Data System (ADS)

    Ostrowski, Alexis D.

    The small molecule nitric oxide (NO) is involved in a variety of biological processes including blood pressure regulation, neural transmission, immune response, and cell apoptosis. In this context, the goal of the described research is to detail the development of systems for photochemical NO release that could be used in a new type of photodynamic therapy (PDT), where site-specific irradiation leads to photochemical NO release. The metal complex trans-Cr(cyclam)(ONO)2 + (CrONO) is a NO precursor, where visible light irradiation of aqueous solutions at muM and lower concentrations, leads to sufficient NO release to activate the enzyme soluble guanylyl cyclase (sGC). In addition, photolysis of solutions 100 nM CrONO and greater leads to significant vasorelaxation of porcine coronary arteries. Irradiation of CrONO in aerated aqueous solutions the presence of the biological reductant glutathione (GSH) also leads to a greater net NO release. The investigation of systems using semi-conductor quantum dots (QDs) as photosensitzers for CrONO is also described. We have demonstrated that water-soluble CdSe/ZnS core/shell QDs form electrostatic assemblies with the CrONO complexes and act as antenna for photosensitized release of nitric oxide (NO). Energy transfer is consistent with a Forster resonance energy transfer (FRET) mechanism, as the rate of energy transfer is a function of the overlap between the QD (donor) emission and the Cr(III) complex (acceptor) absorbance. These results provide a guideline for the design of other QD-based materials and devices that rely on photosensitized energy transfer.

  10. Direct Evidence of Memory Retrieval as a Source of Difficulty in Non-Local Dependencies in Language

    ERIC Educational Resources Information Center

    Fedorenko, Evelina; Woodbury, Rebecca; Gibson, Edward

    2013-01-01

    Linguistic dependencies between non-adjacent words have been shown to cause comprehension difficulty, compared with local dependencies. According to one class of sentence comprehension accounts, non-local dependencies are difficult because they require the retrieval of the first dependent from memory when the second dependent is encountered.…

  11. Correlating spin transport and electrode magnetization in a graphene spin valve: Simultaneous magnetic microscopy and non-local measurements

    SciTech Connect

    Berger, Andrew J. Page, Michael R.; Bhallamudi, Vidya P.; Chris Hammel, P.; Wen, Hua; Kawakami, Roland K.; McCreary, Kathleen M.

    2015-10-05

    Using simultaneous magnetic force microscopy and transport measurements of a graphene spin valve, we correlate the non-local spin signal with the magnetization of the device electrodes. The imaged magnetization states corroborate the influence of each electrode within a one-dimensional spin transport model and provide evidence linking domain wall pinning to additional features in the transport signal.

  12. Once an Outsider, Always an Outsider? The Accessibility of the Dutch Rural Housing Market among Locals and Non-Locals

    ERIC Educational Resources Information Center

    de Groot, Carola; Daalhuizen, Femke B. C.; van Dam, Frank; Mulder, Clara H.

    2012-01-01

    One of the most pressing questions in the rural gentrification literature is whether rural residents face difficulties in finding a home within their locality due to the influx of more wealthy newcomers. In this paper, we investigate the extent to which intended local movers and intended non-local movers have realised their rural residential…

  13. Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport.

    PubMed

    Xie, Hang; Kwok, Yanho; Jiang, Feng; Zheng, Xiao; Chen, GuanHua

    2014-10-28

    Based on the complex absorbing potential (CAP) method, a Lorentzian expansion scheme is developed to express the self-energy. The CAP-based Lorentzian expansion of self-energy is employed to solve efficiently the Liouville-von Neumann equation of one-electron density matrix. The resulting method is applicable for both tight-binding and first-principles models and is used to simulate the transient currents through graphene nanoribbons and a benzene molecule sandwiched between two carbon-atom chains.

  14. Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport

    SciTech Connect

    Xie, Hang Kwok, Yanho; Chen, GuanHua; Jiang, Feng; Zheng, Xiao

    2014-10-28

    Based on the complex absorbing potential (CAP) method, a Lorentzian expansion scheme is developed to express the self-energy. The CAP-based Lorentzian expansion of self-energy is employed to solve efficiently the Liouville-von Neumann equation of one-electron density matrix. The resulting method is applicable for both tight-binding and first-principles models and is used to simulate the transient currents through graphene nanoribbons and a benzene molecule sandwiched between two carbon-atom chains.

  15. Complex-scaling treatment for quantum entanglement in doubly excited helium atom

    NASA Astrophysics Data System (ADS)

    Lin, Chien-Hao; Ho, Yew Kam

    2015-05-01

    Recently, we have investigated entanglement measures in natural atomic systems that involve two highly correlated indistinguishable spin-1/2 fermions (electrons). Linear entropy and von Neumann entropy were calculated for spatial (electron-electron orbital) entanglement measures for ground and singly excited bound states in two-electron atomic systems, such as He, H- and Ps-. In our present work, we carry out an investigation on entanglement in doubly excited resonance states of helium. Since resonance states are lying in the scattering continuum, their energies are no longer bound by the variational theorem; we apply the complex scaling method to solve the complex energy pole with which the resonance energy and resonance width are deduced. Hylleraas-type wave functions are used to consider correlation effects. Once the wave function for a doubly excited state is obtained, we apply the Schmidt decomposition method to calculate the linear entropy and von Neumann entropy for the doubly excited 2s2, 2 s3 s, 2p2, 3s2, and 3p21Se resonance states in the helium atom. Work supported by the Ministry of Science and Technology of Taiwan.

  16. Quantum transport in molecular electronic devices described with complex source and sink potentials

    NASA Astrophysics Data System (ADS)

    Goyer, Francois; Goker, Ali; Ernzerhof, Matthias

    2008-03-01

    We present a non-Hermitian model Hamiltonian containing complex potentials [1,2] that is devised to study ballistic transport in molecular electronic devices (MEDs). The complex potentials replace semi-infinite contacts and act as source and sink of probability current density. This approach is rigorous in the sense that the exact wave function is recovered in the interior of the MED. We employ this technique to calculate the conductance through certain prototypical MEDs [3]. We also extend this method [4] such that we can go beyond the one- electron picture by constructing two-electron states explicitly. We present results for simple model system described by Hubbard-type Hamiltonians. The impact of electron correlation effects on the molecular conductance is discussed. [1] F. Goyer, M. Ernzerhof, M. Zhuang, JCP, 126, 144104 (2007). [2] M. Ernzerhof, JCP, to appear nov. 2007. [3] M. Ernzerhof, H. Bahmann, F. Goyer, M. Zhuang, P. Rocheleau, J. Chem. Theory Comput., 2, 1291 (2006); M. Ernzerhof, M. Zhuang, P. Rocheleau, JCP, 123, 134704 (2005). [4] A. Goker, F. Goyer, M. Ernzerhof, work in pogress.

  17. Nonequilibrium transport on a quantum molecular chain in terms of the complex Liouvillian spectrum.

    PubMed

    Tanaka, Satoshi; Kanki, Kazuki; Petrosky, Tomio

    2011-05-01

    The transport process in a molecular chain in a nonequilibrium stationary state is theoretically investigated. The molecule is interacting at both ends with thermal baths of different temperatures, while no dissipation mechanism is contained inside the molecular chain. We have first obtained the nonequilibrium stationary state outside the Hilbert space in terms of the complex spectral representation of Liouvillian. The nonequilibrium stationary state is obtained as an eigenstate of the Liouvillian, which is constructed through the collision invariant of the kinetic equation. The eigenstate of the Liouvillian contains information on the spatial correlation between the molecular chain and the thermal baths. While energy flow in the nonequilibrium state which is due to the first-order correlation can be described by the Landauer formula, the particle current due to the second-order correlation cannot be described by the Landauer formula. The present method provides a simple way to evaluate the energy transport in a molecular chain in a nonequilibrium situation.

  18. Communication: overcoming the root search problem in complex quantum trajectory calculations.

    PubMed

    Zamstein, Noa; Tannor, David J

    2014-01-28

    Three new developments are presented regarding the semiclassical coherent state propagator. First, we present a conceptually different derivation of Huber and Heller's method for identifying complex root trajectories and their equations of motion [D. Huber and E. J. Heller, J. Chem. Phys. 87, 5302 (1987)]. Our method proceeds directly from the time-dependent Schrödinger equation and therefore allows various generalizations of the formalism. Second, we obtain an analytic expression for the semiclassical coherent state propagator. We show that the prefactor can be expressed in a form that requires solving significantly fewer equations of motion than in alternative expressions. Third, the semiclassical coherent state propagator is used to formulate a final value representation of the time-dependent wavefunction that avoids the root search, eliminates problems with caustics and automatically includes interference. We present numerical results for the 1D Morse oscillator showing that the method may become an attractive alternative to existing semiclassical approaches.

  19. Charge Transfer Between Quantum Dots and Peptide-Coupled Redox Complexes

    DTIC Science & Technology

    2009-01-01

    scale ) Ruthenium complex 190 2009 NRL REVIEW NANOSCIENCE TECHNOLOGY N or m al iz ed C ur re nt (µ A ) Potential, V vs...DHLA QDs Abs 2 Ru /QD Abs 5 Ru /QD FIGURE 4 Enzymatic assay of chymotrypsin activity utilizing QD–Ru peptide conjugates, showing enzymatic ve ...0.01 0.02 0.03 0.04 Vmax = 0.04 +/- 0.02 µM/min KM = 0.83 +/- 0.16 µM KM = 2.2 +/- 0.5 µM Vmax = 0.01 +/- 0.004 µM/min No inhibitor + Chymostatin inhibitor V el oc ity (µ M C hy m -R u cl ea ve d

  20. Modified Scaled Hierarchical Equation of Motion Approach for the Study of Quantum Coherence in Photosynthetic Complexes

    SciTech Connect

    Zhu, J.; Kais, S.; Rebentrost, P.; Aspuru-Guzik, Alan

    2011-02-17

    We present a detailed theoretical study of the transfer of electronic excitation energy through the Fenna-Matthews-Olson (FMO) pigment-protein complex, using the newly developed modified scaled hierarchical approach (Shi, Q.; et al. J. Chem. Phys.2009, 130, 084105). We show that this approach is computationally more efficient than the original hierarchical approach. The modified approach reduces the truncation levels of the auxiliary density operators and the correlation function. We provide a systematic study of how the number of auxiliary density operators and the higher-order correlation functions affect the exciton dynamics. The time scales of the coherent beating are consistent with experimental observations. Furthermore, our theoretical results exhibit population beating at physiological temperature. Additionally, the method does not require a low-temperature correction to obtain the correct thermal equilibrium at long times.

  1. Communication: Overcoming the root search problem in complex quantum trajectory calculations

    SciTech Connect

    Zamstein, Noa; Tannor, David J.

    2014-01-28

    Three new developments are presented regarding the semiclassical coherent state propagator. First, we present a conceptually different derivation of Huber and Heller's method for identifying complex root trajectories and their equations of motion [D. Huber and E. J. Heller, J. Chem. Phys. 87, 5302 (1987)]. Our method proceeds directly from the time-dependent Schrödinger equation and therefore allows various generalizations of the formalism. Second, we obtain an analytic expression for the semiclassical coherent state propagator. We show that the prefactor can be expressed in a form that requires solving significantly fewer equations of motion than in alternative expressions. Third, the semiclassical coherent state propagator is used to formulate a final value representation of the time-dependent wavefunction that avoids the root search, eliminates problems with caustics and automatically includes interference. We present numerical results for the 1D Morse oscillator showing that the method may become an attractive alternative to existing semiclassical approaches.

  2. Non-localization and localization ROC analyses using clinically based scoring

    NASA Astrophysics Data System (ADS)

    Paquerault, Sophie; Samuelson, Frank W.; Myers, Kyle J.; Smith, Robert C.

    2009-02-01

    . The results on the variance analysis differed from those observed in the other study setting. This investigation furthers our understanding of the relationships between non-localization-specific and localization-specific ROC assessment methodologies and their relevance to clinical practice.

  3. Lithium abundances of halo dwarfs based on excitation temperatures. II. Non-local thermodynamic equilibrium

    NASA Astrophysics Data System (ADS)

    Hosford, A.; García Pérez, A. E.; Collet, R.; Ryan, S. G.; Norris, J. E.; Olive, K. A.

    2010-02-01

    Context. The plateau in the abundance of 7Li in metal-poor stars was initially interpreted as an observational indicator of the primordial lithium abundance. However, this observational value is in disagreement with that deduced from calculations of Big Bang nucleosynthesis (BBN), when using the Wilkinson microwave anisotropy probe (WMAP) baryon density measurements. One of the most important factors in determining the stellar lithium abundance is the effective temperature. In a previous study by the authors, new effective temperatures (Teff) for sixteen metal-poor halo dwarfs were derived using a local thermodynamic equilibrium (LTE) description of the formation of Fe lines. This new Teff scale reinforced the discrepancy. Aims: For six of the stars from our previous study we calculate revised temperatures using a non-local thermodynamic equilibrium (NLTE) approach. These are then used to derive a new mean primordial lithium abundance in an attempt to solve the lithium discrepancy. Methods: Using the code MULTI we calculate NLTE corrections to the LTE abundances for the Fe i lines measured in the six stars, and determine new Teff's. We keep other physical parameters, i.e. log g, [Fe/H] and ξ, constant at the values calculated in Paper I. With the revised Teff scale we derive new Li abundances. We compare the NLTE values of Teff with the photometric temperatures of Ryan et al. (1999, ApJ, 523, 654), the infrared flux method (IRFM) temperatures of Meléndez & Ramírez (2004, ApJ, 615, L33), and the Balmer line wing temperatures of Asplund et al. (2006, ApJ, 644, 229). Results: We find that our temperatures are hotter than both the Ryan et al. and Asplund et al. temperatures by typically ~110-160 K, but are still cooler than the temperatures of Meléndez & Ramírez by typically ~190 K. The temperatures imply a primordial Li abundance of 2.19 dex or 2.21 dex, depending on the magnitude of collisions with hydrogen in the calculations, still well below the value of 2

  4. Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

    SciTech Connect

    Jacquet, L. Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G.

    2015-12-15

    The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and

  5. Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

    NASA Astrophysics Data System (ADS)

    Jacquet, L.; Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G.

    2015-12-01

    The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and the

  6. ``Additive'' cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Varfolomeev, Mikhail A.; Klimovitskii, Alexander E.; Abaidullina, Dilyara I.; Madzhidov, Timur I.; Solomonov, Boris N.

    2012-06-01

    Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of Osbnd H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. Osbnd H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact.

  7. "Additive" cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations.

    PubMed

    Varfolomeev, Mikhail A; Klimovitskii, Alexander E; Abaidullina, Dilyara I; Madzhidov, Timur I; Solomonov, Boris N

    2012-06-01

    Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of O-H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. O-H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact.

  8. Structure, vibrations and quantum chemical investigations of hydrogen bonded complex of bis(1-hydroxy-2-methylpropan-2-aminium)selenate

    NASA Astrophysics Data System (ADS)

    Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.

    2017-04-01

    The hydrogen bonded molecular complex bis(1-hydroxy-2-methylpropan-2-aminium)selenate (C8H24N2O6Se) has been prepared by the reaction of 2-amino-2-methyl propanol and selenic acid. The X-ray diffraction analysis revealed that the intermolecular proton transfer from selenic acid (SeO4H2) to 2-amino-2-methylpropanol results in the formation of bis(1-hydroxy-2-methylpropan-2-aminium)selenate (HMPAS) salt and the fragments are connected through H-bonding and ion pairing. The N-H⋯O and O-H⋯O interactions between 2-amino-2-methylpropanol and selenic acid determine the supramolecular arrangement in three-dimensional space. The salt crystallises in the space group P121/n1 of monoclinic system. The complete vibrational assignments of HMPAS have been performed by FTIR and FT-Raman spectroscopy. The experimental data are correlated with the structural properties namely the energy, thermodynamic parameters, atomic charges, hybridization concepts and vibrational frequencies determined by quantum chemical studies performed with B3LYP method using 6-311++G*, 6-31+G* and 6-31G** basis sets.

  9. Synthesis of a uranyl persulfide complex and quantum chemical studies of formation and topologies of hypothetical uranyl persulfide cage clusters.

    PubMed

    Grant, Daniel J; Weng, Zhehui; Jouffret, Laurent J; Burns, Peter C; Gagliardi, Laura

    2012-07-16

    The compound Na(4)[(UO(2))(S(2))(3)](CH(3)OH)(8) was synthesized at room temperature in an oxygen-free environment. It contains a rare example of the [(UO(2))(S(2))(3)](4-) complex in which a uranyl ion is coordinated by three bidentate persulfide groups. We examined the possible linkage of these units to form nanoscale cage clusters analogous to those formed from uranyl peroxide polyhedra. Quantum chemical calculations at the density functional and multiconfigurational wave function levels show that the uranyl-persulfide-uranyl, U-(S(2))-U, dihedral angles of model clusters are bent due to partial covalent interactions. We propose that this bent interaction will favor assembly of uranyl ions through persulfide bridges into curved structures, potentially similar to the family of nanoscale cage clusters built from uranyl peroxide polyhedra. However, the U-(S(2))-U dihedral angles predicted for several model structures may be too tight for them to self-assemble into cage clusters with fullerene topologies in the absence of other uranyl-ion bridges that adopt a flatter configuration. Assembly of species such as [(UO(2))(S(2))(SH)(4)](4-) or [(UO(2))(S(2))(C(2)O(4))(4)](4-) into fullerene topologies with ~60 vertices may be favored by use of large counterions.

  10. Structuring a quantum solvent around a weakly bound dopant: the He-Cs2(3Sigma(u)) complex.

    PubMed

    Prosmiti, Rita; Delgado-Barrio, Gerardo; Villarreal, Pablo; Yurtsever, Ersin; Coccia, Emanuele; Gianturco, Franco A

    2009-12-31

    The structure and energetics of (3,4)HeCs(2)((3)Sigma(u)) molecules are analyzed from first principles. Fixing the cesium dimer at its equilibrium distance, the electronic structure was determined through ab initio methods at the CCSD(T) level of theory using a large basis set to compute the interaction energies. At the T-shaped geometry, there is a shallow well with a depth of approximately 2 cm(-1) placed at R approximately 6.75 A, R being the distance from the center of mass of Cs(2) to He. That depth gradually decreases to approximately 0.75 cm(-1), while R increases to about 11.5 A at linear arrangements. A simple model of adding atom-atom Lennard-Jones potentials with well-depth and equilibrium distance parameters depending on the angular orientation was found to accurately reproduce the ab initio points. Using this analytical form, variational calculations at zero total angular momentum are performed, predicting a single bound level at approximately -0.106 (approximately -0.042) cm(-1) for the boson (fermion) species. Further calculations using Quantum Monte Carlo methods are carried out and found to be in good agreement with the variational ones. On the basis of the present results, such analytical expression could in turn be used to describe the structure and binding of larger complexes and therefore opens the possibility to further studies involving such aggregates.

  11. A chiral rhenium complex with predicted high parity violation effects: synthesis, stereochemical characterization by VCD spectroscopy and quantum chemical calculations.

    PubMed

    Saleh, Nidal; Zrig, Samia; Roisnel, Thierry; Guy, Laure; Bast, Radovan; Saue, Trond; Darquié, Benoît; Crassous, Jeanne

    2013-07-14

    With their rich electronic, vibrational, rotational and hyperfine structure, molecular systems have the potential to play a decisive role in precision tests of fundamental physics. For example, electroweak nuclear interactions should cause small energy differences between the two enantiomers of chiral molecules, a signature of parity symmetry breaking. Enantioenriched oxorhenium(VII) complexes S-(-)- and R-(+)-3 bearing a chiral 2-methyl-1-thio-propanol ligand have been prepared as potential candidates for probing molecular parity violation effects via high resolution laser spectroscopy of the Re=O stretching. Although the rhenium atom is not a stereogenic centre in itself, experimental vibrational circular dichroism (VCD) spectra revealed a surrounding chiral environment, evidenced by the Re=O bond stretching mode signal. The calculated VCD spectrum of the R enantiomer confirmed the position of the sulfur atom cis to the methyl, as observed in the solid-state X-ray crystallographic structure, and showed the presence of two conformers of comparable stability. Relativistic quantum chemistry calculations indicate that the vibrational shift between enantiomers due to parity violation is above the target sensitivity of an ultra-high resolution infrared spectroscopy experiment under active preparation.

  12. Atomistic tight-binding theory of multiexciton complexes in a self-assembled InAs quantum dot

    NASA Astrophysics Data System (ADS)

    Zieliński, M.; Korkusiński, M.; Hawrylak, P.

    2010-02-01

    We present atomistic tight-binding theory of electronic structure and optical properties of InAs/GaAs self-assembled quantum dots. The tight-binding model includes zincblende symmetry, faceting, and sp3d5s∗ atomic orbitals accounting for interband and intervalley couplings. The equilibrium positions of atoms are calculated using valence force field method and modification of the tight-binding Hamiltonian due to strain is accounted for using Harrison’s law. The electronic and optical properties of multiexciton complexes are then determined by diagonalizing the many-body Hamiltonian for interacting electrons and holes using the configuration-interaction approach. The calculations of strain distribution approach 108 atoms while the electron and valence hole single-particle states are calculated by diagonalization of the Hamiltonian matrix with size on the order of 107 . The dependence of predicted electronic and optical properties on InAs/GaAs valence-band offset and InAs absolute valence-band deformation potentials are described. The reliability of the atomistic calculations is assessed by comparison with results obtained from the effective bond orbital model and empirical pseudopotentials method.

  13. Quantitative Quantum Mechanical Spectral Analysis (qQMSA) of (1)H NMR spectra of complex mixtures and biofluids.

    PubMed

    Tiainen, Mika; Soininen, Pasi; Laatikainen, Reino

    2014-05-01

    The quantitative interpretation of (1)H NMR spectra of mixtures like the biofluids is a demanding task due to spectral complexity and overlap. Complications may arise also from water suppression, T2-editing, protein interactions, relaxation differences of the species, experimental artifacts and, furthermore, the spectra may contain unknown components and macromolecular background which cannot be easily separated from baseline. In this work, tools and strategies for quantitative Quantum Mechanical Spectral Analysis (qQMSA) of (1)H NMR spectra from complex mixtures were developed and systematically assessed. In the present approach, the signals of well-defined, stoichiometric components are described by a QM model, while the background is described by a multiterm baseline function and the unknown signals using optimizable and adjustable lines, regular multiplets or any spectral structures which can be composed from spectral lines. Any prior knowledge available from the spectrum can also be added to the model. Fitting strategies for weak and strongly overlapping spectral systems were developed and assessed using two basic model systems, the metabolite mixtures without and with macromolecular (serum) background. The analyses show that if the spectra are measured in high-throughput manner, the consistent absolute quantification demands some calibration to compensate the different response factors of the protons and compounds. On the other hand, the results show that also the T2-edited spectra can be measured so that they obey well the QM rules. In general, qQMSA exploits and interprets the spectral information in maximal way taking full advantage from the QM properties of the spectra and, at the same time, offers chemical confidence which means that individual components can be identified with high confidence on the basis of their accurate spectral parameters.

  14. Molecular Level Design Principle behind Optimal Sizes of Photosynthetic LH2 Complex: Taming Disorder through Cooperation of Hydrogen Bonding and Quantum Delocalization.

    PubMed

    Jang, Seogjoo; Rivera, Eva; Montemayor, Daniel

    2015-03-19

    The light harvesting 2 (LH2) antenna complex from purple photosynthetic bacteria is an efficient natural excitation energy carrier with well-known symmetric structure, but the molecular level design principle governing its structure-function relationship is unknown. Our all-atomistic simulations of nonnatural analogues of LH2 as well as those of a natural LH2 suggest that nonnatural sizes of LH2-like complexes could be built. However, stable and consistent hydrogen bonding (HB) between bacteriochlorophyll and the protein is shown to be possible only near naturally occurring sizes, leading to significantly smaller disorder than for nonnatural ones. Extensive quantum calculations of intercomplex exciton transfer dynamics, sampled for a large set of disorder, reveal that taming the negative effect of disorder through a reliable HB as well as quantum delocalization of the exciton is a critical mechanism that makes LH2 highly functional, which also explains why the natural sizes of LH2 are indeed optimal.

  15. Post-reconstruction non-local means filtering methods using CT side information for quantitative SPECT

    NASA Astrophysics Data System (ADS)

    Chun, Se Young; Fessler, Jeffrey A.; Dewaraja, Yuni K.

    2013-09-01

    Quantitative SPECT techniques are important for many applications including internal emitter therapy dosimetry where accurate estimation of total target activity and activity distribution within targets are both potentially important for dose-response evaluations. We investigated non-local means (NLM) post-reconstruction filtering for accurate I-131 SPECT estimation of both total target activity and the 3D activity distribution. We first investigated activity estimation versus number of ordered-subsets expectation-maximization (OSEM) iterations. We performed simulations using the XCAT phantom with tumors containing a uniform and a non-uniform activity distribution, and measured the recovery coefficient (RC) and the root mean squared error (RMSE) to quantify total target activity and activity distribution, respectively. We observed that using more OSEM iterations is essential for accurate estimation of RC, but may or may not improve RMSE. We then investigated various post-reconstruction filtering methods to suppress noise at high iteration while preserving image details so that both RC and RMSE can be improved. Recently, NLM filtering methods have shown promising results for noise reduction. Moreover, NLM methods using high-quality side information can improve image quality further. We investigated several NLM methods with and without CT side information for I-131 SPECT imaging and compared them to conventional Gaussian filtering and to unfiltered methods. We studied four different ways of incorporating CT information in the NLM methods: two known (NLM CT-B and NLM CT-M) and two newly considered (NLM CT-S and NLM CT-H). We also evaluated the robustness of NLM filtering using CT information to erroneous CT. NLM CT-S and NLM CT-H yielded comparable RC values to unfiltered images while substantially reducing RMSE. NLM CT-S achieved -2.7 to 2.6% increase of RC compared to no filtering and NLM CT-H yielded up to 6% decrease in RC while other methods yielded lower RCs

  16. Post-reconstruction non-local means filtering methods using CT side information for quantitative SPECT.

    PubMed

    Chun, Se Young; Fessler, Jeffrey A; Dewaraja, Yuni K

    2013-09-07

    Quantitative SPECT techniques are important for many applications including internal emitter therapy dosimetry where accurate estimation of total target activity and activity distribution within targets are both potentially important for dose–response evaluations. We investigated non-local means (NLM) post-reconstruction filtering for accurate I-131 SPECT estimation of both total target activity and the 3D activity distribution. We first investigated activity estimation versus number of ordered-subsets expectation–maximization (OSEM) iterations. We performed simulations using the XCAT phantom with tumors containing a uniform and a non-uniform activity distribution, and measured the recovery coefficient (RC) and the root mean squared error (RMSE) to quantify total target activity and activity distribution, respectively. We observed that using more OSEM iterations is essential for accurate estimation of RC, but may or may not improve RMSE. We then investigated various post-reconstruction filtering methods to suppress noise at high iteration while preserving image details so that both RC and RMSE can be improved. Recently, NLM filtering methods have shown promising results for noise reduction. Moreover, NLM methods using high-quality side information can improve image quality further. We investigated several NLM methods with and without CT side information for I-131 SPECT imaging and compared them to conventional Gaussian filtering and to unfiltered methods. We studied four different ways of incorporating CT information in the NLM methods: two known (NLM CT-B and NLM CT-M) and two newly considered (NLM CT-S and NLM CT-H). We also evaluated the robustness of NLM filtering using CT information to erroneous CT. NLM CT-S and NLM CT-H yielded comparable RC values to unfiltered images while substantially reducing RMSE. NLM CT-S achieved −2.7 to 2.6% increase of RC compared to no filtering and NLM CT-H yielded up to 6% decrease in RC while other methods yielded lower

  17. Heuristic approximations for sound fields produced by spherical waves incident on locally and non-locally reacting planar surfaces.

    PubMed

    Li, Kai Ming; Tao, Hongdan

    2014-01-01

    The classic Weyl-van der Pol (WVDP) formula is a well-known asymptotic solution for accurately predicting sound fields above a locally reacting ground surface. However, the form of the WVDP formula is inadequate for predicting sound fields in the vicinity of non-locally reacting surfaces; a correction term is often required in the formula to provide accurate numerical solutions. Even with this correction, there is a singularity in the diffraction wave term when the source is located directly above or below the receiver. This paper explores a heuristic method to remove this singularity and suggests an analytical form comparable to the WVDP formula. This improved formula offers a physically interpretable solution and allows for accurate predictions of the total sound field above locally and non-locally reacting surfaces for all geometrical configurations.

  18. Using non-local databases for the environmental assessment of industrial activities: The case of Latin America

    SciTech Connect

    Osses de Eicker, Margarita; Hischier, Roland; Hurni, Hans; Zah, Rainer

    2010-04-15

    Nine non-local databases were evaluated with respect to their suitability for the environmental assessment of industrial activities in Latin America. Three assessment methods were considered, namely Life Cycle Assessment (LCA), Environmental Impact Assessment (EIA) and air emission inventories. The analysis focused on data availability in the databases and the applicability of their international data to Latin American industry. The study showed that the European EMEP/EEA Guidebook and the U.S. EPA AP-42 database are the most suitable ones for air emission inventories, whereas the LCI database Ecoinvent is the most suitable one for LCA and EIA. Due to the data coverage in the databases, air emission inventories are easier to develop than LCA or EIA, which require more comprehensive information. One strategy to overcome the limitations of non-local databases for Latin American industry is the combination of validated data from international databases with newly developed local datasets.

  19. Refined boundary conditions on the free surface of an elastic half-space taking into account non-local effects

    PubMed Central

    Chebakov, R.; Rogerson, G. A.

    2016-01-01

    The dynamic response of a homogeneous half-space, with a traction-free surface, is considered within the framework of non-local elasticity. The focus is on the dominant effect of the boundary layer on overall behaviour. A typical wavelength is assumed to considerably exceed the associated internal lengthscale. The leading-order long-wave approximation is shown to coincide formally with the ‘local’ problem for a half-space with a vertical inhomogeneity localized near the surface. Subsequent asymptotic analysis of the inhomogeneity results in an explicit correction to the classical boundary conditions on the surface. The order of the correction is greater than the order of the better-known correction to the governing differential equations. The refined boundary conditions enable us to evaluate the interior solution outside a narrow boundary layer localized near the surface. As an illustration, the effect of non-local elastic phenomena on the Rayleigh wave speed is investigated. PMID:27118902

  20. Generalized non-Local Resistance Expression and its Application in F/N/F Spintronic Structure with Graphene Channel

    NASA Astrophysics Data System (ADS)

    Wei, Huazhou; Fu, Shiwei

    We report our work on the spin transport properties in the F/N/F(ferromagnets/normal metal/ferromagnets) spintronic structure from a new theoretical perspective. A significant problem in the field is to explain the inferior measured order of magnitude for spin lifetime. Based on the known non-local resistance formula and the mechanism analysis of spin-flipping within the interfaces between F and N, we analytically derive a broadly applicable new non-local resistance expression and a generalized Hanle curve formula. After employing them in the F/N/F structure under different limits, especially in the case of graphene channel, we find that the fitting from experimental data would yield a longer spin lifetime, which approaches its theoretical predicted value in graphene. The authors acknowledge the financial support by China University of Petroleum-Beijing and the Key Laboratory of Optical Detection Technology for Oil and Gas in this institution.

  1. BOTDA measurements tolerant to non-local effects by using a phase-modulated probe wave and RF demodulation.

    PubMed

    Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2013-07-15

    We demonstrate a Brillouin optical time domain analysis sensor based on a phase-modulated probe wave and RF demodulation that provides measurements tolerant to frequency-dependent variations of the pump pulse power induced by non-local effects. The tolerance to non-local effects is based on the special characteristics of the detection process, which provides an RF phase-shift signal that is largely independent of the Brillouin gain magnitude. Proof-of-concept experiments performed over a 20-km-long fiber demonstrate that the measured RF phase-shift spectrum remains unaltered for large frequency-dependent deformations of the pump pulse power. Therefore, it allows the use of a higher optical power of the probe wave, which leads to an enhancement of the detected signal to noise ratio. This can be used to extend the sensing distance, to improve the accuracy of the Brillouin frequency shift measurements, and to reduce the measurement time.

  2. Quantum Computational Studies of Electron Transfer in Respiratory Complex III and its Application for Designing New Mitocan Drugs

    NASA Astrophysics Data System (ADS)

    Hagras, Muhammad Ahmed

    Electron transfer occurs in many biological systems which are imperative to sustain life; oxidative phosphorylation in prokaryotes and eukaryotes, and photophosphorylation in photosynthetic and plant cells are well-balanced and complementary processes. Investigating electron transfer in those natural systems provides detailed knowledge of the atomistic events that lead eventually to production of ATP, or harvesting light energy. Ubiquinol:cytochrome c oxidoreductase complex (also known as bc 1 complex, or respiratory complex III) is a middle player in the electron transport proton pumping orchestra, located in the inner-mitochondrial membrane in eukaryotes or plasma membrane in prokaryotes, which converts the free energy of redox reactions to electrochemical proton gradient across the membrane, following the fundamental chemiosmotic principle discovered by Peter Mitchell 1. In humans, the malfunctioned bc1 complex plays a major role in many neurodegenerative diseases, stress-induced aging, and cancer development, because it produces most of the reactive oxygen species, which are also involved in cellular signaling 2. The mitochondrial bc1 complex has an intertwined dimeric structure comprised of 11 subunits in each monomer, but only three of them have catalytic function, and those are the only domains found in bacterial bc1 complex. The core subunits include: Rieske domain, which incorporates iron-sulfur cluster [2Fe-2S]; trans-membrane cytochrome b domain, incorporating low-potential heme group (heme b L) and high-potential heme group (heme b H); and cytochrome c1 domain, containing heme c1 group and two separate binding sites, Qo (or QP) site where the hydrophobic electron carrier ubihydroquinol QH2 is oxidized, and Qi (or QN) site where ubiquinone molecule Q is reduced 3. Electrons and protons in the bc1 complex flow according to the proton-motive Q-cycle proposed by Mitchell, which includes a unique electron flow bifurcation at the Qo site. At this site, one

  3. An adaptive non-local means filter for denoising live-cell images and improving particle detection.

    PubMed

    Yang, Lei; Parton, Richard; Ball, Graeme; Qiu, Zhen; Greenaway, Alan H; Davis, Ilan; Lu, Weiping

    2010-12-01

    Fluorescence imaging of dynamical processes in live cells often results in a low signal-to-noise ratio. We present a novel feature-preserving non-local means approach to denoise such images to improve feature recovery and particle detection. The commonly used non-local means filter is not optimal for noisy biological images containing small features of interest because image noise prevents accurate determination of the correct coefficients for averaging, leading to over-smoothing and other artifacts. Our adaptive method addresses this problem by constructing a particle feature probability image, which is based on Haar-like feature extraction. The particle probability image is then used to improve the estimation of the correct coefficients for averaging. We show that this filter achieves higher peak signal-to-noise ratio in denoised images and has a greater capability in identifying weak particles when applied to synthetic data. We have applied this approach to live-cell images resulting in enhanced detection of end-binding-protein 1 foci on dynamically extending microtubules in photo-sensitive Drosophila tissues. We show that our feature-preserving non-local means filter can reduce the threshold of imaging conditions required to obtain meaningful data.

  4. Classical-Quantum Limits

    NASA Astrophysics Data System (ADS)

    Oliynyk, Todd A.

    2016-12-01

    We introduce a new approach to analyzing the interaction between classical and quantum systems that is based on a limiting procedure applied to multi-particle Schrödinger equations. The limit equations obtained by this procedure, which we refer to as the classical-quantum limit, govern the interaction between classical and quantum systems, and they possess many desirable properties that are inherited in the limit from the multi-particle quantum system. As an application, we use the classical-quantum limit equations to identify the source of the non-local signalling that is known to occur in the classical-quantum hybrid scheme of Hall and Reginatto. We also derive the first order correction to the classical-quantum limit equation to obtain a fully consistent first order approximation to the Schrödinger equation that should be accurate for modeling the interaction between particles of disparate mass in the regime where the particles with the larger masses are effectively classical.

  5. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  6. Deterministic quantum teleportation with feed-forward in a solid state system.

    PubMed

    Steffen, L; Salathe, Y; Oppliger, M; Kurpiers, P; Baur, M; Lang, C; Eichler, C; Puebla-Hellmann, G; Fedorov, A; Wallraff, A

    2013-08-15

    Engineered macroscopic quantum systems based on superconducting electronic circuits are attractive for experimentally exploring diverse questions in quantum information science. At the current state of the art, quantum bits (qubits) are fabricated, initialized, controlled, read out and coupled to each other in simple circuits. This enables the realization of basic logic gates, the creation of complex entangled states and the demonstration of algorithms or error correction. Using different variants of low-noise parametric amplifiers, dispersive quantum non-demolition single-shot readout of single-qubit states with high fidelity has enabled continuous and discrete feedback control of single qubits. Here we realize full deterministic quantum teleportation with feed-forward in a chip-based superconducting circuit architecture. We use a set of two parametric amplifiers for both joint two-qubit and individual qubit single-shot readout, combined with flexible real-time digital electronics. Our device uses a crossed quantum bus technology that allows us to create complex networks with arbitrary connecting topology in a planar architecture. The deterministic teleportation process succeeds with order unit probability for any input state, as we prepare maximally entangled two-qubit states as a resource and distinguish all Bell states in a single two-qubit measurement with high efficiency and high fidelity. We teleport quantum states between two macroscopic systems separated by 6 mm at a rate of 10(4) s(-1), exceeding other reported implementations. The low transmission loss of superconducting waveguides is likely to enable the range of this and other schemes to be extended to significantly larger distances, enabling tests of non-locality and the realization of elements for quantum communication at microwave frequencies. The demonstrated feed-forward may also find application in error correction schemes.

  7. Effects of the dielectric properties of the ceramic-solvent interface on the binding of proteins to oxide ceramics: a non-local electrostatic approach

    NASA Astrophysics Data System (ADS)

    Rubinstein, Alexander I.; Sabirianov, Renat F.; Namavar, Fereydoon

    2016-10-01

    The rapid development of nanoscience and nanotechnology has raised many fundamental questions that significantly impede progress in these fields. In particular, understanding the physicochemical processes at the interface in aqueous solvents requires the development and application of efficient and accurate methods. In the present work we evaluate the electrostatic contribution to the energy of model protein-ceramic complex formation in an aqueous solvent. We apply a non-local (NL) electrostatic approach that accounts for the effects of the short-range structure of the solvent on the electrostatic interactions of the interfacial systems. In this approach the aqueous solvent is considered as a non-ionic liquid, with the rigid and strongly correlated dipoles of the water molecules. We have found that an ordered interfacial aqueous solvent layer at the protein- and ceramic-solvent interfaces reduces the charging energy of both the ceramic and the protein in the solvent, and significantly increases the electrostatic contribution to their association into a complex. This contribution in the presented NL approach was found to be significantly shifted with respect to the classical model at any dielectric constant value of the ceramics. This implies a significant increase of the adsorption energy in the protein-ceramic complex formation for any ceramic material. We show that for several biocompatible ceramics (for example HfO2, ZrO2, and Ta2O5) the above effect predicts electrostatically induced protein-ceramic complex formation. However, in the framework of the classical continuum electrostatic model (the aqueous solvent as a uniform dielectric medium with a high dielectric constant ˜80) the above ceramics cannot be considered as suitable for electrostatically induced complex formation. Our results also show that the protein-ceramic electrostatic interactions can be strong enough to compensate for the unfavorable desolvation effect in the process of protein

  8. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    NASA Astrophysics Data System (ADS)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  9. Randomness: Quantum versus classical

    NASA Astrophysics Data System (ADS)

    Khrennikov, Andrei

    2016-05-01

    Recent tremendous development of quantum information theory has led to a number of quantum technological projects, e.g. quantum random generators. This development had stimulated a new wave of interest in quantum foundations. One of the most intriguing problems of quantum foundations is the elaboration of a consistent and commonly accepted interpretation of a quantum state. Closely related problem is the clarification of the notion of quantum randomness and its interrelation with classical randomness. In this short review, we shall discuss basics of classical theory of randomness (which by itself is very complex and characterized by diversity of approaches) and compare it with irreducible quantum randomness. We also discuss briefly “digital philosophy”, its role in physics (classical and quantum) and its coupling to the information interpretation of quantum mechanics (QM).

  10. Organic light-emitting diodes based on a series of new polythienothiophene complexes and highly luminescent quantum dots

    SciTech Connect

    Vashchenko, A. A.; Goriachiy, D. O.; Vitukhnovsky, A. G.; Tananaev, P. N.; Vasnev, V. A.; Rodlovskaya, E. N.

    2016-01-15

    Experimental samples of organic light-emitting diodes with transport layers based on polythienothiophenes and using CdSe/CdS/ZnS semiconductor quantum dots with an internal quantum efficiency up to 85% in the emitting layer are investigated. It is shown that solubility and film-forming properties are key for using polythienothiophenes in light-emitting diodes. The most promising polythienothiophenes are identified on the basis of the results obtained.

  11. Quantum and classical dynamics of H + CaCl(X (2)Σ(+)) → HCl + Ca((1)S) reaction and vibrational energy levels of the HCaCl complex.

    PubMed

    Tan, Rui Shan; Zhai, Huan Chen; Gao, Feng; Tong, Dianmin; Lin, Shi Ying

    2016-06-21

    We carried out accurate quantum wave packet as well as quasi-classical trajectory (QCT) calculations for H + CaCl (νi = 0, ji = 0) reaction occurring on an adiabatic ground state using the recent ab initio potential energy surface to obtain the quantum and QCT reaction probabilities for several partial waves (J = 0, 10, and 20) as well as state resolved QCT integral and differential cross sections. The complete list of vibrational energy levels supported by the intermediate HCaCl complex is also obtained using the Lanczos algorithm. The QCT reaction probabilities show excellent agreement with the quantum ones except for the failure in reproducing the highly oscillatory resonance structure. Despite the fact that the reaction is exothermic and the existence of a barrier that is energetically lower than the bottom of the reactant valley, the reaction probability for J = 0 shows threshold-like behavior and the reactivity all through the energies is very low (<0.1). The dynamical features at two different energy regions (<0.35 eV and >0.35 eV) are found to be different drastically from each other. The analyses of these results suggest that the reaction is governed by one of the two different types of reaction mechanism, one is the direct mechanism at the high energy region and the other is the indirect mechanism at the low energy region by which the reaction proceeds through the long-lived intermediate complex followed by a statistical dissociation into asymptotic channels.

  12. Luminescent pincer platinum(II) complexes with emission quantum yields up to almost unity: photophysics, photoreductive C-C bond formation, and materials applications.

    PubMed

    Chow, Pui-Keong; Cheng, Gang; Tong, Glenna So Ming; To, Wai-Pong; Kwong, Wai-Lun; Low, Kam-Hung; Kwok, Chi-Chung; Ma, Chensheng; Che, Chi-Ming

    2015-02-09

    Luminescent pincer-type Pt(II)  complexes supported by C-deprotonated π-extended tridentate RC^N^NR' ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time-resolved fluorescence measurements and time-dependent DFT calculations together reveal the dependence of excited-state structural distortions of [Pt(RC^N^NR')(CC-C6 F5 )] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R-C^N^NR')(CC-Ar)] are efficient photocatalysts for visible-light-induced reductive CC bond formation. The [Pt(R-C^N^NR')(CC-C6 F5 )] complexes perform strongly as phosphorescent dopants for green- and red-emitting organic light-emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two-photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs).

  13. Quantum teleportation without classical channel

    NASA Astrophysics Data System (ADS)

    Al Amri, M.; Li, Zheng-Hong; Zubairy, M. Suhail

    2016-11-01

    For the first time, we show how quantum teleportation can be achieved without the assistance of classical channels. Our protocol does not need any pre-established entangled photon pairs beforehand. Just by utilizing quantum Zeno effect and couterfactual communication idea, we can achieve two goals; entangling a photon and an atom and also disentangling them by non-local interaction. Information is completely transferred from atom to photon with controllable disentanglement processes. More importantly, there is no need to confirm teleportation results via classical channels.

  14. Quantum Entanglement in Open Systems

    SciTech Connect

    Isar, Aurelian

    2008-01-24

    In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, the master equation for two independent harmonic oscillators interacting with an environment is solved in the asymptotic long-time regime. Using the Peres-Simon necessary and sufficient condition for separability of two-mode Gaussian states, we show that the two non-interacting systems become asymptotically entangled for certain environments, so that in the long-time regime they manifest non-local quantum correlations. We calculate also the logarithmic negativity characterizing the degree of entanglement of the asymptotic state.

  15. Quantum Indeterminacy of Cosmic Systems

    SciTech Connect

    Hogan, Craig J.

    2013-12-30

    It is shown that quantum uncertainty of motion in systems controlled mainly by gravity generally grows with orbital timescale $H^{-1}$, and dominates classical motion for trajectories separated by distances less than $\\approx H^{-3/5}$ in Planck units. For example, the cosmological metric today becomes indeterminate at macroscopic separations, $H_0^{-3/5}\\approx 60$ meters. Estimates suggest that entangled non-localized quantum states of geometry and matter may significantly affect fluctuations during inflation, and connect the scale of dark energy to that of strong interactions.

  16. Deterministic quantum teleportation of atomic qubits.

    PubMed

    Barrett, M D; Chiaverini, J; Schaetz, T; Britton, J; Itano, W M; Jost, J D; Knill, E; Langer, C; Leibfried, D; Ozeri, R; Wineland, D J

    2004-06-17

    Quantum teleportation provides a means to transport quantum information efficiently from one location to another, without the physical transfer of the associated quantum-information carrier. This is achieved by using the non-local correlations of previously distributed, entangled quantum bits (qubits). Teleportation is expected to play an integral role in quantum communication and quantum computation. Previous experimental demonstrations have been implemented with optical systems that used both discrete and continuous variables, and with liquid-state nuclear magnetic resonance. Here we report unconditional teleportation of massive particle qubits using atomic (9Be+) ions confined in a segmented ion trap, which aids individual qubit addressing. We achieve an average fidelity of 78 per cent, which exceeds the fidelity of any protocol that does not use entanglement. This demonstration is also important because it incorporates most of the techniques necessary for scalable quantum information processing in an ion-trap system.

  17. Merging Structural Information from X-ray Crystallography, Quantum Chemistry, and EXAFS Spectra: The Oxygen-Evolving Complex in PSII.

    PubMed

    Chernev, Petko; Zaharieva, Ivelina; Rossini, Emanuele; Galstyan, Artur; Dau, Holger; Knapp, Ernst-Walter

    2016-10-12

    Structural data of the oxygen-evolving complex (OEC) in photosystem II (PSII) determined by X-ray crystallography, quantum chemistry (QC), and extended X-ray absorption fine structure (EXAFS) analyses are presently inconsistent. Therefore, a detailed study of what information can be gained about the OEC through a comparison of QC and crystallographic structure information combined with the information from range-extended EXAFS spectra was undertaken. An analysis for determining the precision of the atomic coordinates of the OEC by QC is carried out. OEC model structures based on crystallographic data that are obtained by QC from different research groups are compared with one another and with structures obtained by high-resolution crystallography. The theory of EXAFS spectra is summarized, and the application of EXAFS spectra to the experimental determination of the structure of the OEC is detailed. We discriminate three types of parameters entering the formula for the EXAFS spectrum: (1) model-independent, predefined, and fixed; (2) model-dependent that can be computed or adjusted; and (3) model-dependent that must be adjusted. The information content of EXAFS spectra is estimated and is related to the precision of atomic coordinates and resolution power to discriminate different atom-pair distances of the OEC. It is demonstrated how a precise adjustment of atomic coordinates can yield a nearly perfect representation of the experimental OEC EXAFS spectrum, but at the expense of overfitting and losing the knowledge of the initial OEC model structure. Introducing a novel type of penalty function, it is shown that moderate adjustment of atomic coordinates to the EXAFS spectrum limited by constraints avoids overfitting and can be used to validate different OEC model structures. This technique is used to identify the OEC model structures whose computed OEC EXAFS spectra agree best with the measured spectrum. In this way, the most likely S-state and protonation pattern

  18. Comparison of Fickian and Temporally Non-Local Transport Theories Over Many Scales in an Exhaustively Sampled Sandstone Slab

    NASA Astrophysics Data System (ADS)

    Benson, D. A.; Major, E.; Ibrahim, H.; Dean, A. M.; Maxwell, R. M.; Poeter, E. P.; Dogan, M.

    2011-12-01

    It is not a compelling argument, based solely on a better fit to solute breakthrough curve (BTC) data, that a temporally non-local model is necessary to simulate transport in an advection-dominated system. One may counter that the classical advection-dispersion equation (ADE) is a valid model at some small scale and that the detailed hydraulic conductivity (K) data must be well represented: Then the nonlocality is only a result of upscaling and loss of information. But is the non-local model demonstrably necessary at all scales? We examine the experiment conducted by Klise et al. [2008] in which a 30.5 ± 30.5 cm slab of relatively homogeneous, cross-bedded sandstone was exhaustively sampled for K. The slab was sealed, saturated with potassium iodide, and x-rayed ten times while being flushed with fresh water. The 8,649 air-permeameter measurements were down- and up-scaled to make finer and coarser grids on which the velocity field was solved and the ADE applied. The optimized parameters in the ADE were found to scale predictably---most notably the longitudinal dispersivity (α L), which grew linearly with up-scaling. But at all levels of up- and down-scaling, including the original K measurement scale of 0.33 cm, the ADE did not adequately represent the late-time tails. The temporally non-local, time-fractional, ADE (t-FADE) was applied and the optimized parameters (α L and the immobile capacity &beta) did not depend on scale. The better fit provided by the t-FADE in the late BTC tails did not bring about a sacrificed fit elsewhere in the BTC. Furthermore, the optimized ADE and t-FADE solutions do not converge at the smallest scale, directly implying that the temporal non-locality is a necessary model component. We conclude that the logical inference ``if the ADE is valid in heterogeneous material, then there is tailing in the BTC'' is not a proof that the reverse is true. We provide a clear counterexample. A corollary is that a mismatch between data and a

  19. Quantum Correlations Evolution Asymmetry in Quantum Channels

    NASA Astrophysics Data System (ADS)

    Li, Meng; Huang, Yun-Feng; Guo, Guang-Can

    2017-03-01

    It was demonstrated that the entanglement evolution of a specially designed quantum state in the bistochastic channel is asymmetric. In this work, we generalize the study of the quantum correlations, including entanglement and quantum discord, evolution asymmetry to various quantum channels. We found that the asymmetry of entanglement and quantum discord only occurs in some special quantum channels, and the behavior of the entanglement evolution may be quite different from the behavior of the quantum discord evolution. To quantum entanglement, in some channels it decreases monotonously with the increase of the quantum channel intensity. In some other channels, when we increase the intensity of the quantum channel, it decreases at first, then keeps zero for some time, and then rises up. To quantum discord, the evolution becomes more complex and you may find that it evolutes unsmoothly at some points. These results illustrate the strong dependence of the quantum correlations evolution on the property of the quantum channels. Supported by the National Natural Science Foundation of China under Grant Nos. 61327901, 61490711, 61225025, 11474268, and the Fundamental Research Funds for the Central Universities under Grant No. WK2470000018

  20. Laplacian based non-local means denoising of MR images with Rician noise.

    PubMed

    Bhujle, Hemalata V; Chaudhuri, Subhasis

    2013-11-01

    Magnetic Resonance (MR) image is often corrupted with a complex white Gaussian noise (Rician noise) which is signal dependent. Considering the special characteristics of Rician noise, we carry out nonlocal means denoising on squared magnitude images and compensate the introduced bias. In this paper, we propose an algorithm which not only preserves the edges and fine structures but also performs efficient denoising. For this purpose we have used a Laplacian of Gaussian (LoG) filter in conjunction with a nonlocal means filter (NLM). Further, to enhance the edges and to accelerate the filtering process, only a few similar patches have been preselected on the basis of closeness in edge and inverted mean values. Experiments have been conducted on both simulated and clinical data sets. The qualitative and quantitative measures demonstrate the efficacy of the proposed method.