One-dimensional Quantum Fluids
NASA Astrophysics Data System (ADS)
Gervais, Guillaume
2015-03-01
Fifty year ago, Joachim Mazdak Luttinger generalized the Tomonaga theory of interactions in a one-dimensional metal and show that the prior restrictions imposed by Tomonaga were not necessary. This model is now known as the Tomonaga- Luttinger liquid model (TLL) and most remarkably it does have mathematically exact solutions. In the case of electrons, it predicts that the spin and charge sector should separate, with each of them propagating with their own velocities. While there has been many attempts (some with great success) to observe TLL behaviour in clean quantum wires designed on an ultra-clean semiconductor platform, overall the Luttinger physics is experimentally still in its infancy. For instance, little is known regarding the 1D physics in a strongly-interacting neutral system, whether from the point-of-view of TLL theory or even localization physics. Helium-4, the paradigm superfluid, and Helium-3, the paradigm Fermi liquid, should in principleboth become Luttinger liquids if taken to the one-dimensional limit. In the bosonic case, this is supported by large-scale Quantum Monte Carlo simulations which found that a lengthscale of ~ 2 nm is sufficient for the system to crossover to the 1D regime and display universal Luttinger scaling. At McGill University, an experiment has been constructed to measure the liquid helium mass flow through a single nanopore. The technique consists of drilling a single nanopore in a SiN membrane using a TEM, and then applying a pressure gradient across the membrane. Previously published data in 45nm diameter hole determined the superfluid critical velocity to be close to the limit set by the Feynman vortex rings model. More recent work performed on nanopores with radii as small as 3 nm (and a length of 30nm) show the critical exponent for superfluid velocity to significantly deviate from its bulk value, 2/3. This is an important hint for the crossing over to the one-dimensional state in a strongly-correlated bosonic liquid.
Zakharov equations in quantum dusty plasmas
Sayed, F.; Vladimirov, S. V.; Ishihara, O.
2015-08-15
By generalizing the formalism of modulational interactions in quantum dusty plasmas, we derive the kinetic quantum Zakharov equations in dusty plasmas that describe nonlinear coupling of high frequency Langmuir waves to low frequency plasma density variations, for cases of non-degenerate and degenerate plasma electrons.
One dimensional representations in quantum optics
NASA Technical Reports Server (NTRS)
Janszky, J.; Adam, P.; Foldesi, I.; Vinogradov, An. V.
1993-01-01
The possibility of representing the quantum states of a harmonic oscillator not on the whole alpha-plane but on its one dimensional manifolds is considered. It is shown that a simple Gaussian distribution along a straight line describes a quadrature squeezed state while a similar Gaussian distribution along a circle leads to the amplitude squeezed state. The connection between the one dimensional representations and the usual Glauber representation is discussed.
Pattern dynamics and spatiotemporal chaos in the quantum Zakharov equations.
Misra, A P; Shukla, P K
2009-05-01
The dynamical behavior of the nonlinear interaction of quantum Langmuir waves (QLWs) and quantum ion-acoustic waves (QIAWs) is studied in the one-dimensional quantum Zakharov equations. Numerical simulations of coupled QLWs and QIAWs reveal that many coherent solitary patterns can be excited and saturated via the modulational instability of unstable harmonic modes excited by a modulation wave number of monoenergetic QLWs. The evolution of such solitary patterns may undergo the states of spatially partial coherence (SPC), coexistence of temporal chaos and spatiotemporal chaos (STC), as well as STC. The SPC state is essentially due to ion-acoustic wave emission and due to quantum diffraction, while the STC is caused by the combined effects of SPC and quantum diffraction, as well as by collisions and fusions among patterns in stochastic motion. The energy in the system is strongly redistributed, which may switch on the onset of weak turbulence in dense quantum plasmas. PMID:19518570
Pattern dynamics and spatiotemporal chaos in the quantum Zakharov equations
Misra, A. P.; Shukla, P. K.
2009-05-15
The dynamical behavior of the nonlinear interaction of quantum Langmuir waves (QLWs) and quantum ion-acoustic waves (QIAWs) is studied in the one-dimensional quantum Zakharov equations. Numerical simulations of coupled QLWs and QIAWs reveal that many coherent solitary patterns can be excited and saturated via the modulational instability of unstable harmonic modes excited by a modulation wave number of monoenergetic QLWs. The evolution of such solitary patterns may undergo the states of spatially partial coherence (SPC), coexistence of temporal chaos and spatiotemporal chaos (STC), as well as STC. The SPC state is essentially due to ion-acoustic wave emission and due to quantum diffraction, while the STC is caused by the combined effects of SPC and quantum diffraction, as well as by collisions and fusions among patterns in stochastic motion. The energy in the system is strongly redistributed, which may switch on the onset of weak turbulence in dense quantum plasmas.
Unitary equivalent classes of one-dimensional quantum walks
NASA Astrophysics Data System (ADS)
Ohno, Hiromichi
2016-06-01
This study investigates unitary equivalent classes of one-dimensional quantum walks. We prove that one-dimensional quantum walks are unitary equivalent to quantum walks of Ambainis type and that translation-invariant one-dimensional quantum walks are Szegedy walks. We also present a necessary and sufficient condition for a one-dimensional quantum walk to be a Szegedy walk.
Coherent and passive one dimensional quantum memory
NASA Astrophysics Data System (ADS)
Ping, Yuting; Jefferson, John H.; Lovett, Brendon W.
2014-10-01
We show that the state of a flying qubit may be transferred to a chain of identical, (near) ferromagnetically polarized, but non-interacting, static spin-\\frac{1}{2} particles in a passive way. During this process the flying qubit is coherently polarized, emerging in the direction of the majority static spins. We conjecture that this process is reversible for any number of flying qubits injected sequentially in an arbitrary superposition state, proving this explicitly for an arbitrary state of one and two flying qubits. We also find a special case in which we are able to prove the conjecture for an arbitrary number of qubits. Our architecture thus has the potential to be exploited as a passive quantum memory to encode the flying qubits without the necessity of resetting between successive encoding operations. We also illustrate that the quantum information may be spread over many static spins in the memory chain, making the mechanism resistant to spin decoherence and other imperfections. We discuss implementing the memory system with trapped bosonic atoms, controlled by a spatial light modulator.
Fate of classical solitons in one-dimensional quantum systems.
Pustilnik, M.; Matveev, K. A.
2015-11-23
We study one-dimensional quantum systems near the classical limit described by the Korteweg-de Vries (KdV) equation. The excitations near this limit are the well-known solitons and phonons. The classical description breaks down at long wavelengths, where quantum effects become dominant. Focusing on the spectra of the elementary excitations, we describe analytically the entire classical-to-quantum crossover. We show that the ultimate quantum fate of the classical KdV excitations is to become fermionic quasiparticles and quasiholes. We discuss in detail two exactly solvable models exhibiting such crossover, the Lieb-Liniger model of bosons with weak contact repulsion and the quantum Toda model, and argue that the results obtained for these models are universally applicable to all quantum one-dimensional systems with a well-defined classical limit described by the KdV equation.
Quantum rectifier in a one-dimensional photonic channel
NASA Astrophysics Data System (ADS)
Mascarenhas, E.; Santos, M. F.; Auffèves, A.; Gerace, D.
2016-04-01
By using a fully quantum approach based on an input-output formulation of the stochastic Schrödinger equation, we show rectification of radiation fields in a one-dimensional waveguide doped with a pair of ideal two-level systems for three topical cases: classical driving, under the action of noise, and single-photon pulsed excitation. We show that even under the constant action of unwanted noise the device still operates effectively as an optical isolator, which is of critical importance for noise resistance. Finally, harnessing stimulated emission allows for nonreciprocal behavior for single-photon inputs, thus showing purely quantum rectification at the single-photon level. The latter is a considerable step towards the ultimate goal of devising an unconditional quantum rectifier for arbitrary quantum states.
Casimir forces between defects in one-dimensional quantum liquids
Recati, A.; Fuchs, J.N.; Peca, C.S.; Zwerger, W.
2005-08-15
We discuss the effective interactions between two localized perturbations in one-dimensional quantum liquids. For noninteracting fermions, the interactions exhibit Friedel oscillations, giving rise to a Ruderman-Kittel-Kasuya-Yosida-type interaction familiar from impurity spins in metals. In the interacting case, at low energies, a Luttinger-liquid description applies. In the case of repulsive fermions, the Friedel oscillations of the interacting system are replaced, at long distances, by a universal Casimir-type interaction which depends only on the sound velocity and decays inversely with the separation. The Casimir-type interaction between localized perturbations embedded in a fermionic environment gives rise to a long-range coupling between quantum dots in ultracold Fermi gases, opening an alternative to couple qubits with neutral atoms. We also briefly discuss the case of bosonic quantum liquids in which the interaction between weak impurities turns out to be short ranged, decaying exponentially on the scale of the healing length.
Decay of fermionic quasiparticles in one-dimensional quantum liquids.
Matveev, K A; Furusaki, A
2013-12-20
The low-energy properties of one-dimensional quantum liquids are commonly described in terms of the Tomonaga-Luttinger liquid theory, in which the elementary excitations are free bosons. To this approximation, the theory can be alternatively recast in terms of free fermions. In both approaches, small perturbations give rise to finite lifetimes of excitations. We evaluate the decay rate of fermionic excitations and show that it scales as the eighth power of energy, in contrast to the much faster decay of bosonic excitations. Our results can be tested experimentally by measuring the broadening of power-law features in the density structure factor or spectral functions. PMID:24483750
One-dimensional quantum spin heterojunction as a thermal switch
NASA Astrophysics Data System (ADS)
Yang, Chuan-Jing; Jin, Li-Hui; Gong, Wei-Jiang
2016-03-01
We study the thermal transport through a quantum spin-1 2 heterojunction, which consists of a finite-size chain with two-site anisotropic XY interaction and three-site XZX+YZY interaction coupled at its ends to two semi-infinite isotropic XY chains. By performing the Jordan-Wigner transformation, the original spin Hamiltonian is mapped onto a fermionic Hamiltonian. Then, the fermionic structure is discussed, and the heat current as a function of structural parameters is evaluated. It is found that the magnetic fields applied at respective chains play different roles in adjusting the heat current in this heterojunction. Moreover, the interplay between the anisotropy of the XY interaction and the three-site spin interaction assists to further control the thermal transport. In view of the numerical results, we propose this heterojunction to be an alternate candidate for manipulating the heat current in one-dimensional (1D) systems.
Dynamics of Mobile Impurities in One-Dimensional Quantum Liquids
NASA Astrophysics Data System (ADS)
Schecter, Michael
2014-09-01
We study the dynamics of mobile impurities in a one-dimensional quantum liquid. Due to singular scattering with low-energy excitations of the host liquid, the impurity spectral properties become strongly renormalized even at weak coupling. This leads to universal phenomena with no higher-dimensional counterparts, such as lattice-free Bloch oscillations, power-law threshold behavior in the impurity spectral function and a quantum phase transition as the impurity mass exceeds a critical value. The additional possibility of integrability in one-dimension leads to the absence of thermal viscosity at special points in parameter space. The vanishing of the phonon-mediated Casimir interaction between separate impurities can be understood on the same footing. We explore these remarkable phenomena by developing an effective low-energy theory that identifies the proper collective coordinates of the dressed impurity, and their coupling to the low-energy excitations of the host liquid. The main appeal of our approach lies in its ability to describe a dynamic response using effective parameters which obey exact thermodynamic relations. The latter may be extracted using powerful numerical or analytical techniques available in one-dimension, yielding asymptotically exact results for the low-energy impurity dynamics.
Bulk-edge correspondence of one-dimensional quantum walks
NASA Astrophysics Data System (ADS)
Cedzich, C.; Grünbaum, F. A.; Stahl, C.; Velázquez, L.; Werner, A. H.; Werner, R. F.
2016-05-01
We outline a theory of symmetry protected topological phases of one-dimensional quantum walks. We assume spectral gaps around the symmetry-distinguished points +1 and ‑1, in which only discrete eigenvalues are allowed. The phase classification by integer or binary indices extends the classification known for translation invariant systems in terms of their band structure. However, our theory requires no translation invariance whatsoever, and the indices we define in this general setting are invariant under arbitrary symmetric local perturbations, even those that cannot be continuously contracted to the identity. More precisely we define two indices for every walk, characterizing the behavior far to the right and far to the left, respectively. Their sum is a lower bound on the number of eigenstates at +1 and ‑1. For a translation invariant system the indices add up to zero, so one of them already characterizes the phase. By joining two bulk phases with different indices we get a walk in which the right and left indices no longer cancel, so the theory predicts bound states at +1 or ‑1. This is a rigorous statement of bulk-edge correspondence. The results also apply to the Hamiltonian case with a single gap at zero.
Quantum walks with a one-dimensional coin
NASA Astrophysics Data System (ADS)
Bisio, Alessandro; D'Ariano, Giacomo Mauro; Erba, Marco; Perinotti, Paolo; Tosini, Alessandro
2016-06-01
Quantum walks (QWs) describe particles evolving coherently on a graph. The internal degree of freedom corresponds to a Hilbert space, called a coin system. We consider QWs on Cayley graphs of some group G . In the literature, investigations concerning infinite G have been focused on graphs corresponding to G =Zd with a coin system of dimension 2, whereas for a one-dimensional coin (so-called scalar QWs) only the case of finite G has been studied. Here we prove that the evolution of a scalar QW with G infinite Abelian is trivial, providing a thorough classification of this kind of walks. Then we consider the infinite dihedral group D∞, that is, the unique non-Abelian group G containing a subgroup H ≅Z with two cosets. We characterize the class of QWs on the Cayley graphs of D∞, and, via a coarse-graining technique, we show that it coincides with the class of spinorial walks on Z which satisfies parity symmetry. This class of QWs includes the Weyl and the Dirac QWs. Remarkably, there exist also spinorial walks that are not coarse graining of a scalar QW, such as the Hadamard walk.
Quench dynamics in one-dimensional quantum systems
NASA Astrophysics Data System (ADS)
Lancaster, Jarrett L.
The possibility of simulating non-equilibrium physics using cold atomic systems motivates many open questions regarding the dynamics of systems whose equilibrium properties are well understood. We first consider the non-equilibrium dynamics in a one-dimensional quantum spin chain by arranging the spins in an inhomogeneous initial state by application of a spatially varying magnetic field and rapidly switching off the field, also allowing for a sudden change in the interaction strength. The non-interacting case is treated exactly. To treat interactions, we employ a low-energy bosonization approach which correctly reproduces the long-time behavior in the non-interacting case. Depending on the strength of interactions, we find two different types of behavior. In the gapless region, expansion of the domain wall is ballistic. In the gapped phase, time evolution is substantially more complicated. To explore the time evolution within a gapped system, we turn our attention to a numerical investigation of a more general, low-energy theory: the quantum sine-Gordon model. Beginning with a domain wall density configuration, we study dynamics using the semi-classical truncated Wigner approximation. The numerical study is complemented by an analytical investigation of how an initial current-carrying state evolves when an energy gap is suddenly switched on. Both approaches reveal the persistence of some part of the initial current in the long-time limit. Finally, we apply the random phase approximation to treat weak interactions in a system of fermions after an interaction quench. We study how collective modes are modified by the quench. Compared to equilibrium, we find an enhanced particle-hole continuum which damps the collective mode for attractive interactions, while a single undamped mode survives for repulsive interactions. The situation is also investigated in the presence of a current.
Quantum solution for the one-dimensional Coulomb problem
Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A.
2011-06-15
The one-dimensional hydrogen atom has been a much studied system with a wide range of applications. Since the pioneering work of Loudon [R. Loudon, Am. J. Phys. 27, 649 (1959).], a number of different features related to the nature of the eigenfunctions have been found. However, many of the claims made throughout the years in this regard are not correct--such as the existence of only odd eigenstates or of an infinite binding-energy ground state. We explicitly show that the one-dimensional hydrogen atom does not admit a ground state of infinite binding energy and that the one-dimensional Coulomb potential is not its own supersymmetric partner. Furthermore, we argue that at the root of many such false claims lies the omission of a superselection rule that effectively separates the right side from the left side of the singularity of the Coulomb potential.
Quantum mechanics of graphene with a one-dimensional potential
Miserev, D. S.; Entin, M. V.
2012-10-15
Electron states in graphene with a one-dimensional potential have been studied. An approximate solution has been obtained for a small angle between vectors of the incident electron momentum and potential gradient. Exactly solvable problems with a potential of the smoothened step type U(x) Utanh(x/a) and a potential with a singularity U(x) = -U/(|x| + d) are considered. The transmission/reflection coefficients and phases for various potential barriers are determined. A quasi-classical solution is obtained.
Quantum diffusion on a cyclic one-dimensional lattice
NASA Astrophysics Data System (ADS)
de La Torre, A. C.; Mártin, H. O.; Goyeneche, D.
2003-09-01
The quantum diffusion of a particle in an initially localized state on a cyclic lattice with N sites is studied. Diffusion and reconstruction time are calculated. Strong differences are found for even or odd number of sites and the limit N→∞ is studied. The predictions of the model could be tested with microtechnology and nanotechnology devices.
Dubinov, Alexander E.; Kitayev, Ilya N.
2014-02-15
New multiplicative solutions of the Zakharov's quantum system of equations using the separation of variables method are found. The found solutions are interpreted as spatial-periodical lattices of non-linear plasma bursts. It is shown that the bursts could be both symmetrical and asymmetrical by an electric field.
Glimmers of a Quantum KAM Theorem: Insights from Quantum Quenches in One-Dimensional Bose Gases
NASA Astrophysics Data System (ADS)
Brandino, G. P.; Caux, J.-S.; Konik, R. M.
2015-10-01
Real-time dynamics in a quantum many-body system are inherently complicated and hence difficult to predict. There are, however, a special set of systems where these dynamics are theoretically tractable: integrable models. Such models possess nontrivial conserved quantities beyond energy and momentum. These quantities are believed to control dynamics and thermalization in low-dimensional atomic gases as well as in quantum spin chains. But what happens when the special symmetries leading to the existence of the extra conserved quantities are broken? Is there any memory of the quantities if the breaking is weak? Here, in the presence of weak integrability breaking, we show that it is possible to construct residual quasiconserved quantities, thus providing a quantum analog to the KAM theorem and its attendant Nekhoreshev estimates. We demonstrate this construction explicitly in the context of quantum quenches in one-dimensional Bose gases and argue that these quasiconserved quantities can be probed experimentally.
Quantum information entropy for one-dimensional system undergoing quantum phase transition
NASA Astrophysics Data System (ADS)
Xu-Dong, Song; Shi-Hai, Dong; Yu, Zhang
2016-05-01
Calculations of the quantum information entropy have been extended to a non-analytically solvable situation. Specifically, we have investigated the information entropy for a one-dimensional system with a schematic “Landau” potential in a numerical way. Particularly, it is found that the phase transitional behavior of the system can be well expressed by the evolution of quantum information entropy. The calculated results also indicate that the position entropy Sx and the momentum entropy Sp at the critical point of phase transition may vary with the mass parameter M but their sum remains as a constant independent of M for a given excited state. In addition, the entropy uncertainty relation is proven to be robust during the whole process of the phase transition. Project supported by the National Natural Science Foundation of China (Grant No. 11375005) and partially by 20150964-SIP-IPN, Mexico.
Fluctuations and Stochastic Processes in One-Dimensional Many-Body Quantum Systems
Stimming, H.-P.; Mauser, N. J.; Mazets, I. E.
2010-07-02
We study the fluctuation properties of a one-dimensional many-body quantum system composed of interacting bosons and investigate the regimes where quantum noise or, respectively, thermal excitations are dominant. For the latter, we develop a semiclassical description of the fluctuation properties based on the Ornstein-Uhlenbeck stochastic process. As an illustration, we analyze the phase correlation functions and the full statistical distributions of the interference between two one-dimensional systems, either independent or tunnel-coupled, and compare with the Luttinger-liquid theory.
Quantum trajectories in complex space: one-dimensional stationary scattering problems.
Chou, Chia-Chun; Wyatt, Robert E
2008-04-21
One-dimensional time-independent scattering problems are investigated in the framework of the quantum Hamilton-Jacobi formalism. The equation for the local approximate quantum trajectories near the stagnation point of the quantum momentum function is derived, and the first derivative of the quantum momentum function is related to the local structure of quantum trajectories. Exact complex quantum trajectories are determined for two examples by numerically integrating the equations of motion. For the soft potential step, some particles penetrate into the nonclassical region, and then turn back to the reflection region. For the barrier scattering problem, quantum trajectories may spiral into the attractors or from the repellers in the barrier region. Although the classical potentials extended to complex space show different pole structures for each problem, the quantum potentials present the same second-order pole structure in the reflection region. This paper not only analyzes complex quantum trajectories and the total potentials for these examples but also demonstrates general properties and similar structures of the complex quantum trajectories and the quantum potentials for one-dimensional time-independent scattering problems. PMID:18433189
Wurtzite GaAs Quantum Wires: One-Dimensional Subband Formation.
Vainorius, Neimantas; Lehmann, Sebastian; Gustafsson, Anders; Samuelson, Lars; Dick, Kimberly A; Pistol, Mats-Erik
2016-04-13
It is of contemporary interest to fabricate nanowires having quantum confinement and one-dimensional subband formation. This is due to a host of applications, for example, in optical devices, and in quantum optics. We have here fabricated and optically investigated narrow, down to 10 nm diameter, wurtzite GaAs nanowires which show strong quantum confinement and the formation of one-dimensional subbands. The fabrication was bottom up and in one step using the vapor-liquid-solid growth mechanism. Combining photoluminescence excitation spectroscopy with transmission electron microscopy on the same individual nanowires, we were able to extract the effective masses of the electrons in the two lowest conduction bands as well as the effective masses of the holes in the two highest valence bands. Our results, combined with earlier demonstrations of thin crystal phase nanodots in GaAs, set the stage for the fabrication of crystal phase quantum dots having full three-dimensional confinement. PMID:27004550
Simple One-Dimensional Quantum-Mechanical Model for a Particle Attached to a Surface
ERIC Educational Resources Information Center
Fernandez, Francisco M.
2010-01-01
We present a simple one-dimensional quantum-mechanical model for a particle attached to a surface. It leads to the Schrodinger equation for a harmonic oscillator bounded on one side that we solve in terms of Weber functions and discuss the behaviour of the eigenvalues and eigenfunctions. We derive the virial theorem and other exact relationships…
Quantum bright solitons in a quasi-one-dimensional optical lattice
NASA Astrophysics Data System (ADS)
Barbiero, Luca; Salasnich, Luca
2014-06-01
We study a quasi-one-dimensional attractive Bose gas confined in an optical lattice with a superimposed harmonic potential by analyzing the one-dimensional Bose-Hubbard Hamiltonian of the system. Starting from the three-dimensional many-body quantum Hamiltonian, we derive strong inequalities involving the transverse degrees of freedom under which the one-dimensional Bose-Hubbard Hamiltonian can be safely used. To have a reliable description of the one-dimensional ground state, which we call a quantum bright soliton, we use the density-matrix-renormalization-group (DMRG) technique. By comparing DMRG results with mean-field (MF) ones, we find that beyond-mean-field effects become relevant by increasing the attraction between bosons or by decreasing the frequency of the harmonic confinement. In particular, we find that, contrary to the MF predictions based on the discrete nonlinear Schrödinger equation, average density profiles of quantum bright solitons are not shape-invariant. We also use the time-evolving-block-decimation method to investigate the dynamical properties of bright solitons when the frequency of the harmonic potential is suddenly increased. This quantum quench induces a breathing mode whose period crucially depends on the final strength of the superimposed harmonic confinement.
Conditioned quantum motion of an atom in a continuously monitored one-dimensional lattice
NASA Astrophysics Data System (ADS)
Blattmann, Ralf; Mølmer, Klaus
2016-05-01
We consider a quantum particle on a one-dimensional lattice subject to weak local measurements and study its stochastic dynamics conditioned on the measurement outcomes. Depending on the measurement strength our analysis of the quantum trajectories reveals dynamical regimes ranging from quasicoherent wave-packet oscillations to a Zeno-type dynamics. We analyze how these dynamical regimes are directly reflected in the spectral properties of the noisy measurement records.
NASA Astrophysics Data System (ADS)
Buchholz, S. S.; Fischer, S. F.; Kunze, U.; Schuh, D.; Abstreiter, G.
2008-03-01
Vertically stacked quantum point contacts (QPCs) are prepared by atomic force microscope (AFM) lithography from an asymmetric GaAs/AlGaAs double quantum well (DQW) heterostructure. Top- and back-gate voltages are used to tune the tunnel-coupled QPCs, and back-gate bias cooling is employed to investigate coupled and decoupled one-dimensional (1D) modes. Parity dependent mode coupling is invoked by the particular asymmetry in the vertical DQW confinement.
Non-Luttinger quantum liquid of one-dimensional spin-orbit-coupled bosons
NASA Astrophysics Data System (ADS)
Po, Hoi Chun; Chen, Weiqiang; Zhou, Qi
2014-07-01
We show that the synthetic spin-orbit coupling created in current ultracold atom experiments provides physicists a unique tool to control the Luttinger liquid parameter K of weakly interacting bosons in one dimension. At a critical value of the Raman coupling strength Ωc, K is suppressed down to zero, and the characteristic quasi-long-range order for ordinary one-dimensional quantum systems disappears. Consequently, the single-particle correlation function decays exponentially at the ground state, signifying the rise of a one-dimensional quantum many-body state beyond the standard Luttinger liquid paradigm. Momentum distribution, as well as scaling relations for various quantities in the vicinity of the critical point, can be used as a direct diagnosis of this non-Luttinger quantum liquid.
Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well
Huang, H. J. E-mail: hhjhuangkimo@gmail.com; Liu, B. H.; Lin, C. T.; Su, W. S.
2015-11-15
The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC), or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt) thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles) is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.
Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well
NASA Astrophysics Data System (ADS)
Huang, H. J.; Liu, B.-H.; Lin, C.-T.; Su, W. S.
2015-11-01
The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC), or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt) thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles) is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.
A one-dimensional quantum walk with multiple-rotation on the coin
Xue, Peng; Zhang, Rong; Qin, Hao; Zhan, Xiang; Bian, Zhihao; Li, Jian
2016-01-01
We introduce and analyze a one-dimensional quantum walk with two time-independent rotations on the coin. We study the influence on the property of quantum walk due to the second rotation on the coin. Based on the asymptotic solution in the long time limit, a ballistic behaviour of this walk is observed. This quantum walk retains the quadratic growth of the variance if the combined operator of the coin rotations is unitary. That confirms no localization exhibits in this walk. This result can be extended to the walk with multiple time-independent rotations on the coin. PMID:26822563
Extended supersymmetry and hidden symmetries in one-dimensional matrix quantum mechanics
NASA Astrophysics Data System (ADS)
Andrianov, A. A.; Sokolov, A. V.
2016-01-01
We study properties of nonlinear supersymmetry algebras realized in the one-dimensional quantum mechanics of matrix systems. Supercharges of these algebras are differential operators of a finite order in derivatives. In special cases, there exist independent supercharges realizing an (extended) supersymmetry of the same super-Hamiltonian. The extended supersymmetry generates hidden symmetries of the super-Hamiltonian. Such symmetries have been found in models with (2×2)-matrix potentials.
Berry's phase in a one-dimensional quantum many-body system
Schuetz, G. )
1994-03-01
We study an interacting one-dimensional quantum lattice gas of massive fermions on a ring with [ital L] lattice sites. The ring is threaded by a magnetic flux corresponding to a twist in boundary conditions. We compute the periodicity of the ground state under an adiabatically increasing flux and the associated Berry's phase occurring in this process. The model has a second-order phase transition line which coincides with a line where the Berry phase changes nonanalytically.
Bose-Fermi solid and its quantum melting in a one-dimensional optical lattice
Wang Bin; Das Sarma, S.; Wang, Daw-Wei
2010-08-15
We investigate the quantum phase diagram of Bose-Fermi mixtures of ultracold dipolar particles trapped in one-dimensional optical lattices in the thermodynamic limit. With the presence of nearest-neighbor (NN) interactions, a long-ranged ordered crystalline phase (Bose-Fermi solid) is found stabilized in the limit of weak intersite tunneling (J). When J is increased, such a Bose-Fermi solid can be quantum melted into a Bose-Fermi liquid through different procedures, depending on whether the crystalline order is dominated by the NN interaction between fermions or bosons. These properties are qualitatively different from the classical picture of solid-liquid phase transition.
Numerical Analysis of Quantum Transport Equation for Bose Gas in One Dimensional Optical Lattice
NASA Astrophysics Data System (ADS)
Kuwahara, Yukiro; Nakamura, Yusuke; Yamanaka, Yoshiya
The quantum transport equation and the correction of the quasiparticle energy are derived by imposing the renormalization conditions on the improved time-dependent on-shell self-energy in nonequilibrium Thermo Field Dynamics. They are numerically analyzed for the one dimensional system of cold neutral atomic Bose gas confined by a combined harmonic and optical lattice potentials. The analysis indicates that the correction of the quaisparticle energy plays a crucial role in the thermal relaxation processes described by the quantum transport equation.
Dynamic behavior of the quantum Zakharov-Kuznetsov equations in dense quantum magnetoplasmas
Zhen, Hui-Ling; Tian, Bo Wang, Yu-Feng; Zhong, Hui; Sun, Wen-Rong
2014-01-15
Quantum Zakharov-Kuznetsov (qZK) equation is found in a dense quantum magnetoplasma. Via the spectral analysis, we investigate the Hamiltonian and periodicity of the qZK equation. Using the Hirota method, we obtain the bilinear forms and N-soliton solutions. Asymptotic analysis on the two-soliton solutions shows that the soliton interaction is elastic. Figures are plotted to reveal the propagation characteristics and interaction between the two solitons. We find that the one soliton has a single peak and its amplitude is positively related to H{sub e}, while the two solitons are parallel when H{sub e} < 2, otherwise, the one soliton has two peaks and the two solitons interact with each other. Hereby, H{sub e} is proportional to the ratio of the strength of magnetic field to the electronic Fermi temperature. External periodic force on the qZK equation yields the chaotic motions. Through some phase projections, the process from a sequence of the quasi-period doubling to chaos can be observed. The chaotic behavior is observed since the power spectra are calculated, and the quasi-period doubling states of perturbed qZK equation are given. The final chaotic state of the perturbed qZK is obtained.
Quantum effects on one-dimensional collision dynamics of fermion clusters
NASA Astrophysics Data System (ADS)
Ozaki, Jun'ichi; Tezuka, Masaki; Kawakami, Norio
2012-12-01
Recently, many experiments with cold atomic gases have been conducted from interest in the non-equilibrium dynamics of correlated quantum systems. Of these experiments, the mixing dynamics of fermion clusters motivates us to research cluster-cluster collision dynamics in one-dimensional Fermi systems. We adopt the one-dimensional Fermi-Hubbard model and apply the time-dependent density matrix renormalization group method. We simulate collisions between two fermion clusters of spin-up and spin-down and calculate reflectance of the clusters R changing the particle number in each cluster and the interaction strength between two fermions with up and down spins. We also evaluate the quasi-classical (independent collision) reflectance Rqc to compare it with R. The quasi-classical picture is quantitatively valid in the limit of weak interaction, but it is not valid when interaction is strong.
Magnetoresistance of One-Dimensional Subbands in Tunnel-Coupled Double Quantum Wires
Moon, J.S.; Blount, M.A.; Simmons, J.A.; Wendt, J.R.; Lyo, S.K.; Reno, J.L.
1999-08-04
The authors study the low-temperature in-plane magnetoresistance of tunnel-coupled quasi-one-dimensional quantum wires. The wires are defined by two pairs of mutually aligned split gates on opposite sides of a {le} 1 micron thick AlGaAs/GaAs double quantum well heterostructure, allowing independent control of the width of each quantum well. In the ballistic regime, when both wires are defined and the field is perpendicular to the current, a large resistance peak at {approximately}6 Tesla is observed with a strong gate voltage dependence. The data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.
Bosonization study of quantum phase transitions in the one-dimensional asymmetric Hubbard model
Wang, Z. G.; Chen, Y. G.; Gu, S. J.
2007-04-15
The quantum phase transitions in the one-dimensional asymmetric Hubbard model are investigated with the bosonization approach. The conditions for the phase transition from density wave to phase separation, the correlation functions, and their exponents are obtained analytically. Our results show that the difference between the hopping integrals for up- and down-spin electrons is crucial for the occurrence of the phase separation. When the difference is large enough, the phase separation will appear even if the on-site interaction is small.
One-Dimensional Quantum Liquids with Power-Law Interactions: The Luttinger Staircase
Dalmonte, M.; Pupillo, G.; Zoller, P.
2010-10-01
We study one-dimensional fermionic and bosonic gases with repulsive power-law interactions 1/|x|{sup {beta}}, with {beta}>1, in the framework of Tomonaga-Luttinger liquid (TLL) theory. We obtain an accurate analytical expression linking the TLL parameter to the microscopic Hamiltonian, for arbitrary {beta} and strength of the interactions. In the presence of a small periodic potential, power-law interactions make the TLL unstable towards the formation of a cascade of lattice solids with fractional filling, a 'Luttinger staircase'. Several of these quantum phases and phase transitions are realized with ground state polar molecules and weakly bound magnetic Feshbach molecules.
Quantum and Thermal Effects of Dark Solitons in a One-Dimensional Bose Gas
Martin, A. D.; Ruostekoski, J.
2010-05-14
We numerically study the imprinting and dynamics of dark solitons in a bosonic atomic gas in a tightly confined one-dimensional harmonic trap both with and without an optical lattice. Quantum and thermal fluctuations are synthesized within the truncated Wigner approximation in the quasicondensate description. We track the soliton coordinates and calculate position and velocity uncertainties. We find that the phase fluctuations lower the classically predicted soliton speed and seed instabilities. Individual runs show interactions of solitons with sound waves, splitting, and disappearing solitons.
Magnetoresistance of One-Dimensional Subbands in Tunnel-Coupled Double Quantum Wires
Blount, M.A.; Lyo, S.K.; Moon, J.S.; Reno, J.L.; Simmons, J.A.; Wendt, J.R.
1999-04-27
We study the low-temperature in-plane magnetoresistance of tunnel-coupled quasi-one-dimensional quantum wires. The wires are defined by two pairs of mutually aligned split gates on opposite sides of a < 1 micron thick AlGaAs/GaAs double quantum well heterostructure, allowing independent control of their widths. In the ballistic regime, when both wires are defined and the field is perpendicular to the current, a large resistance peak at ~6 Tesla is observed with a strong gate voltage dependence. The data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.
Quantum magnetism without lattices in strongly interacting one-dimensional spinor gases
NASA Astrophysics Data System (ADS)
Deuretzbacher, F.; Becker, D.; Bjerlin, J.; Reimann, S. M.; Santos, L.
2014-07-01
We show that strongly interacting multicomponent gases in one dimension realize an effective spin chain, offering an alternative simple scenario for the study of one-dimensional (1D) quantum magnetism in cold gases in the absence of an optical lattice. The spin-chain model allows for an intuitive understanding of recent experiments and for a simple calculation of relevant observables. We analyze the adiabatic preparation of antiferromagnetic and ferromagnetic ground states, and show that many-body spin states may be efficiently probed in tunneling experiments. The spin-chain model is valid for more than two components, opening the possibility of realizing SU(N) quantum magnetism in strongly interacting 1D alkaline-earth-metal or ytterbium Fermi gases.
Mechanism of spin and charge separation in one-dimensional quantum antiferromagnets
Mudry, C.; Fradkin, E. )
1994-10-15
We reconsider the problem of separation of spin and charge in one-dimensional quantum antiferromagnets. We show that spin and charge separation in one-dimensional strongly correlated systems cannot be described by the slave-boson or fermion representation within any perturbative treatment of the interactions between the slave holons and slave spinons. The constraint of single occupancy must be implemented exactly. As a result the slave fermions and bosons are not part of the physical spectrum. Instead, the excitations that carry the separate spin and charge quantum numbers are solitons. To prove this result, it is sufficient to study the pure spinon sector in the slave-boson representation. We start with a short-range resonating-valence-bond state spin liquid mean-field theory for the frustrated antiferromagnetic spin-1/2 chain. We derive an effective theory for the fluctuations of the Affleck-Marston and Anderson order parameters. We show how to recover the phase diagram as a function of the frustration by treating the fluctuations nonperturbatively.
Quantum magnetism in strongly interacting one-dimensional spinor Bose systems
Dehkharghani, Amin; Volosniev, Artem; Lindgren, Jonathan; Rotureau, Jimmy; Forssén, Christian; Fedorov, Dmitri; Jensen, Aksel; Zinner, Nikolaj
2015-01-01
Strongly interacting one-dimensional quantum systems often behave in a manner that is distinctly different from their higher-dimensional counterparts. When a particle attempts to move in a one-dimensional environment it will unavoidably have to interact and ‘push’ other particles in order to execute a pattern of motion, irrespective of whether the particles are fermions or bosons. A present frontier in both theory and experiment are mixed systems of different species and/or particles with multiple internal degrees of freedom. Here we consider trapped two-component bosons with short-range inter-species interactions much larger than their intra-species interactions and show that they have novel energetic and magnetic properties. In the strongly interacting regime, these systems have energies that are fractions of the basic harmonic oscillator trap quantum and have spatially separated ground states with manifestly ferromagnetic wave functions. Furthermore, we predict excited states that have perfect antiferromagnetic ordering. This holds for both balanced and imbalanced systems, and we show that it is a generic feature as one crosses from few- to many-body systems. PMID:26073680
NASA Astrophysics Data System (ADS)
Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo
2016-02-01
We propose a quantum processor for the scalable quantum computation on microwave photons in distant one-dimensional superconducting resonators. It is composed of a common resonator R acting as a quantum bus and some distant resonators rj coupled to the bus in different positions assisted by superconducting quantum interferometer devices (SQUID), different from previous processors. R is coupled to one transmon qutrit, and the coupling strengths between rj and R can be fully tuned by the external flux through the SQUID. To show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high-fidelity quantum state transfer between two distant microwave-photon resonators and another one for the high-fidelity controlled-phase gate on them. By using the technique for catching and releasing the microwave photons from resonators, our processor may play an important role in quantum communication as well.
Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo
2016-01-01
We propose a quantum processor for the scalable quantum computation on microwave photons in distant one-dimensional superconducting resonators. It is composed of a common resonator R acting as a quantum bus and some distant resonators rj coupled to the bus in different positions assisted by superconducting quantum interferometer devices (SQUID), different from previous processors. R is coupled to one transmon qutrit, and the coupling strengths between rj and R can be fully tuned by the external flux through the SQUID. To show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high-fidelity quantum state transfer between two distant microwave-photon resonators and another one for the high-fidelity controlled-phase gate on them. By using the technique for catching and releasing the microwave photons from resonators, our processor may play an important role in quantum communication as well. PMID:26907366
Hua, Ming; Tao, Ming-Jie; Deng, Fu-Guo
2016-01-01
We propose a quantum processor for the scalable quantum computation on microwave photons in distant one-dimensional superconducting resonators. It is composed of a common resonator R acting as a quantum bus and some distant resonators rj coupled to the bus in different positions assisted by superconducting quantum interferometer devices (SQUID), different from previous processors. R is coupled to one transmon qutrit, and the coupling strengths between rj and R can be fully tuned by the external flux through the SQUID. To show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high-fidelity quantum state transfer between two distant microwave-photon resonators and another one for the high-fidelity controlled-phase gate on them. By using the technique for catching and releasing the microwave photons from resonators, our processor may play an important role in quantum communication as well. PMID:26907366
NASA Astrophysics Data System (ADS)
Lei, Shuguo; Tong, Peiqing
2016-04-01
The quantum coherence based on Wigner-Yanase skew information and its relations with quantum phase transitions (QPTs) in one-dimensional quantum spin-1/2 chains are studied. Different from those at the critical point (CP) of the Ising transition in the transverse-field XY chain, the single-spin quantum coherence and the two-spin local σ ^z quantum coherence are extremal at the CP of the anisotropy transition, and the first-order derivatives of the two-spin local σ ^x and σ ^y quantum coherence have logarithmic divergence with the chain size. For the QPT between the gapped and gapless phases in the chain with three-spin interactions, however, no finite-size scaling behavior of the derivatives of quantum coherence is found.
Interplay of classical and quantum capacitance in a one-dimensional array of Josephson junctions
NASA Astrophysics Data System (ADS)
Ribeiro, Pedro; García-García, Antonio M.
2014-02-01
Even in the absence of Coulomb interactions, phase fluctuations induced by quantum size effects become increasingly important in superconducting nanostructures as the mean level spacing becomes comparable with the bulk superconducting gap. Here we study the role of these fluctuations, termed "quantum capacitance," in the phase diagram of a one-dimensional ring of ultrasmall Josephson junctions at zero temperature by using path-integral techniques. Our analysis also includes dissipation due to quasiparticle tunneling and Coulomb interactions through a finite mutual and self-capacitance. The resulting phase diagram has several interesting features: A finite quantum capacitance can stabilize superconductivity even in the limit of only a finite mutual-capacitance energy, which classically leads to breaking of phase coherence. In the case of vanishing charging effects, relevant in cold-atom settings where Coulomb interactions are absent, we show analytically that superfluidity is robust to small quantum finite-size fluctuations and identify the minimum grain size for phase coherence to exist in the array. We have also found that the renormalization group results are in some cases very sensitive to relatively small changes of the instanton fugacity. For instance, a certain combination of capacitances could lead to a nonmonotonic dependence of the superconductor-insulator transition on the Josephson coupling.
One-dimensional multicomponent Fermi gas in a trap: quantum Monte Carlo study
NASA Astrophysics Data System (ADS)
Matveeva, N.; Astrakharchik, G. E.
2016-06-01
A one-dimensional world is very unusual as there is an interplay between quantum statistics and geometry, and a strong short-range repulsion between atoms mimics Fermi exclusion principle, fermionizing the system. Instead, a system with a large number of components with a single atom in each, on the opposite acquires many bosonic properties. We study the ground-state properties of a multicomponent repulsive Fermi gas trapped in a harmonic trap by a fixed-node diffusion Monte Carlo method. The interaction between all components is considered to be the same. We investigate how the energetic properties (energy, contact) and correlation functions (density profile and momentum distribution) evolve as the number of components is changed. It is shown that the system fermionizes in the limit of strong interactions. Analytical expressions are derived in the limit of weak interactions within the local density approximation for an arbitrary number of components and for one plus one particle using an exact solution.
A new method to calculate Berry phase in one-dimensional quantum anomalous Hall insulator
NASA Astrophysics Data System (ADS)
Liao, Yi
2016-08-01
Based on the residue theorem and degenerate perturbation theory, we derive a new, simple and general formula for Berry phase calculation in a two-level system for which the Hamiltonian is a real symmetric matrix. The special torus topology possessed by the first Brillouin zone (1 BZ) of this kind of systems ensures the existence of a nonzero Berry phase. We verify the correctness of our formula on the Su-Schrieffer-Heeger (SSH) model. Then the Berry phase of one-dimensional quantum anomalous Hall insulator (1DQAHI) is calculated analytically by applying our method, the result being -π/2 -π/4 sgn (B) [ sgn (Δ - 4 B) + sgn (Δ) ]. Finally, illuminated by this idea, we investigate the Chern number in the two-dimensional case, and find a very simple way to determine the parameter range of the non-trivial Chern number in the phase diagram.
Quantum spin fluctuations in quasi-one-dimensional chlorine-bridged platinum complexes
NASA Astrophysics Data System (ADS)
Wei, Xing; Donohoe, Robert J.; Wang, Wen Z.; Bishop, Alan R.; Gammel, Jan T.
1997-12-01
We report experimental and theoretical studies of spin dynamic process in the quasi-one-dimensional chlorine- bridged platinum complex, [PtII(en)2][PtIV(en)2Cl2](ClO4)4, where en equals ethylenediamine, C2N2H8. The process manifests itself in collapsing of the hyperfine and superhyperfine structures in the electron spin resonance spectrum and non-statistical distribution of spectral weight of the Pt isotopes. More surprisingly, it is activated only at temperatures below 6 K. We interpret the phenomenon in terms of quantum tunneling of the electronic spin in a strong electron-electron and electron-phonon coupling regime. This is modeled using a non-adiabatic many-body approach, in which polarons and solitons represent local spin-Peierls regions in a strongly disproportional charge- density-wave background and display intriguing spin-charge separation in the form of pinned charge and tunneling spin fluctuations.
Quantum phase transition of light in a one-dimensional photon-hopping-controllable resonator array
Wu Chunwang; Gao Ming; Deng Zhijiao; Dai Hongyi; Chen Pingxing; Li Chengzu
2011-10-15
We give a concrete experimental scheme for engineering the insulator-superfluid transition of light in a one-dimensional (1D) array of coupled superconducting stripline resonators. In our proposed architecture, the on-site interaction and the photon-hopping rate can be tuned independently by adjusting the transition frequencies of the charge qubits inside the resonators and at the resonator junctions, respectively, which permits us to systematically study the quantum phase transition of light in a complete parameter space. By combining the techniques of photon-number-dependent qubit transition and fast readout of the qubit state using a separate low-Q resonator mode, the statistical property of the excitations in each resonator can be obtained with a high efficiency. An analysis of the various decoherence sources and disorders shows that our scheme can serve as a guide to upcoming experiments involving a small number of coupled resonators.
Effective interactions, large-scale diagonalization, and one-dimensional quantum dots
NASA Astrophysics Data System (ADS)
Kvaal, Simen; Hjorth-Jensen, Morten; Nilsen, Halvor Møll
2007-08-01
The widely used large-scale diagonalization method using harmonic oscillator basis functions (an instance of the Rayleigh-Ritz method [S. Gould, Variational Methods for Eigenvalue Problems: An Introduction to the Methods of Rayleigh, Ritz, Weinstein, and Aronszajn (Dover, New York, 1995)], also called a spectral method, configuration-interaction method, or “exact diagonalization” method) is systematically analyzed using results for the convergence of Hermite function series. We apply this theory to a Hamiltonian for a one-dimensional model of a quantum dot. The method is shown to converge slowly, and the nonsmooth character of the interaction potential is identified as the main problem with the chosen basis, while, on the other hand, its important advantages are pointed out. An effective interaction obtained by a similarity transformation is proposed for improving the convergence of the diagonalization scheme, and numerical experiments are performed to demonstrate the improvement. Generalizations to more particles and dimensions are discussed.
Continuous wavelet transform analysis of one-dimensional quantum bound states from first principles
Handy, C.R.; Murenzi, R.
1996-11-01
Over the last decade, Handy and Bessis have developed a moment-problem-based, multiscale quantization theory, the eigenvalue moment method (EMM), which has proven effective in solving singular, strongly coupled, multidimensional Schr{umlt o}dinger Hamiltonians. We extend the scope of EMM by demonstrating its essential role in the generation of wavelet transforms for one-dimensional quantum systems. Combining this with the function-wavelet reconstruction formulas currently available, we are able to recover the wave function systematically, from first principles, through a multiscale process proceeding from large spatial scales to smaller ones. This accomplishment also addresses another outstanding problem, that of reconstructing a function from its moments. For the class of problems considered, the combined EMM-wavelet analysis yields a definitive solution. {copyright} {ital 1996 The American Physical Society.}
Anomalous quantum heat transport in a one-dimensional harmonic chain with random couplings.
Yan, Yonghong; Zhao, Hui
2012-07-11
We investigate quantum heat transport in a one-dimensional harmonic system with random couplings. In the presence of randomness, phonon modes may normally be classified as ballistic, diffusive or localized. We show that these modes can roughly be characterized by the local nearest-neighbor level spacing distribution, similarly to their electronic counterparts. We also show that the thermal conductance G(th) through the system decays rapidly with the system size (G(th) ∼ L(-α)). The exponent α strongly depends on the system size and can change from α < 1 to α > 1 with increasing system size, indicating that the system undergoes a transition from a heat conductor to a heat insulator. This result could be useful in thermal control of low-dimensional systems. PMID:22713930
Engineering quantum magnetism in one-dimensional trapped Fermi gases with p -wave interactions
NASA Astrophysics Data System (ADS)
Yang, Lijun; Guan, Xiwen; Cui, Xiaoling
2016-05-01
The highly controllable ultracold atoms in a one-dimensional (1D) trap provide a new platform for the ultimate simulation of quantum magnetism. In this regard, the Néel antiferromagnetism and the itinerant ferromagnetism are of central importance and great interest. Here we show that these magnetic orders can be achieved in the strongly interacting spin-1/2 trapped Fermi gases with additional p -wave interactions. In this strong-coupling limit, the 1D trapped Fermi gas exhibits an effective Heisenberg spin X X Z chain in the anisotropic p -wave scattering channels. For a particular p -wave attraction or repulsion within the same species of fermionic atoms, the system displays ferromagnetic domains with full spin segregation or the antiferromagnetic spin configuration in the ground state. Such engineered magnetisms are likely to be probed in a quasi-1D trapped Fermi gas of 40K atoms with very close s -wave and p -wave Feshbach resonances.
Quantum walks accompanied by spin flipping in one-dimensional optical lattices
NASA Astrophysics Data System (ADS)
Wang, Li; Liu, Na; Chen, Shu; Zhang, Yunbo
2015-11-01
We investigate continuous-time quantum walks of two fermionic atoms loaded in one-dimensional optical lattices with on-site interaction and subjected to a Zeeman field. The quantum walks are accompanied by spin-flipping processes. We calculate the time-dependent density distributions of the two fermions with opposite spins which are initially positioned at the center site by means of an exact numerical method. Besides the usual fast linear expansion behavior, we find an interesting spin-flipping-induced localization in the time evolution of density distributions. We show that the fast linear expansion behavior can be restored by simply ramping up the Zeeman field or further increasing the spin-flipping strength. The intrinsic origin of this exotic phenomenon is attributed to the emergence of a flat band in the single-particle spectrum of the system. Furthermore, we investigate the effect of on-site interaction on the dynamics of the quantum walkers. The two-particle correlations are calculated and the signal of localization is also shown therein. A simple potential experimental application of this interesting phenomenon is proposed.
Unveiling -tangle and quantum phase transition in the one-dimensional anisotropic XY model
NASA Astrophysics Data System (ADS)
Liu, Cheng-Cheng; Xu, Shuai; He, Juan; Ye, Liu
2015-06-01
In this paper, the relationship between -tangle and quantum phase transition (QPT) is investigated by employing the quantum renormalization-group method in the one-dimensional anisotropic XY model. The results show that all the 1-tangles increase firstly and then decrease with the anisotropy parameter increasing, and the Coffman-Kundu-Wootters monogamy inequality is always tenable for this system. The entanglement's status of subsystems depends on its site position, and this proposition can be generalized to a multipartite system. Meanwhile, with the increasing of the size of the system, the -tangle decreases slowly and tends to a fixed value finally. Additionally, it exhibits a QPT and a maximum value for the next-nearest-neighbor entanglement at the critical point in our model, which is different from the case of two-body system. After several iterations of the renormalization, the quantum entanglement measure can develop two saturated values, which are associated with two different phases: spin-fluid phase and the Néel phase. To gain further insight, the nonanalytic and scaling behaviors of -tangle have also been analyzed in detail.
Quantum phase transitions in exactly solvable one-dimensional compass models
NASA Astrophysics Data System (ADS)
You, Wen-Long; Horsch, Peter; Oleś, Andrzej M.
2014-03-01
We present an exact solution for a class of one-dimensional compass models which stand for interacting orbital degrees of freedom in a Mott insulator. By employing the Jordan-Wigner transformation we map these models on noninteracting fermions and discuss how spin correlations, high degeneracy of the ground state, and Z2 symmetry in the quantum compass model are visible in the fermionic language. Considering a zigzag chain of ions with singly occupied eg orbitals (eg orbital model) we demonstrate that the orbital excitations change qualitatively with increasing transverse field, and that the excitation gap closes at the quantum phase transition to a polarized state. This phase transition disappears in the quantum compass model with maximally frustrated orbital interactions which resembles the Kitaev model. Here we find that the finite transverse field destabilizes the orbital-liquid ground state with macroscopic degeneracy, and leads to peculiar behavior of the specific heat and orbital susceptibility at finite temperature. We show that the entropy and the cooling rate at finite temperature exhibit quite different behavior near the critical point for these two models.
Quantum transport of strongly interacting photons in a one-dimensional nonlinear waveguide
NASA Astrophysics Data System (ADS)
Hafezi, Mohammad; Chang, Darrick E.; Gritsev, Vladimir; Demler, Eugene; Lukin, Mikhail D.
2012-01-01
We present a theoretical technique for solving the quantum transport problem of a few photons through a one-dimensional, strongly nonlinear waveguide. We specifically consider the situation where the evolution of the optical field is governed by the quantum nonlinear Schrödinger equation. Although this kind of nonlinearity is quite general, we focus on a realistic implementation involving cold atoms loaded in a hollow-core optical fiber, where the atomic system provides a tunable nonlinearity that can be large even at a single-photon level. In particular, we show that when the interaction between photons is effectively repulsive, the transmission of multiphoton components of the field is suppressed. This leads to antibunching of the transmitted light and indicates that the system acts as a single-photon switch. On the other hand, in the case of attractive interaction, the system can exhibit either antibunching or bunching, which is in stark contrast to semiclassical calculations. We show that the bunching behavior is related to the resonant excitation of bound states of photons inside the system.
Quantum phases of quadrupolar Fermi gases in coupled one-dimensional systems
NASA Astrophysics Data System (ADS)
Huang, Wen-Min; Lahrz, M.; Mathey, L.
2014-01-01
Following the recent proposal to create quadrupolar gases [Bhongale et al., Phys. Rev. Lett. 110, 155301 (2013), 10.1103/PhysRevLett.110.155301], we investigate what quantum phases can be created in these systems in one dimension. We consider a geometry of two coupled one-dimensional (1D) systems, and derive the quantum phase diagram of ultracold fermionic atoms interacting via quadrupole-quadrupole interactions within a Tomonaga-Luttinger-liquid framework. We map out the phase diagram as a function of the distance between the two tubes and the angle between the direction of the tubes and the quadrupolar moments. The latter can be controlled by an external field. We show that there are two magic angles θB,1c and θB,2c between 0 and π /2, where the intratube quadrupolar interactions vanish and change signs. Adopting a pseudospin language with regard to the two 1D systems, the system undergoes a spin-gap transition and displays a zigzag density pattern, above θB,2c and below θB,1c. Between the two magic angles, we show that polarized triplet superfluidity and a planar spin-density-wave order compete with each other. The latter corresponds to a bond-order solid in higher dimensions. We demonstrate that this order can be further stabilized by applying a commensurate periodic potential along the tubes.
Anomalous behavior of the energy gap in the one-dimensional quantum XY model.
Okuyama, Manaka; Yamanaka, Yuuki; Nishimori, Hidetoshi; Rams, Marek M
2015-11-01
We reexamine the well-studied one-dimensional spin-1/2 XY model to reveal its nontrivial energy spectrum, in particular the energy gap between the ground state and the first excited state. In the case of the isotropic XY model, the XX model, the gap behaves very irregularly as a function of the system size at a second order transition point. This is in stark contrast to the usual power-law decay of the gap and is reminiscent of the similar behavior at the first order phase transition in the infinite-range quantum XY model. The gap also shows nontrivial oscillatory behavior for the phase transitions in the anisotropic model in the incommensurate phase. We observe a close relation between this anomalous behavior of the gap and the correlation functions. These results, those for the isotropic case in particular, are important from the viewpoint of quantum annealing where the efficiency of computation is strongly affected by the size dependence of the energy gap. PMID:26651656
Quantum Spin Fluctuations in Quasi-One-Dimensional Chlorine-Bridged Platinum Complexes
Wei, X.; Donohoe, R. J.; Wang, W. Z.; Bishop, A. R.; Gammel, J. T.
1997-01-01
We report experimental and theoretical studies of spin dynamic process in the quasi-one-dimensional chlorine-bridged platinum complex, [Pt{sup II}(en){sub 2}][Pt{sup IV}(en){sub 2}Cl{sub 2}](ClO{sub 4}){sub 4}, where en = ethylenediamine, C{sub 2}N{sub 2}H{sub 8}. The process manifests itself in collapsing of the hyperfine and superhyperfine structures in the electron spin resonance (ESR) spectrum and non-statistical distribution of spectral weight of the Pt isotopes. More surprisingly, it is activated only at temperatures below 6 K. We interpret the phenomenon in terms of quantum tunneling of the electronic spin in a strong electron-electron and electron-phonon coupling regime. This is modeled using a non-adiabatic many-body approach, in which polarons and solitons represent local spin-Peierls regions in a strongly disproportional charge-density-wave background and display intriguing spin-charge separation in the form of pinned charge and tunneling spin fluctuations. 24 refs., 5 figs., 1 tab.
Dynamics and Bloch oscillations of mobile impurities in one-dimensional quantum liquids
NASA Astrophysics Data System (ADS)
Schecter, M.; Gangardt, D. M.; Kamenev, A.
2012-03-01
We study the dynamics of a mobile impurity moving in a one-dimensional quantum liquid. Such an impurity induces a strong, non-linear depletion of the liquid around it. The dispersion relation of the combined object, called depleton, is a periodic function of its momentum with the period 2πn, where n is the mean density of the liquid. In the adiabatic approximation, a constant external force acting on the impurity leads to the Bloch oscillations of the impurity around a fixed position. Dynamically, such oscillations are accompanied by the radiation of energy in the form of phonons. The ensuing energy loss results in the uniform drift of the oscillation center. We derive exact results for the radiation-induced mobility as well as the thermal friction force in terms of the equilibrium dispersion relation of the dressed impurity (depleton). These results show that there is a wide range of external forces where the (drifted) Bloch oscillations exist and may be observed experimentally.
A New One-dimensional Quantum Material - Ta2Pd3Se8 Atomic Chain
NASA Astrophysics Data System (ADS)
Liu, Xue; Liu, Jinyu; Hu, Jin; Yue, Chunlei; Mao, Zhiqiang; Wei, Jiang; Antipina, Liubov; Sorokin, Pavel; Sanchez, Ana
Since the discovery of carbon nanotube, there has been a persistent effort to search for other one dimensional (1D) quantum systems. However, only a few examples have been found. We report a new 1D example - semiconducting Ta2Pd3Se8. We demonstrate that the Ta2Pd3Se8 nanowire as thin as 1.3nm can be easily obtained by applying simple mechanical exfoliation from its bulk counterpart. High resolution TEM shows an intrinsic 1D chain-like crystalline morphology on these nano wires, indicating weak bonding between these atomic chains. Theoretical calculation shows a direct bandgap structure, which evolves from 0.53eV in the bulk to 1.04eV in single atomic chain. The field effect transistor based on Ta2Pd3Se8 nanowire achieved a promising performance with 104On/Off ratio and 80 cm2V-1s-1 mobility. Low temperature transport study reflects two different mechanisms, variable range hopping and thermal activation, which dominate the transport properties at different temperature regimes. Ta2Pd3Se8 nanowire provides an intrinsic 1D material system for the study low dimensional condensed matter physics.
NASA Astrophysics Data System (ADS)
Eliëns, I. S.; Ramos, F. B.; Xavier, J. C.; Pereira, R. G.
2016-05-01
We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-S chains with S =1 /2 , 1, and 3 /2 .
Quantum recurrences in a one-dimensional gas of impenetrable bosons.
Solano-Carrillo, E
2015-10-01
It is well-known that a dilute one-dimensional (1D) gas of bosons with infinitely strong repulsive interactions behaves like a gas of free fermions. Just as with conduction electrons in metals, we consider a single-particle picture of the resulting dynamics, when the gas is isolated by enclosing it into a box with hard walls and preparing it in a special initial state. We show, by solving the nonstationary problem of a free particle in a 1D hard-wall box, that the single-particle state recurs in time, signaling the intuitively expected back-and-forth motion of a free particle moving in a confined space. Under suitable conditions, the state of the whole gas can then be made to recur if all the particles are put in the same initial momentum superposition. We introduce this problem here as a modern instance of the discussions giving rise to the famous recurrence paradox in statistical mechanics: on one hand, our results may be used to develop a poor man's interpretation of the recurrence of the initial state observed [T. Kinoshita et al., Nature 440, 900 (2006)] in trapped 1D Bose gases of cold atoms, for which our estimated recurrence time is in fair agreement with the period of the oscillations observed; but this experiment, on the other hand, has been substantially influential on the belief that an isolated quantum many-body system can equilibrate as a consequence of its own unitary nonequilibrium dynamics. Some ideas regarding the latter are discussed. PMID:26565225
Quantum entanglement in the one-dimensional spin-orbital SU (2 )⊗XXZ model
NASA Astrophysics Data System (ADS)
You, Wen-Long; Horsch, Peter; Oleś, Andrzej M.
2015-08-01
We investigate the phase diagram and the spin-orbital entanglement of a one-dimensional SU (2 )⊗XXZ model with SU(2) spin exchange and anisotropic XXZ orbital exchange interactions and negative exchange coupling constant. As a unique feature, the spin-orbital entanglement entropy in the entangled ground states increases here linearly with system size. In the case of Ising orbital interactions, we identify an emergent phase with long-range spin-singlet dimer correlations triggered by a quadrupling of correlations in the orbital sector. The peculiar translational-invariant spin-singlet dimer phase has finite von Neumann entanglement entropy and survives when orbital quantum fluctuations are included. It even persists in the isotropic SU (2 )⊗SU (2) limit. Surprisingly, for finite transverse orbital coupling, the long-range spin-singlet correlations also coexist in the antiferromagnetic spin and alternating orbital phase making this phase also unconventional. Moreover, we also find a complementary orbital singlet phase that exists in the isotropic case but does not extend to the Ising limit. The nature of entanglement appears essentially different from that found in the frequently discussed model with positive coupling. Furthermore, we investigate the collective spin and orbital wave excitations of the disentangled ferromagnetic-spin/ferro-orbital ground state and explore the continuum of spin-orbital excitations. Interestingly, one finds among the latter excitations two modes of exciton bound states. Their spin-orbital correlations differ from the remaining continuum states and exhibit logarithmic scaling of the von Neumann entropy with increasing system size. We demonstrate that spin-orbital excitons can be experimentally explored using resonant inelastic x-ray scattering, where the strongly entangled exciton states can be easily distinguished from the spin-orbital continuum.
Quantum recurrences in a one-dimensional gas of impenetrable bosons
NASA Astrophysics Data System (ADS)
Solano-Carrillo, E.
2015-10-01
It is well-known that a dilute one-dimensional (1D) gas of bosons with infinitely strong repulsive interactions behaves like a gas of free fermions. Just as with conduction electrons in metals, we consider a single-particle picture of the resulting dynamics, when the gas is isolated by enclosing it into a box with hard walls and preparing it in a special initial state. We show, by solving the nonstationary problem of a free particle in a 1D hard-wall box, that the single-particle state recurs in time, signaling the intuitively expected back-and-forth motion of a free particle moving in a confined space. Under suitable conditions, the state of the whole gas can then be made to recur if all the particles are put in the same initial momentum superposition. We introduce this problem here as a modern instance of the discussions giving rise to the famous recurrence paradox in statistical mechanics: on one hand, our results may be used to develop a poor man's interpretation of the recurrence of the initial state observed [T. Kinoshita et al., Nature 440, 900 (2006), 10.1038/nature04693] in trapped 1D Bose gases of cold atoms, for which our estimated recurrence time is in fair agreement with the period of the oscillations observed; but this experiment, on the other hand, has been substantially influential on the belief that an isolated quantum many-body system can equilibrate as a consequence of its own unitary nonequilibrium dynamics. Some ideas regarding the latter are discussed.
NASA Astrophysics Data System (ADS)
Pokrovskii, Vadim Ya; Zybtsev, Sergey G.; Nikitin, Maksim V.; Gorlova, Irina G.; Nasretdinova, Venera F.; Zaitsev-Zotov, Sergei V.
2013-01-01
Recent results (some previously unpublished) on the physics of charge density waves (CDWs) are reviewed. The synthesis conditions and unique properties of the quasi-one-dimensional compound {NbS_3}, with highly coherent room temperature CDWs, are described. A peculiar type of 'quantization' is discussed, which is observed in micro- and nanosamples of {K_{0.3}MoO_3} and {NbSe_3} due to the discrete nature of CDW wave vector values. The electric-field-induced torsional strain (TS) in quasi-one-dimensional conductors is considered. Research results on the TS of a noise character induced by sliding CDWs are presented, along with those on the inverse effect, the modulation of the voltage induced by externally driven TS. Results on the nonlinear conduction of {TiS_3}, a quasi-one-dimensional compound not belonging to the family of classical Peierls conductors, are also described.
NASA Astrophysics Data System (ADS)
Wang, Hai Tao; Cho, Sam Young
2015-01-01
In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies.
Wang, Hai Tao; Cho, Sam Young
2015-01-14
In order to investigate the quantum phase transition in the one-dimensional quantum compass model, we numerically calculate non-local string correlations, entanglement entropy and fidelity per lattice site by using the infinite matrix product state representation with the infinite time evolving block decimation method. In the whole range of the interaction parameters, we find that four distinct string orders characterize the four different Haldane phases and the topological quantum phase transition occurs between the Haldane phases. The critical exponents of the string order parameters β = 1/8 and the cental charges c = 1/2 at the critical points show that the topological phase transitions between the phases belong to an Ising type of universality classes. In addition to the string order parameters, the singularities of the second derivative of the ground state energies per site, the continuous and singular behaviors of the Von Neumann entropy and the pinch points of the fidelity per lattice site manifest that the phase transitions between the phases are of the second-order, in contrast to the first-order transition suggested in previous studies. PMID:25478955
Spatial mapping and statistical reproducibility of an array of 256 one-dimensional quantum wires
Al-Taie, H. Kelly, M. J.; Smith, L. W.; Lesage, A. A. J.; Griffiths, J. P.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Smith, C. G.; See, P.
2015-08-21
We utilize a multiplexing architecture to measure the conductance properties of an array of 256 split gates. We investigate the reproducibility of the pinch off and one-dimensional definition voltage as a function of spatial location on two different cooldowns, and after illuminating the device. The reproducibility of both these properties on the two cooldowns is high, the result of the density of the two-dimensional electron gas returning to a similar state after thermal cycling. The spatial variation of the pinch-off voltage reduces after illumination; however, the variation of the one-dimensional definition voltage increases due to an anomalous feature in the center of the array. A technique which quantifies the homogeneity of split-gate properties across the array is developed which captures the experimentally observed trends. In addition, the one-dimensional definition voltage is used to probe the density of the wafer at each split gate in the array on a micron scale using a capacitive model.
Quantum phase transitions in composite matrix product states of one-dimensional spin-1/2 chains
NASA Astrophysics Data System (ADS)
Zhu, Jing-Min
2015-02-01
For matrix product states of one-dimensional spin-1/2 chains, we investigate the properties of quantum phase transition of the proposed composite system. We find that the system has three different ferromagnetic phases, one line of the two ferromagnetic phases coexisting equally describes the paramagnetic state, and the other two lines of two ferromagnetic phases coexisting equally describe the ferrimagnetic states, while the three phases coexisting equally point describes the ferromagnetic state. Whether on phase transition lines or at the phase transition point, the system is always in an isolated mediate-coupling state, the physical quantities are discontinuous and the system has long-range correlation and has long-range classical correlation and long-range quantum correlation. We believe that our work is helpful for comprehensively and profoundly understanding the quantum phase transitions, and of some certain guidance and enlightening on the classification and measure of quantum correlation of quantum many-body systems.
Monogamy of quantum correlations in the one-dimensional anisotropic XY model
NASA Astrophysics Data System (ADS)
Xu, Shuai; Song, Xue-Ke; Ye, Liu
2014-01-01
In this paper, the monogamy properties of some quantum correlations, including the geometric quantum discord, concurrence, entanglement of formation and entropy quantum discord, in the anisotropic spin-1/2 XY model with staggered Dzyaloshinskii—Moriya (DM) interaction have been investigated using the quantum renormalization group (QRG) method. We summarize the monogamy relation for different quantum correlation measures and make an explicit comparison. Through mathematical calculations and analysis, we obtain that no matter whether the QRG steps are carried out, the monogamy of the given states are always unaltered. Moreover, we conclude that the geometric quantum discord and concurrence obey the monogamy property while other quantum correlation measures, such as entanglement of formation and quantum discord, violate it for this given model.
NASA Astrophysics Data System (ADS)
Park, Sung-Been; Cha, Min-Chul
2015-11-01
We investigate the finite-size scaling properties of the quantum phase transition in the one-dimensional quantum Ising model with periodic boundary conditions by representing the ground state in matrix product state forms. The infinite time-evolving block decimation technique is used to optimize the states. A trace over a product of the matrices multiplied as many times as the number of sites yields the finite-size effects. For sufficiently large Schmidt ranks, the finite-size scaling behavior determines the critical point and the critical exponents whose values are consistent with the analytical results.
Generalized Airy functions for use in one-dimensional quantum mechanical problems
NASA Technical Reports Server (NTRS)
Eaves, J. O.
1972-01-01
The solution of the one dimensional, time independent, Schroedinger equation in which the energy minus the potential varies as the nth power of the distance is obtained from proper linear combinations of Bessel functions. The linear combinations called generalized Airy functions, reduce to the usual Airy functions Ai(x) and Bi(x) when n equals 1 and have the same type of simple asymptotic behavior. Expressions for the generalized Airy functions which can be evaluated by the method of generalized Gaussian quadrature are obtained.
Quantum-mechanical Brayton engine working with a particle in a one-dimensional harmonic trap
NASA Astrophysics Data System (ADS)
Wang, H.
2013-05-01
Based on the quantum version of thermodynamic processes, a quantum-mechanical Brayton engine model has been established. Expressions for the power output and efficiency of the engine are derived. Some fundamental optimal relations and general performance characteristic curves of the cycle are obtained. Furthermore, we note that it is possible to resist the reduction in efficiency, caused by compression of the adiabatic process, by decreasing the amount of energy levels of the quantum system. The results obtained here will provide theoretical guidance for the design of some new quantum-mechanical engines.
Liu Benqiong; Shao Bin; Li Jungang; Zou Jian; Wu Lianao
2011-05-15
We study the effect of Dzyaloshinskii-Moriya (DM) interaction on pairwise quantum discord, entanglement, and classical correlation in the anisotropic XY spin-half chain. Analytical expressions for both quantum and classical correlations are obtained from the spin-spin correlation functions. These pairwise quantities exhibit interesting behaviors in relation to the relative strengths of the physical parameters. For the infinite chain, we show that the quantum discord can be useful to highlight the quantum phase transition, especially for the long-distance spins, where entanglement decays rapidly. We observe nonanalyticities of the derivatives of both quantum and classical correlations with respect to the magnetic intensity at the critical point; interestingly, the DM interaction weakens the critical behavior in the derivatives of these correlations. While the DM interaction suppresses the standard behaviors of the XY model, it enhances surprisingly the pairwise entanglement for the third nearest neighbor spins.
The monogamy relation and quantum phase transition in one-dimensional anisotropic XXZ model
NASA Astrophysics Data System (ADS)
Song, Xue-ke; Wu, Tao; Ye, Liu
2013-10-01
In the paper, we have researched the monogamy relation and the quantum phase transition (QPT) in the anisotropic spin XXZ model by exploiting the quantum renormalization group method. The results show that there exits QPT after several iterations of renormalization in the present system. And we can find out that the monogamy inequality of entanglement of formation (EOF) and entropy quantum discord develop two saturated values which associate with spin-liquid and Néel phases after several iterations of the renormalization. Furthermore, we can also find out that the renormalization of EOF and entropy quantum discord violate the monogamy property while the renormalized geometric quantum discord obeys it no matter whether the QPT iterations are carried out. As a byproduct, the nonanalytic phenomenon and scaling behavior of the spin system are analyzed in detail.
One-dimensional quantum magnetism in the anhydrous alum KTi(SO4)2
NASA Astrophysics Data System (ADS)
Nilsen, GJ; Raja, A.; Tsirlin, AA; Mutka, H.; Kasinathan, D.; Ritter, C.; Rønnow, HM
2015-11-01
The anhydrous alum KTi(SO4)2, where the Ti3+ (d1, S = 1/2) ions form an anisotropic triangular lattice, has been prepared by a new hydrothermal route and characterized by magnetic susceptibility and neutron scattering measurements. Contrary to expectations, fits to the magnetic susceptibility indicate that the spins are isotropic (i.e. Heisenberg) and that the frustrating couplings are weak; indeed, the system is well modelled by nearly isolated chains. The inelastic neutron scattering data furthermore shows excellent agreement with an exact theoretical calculation for the one-dimensional spinon continuum. The unexpected magnetic properties of KTi(SO4)2 are explained in the light of density functional calculations, which reveal an unusual orbital ground state for the Ti3 + ion.
NASA Astrophysics Data System (ADS)
Jones, Marvin Quenten, Jr.
The motion and behavior of quantum processes can be described by the Schrodinger equation using the wave function, Psi(x,t). The use of the Schrodinger equation to study quantum phenomena is known as Quantum Mechanics, akin to classical mechanics being the tool to study classical physics. This research focuses on the emphasis of numerical techniques: Finite-Difference, Fast Fourier Transform (spectral method), finite difference schemes such as the Leapfrog method and the Crank-Nicolson scheme and second quantization to solve and analyze the Schrodinger equation for the infinite square well problem, the free particle with periodic boundary conditions, the barrier problem, tight-binding hamiltonians and a potential wall problem. We discuss these techniques and the problems created to test how these different techniques draw both physical and numerical conclusions in a tabular summary. We observed both numerical stability and quantum stability (conservation of energy, probability, momentum, etc.). We found in our results that the Crank-Nicolson scheme is an unconditionally stable scheme and conserves probability (unitary), and momentum, though dissipative with energy. The time-independent problems conserved energy, momentum and were unitary, which is of interest, but we found when time-dependence was introduced, quantum stability (i.e. conservation of mass, momentum, etc.) was not implied by numerical stability. Hence, we observed schemes that were numerically stable, but not quantum stable as well as schemes that were quantum stable, but not numerically stable for all of time, t. We also observed that second quantization removed the issues with stability as the problem was transformed into a discrete problem. Moreover, all quantum information is conserved in second quantization. This method, however, does not work universally for all problems.
Quantum Correlation in Matrix Product States of One-Dimensional Spin Chains
NASA Astrophysics Data System (ADS)
Zhu, Jing-Min
2015-09-01
For our proposed composite parity-conserved matrix product state (MPS), if only a spin block length is larger than 1, any two such spin blocks have correlation including classical correlation and quantum correlation. Both the total correlation and the classical correlation become larger than that in any subcomponent; while the quantum correlations of the two nearest-neighbor spin blocks and the two next-nearest-neighbor spin blocks become smaller and for other conditions the quantum correlation becomes larger, i.e., the increase or the production of the long-range quantum correlation is at the cost of reducing the short-range quantum correlation, which deserves to be investigated in the future; and the ration of the quantum correlation to the total correlation monotonically decreases to a steady value as the spacing spin length increasing. Supported by the National Natural Science Foundation of China under Grant No. 10974137 and the Major Natural Science Foundation of the Educational Department of Sichuan Province under Grant No. 14ZA0167
One-dimensional chain of quantum molecule motors as a mathematical physics model for muscle fibers
NASA Astrophysics Data System (ADS)
Si, Tie-Yan
2015-12-01
A quantum chain model of multiple molecule motors is proposed as a mathematical physics theory for the microscopic modeling of classical force-velocity relation and tension transients in muscle fibers. The proposed model was a quantum many-particle Hamiltonian to predict the force-velocity relation for the slow release of muscle fibers, which has not yet been empirically defined and was much more complicated than the hyperbolic relationships. Using the same Hamiltonian model, a mathematical force-velocity relationship was proposed to explain the tension observed when the muscle was stimulated with an alternative electric current. The discrepancy between input electric frequency and the muscle oscillation frequency could be explained physically by the Doppler effect in this quantum chain model. Further more, quantum physics phenomena were applied to explore the tension time course of cardiac muscle and insect flight muscle. Most of the experimental tension transient curves were found to correspond to the theoretical output of quantum two- and three-level models. Mathematical modeling electric stimulus as photons exciting a quantum three-level particle reproduced most of the tension transient curves of water bug Lethocerus maximus. Project supported by the Fundamental Research Foundation for the Central Universities of China.
NASA Astrophysics Data System (ADS)
Omidi, Mahboubeh; Faizabadi, Edris
2015-09-01
We use a simple model to study the electron-phonon interaction influences on persistent current in a one-dimensional quantum ring enclosed by a magnetic flux. With increasing the temperature, persistent current amplitude is reduced, especially in a quantum ring with two ions per primitive cell (diatomic ring) because of the participation of optical phonons. Furthermore, the periodicity of the Aharonov-Bohm oscillations changes to Φ0 / 2 (Φ0 is magnetic flux quantum). In a diatomic ring, by increasing the difference between left and right nearest-neighbor hopping integrals at zero temperature, persistent current variations show a transition from metallic to insulator against distinctive behavior at nonzero temperature.
NASA Astrophysics Data System (ADS)
Ghosh, Joydip
2014-12-01
Spin-1 systems, in comparison to spin-1/2 systems, offer a better security for encoding and transferring quantum information, primarily due to their larger Hilbert spaces. Superconducting artificial atoms possess multiple energy levels, thereby being capable of emulating higher-spin systems. Here I consider a one-dimensional lattice of nearest-neighbor-coupled superconducting transmon systems, and devise a scheme to transfer an arbitrary qutrit state (a state encoded in a three-level quantum system) across the chain. I assume adjustable couplings between adjacent transmons, derive an analytic constraint for the control pulse, and show how to satisfy the constraint to achieve a high-fidelity state transfer under current experimental conditions. My protocol thus enables enhanced quantum communication and information processing with promising superconducting qutrits.
Quantum Monte Carlo study of quasi-one-dimensional Bose gases
NASA Astrophysics Data System (ADS)
Astrakharchik, G. E.; Blume, D.; Giorgini, S.; Granger, B. E.
2004-04-01
We study the behaviour of quasi-one-dimensional (quasi-1D) Bose gases by Monte Carlo techniques, i.e. by the variational Monte Carlo, the diffusion Monte Carlo and the fixed-node diffusion Monte Carlo techniques. Our calculations confirm and extend our results of an earlier study (Astrakharchik et al 2003 Preprint cond-mat/0308585). We find that a quasi-1D Bose gas (i) is well described by a 1D model Hamiltonian with contact interactions and renormalized coupling constant; (ii) reaches the Tonks-Girardeau regime for a critical value of the 3D scattering length a3D; (iii) enters a unitary regime for |a3D| rarr infin, where the properties of the gas are independent of a3D and are similar to those of a 1D gas of hard-rods and (iv) becomes unstable against cluster formation for a critical value of the 1D gas parameter. The accuracy and implications of our results are discussed in detail.
Quantum Monte Carlo study of a one-dimensional phase-fluctuating condensate in a harmonic trap
Gils, C.; Pollet, L.; Troyer, M.; Vernier, A.; Hebert, F.; Batrouni, G. G.
2007-06-15
We study numerically the low-temperature behavior of a one-dimensional Bose gas trapped in an optical lattice. For a sufficient number of particles and weak repulsive interactions, we find a clear regime of temperatures where density fluctuations are negligible but phase fluctuations are considerable, i.e., a quasicondensate. In the weakly interacting limit, our results are in very good agreement with those obtained using a mean-field approximation. In coupling regimes beyond the validity of mean-field approaches, a phase-fluctuating condensate also appears, but the phase-correlation properties are qualitatively different. It is shown that quantum depletion plays an important role.
One-Dimensional Three-State Quantum Walk with Single-Point Phase Defects
NASA Astrophysics Data System (ADS)
Xu, Yong-Zhen; Guo, Gong-De; Lin, Song
2016-09-01
In this paper, we study a three-state quantum walk with a phase defect at a designated position. The coin operator is a parametrization of the eigenvectors of the Grover matrix. We numerically investigate the properties of the proposed model via the position probability distribution, the position standard deviation, and the time-averaged probability at the designated position. It is shown that the localization effect can be governed by the phase defect's position and strength, coin parameter and initial state.
A one-dimensional lattice model for a quantum mechanical free particle
NASA Astrophysics Data System (ADS)
de La Torre, A. C.; Daleo, A.
2000-01-01
Two types of particles, A and B with their corresponding antiparticles, are defined in a onedimensional cyclic lattice with an odd number of sites. In each step of time evolution, each particle acts as a source for the polarization field of the other type of particle with nonlocal action but with an effect decreasing with the distance: A to \\cdots bar BBbar BBbar B \\cdots ;B to \\cdots Abar AAbar AA \\cdots . It is shown that the combined distribution of these particles obeys the time evolution of a free particle as given by quantum mechanics.
NASA Astrophysics Data System (ADS)
Kaibiao, Zhang; Hong, Zhang; Xinlu, Cheng
2016-03-01
The graphene/hexagonal boron-nitride (h-BN) hybrid structure has emerged to extend the performance of graphene-based devices. Here, we investigate the tunable plasmon in one-dimensional h-BN/graphene/h-BN quantum-well structures. The analysis of optical response and field enhancement demonstrates that these systems exhibit a distinct quantum confinement effect for the collective oscillations. The intensity and frequency of the plasmon can be controlled by the barrier width and electrical doping. Moreover, the electron doping and the hole doping lead to very different results due to the asymmetric energy band. This graphene/h-BN hybrid structure may pave the way for future optoelectronic devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474207 and 11374217) and the Scientific Research Fund of Sichuan University of Science and Engineering, China (Grant No. 2014PY07).
Sacha, Krzysztof; Timmermans, Eddy
2006-06-15
We consider the self-localization of neutral impurity atoms in a Bose-Einstein condensate in a one-dimensional model. Within the strong coupling approach, we show that the self-localized state exhibits parametric soliton behavior. The corresponding stationary states are analogous to the solitons of nonlinear optics and to the solitonic solutions of the Schroedinger-Newton equation (which appears in models that consider the connection between quantum mechanics and gravitation). In addition, we present a Bogoliubov-de Gennes formalism to describe the quantum fluctuations around the product state of the strong coupling description. Our fluctuation calculations yield the excitation spectrum and reveal considerable corrections to the strong coupling description. The knowledge of the spectrum allows a spectroscopic detection of the impurity self-localization phenomenon.
Comment on ``Adiabatic quantum computation with a one-dimensional projector Hamiltonian''
NASA Astrophysics Data System (ADS)
Kay, Alastair
2013-10-01
The partial adiabatic search algorithm was introduced in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] as a modification of the usual adiabatic algorithm for a quantum search with the idea that most of the interesting computation only happens over a very short range of the adiabatic path. By focusing on that restricted range, one can potentially gain an advantage by reducing the control requirements on the system, enabling a uniform rate of evolution. In this Comment, we point out an oversight in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] that invalidates its proof. However, the argument can be corrected, and the calculations in Tulsi's paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.052328 80, 052328 (2009)] are then sufficient to show that the scheme still works. Nevertheless, subsequent works [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.034304 82, 034304 (2010), Chin. Phys. BCPBHAJ1674-105610.1088/1674-1056/20/4/040309 20, 040309 (2011), Chin. Phys. BCPBHAJ1674-105610.1088/1674-1056/21/1/010306 21, 010306 (2012), AASRI Procedia 1, 5862 (2012), and Quantum Inf. Process.10.1007/s11128-013-0557-1 12, 2689 (2013)] cannot all be recovered in the same way.
NASA Astrophysics Data System (ADS)
Liu, Cheng-cheng; Shi, Jia-dong; Ding, Zhi-yong; Ye, Liu
2016-08-01
In this paper, the effect of external magnet field g on the relationship among the quantum discord, Bell non-locality and quantum phase transition by employing quantum renormalization-group (QRG) method in the one-dimensional transverse Ising model is investigated. In our model, external magnet field g can influence the phase diagrams. The results have shown that both the two quantum correlation measures can develop two saturated values, which are associated with two distinct phases: long-ranged ordered Ising phase and the paramagnetic phase with the number of QRG iterations increasing. Additionally, quantum non-locality always existent in the long-ranged ordered Ising phase no matter whatever the value of g is and what times QRG steps are carried out and we conclude that the quantum non-locality always exists not only suitable for the two sites of block, but for nearest-neighbor blocks in the long-ranged ordered Ising phase. However, the block-block correlation in the paramagnetic phase is not strong enough to violate the Bell-CHSH inequality as the size of system becomes large. Furthermore, when the system violates the CHSH inequality, i.e., satisfies quantum non-locality, it needs to be entangled. On the other way, if the system obeys the CHSH inequality, it may be entangled or not. To gain further insight, the non-analytic and scaling behavior of QD and Bell non-locality have also been analyzed in detail and this phenomenon indicates that the behavior of the correlation can perfectly help one to observe the quantum critical properties of the model.
Casimir interaction between mobile impurities in one-dimensional quantum liquids
NASA Astrophysics Data System (ADS)
Schecter, Michael; Kamenev, Alex
2014-03-01
At zero temperature virtual phonons of a quantum liquid scatter off impurities and mediate a long-range interaction, analogous to the Casimir effect. At finite temperature, moving impurities also experience a correlated friction due to coherent exchange of real phonons. In one dimension the effect is universal and the induced interaction decays as 1 /r3 , much slower than the van der Waals interaction ~ 1 /r6 where r is the impurity separation. The magnitude of the effect is characterized by the product of impurity-phonon scattering amplitudes, which are seen to vanish for the class of integrable impurity models. By tuning the parameters near integrability one can thus observe an attractive interaction turned into a repulsive one.
Phonon-Mediated Casimir Interaction between Mobile Impurities in One-Dimensional Quantum Liquids
NASA Astrophysics Data System (ADS)
Schecter, Michael; Kamenev, Alex
2014-04-01
Virtual phonons of a quantum liquid scatter off impurities and mediate a long-range interaction, analogous to the Casimir effect. In one dimension the effect is universal and the induced interaction decays as 1/r3, much slower than the van der Waals interaction ˜1/r6, where r is the impurity separation. The sign of the effect is characterized by the product of impurity-phonon scattering amplitudes, which take a universal form and have been seen to vanish for several integrable impurity models. Thus, if the impurity parameters can be independently tuned to lie on opposite sides of such integrable points, one can observe an attractive interaction turned into a repulsive one.
Quantum Tunneling of Charge-Density Waves in Quasi One-Dimensional Conductors
NASA Astrophysics Data System (ADS)
Miller, John Harris, Jr.
The charge-density wave (CDW) dynamics of the linear chain compound orthorhombic TaS(,3) is characterized by extensive measurements of dc conductivity, ac admittance, direct mixing, harmonic mixing, second harmonic generation, and third harmonic generation as functions of dc bias voltage, applied frequencies, and, in some cases, the amplitude of an additional ac signal. Measurements of the direct and harmonic mixing responses of NbSe(,3) are also reported. The results are analyzed in terms of an extension of the tunneling theory of CDW depinning, proposed by John Bardeen, coupled to the theory of photon-assisted tunneling (PAT). Where possible, the results are also compared with predictions of the classical overdamped oscillator model of CDW transport. The tunneling model is shown to provide a complete and semiquantitative interpretation of the entire small -signal ac dynamics at megahertz frequencies, using only the measured dc I-V curve and an experimentally inferred frequency-voltage scaling parameter, and also accounts for much of the large-signal behavior studied thus far. The observation of both an induced ac harmonic mixing current and a third harmonic generation current whose amplitudes peak at output frequencies far below the measured "cross -over frequency" for ac conductivity agrees with the phenomenological tunneling model, but is in serious disagreement with the classical overdamped oscillator model of CDW motion. Furthermore, the absence of any observed quadrature component in the harmonic mixing response, even though the measured linear response at the applied frequencies has substantial frequency -dependent in-phase and quadrature components, is probably impossible to reconcile with any classical theory. The results reported here thus provide compelling evidence in favor of collective, coherent quantum tunneling as the mechanism of charge-density wave depinning, and indicate that macroscopic quantum effects are observed in the megahertz frequency
Quantum radiation reaction force on a one-dimensional cavity with two relativistic moving mirrors
NASA Astrophysics Data System (ADS)
Alves, Danilo T.; Granhen, Edney R.; Pires, Wagner P.
2010-08-01
We consider a real massless scalar field inside a cavity with two moving mirrors in a two-dimensional spacetime, satisfying the Dirichlet boundary condition at the instantaneous position of the boundaries, for arbitrary and relativistic laws of motion. Considering vacuum as the initial field state, we obtain formulas for the exact value of the energy density of the field and the quantum force acting on the boundaries, which extend results found in previous papers [D. T. Alves, E. R. Granhen, H. O. Silva, and M. G. Lima, Phys. Rev. DPRVDAQ1550-7998 81, 025016 (2010); 10.1103/PhysRevD.81.025016L. Li and B.-Z. Li, Phys. Lett. APYLAAG0375-9601 300, 27 (2002); 10.1016/S0375-9601(02)00674-6L. Li and B.-Z. Li, Chin. Phys. Lett.CPLEEU0256-307X 19, 1061 (2002); 10.1088/0256-307X/19/8/310L. Li and B.-Z. Li, Acta Phys. Sin.WLHPAR1000-3290 52, 2762 (2003); C. K. Cole and W. C. Schieve, Phys. Rev. A 64, 023813 (2001)PLRAAN1050-294710.1103/PhysRevA.64.023813]. For the particular cases of a cavity with just one moving boundary, nonrelativistic velocities, or in the limit of infinity length of the cavity (a single mirror), our results coincide with those found in the literature.
Quantum radiation reaction force on a one-dimensional cavity with two relativistic moving mirrors
Alves, Danilo T.; Granhen, Edney R.; Pires, Wagner P.
2010-08-15
We consider a real massless scalar field inside a cavity with two moving mirrors in a two-dimensional spacetime, satisfying the Dirichlet boundary condition at the instantaneous position of the boundaries, for arbitrary and relativistic laws of motion. Considering vacuum as the initial field state, we obtain formulas for the exact value of the energy density of the field and the quantum force acting on the boundaries, which extend results found in previous papers [D. T. Alves, E. R. Granhen, H. O. Silva, and M. G. Lima, Phys. Rev. D 81, 025016 (2010); L. Li and B.-Z. Li, Phys. Lett. A 300, 27 (2002); L. Li and B.-Z. Li, Chin. Phys. Lett. 19, 1061 (2002); L. Li and B.-Z. Li, Acta Phys. Sin. 52, 2762 (2003); C. K. Cole and W. C. Schieve, Phys. Rev. A 64, 023813 (2001)]. For the particular cases of a cavity with just one moving boundary, nonrelativistic velocities, or in the limit of infinity length of the cavity (a single mirror), our results coincide with those found in the literature.
Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels
Huang, Danhong; Gumbs, Godfrey; Abranyos, Yonatan; Pepper, Michael; Kumar, Sanjeev
2015-11-15
For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.
NASA Astrophysics Data System (ADS)
Romanovsky, Igor; Yannouleas, Constantine; Landman, Uzi
2012-10-01
Systematic tight-binding investigations of the electronic spectra (as a function of the magnetic field) are presented for trigonal graphene nanoflakes with reconstructed zigzag edges, where a succession of pentagons and heptagons, that is 5-7 defects, replaces the hexagons at the zigzag edge. For nanoflakes with such reczag defective edges, emphasis is placed on topological aspects and connections underlying the patterns dominating the spectra of these systems. The electronic spectra of trigonal graphene nanoflakes with reczag edge terminations exhibit certain unique features, in addition to those that are well known to appear for graphene dots with zigzag edge termination. These unique features include breaking of the particle-hole symmetry, and they are associated with nonlinear dispersion of the energy as a function of momentum, which may be interpreted as nonrelativistic behavior. The general topological features shared with the zigzag flakes include the appearance of energy gaps at zero and low magnetic fields due to finite size, the formation of relativistic Landau levels at high magnetic fields, and the presence between the Landau levels of edge states (the so-called Halperin states) associated with the integer quantum Hall effect. Topological regimes, unique to the reczag nanoflakes, appear within a stripe of negative energies ɛb<ɛ<0, and along a separate feature forming a constant-energy line outside this stripe. The ɛb lower bound specifying the energy stripe is independent of size. Prominent among the patterns within the ɛb<ɛ<0 energy stripe is the formation of three-member braid bands, similar to those present in the spectra of narrow graphene nanorings; they are associated with Aharonov-Bohm-type oscillations, i.e., the reczag edges along the three sides of the triangle behave like a nanoring (with the corners acting as scatterers) enclosing the magnetic flux through the entire area of the graphene flake. Another prominent feature within the
Ayvaz, Muzaffer; Demiralp, Metin
2012-12-10
This study focuses on the construction of the optimal control equations for one dimensional quantum harmonic oscillator under the influence of external dipol effects and the solution of these equations by using Fluctuationlessness Theorem and a recently developed scheme called Characteristic Evolutions Method. The dipole function of the system has been taken as odd cubic spatial polynomial. Optimal control equations of the system under consideration are constructed by using expectation values of the position and the momentum operators instead of the wave and costate evolutions. It is shown that, the resulting equations are systems of ordinary differential equations and there are infinitely many ODEs. The solution strategy is based on the approximation of the expectation values for the operator products in the sense of Fluctuationlessness Theorem.
Zou, Fengming; Zhou, Hongjian; Tan, Tran Van; Kim, Jeonghyo; Koh, Kwangnak; Lee, Jaebeom
2015-06-10
A novel dual-mode immunoassay based on surface-enhanced Raman scattering (SERS) and fluorescence was designed using graphene quantum dot (GQD) labels to detect a tuberculosis (TB) antigen, CFP-10, via a newly developed sensing platform of linearly aligned magnetoplasmonic (MagPlas) nanoparticles (NPs). The GQDs were excellent bilabeling materials for simultaneous Raman scattering and photoluminescence (PL). The one-dimensional (1D) alignment of MagPlas NPs simplified the immunoassay process and enabled fast, enhanced signal transduction. With a sandwich-type immunoassay using dual-mode nanoprobes, both SERS signals and fluorescence images were recognized in a highly sensitive and selective manner with a detection limit of 0.0511 pg mL(-1). PMID:26006156
Campostrini, Massimo; Vicari, Ettore
2010-06-15
We study the quantum (zero-temperature) critical behaviors of confined particle systems described by the one-dimensional (1D) Bose-Hubbard model in the presence of a confining potential, at the Mott insulator to superfluid transitions, and within the gapless superfluid phase. Specifically, we consider the hard-core limit of the model, which allows us to study the effects of the confining potential by exact and very accurate numerical results. We analyze the quantum critical behaviors in the large trap-size limit within the framework of the trap-size scaling (TSS) theory, which introduces a new trap exponent {theta} to describe the dependence on the trap size. This study is relevant for experiments of confined quasi-1D cold atom systems in optical lattices. At the low-density Mott transition, TSS can be shown analytically within the spinless fermion representation of the hard-core limit. The trap-size dependence turns out to be more subtle in the other critical regions, when the corresponding homogeneous system has a nonzero filling f, showing an infinite number of level crossings of the lowest states when increasing the trap size. At the n=1 Mott transition, this gives rise to a modulated TSS: The TSS is still controlled by the trap-size exponent {theta}, but it gets modulated by periodic functions of the trap size. Modulations of the asymptotic power-law behavior is also found in the gapless superfluid region, with additional multiscaling behaviors.
Kotani, Teruhisa; Birner, Stefan; Lugli, Paolo; Hamaguchi, Chihiro
2014-04-14
We present theoretical investigations of miniband structures and optical properties of InAs/GaAs one-dimensional quantum dot superlattices (1D-QDSLs). The calculation is based on the multi-band k·p theory, including the conduction and valence band mixing effects, the strain effect, and the piezoelectric effect; all three effects have periodic boundary conditions. We find that both the electronic and optical properties of the 1D-QDSLs show unique states which are different from those of well known single quantum dots (QDs) or quantum wires. We predict that the optical absorption spectra of the 1D-QDSLs strongly depend on the inter-dot spacing because of the inter-dot carrier coupling and changing strain states, which strongly influence the conduction and valence band potentials. The inter-miniband transitions form the absorption bands. Those absorption bands can be tuned from almost continuous (closely stacked QD case) to spike-like shape (almost isolated QD case) by changing the inter-dot spacing. The polarization of the lowest absorption peak for the 1D-QDSLs changes from being parallel to the stacking direction to being perpendicular to the stacking direction as the inter-dot spacing increases. In the case of closely stacked QDs, in-plane anisotropy, especially [110] and [11{sup ¯}0] directions also depend on the inter-dot spacing. Our findings and predictions will provide an additional degree of freedom for the design of QD-based optoelectronic devices.
NASA Astrophysics Data System (ADS)
Knaflič, Tilen; Klanjšek, Martin; Sans, Annette; Adler, Peter; Jansen, Martin; Felser, Claudia; Arčon, Denis
2015-05-01
Recently, it was proposed that the orbital ordering of πx,y * molecular orbitals in the superoxide CsO2 compound leads to the formation of spin-1/2 chains below the structural phase transition occurring at Ts 1=61 K on cooling. Here we report a detailed X -band electron paramagnetic resonance (EPR) study of this phase in CsO2 powder. The EPR signal appears as a broad line below Ts 1, which is replaced by the antiferromagnetic resonance below the Néel temperature TN=8.3 K . The temperature dependence of the EPR linewidth between Ts 1 and TN agrees with the predictions for the one-dimensional Heisenberg antiferromagnetic chain of S =1 /2 spins in the presence of symmetric anisotropic exchange interaction. Complementary analysis of the EPR line shape, linewidth, and the signal intensity within the Tomonaga-Luttinger liquid (TLL) framework allows for a determination of the TLL exponent K =0.48 . Present EPR data thus fully comply with the quantum antiferromagnetic state of spin-1/2 chains in the orbitally ordered phase of CsO2, which is therefore a unique p -orbital system where such a state could be studied.
NASA Astrophysics Data System (ADS)
Sankar, I. V.; Chatterjee, Ashok
2016-05-01
The quantum phase transition from a spin-density wave phase to a charge-density wave phase is studied within the framework of the one-dimensional Holstein-Hubbard model. The phonons are first eliminated by using a variational phonon state and the effective electronic Hamiltonian is then exactly solved using the Bethe ansatz technique to get the ground state energy. The entanglement entropy is finally calculated to show the possibility of existence of an intervening metallic phase at the cross-over region of the spin-density and charge-density wave phases in the thermodynamic limit at half-filling.
One-dimensional electronic systems in ultra-fine mesa etched InGaAs-InAlAs-InP quantum wires
NASA Astrophysics Data System (ADS)
Kern, K.; Demel, T.; Heitmann, D.; Grambow, P.; Ploog, K.; Razeghi, M.
1990-04-01
Quantum wire structures have been prepared by deep mesa etching of modulation doped InGaAs-InAlAs-InP heterostructures. In very narrow wires (width t ≈ 300 nm) it was possible to realize one-dimensional electronic systems (IDES) with quantum confined energy levels. The separation of the ID subbands was, as determined from magnetic depopulation, about 2.5 meV.
NASA Astrophysics Data System (ADS)
Liu, Cheng-cheng; Shi, Jia-dong; Ding, Zhi-yong; Ye, Liu
2016-05-01
Quantum coherence is an important physical resource in quantum computation and quantum information processing. In this paper, we firstly obtain an uncertainty-like expression relating two coherences contained in corresponding local bipartite quantum system. This uncertainty-like inequality shows that the larger the coherence of one subsystem, the less coherence contained in other subsystems. Further, we discuss in detail the uncertainty-like relation among three single-partite quantum systems. We show that the coherence contained in pure tripartite quantum system is greater than the sum of the coherence of all local subsystems.
Wang, S; Tian, W; Wu, F; Zhang, J; Dai, J N; Wu, Z H; Fang, Y Y; Tian, Y; Chen, C Q
2015-04-01
In this letter, a new kind of grating, quasi-one-dimensional gold grating, has been proposed to enhance the optical coupling in AlGaN/GaN quantum well infrared photodetector (QWIP). The electric field distribution, current density and energy flow are analyzed by an algorithm of finite element method (FEM). Significantly enhanced electric field component E(z) perpendicular to multiple quantum wells (MQWs) is explained by introducing the resonant coupling of surface plasmon polariton (SPP) and localized surface plasmon (LSP). The |E(z)|(2) in MQWs reaches 0.85 (V/m(2) when the electric field intensity (|E(0)|(2)) of normal incidence is 1 (V/m(2) at 4.65 μm, showing 2 times and 1.3 times increase compared with that obtained via a one-dimensional gold grating and a two-dimensional gold grating, respectively. The results confirm that the quasi-one-dimensional gold grating provides more plasma excitation source and higher charge density with structure optimization, resulting in a high optical coupling efficiency of 85% in quantum well region. PMID:25968712
NASA Astrophysics Data System (ADS)
Qiu, Liang; Tang, Gang; Yang, Xian-qing; Wang, An-min
2014-02-01
In order to define quantum correlations, there are two important paradigms in quantum information theory, viz. the information-theoretic and the entanglement-separability ones. In this paper, we give an analytical relation between two measures of quantum correlations. One of them is related to the monogamy of squared bipartite quantum discord, which is a information-theoretic multipartite quantum correlation measure, while the other is the generalized geometric measure which lies in the entanglement-separability paradigm. We find a certain cone-like region on the two-dimensional spaces spanned by the two measures. Moreover, we have investigated the quantum phase transition with the two measures in the anisotropic spin XXZ model by exploiting the quantum renormalization group method.
NASA Astrophysics Data System (ADS)
Jafari, R.
2012-05-01
The presence of a quantum critical point can significantly affect the thermodynamic properties of a material at finite temperatures. This is reflected, e.g., in the entropy landscape S(T, c) in the vicinity of a quantum critical point, yielding particularly strong variations for varying the tuning parameter c such as magnetic field. In this work we have studied the thermodynamic properties of the quantum compass model in the presence of a transverse field. The specific heat, entropy and cooling rate under an adiabatic demagnetization process have been calculated. During an adiabatic (de)magnetization process temperature drops in the vicinity of a field-induced zero-temperature quantum phase transitions. However close to field-induced quantum phase transitions we observe a large magnetocaloric effect.
NASA Astrophysics Data System (ADS)
Larré, Pierre-Élie; Carusotto, Iacopo
2016-03-01
We study the coherence properties of a laser beam after propagation along a one-dimensional lossless nonlinear optical waveguide. Within the paraxial, slowly-varying-envelope, and single-transverse-mode approximations, the quantum propagation of the light field in the nonlinear medium is mapped onto a quantum Gross-Pitaevskii-type evolution of a closed one-dimensional system of many interacting photons. Upon crossing the entrance and the back faces of the waveguide, the photon-photon interaction parameter undergoes two sudden jumps, resulting in a pair of quantum quenches of the system's Hamiltonian. In the weak-interaction regime, we use the modulus-phase Bogoliubov theory of dilute Bose gases to describe the quantum fluctuations of the fluid of light and predict that correlations typical of a prethermalized state emerge locally in their final form and propagate in a light-cone way at the Bogoliubov speed of sound in the photon fluid. This peculiar relaxation dynamics, visible in the light exiting the waveguide, results in a loss of long-lived coherence in the beam of light.
NASA Astrophysics Data System (ADS)
Kurosaki, Yuzuru; Ho, Tak-San; Rabitz, Herschel
2014-02-01
We construct a two-state one-dimensional reaction-path model for ozone open → cyclic isomerization dynamics. The model is based on the intrinsic reaction coordinate connecting the cyclic and open isomers with the O2 + O asymptote on the ground-state 1A' potential energy surface obtained with the high-level ab initio method. Using this two-state model time-dependent wave packet optimal control simulations are carried out. Two possible pathways are identified along with their respective band-limited optimal control fields; for pathway 1 the wave packet initially associated with the open isomer is first pumped into a shallow well on the excited electronic state potential curve and then driven back to the ground electronic state to form the cyclic isomer, whereas for pathway 2 the corresponding wave packet is excited directly to the primary well of the excited state potential curve. The simulations reveal that the optimal field for pathway 1 produces a final yield of nearly 100% with substantially smaller intensity than that obtained in a previous study [Y. Kurosaki, M. Artamonov, T.-S. Ho, and H. Rabitz, J. Chem. Phys. 131, 044306 (2009)] using a single-state one-dimensional model. Pathway 2, due to its strong coupling to the dissociation channel, is less effective than pathway 1. The simulations also show that nonlinear field effects due to molecular polarizability and hyperpolarizability are small for pathway 1 but could become significant for pathway 2 because much higher field intensity is involved in the latter. The results suggest that a practical control may be feasible with the aid of a few lowly excited electronic states for ozone isomerization.
Kurosaki, Yuzuru; Ho, Tak-San Rabitz, Herschel
2014-02-28
We construct a two-state one-dimensional reaction-path model for ozone open → cyclic isomerization dynamics. The model is based on the intrinsic reaction coordinate connecting the cyclic and open isomers with the O{sub 2} + O asymptote on the ground-state {sup 1}A{sup ′} potential energy surface obtained with the high-level ab initio method. Using this two-state model time-dependent wave packet optimal control simulations are carried out. Two possible pathways are identified along with their respective band-limited optimal control fields; for pathway 1 the wave packet initially associated with the open isomer is first pumped into a shallow well on the excited electronic state potential curve and then driven back to the ground electronic state to form the cyclic isomer, whereas for pathway 2 the corresponding wave packet is excited directly to the primary well of the excited state potential curve. The simulations reveal that the optimal field for pathway 1 produces a final yield of nearly 100% with substantially smaller intensity than that obtained in a previous study [Y. Kurosaki, M. Artamonov, T.-S. Ho, and H. Rabitz, J. Chem. Phys. 131, 044306 (2009)] using a single-state one-dimensional model. Pathway 2, due to its strong coupling to the dissociation channel, is less effective than pathway 1. The simulations also show that nonlinear field effects due to molecular polarizability and hyperpolarizability are small for pathway 1 but could become significant for pathway 2 because much higher field intensity is involved in the latter. The results suggest that a practical control may be feasible with the aid of a few lowly excited electronic states for ozone isomerization.
NASA Astrophysics Data System (ADS)
Jafari, R.
2016-05-01
We study the ground state fidelity, fidelity susceptibility, and quench dynamics of the extended quantum compass model in a transverse field. This model reveals a rich phase diagram which includes several critical surfaces depending on exchange couplings. We present a characterization of quantum phase transitions in terms of the ground state fidelity between two ground states obtained for two different values of external parameters. We also derive scaling relations describing the singular behavior of the fidelity susceptibility in the quantum critical surfaces. Moreover, we study the time evolution of the system after a critical quantum quench using the Loschmidt echo (LE). We find that the revival times of LE are given by {T}{rev}=N/2{v}{max}, where N is the size of the system and v max is the maximum of the lower bound group velocity of quasi-particles. Although the fidelity susceptibility shows the same exponent in all critical surfaces, the structure of the revivals after critical quantum quenches displays two different regimes reflecting different equilibration dynamics.
Dong, Yunxia; Zhang, Xiangdong
2008-10-13
The quantum radiation through the multilayer structures containing the left-handed materials is investigated based on the Green-function approach to the quantization of the phenomenological Maxwell theory. Emphasis is placed on the effect of randomness on the generation and transmission of entangled-states. It is shown that some unusual properties appear for the present systems in comparison with those of the conventional dielectric structures. The quantum relative entropy is always enhanced with the increase of random degree due to the existence of nonlocalized mode in the present systems, while the maximal entanglement can be observed only at some certain randomness for the conventional dielectric structures. In contrast to exponential decrease in the conventional systems, the entanglement degrades slowly with the increase of disorder and thickness of the sample near the nonlocalized mode after transmission through the present systems. This will benefit the quantum communication for long distances. PMID:18852803
NASA Astrophysics Data System (ADS)
Rajak, Atanu; Divakaran, Uma
2016-04-01
We study the effect of two simultaneous local quenches on the evolution of the Loschmidt echo (LE) and entanglement entropy (EE) of a one dimensional transverse Ising model. In this work, one of the local quenches involves the connection of two spin-1/2 chains at a certain time and the other corresponds to a sudden change in the magnitude of the transverse field at a given site in one of the spin chains. We numerically calculate the dynamics associated with the LE and the EE as a result of such double quenches, and discuss the various timescales involved in this problem using the picture of quasiparticles (QPs) generated as a result of such quenches. We perform a detailed analysis of the probability of QPs produced at the two sites and the nature of the QPs in various phases, and obtain interesting results. More specifically, we find partial reflection of these QPs at the defect center or the site of h-quench, resulting in new timescales which have never been reported before.
NASA Astrophysics Data System (ADS)
Ncube, Siphephile; Chimowa, George; Chiguvare, Zivayi; Bhattacharyya, Somnath
2014-07-01
The superiority of the electronic transport properties of single-walled carbon nanotube (SWNT) ropes over SWNT mats is verified from low temperature and frequency-dependent transport. The overall change of resistance versus in nanotube mats shows that 3D variable range hopping is the dominant conduction mechanism within the 2-300 K range. The magneto-resistance (MR) is found to be predominantly negative with a parabolic nature, which can also be described by the hopping model. Although the positive upturn of the MR at low temperatures establishes the contribution from quantum interference, the inherent quantum transport in individual tubes is suppressed at elevated temperatures. Therefore, to minimize multi-channel effects from inter-tube interactions and other defects, two-terminal devices were fabricated from aligned SWNT (extracted from a mat) for low temperature transport as well as high-frequency measurements. In contrast to the mat, the aligned ropes exhibit step-like features in the differential conductance within the 80-300 K temperature range. The effects of plasmon propagation, unique to one dimension, were identified in electronic transport as a non-universal power-law dependence of the differential conductance on temperature and source-drain voltage. The complex impedance showed high power transmission capabilities up to 65 GHz as well as oscillations in the frequency range up to 30 GHz. The measurements suggest that aligned SWNT ropes have a realistic potential for high-speed device applications.
Ncube, Siphephile; Chimowa, George; Chiguvare, Zivayi; Bhattacharyya, Somnath
2014-07-14
The superiority of the electronic transport properties of single-walled carbon nanotube (SWNT) ropes over SWNT mats is verified from low temperature and frequency-dependent transport. The overall change of resistance versus in nanotube mats shows that 3D variable range hopping is the dominant conduction mechanism within the 2–300 K range. The magneto-resistance (MR) is found to be predominantly negative with a parabolic nature, which can also be described by the hopping model. Although the positive upturn of the MR at low temperatures establishes the contribution from quantum interference, the inherent quantum transport in individual tubes is suppressed at elevated temperatures. Therefore, to minimize multi-channel effects from inter-tube interactions and other defects, two-terminal devices were fabricated from aligned SWNT (extracted from a mat) for low temperature transport as well as high-frequency measurements. In contrast to the mat, the aligned ropes exhibit step-like features in the differential conductance within the 80–300 K temperature range. The effects of plasmon propagation, unique to one dimension, were identified in electronic transport as a non-universal power-law dependence of the differential conductance on temperature and source-drain voltage. The complex impedance showed high power transmission capabilities up to 65 GHz as well as oscillations in the frequency range up to 30 GHz. The measurements suggest that aligned SWNT ropes have a realistic potential for high-speed device applications.
Nolde, Jill A. Kim, Chul Soo; Jackson, Eric M.; Ellis, Chase T.; Abell, Joshua; Glembocki, Orest J.; Canedy, Chadwick L.; Tischler, Joseph G.; Vurgaftman, Igor; Meyer, Jerry R.; Aifer, Edward H.; Kim, Mijin
2015-06-29
We demonstrate up to 39% resonant enhancement of the quantum efficiency (QE) of a low dark current nBn midwave infrared photodetector with a 0.5 μm InAsSb absorber layer. The enhancement was achieved by using a 1D plasmonic grating to couple incident light into plasmon modes propagating in the plane of the device. The plasmonic grating is composed of stripes of deposited amorphous germanium overlaid with gold. Devices with and without gratings were processed side-by-side for comparison of their QEs and dark currents. The peak external QE for a grating device was 29% compared to 22% for a mirror device when the illumination was polarized perpendicularly to the grating lines. Additional experiments determined the grating coupling efficiency by measuring the reflectance of analogous gratings deposited on bare GaSb substrates.
Basu, Banasri; Bandyopadhyay, Pratul; Majumdar, Priyadarshi
2011-03-15
We have studied quantum phase transition induced by a quench in different one-dimensional spin systems. Our analysis is based on the dynamical mechanism which envisages nonadiabaticity in the vicinity of the critical point. This causes spin fluctuation which leads to the random fluctuation of the Berry phase factor acquired by a spin state when the ground state of the system evolves in a closed path. The two-point correlation of this phase factor is associated with the probability of the formation of defects. In this framework, we have estimated the density of defects produced in several one-dimensional spin chains. At the critical region, the entanglement entropy of a block of L spins with the rest of the system is also estimated which is found to increase logarithmically with L. The dependence on the quench time puts a constraint on the block size L. It is also pointed out that the Lipkin-Meshkov-Glick model in point-splitting regularized form appears as a combination of the XXX model and Ising model with magnetic field in the negative z axis. This unveils the underlying conformal symmetry at criticality which is lost in the sharp point limit. Our analysis shows that the density of defects as well as the scaling behavior of the entanglement entropy follows a universal behavior in all these systems.
NASA Astrophysics Data System (ADS)
Cabrera, Ivelisse; Thompson, Jordan; Coldea, Radu; Robinson, Neil; Essler, Fabian; Prabhakaran, Dharmalingam; Bewley, Robert; Guidi, Tatiana
2013-03-01
The Ising chain in a transverse magnetic field is one of the canonical examples of a quantum phase transition. We have recently realized this model experimentally in the quasi-one-dimensional (1D) Ising-like ferromagnet CoNb2O6. Here, we present single-crystal inelastic neutron scattering measurements of the magnetic dispersion relations in the full three-dimensional (3D) Brillouin zone for magnetic fields near the critical point and in the high field paramagnetic phase. We explore the gap dependence as a function of field and quantify the cross-over to 3D physics at the lowest energies due to the finite interchain couplings. We parametrize the dispersion relations in the high-field paramagnetic phase to a spin wave model to quantify the sub-leading terms in the spin Hamiltonian beyond the dominant 1D Ising exchange.
NASA Astrophysics Data System (ADS)
Liu, Cheng-cheng; Xu, Shuai; He, Juan; Ye, Liu
2015-05-01
In this paper, the effect of Dzyaloshinskii-Moriya interaction and anisotropy on the π-tangle and quantum phase transition (QPT) by employing the QRG method in the one-dimensional anisotropic XY model is investigated. In our model the anisotropy and DM interaction parameters can influence the phase diagrams. While the anisotropy suppresses the entanglement due to favoring of the alignment of spins, the DM interaction restores the spoiled entanglement via creation of the quantum fluctuations. When the value of DM interaction is certain, the π-tangle develops into two different values which separate the system into two phases i.e. the spin-fluid phase and the Néel phase with the number of QRG iterations increased. Meanwhile, the π-tangle decreases slowly as the sites of the chain became larger, but the π-tangle tends to be a fixed value finally. Additionally, it exhibits a maximum for the next-nearest-neighbor entanglement at the critical point in our model which is different from the situation of the two-body system. To gain further insight, the nonanalytic and scaling behaviors of π-tangle have also been analyzed in detail and this phenomenon indicates that the behavior of the entanglement can perfectly help one to observe the quantum critical properties of the model.
Kerstein, A.R.
1996-12-31
One-Dimensional Turbulence is a new turbulence modeling strategy involving an unsteady simulation implemented in one spatial dimension. In one dimension, fine scale viscous and molecular-diffusive processes can be resolved affordably in simulations at high turbulence intensity. The mechanistic distinction between advective and molecular processes is thereby preserved, in contrast to turbulence models presently employed. A stochastic process consisting of mapping {open_quote}events{close_quote} applied to a one-dimensional velocity profile represents turbulent advection. The local event rate for given eddy size is proportional to the velocity difference across the eddy. These properties cause an imposed shear to induce an eddy cascade analogous in many respects to the eddy cascade in turbulent flow. Many scaling and fluctuation properties of self-preserving flows, and of passive scalars introduced into these flows, are reproduced.
NASA Astrophysics Data System (ADS)
Xiong, Bo; Yang, Tao; Benedict, Keith A.
2013-07-01
We study the effect of quantum fluctuations on the dynamics of a quasi-one-dimensional Bose gas in an optical lattice at zero temperature using the truncated Wigner approximation with a variety of basis sets for the initial fluctuation modes. The initial spatial distributions of the quantum fluctuations are very different when using a limited number of plane-wave (PW), simple-harmonic-oscillator (SHO) and self-consistently determined Bogoliubov (SCB) modes. The short-time transport properties of the Bose gas, characterized by the phase coherence in the PW basis, are distinct from those gained using the SHO and SCB basis. The calculations using the SCB modes predict greater phase decoherence and stronger number fluctuations than the other choices. Furthermore, we observe that the use of PW modes overestimates the extent to which atoms are expelled from the core of the cloud, while the use of the other modes only breaks the cloud structure slightly, which is in agreement with the experimental observations by Fertig et al (2005 Phys. Rev. Lett. 94 120403).
Haldane-gap excitations in the low-Hc one-dimensional quantum antiferromagnet Ni(C5D14N2)2N3(PF6)
NASA Astrophysics Data System (ADS)
Zheludev, A.; Chen, Y.; Broholm, C. L.; Honda, Z.; Katsumata, K.
2001-03-01
Inelastic neutron scattering on deuterated single-crystal samples is used to study Haldane-gap excitations in the new S=1 one-dimensional quantum antiferromagnet Ni(C5D14N2)2N3(PF6), that was recently recognized as an ideal model system for high-field studies. The Haldane gap energies Δx=0.42(3) meV, Δy=0.52(6) meV, and Δz=1.9(1) meV, for excitations polarized along the a, b, and c crystallographic axes, respectively, are measured. The dispersion relation is studied for momentum transfers both along and perpendicular to the chains' direction. The in-chain exchange constant J=2.8 meV is found to be much larger than interchain coupling, Jy=1.8(4)×10-3 meV and Jx=4(3)×10-4 meV, along the b and a axes, respectively. The results are discussed in the context of future experiments in high magnetic fields.
NASA Astrophysics Data System (ADS)
Han, Minmin; Chen, Wenyuan; Guo, Hongjian; Yu, Limin; Li, Bo; Jia, Junhong
2016-06-01
In the typical solution-based synthesis of colloidal quantum dots (QDs), it always resorts to some surface treatment, ligand exchange processing or post-synthesis processing, which might involve some toxic chemical regents injurious to the performance of QD sensitized solar cells. In this work, the CuInS2 QDs are deposited on the surface of one-dimensional TiO2 nanorod arrays by the pulsed laser deposition (PLD) technique. The CuInS2 QDs are coated on TiO2 nanorods without any ligand engineering, and the performance of the obtained CuInS2 QD sensitized solar cells is optimized by adjusting the laser energy. An energy conversion efficiency of 3.95% is achieved under one sun illumination (AM 1.5, 100 mW cm-2). The improved performance is attributed to enhanced absorption in the longer wavelength region, quick interfacial charge transfer and few chance of carrier recombination with holes for CuInS2 QD-sensitized solar cells. Moreover, the photovoltaic device exhibits high stability in air without any specific encapsulation. Thus, the PLD technique could be further applied for the fabrication of QDs or other absorption materials.
One-Dimensionality and Whiteness
ERIC Educational Resources Information Center
Calderon, Dolores
2006-01-01
This article is a theoretical discussion that links Marcuse's concept of one-dimensional society and the Great Refusal with critical race theory in order to achieve a more robust interrogation of whiteness. The author argues that in the context of the United States, the one-dimensionality that Marcuse condemns in "One-Dimensional Man" is best…
NASA Astrophysics Data System (ADS)
Cabrera, I.; Thompson, J. D.; Coldea, R.; Prabhakaran, D.; Bewley, R. I.; Guidi, T.; Rodriguez-Rivera, J. A.; Stock, C.
2014-07-01
The quasi-one-dimensional (1D) Ising ferromagnet CoNb2O6 has recently been driven via applied transverse magnetic fields through a continuous quantum phase transition from spontaneous magnetic order to a quantum paramagnet, and dramatic changes were observed in the spin dynamics, characteristic of weakly perturbed 1D Ising quantum criticality. We report here extensive single-crystal inelastic neutron scattering measurements of the magnetic excitations throughout the three-dimensional (3D) Brillouin zone in the quantum paramagnetic phase just above the critical field to characterize the effects of the finite interchain couplings. In this phase, we observe that excitations have a sharp, resolution-limited line shape at low energies and over most of the dispersion bandwidth, as expected for spin-flip quasiparticles. We map the full bandwidth along the strongly dispersive chain direction and resolve clear modulations of the dispersions in the plane normal to the chains, characteristic of frustrated interchain couplings in an antiferromagnetic isosceles triangular lattice. The dispersions can be well parametrized using a linear spin-wave model that includes interchain couplings and further neighbor exchanges. The observed dispersion bandwidth along the chain direction is smaller than that predicted by a linear spin-wave model using exchange values determined at zero field, and this effect is attributed to quantum renormalization of the dispersion beyond the spin-wave approximation in fields slightly above the critical field, where quantum fluctuations are still significant.
NASA Astrophysics Data System (ADS)
Calvo, Rafael; Abud, Julián E.; Sartoris, Rosana P.; Santana, Ricardo C.
2011-09-01
Binuclear (also called dimeric) compounds with pairs of antiferromagnetically coupled spins ½, S1 and S2 (Hex = -J0 S1.S2, with J0<0 for antiferromagnets), have been around for ˜60 years, providing roots to the field of molecular magnetism. In addition, as reported in recent years, weak interactions between binuclear units in a crystalline network give rise to interesting systems of interacting bosons having an energy gap, which are important in the study of quantum phenomena in many body systems coupled by stochastic distributions of interactions. Binuclear compounds have gained new relevance in the last decade with the observation of Bose-Einstein condensation. In this work, we use electron paramagnetic resonance (EPR) to study the role of weak inter-binuclear exchange couplings J’ (|J’| ≪|J0|) in the spectra, elementary excitations, and spin dynamics of a one-dimensional (1-D) array of antiferromagnetic (AFM) binuclear units in the hybrid (organic-inorganic) CuII compound [Cu(CH3COO)(phen)(H2O)]2·(NO3)2·4H2O. In this material, the acetate (CH3COO)- anion supports the intra-binuclear exchange coupling J0, and the stacking of the (phen) = 1,10-phenanthroline rings of neighbor units supports the inter-binuclear interactions J', giving rise to well-isolated chains. This has advantages over other binuclear compounds studied previously because magnetically equal units are arranged in a 1-D spatial arrangement along the direction of their symmetry axis, simplifying the analysis of the data and allowing a simpler treatment. In addition, single crystals of good quality allow detailed EPR experiments.EPR spectra were collected at ˜33.8 and ˜9.4-9.8 GHz in oriented single crystals at room temperature and in powder samples at temperatures (T) between 10 and 300 K. By varying the energy levels of the binuclear units with the magnetic field orientation, or changing the population of the excited triplet state with temperature and, consequently, the effective
One-Dimensional Oscillator in a Box
ERIC Educational Resources Information Center
Amore, Paolo; Fernandez, Francisco M.
2010-01-01
We discuss a quantum-mechanical model of two particles that interact by means of a harmonic potential and are confined to a one-dimensional box with impenetrable walls. We apply perturbation theory to the cases of different and equal masses and analyse the symmetry of the states in the latter case. We compare the approximate perturbation results…
Gamouras, A.; Britton, M.; Khairy, M. M.; Mathew, R.; Hall, K. C.; Dalacu, D.; Poole, P.; Poitras, D.; Williams, R. L.
2013-12-16
We demonstrate the selective optical excitation and detection of subsets of quantum dots (QDs) within an InAs/InP ensemble using a SiO{sub 2}/Ta{sub 2}O{sub 5}-based optical microcavity. The low variance of the exciton transition energy and dipole moment tied to the narrow linewidth of the microcavity mode is expected to facilitate effective qubit encoding and manipulation in a quantum dot ensemble with ease of quantum state readout relative to qubits encoded in single quantum dots.
NASA Astrophysics Data System (ADS)
Bois, V.; Fromholz, P.; Lecheminant, P.
2016-04-01
We investigate the zero-temperature phase diagram of two-orbital SU (N ) fermionic models at incommensurate filling which are directly relevant to strontium and ytterbium ultracold atoms loading into a one-dimensional optical lattice. Using a low-energy approach that takes into account explicitly the SU (N ) symmetry, we find that a spectral gap for the nuclear-spin degrees of freedom is formed for generic interactions. Several phases with one or two gapless modes are then stabilized which describe the competition between different density instabilities. In stark contrast to the N =2 case, no dominant pairing instabilities emerge and the leading superfluid one is rather formed from bound states of 2 N fermions.
NASA Astrophysics Data System (ADS)
Heidrich-Meisner, Fabian; Pollet, Lode; Sorg, Stefan; Vidmar, Lev
2015-03-01
We study the relaxation dynamics and thermalization in the one-dimensional Bose-Hubbard model induced by a global interaction quench. Specifically, we start from an initial state that has exactly one boson per site and is the ground state of a system with infinitely strong repulsive interactions at unit filling. The same interaction quench was realized in a recent experiment. Using exact diagonalization and the density-matrix renormalization-group method, we compute the time dependence of such observables as the multiple occupancy and the momentum distribution function. We discuss our numerical results in the framework of the eigenstate thermalization hypothesis and we observe that the microcanonical ensemble describes the time averages of many observables reasonably well for small and intermediate interaction strength. Moreover, the diagonal and the canonical ensembles are practically identical for our initial conditions already on the level of their respective energy distributions for small interaction strengths. Supported by the DFG through FOR 801 and the Alexander von Humboldt foundation.
NASA Astrophysics Data System (ADS)
Jackson, Howard; Badada, Bekele; Shi, Teng; Smith, Leigh; Zheng, Changlin; Etheridge, Joanne; Jiang, Nian; Tan, Hoe; Jagadish, Channupati
We explore the nature of exciton localization in single GaAs/AlGaAs nanowire quantum well tube (QWT) devices using photocurrent (PC) spectroscopy combined with simultaneous photoluminescence (PL) and photoluminescence excitation (PLE) measurements. Excitons confined to GaAs quantum well tubes of 8 and 4 nm widths embedded into an AlGaAs barrier are seen to ionize at high bias. Spectroscopic signatures of the ground and excited states confined to the QWT seen in PL, PLE and PC data are consistent with simple numerical calculations. The demonstration of good electrical contact with the QWTs enables the study of Stark effect shifts in the sharp emission lines of excitons localized to quantum dot-like states within the QWT. Atomic resolution cross-sectional TEM measurements, an analysis of the temperature dependence of PL and time-resolved PL as well as the quantum confined Stark effect of these dots provide insights into the nature of the exciton localization in these nanostructures. We acknowledge the financial support of NSF DMR 1507844, DMR 151373 and ECCS 1509706 and the Australian Research Council.
NASA Astrophysics Data System (ADS)
Sundar, Bhuvanesh; Mueller, Erich J.
2013-12-01
We describe how microwave spectroscopy of cold fermions in quasi-1D traps can be used to detect, manipulate, and entangle exotic nonlocal qubits associated with "Majorana" edge modes. We present different approaches to generate the p-wave superfluidity which is responsible for these topological zero-energy edge modes. We find that the edge modes have clear signatures in the microwave spectrum and that the line shape distinguishes between the degenerate states of a qubit encoded in these edge modes. Moreover, the microwaves rotate the system in its degenerate ground-state manifold. We use these rotations to implement a set of universal quantum gates, allowing the system to be used as a universal quantum computer.
NASA Astrophysics Data System (ADS)
Zhan, Fei; Sabbatini, Jacopo; Davis, Matthew J.; McCulloch, Ian P.
2014-08-01
We study the miscible-immiscible quantum phase transition in a linearly coupled binary Bose-Hubbard model in one dimension that can describe the low-energy properties of a two-component Bose-Einstein condensate in optical lattices. With the quantum many-body ground state obtained from the density matrix renormalization group algorithm, we calculate the characteristic physical quantities of the phase transition controlled by the linear coupling between the two components. Furthermore we calculate the Binder cumulant to determine the critical point and construct the phase diagram. The strong-coupling expansion shows that in the Mott insulator regime the model Hamiltonian can be mapped to a spin-1/2 XXZ model with a transverse magnetic field.
One-Dimensional Grid Turbulence
NASA Astrophysics Data System (ADS)
Kerstein, Alan R.; Nilsen, Vebjørn
1998-11-01
To capture molecular mixing and other small scale phenomena such as chemical reactions and differential diffusion, it is essential to resolve all the length (and time) scales. For large Reynolds number flows this is impossible to do in three-dimensional turbulence simulations with the current and foreseeable future computer technology. To circumvent this problem the one-dimensional turbulence (ODT) model, as the name implies, considers only one spatial dimension in which all the length scales can be resolved even at very large Reynolds numbers. To incorporate the effect of advection on a one-dimensional domain, the evolution of the velocity and scalar profiles is randomly interrupted by a sequence of profile rearrangements representing the effect of turbulent eddies. Results obtained from ODT simulations of grid turbulence with a passive scalar are presented. The decay exponents for the velocity and passive scalar fluctuations, as predicted by ODT, compare favorably with experimental data.
NASA Astrophysics Data System (ADS)
Dupuis, N.; Yakovenko, V. M.
1999-02-01
We study the collective modes in the magnetic-field induced spin-density-wave (FISDW) phases experimentally observed in organic conductors of the Bechgaard salts family. In phases that exhibit a sign reversal of the quantum Hall effect (Ribault anomaly), the coexistence of two spin-density waves gives rise to additional long-wavelength collective modes besides the Goldstone modes due to spontaneous translation and rotation symmetry breaking. These modes strongly affect the charge and spin response functions. We discuss some experimental consequences for the Bechgaard salts.
NASA Astrophysics Data System (ADS)
Basu, Banasri; Bandyopadhyay, Pratul; Majumdar, Priyadarshi
2012-08-01
We study the magnetic-field dependence of the entanglement entropy in quantum phase transition induced by a quench of the XX, XXX, and Lipkin-Meshkov-Glick (LMG) models. The entropy for a block of L spins with the rest follows a logarithmic scaling law where the block size L is restricted due to the dependence of the prefactor on the quench time. Within this restricted region the entropy undergoes a renormalization group (RG) flow. From the RG flow equation we have analytically determined the magnetic field dependence of the entropy. The anisotropy parameter dependence of the entropy for the XY and the LMG models has also been studied in this framework. The results are found to be in excellent agreement with that obtained by other authors from numerical studies without any quench.
One-Dimensional Heat Conduction
Sutton, Steven B.
1992-03-09
ICARUS-LLNL was developed to solve one-dimensional planar, cylindrical, or spherical conduction heat transfer problems. The IBM PC version is a family of programs including ICARUSB, an interactive BASIC heat conduction program; ICARUSF, a FORTRAN heat conduction program; PREICAR, a BASIC preprocessor for ICARUSF; and PLOTIC and CPLOTIC, interpretive BASIC and compiler BASIC plot postprocessor programs. Both ICARUSB and ICARUSF account for multiple material regions and complex boundary conditions, such as convection or radiation. In addition, ICARUSF accounts for temperature-dependent material properties and time or temperature-dependent boundary conditions. PREICAR is a user-friendly preprocessor used to generate or modify ICARUSF input data. PLOTIC and CPLOTIC generate plots of the temperature or heat flux profile at specified times, plots of the variation of temperature or heat flux with time at selected nodes, or plots of the solution grid. First developed in 1974 to allow easy modeling of complex one-dimensional systems, its original application was in the nuclear explosive testing program. Since then it has undergone extensive revision and been applied to problems dealing with laser fusion target fabrication, heat loads on underground tests, magnetic fusion switching tube anodes, and nuclear waste isolation canisters.
One-Dimensional Heat Conduction
1992-03-09
ICARUS-LLNL was developed to solve one-dimensional planar, cylindrical, or spherical conduction heat transfer problems. The IBM PC version is a family of programs including ICARUSB, an interactive BASIC heat conduction program; ICARUSF, a FORTRAN heat conduction program; PREICAR, a BASIC preprocessor for ICARUSF; and PLOTIC and CPLOTIC, interpretive BASIC and compiler BASIC plot postprocessor programs. Both ICARUSB and ICARUSF account for multiple material regions and complex boundary conditions, such as convection or radiation. In addition,more » ICARUSF accounts for temperature-dependent material properties and time or temperature-dependent boundary conditions. PREICAR is a user-friendly preprocessor used to generate or modify ICARUSF input data. PLOTIC and CPLOTIC generate plots of the temperature or heat flux profile at specified times, plots of the variation of temperature or heat flux with time at selected nodes, or plots of the solution grid. First developed in 1974 to allow easy modeling of complex one-dimensional systems, its original application was in the nuclear explosive testing program. Since then it has undergone extensive revision and been applied to problems dealing with laser fusion target fabrication, heat loads on underground tests, magnetic fusion switching tube anodes, and nuclear waste isolation canisters.« less
One-dimensional wave turbulence
NASA Astrophysics Data System (ADS)
Zakharov, Vladimir; Dias, Frédéric; Pushkarev, Andrei
2004-08-01
The problem of turbulence is one of the central problems in theoretical physics. While the theory of fully developed turbulence has been widely studied, the theory of wave turbulence has been less studied, partly because it developed later. Wave turbulence takes place in physical systems of nonlinear dispersive waves. In most applications nonlinearity is small and dispersive wave interactions are weak. The weak turbulence theory is a method for a statistical description of weakly nonlinear interacting waves with random phases. It is not surprising that the theory of weak wave turbulence began to develop in connection with some problems of plasma physics as well as of wind waves. The present review is restricted to one-dimensional wave turbulence, essentially because finer computational grids can be used in numerical computations. Most of the review is devoted to wave turbulence in various wave equations, and in particular in a simple one-dimensional model of wave turbulence introduced by Majda, McLaughlin and Tabak in 1997. All the considered equations are model equations, but consequences on physical systems such as ocean waves are discussed as well. The main conclusion is that the range in which the theory of pure weak turbulence is valid is narrow. In general, wave turbulence is not completely weak. Together with the weak turbulence component, it can include coherent structures, such as solitons, quasisolitons, collapses or broad collapses. As a result, weak and strong turbulence coexist. In situations where coherent structures cannot develop, weak turbulence dominates. Even though this is primarily a review paper, new results are presented as well, especially on self-organized criticality and on quasisolitonic turbulence.
The one-dimensional hydrogen atom revisited
NASA Astrophysics Data System (ADS)
Palma, G.; Raff, U.
2006-09-01
The one-dimensional Schrodinger hydrogen atom is an interesting mathematical and physical problem for the study of bound states, eigenfunctions, and quantum-degeneracy issues. This one-dimensional physical system has given rise to some intriguing controversy for more than four decades. Presently, still no definite consensus seems to have been reached. We reanalyzed this apparently controversial problem, approaching it from a Fourier-transform representation method combined with some fundamental (basic) ideas found in self-adjoint extensions of symmetric operators. In disagreement with some previous claims, we found that the complete Balmer energy spectrum is obtained together with an odd-parity set of eigenfunctions. Closed-form solutions in both coordinate and momentum spaces were obtained. No twofold degeneracy was observed as predicted by the degeneracy theorem in one dimension, though it does not necessarily have to hold for potentials with singularities. No ground state with infinite energy exists since the corresponding eigenfunction does not satisfy the Schrodinger equation at the origin.
One-dimensional silicone nanofilaments.
Artus, Georg R J; Seeger, Stefan
2014-07-01
A decade ago one-dimensional silicone nanofilaments (1D-SNF) such as fibres and wires were described for the first time. Since then, the exploration of 1D-SNF has led to remarkable advancements with respect to material science and surface science: one-, two- and three-dimensional nanostructures of silicone were unknown before. The discovery of silicone nanostructures marks a turning point in the research on the silicone material at the nanoscale. Coatings made of 1D-SNF are among the most superhydrophobic surfaces known today. They are free of fluorine, can be applied to a large range of technologically important materials and their properties can be modified chemically. This opens the way to many interesting applications such as water harvesting, superoleophobicity, separation of oil and water, patterned wettability and storage and manipulation of data on a surface. Because of their high surface area, coatings consisting of 1D-SNF are used for protein adsorption experiments and as carrier systems for catalytically active nanoparticles. This paper reviews the current knowledge relating to the broad development of 1D-SNF technologies. Common preparation and coating techniques are presented along with a comparison and discussion of the published coating parameters to provide an insight on how these affect the topography of the 1D-SNF or coating. The proposed mechanisms of growth are presented, and their potentials and shortcomings are discussed. We introduce all explored applications and finally identify future prospects and potentials of 1D-SNF with respect to applications in material science and surface science. PMID:24742356
Zheludev, A.; Chen, Y.; Broholm, C. L.; Honda, Z.; Katsumata, K.
2001-03-01
Inelastic neutron scattering on deuterated single-crystal samples is used to study Haldane-gap excitations in the new S=1 one-dimensional quantum antiferromagnet Ni(C{sub 5}D{sub 14}N{sub 2}){sub 2}N{sub 3}(PF{sub 6}), that was recently recognized as an ideal model system for high-field studies. The Haldane gap energies {Delta}{sub x}=0.42(3) meV, {Delta}{sub y}=0.52(6) meV, and {Delta}{sub z}=1.9(1) meV, for excitations polarized along the a, b, and c crystallographic axes, respectively, are measured. The dispersion relation is studied for momentum transfers both along and perpendicular to the chains' direction. The in-chain exchange constant J=2.8 meV is found to be much larger than interchain coupling, J{sub y}=1.8(4)x10{sup -3} meV and J{sub x}=4(3)x10{sup -4} meV, along the b and a axes, respectively. The results are discussed in the context of future experiments in high magnetic fields.
Some topological states in one-dimensional cold atomic systems
Mei, Feng; Zhang, Dan-Wei; Zhu, Shi-Liang
2015-07-15
Ultracold atoms trapped in optical lattices nowadays have been widely used to mimic various models from condensed-matter physics. Recently, many great experimental progresses have been achieved for producing artificial magnetic field and spin–orbit coupling in cold atomic systems, which turn these systems into a new platform for simulating topological states. In this paper, we give a review focusing on quantum simulation of topologically protected soliton modes and topological insulators in one-dimensional cold atomic system. Firstly, the recent achievements towards quantum simulation of one-dimensional models with topological non-trivial states are reviewed, including the celebrated Jackiw–Rebbi model and Su–Schrieffer–Heeger model. Then, we will introduce a dimensional reduction method for systematically constructing high dimensional topological states in lower dimensional models and review its applications on simulating two-dimensional topological insulators in one-dimensional optical superlattices.
Transport in a one-dimensional hyperconductor
NASA Astrophysics Data System (ADS)
Plamadeala, Eugeniu; Mulligan, Michael; Nayak, Chetan
2016-03-01
We define a "hyperconductor" to be a material whose electrical and thermal dc conductivities are infinite at zero temperature and finite at any nonzero temperature. The low-temperature behavior of a hyperconductor is controlled by a quantum critical phase of interacting electrons that is stable to all potentially gap-generating interactions and potentially localizing disorder. In this paper, we compute the low-temperature dc and ac electrical and thermal conductivities in a one-dimensional hyperconductor, studied previously by the present authors, in the presence of both disorder and umklapp scattering. We identify the conditions under which the transport coefficients are finite, which allows us to exhibit examples of violations of the Wiedemann-Franz law. The temperature dependence of the electrical conductivity, which is characterized by the parameter ΔX, is a power law, σ ∝1 /T1 -2 (2 -ΔX) when ΔX≥2 , down to zero temperature when the Fermi surface is commensurate with the lattice. There is a surface in parameter space along which ΔX=2 and ΔX≈2 for small deviations from this surface. In the generic (incommensurate) case with weak disorder, such scaling is seen at high temperatures, followed by an exponential increase of the conductivity lnσ ˜1 /T at intermediate temperatures and, finally, σ ∝1 /T2 -2 (2 -ΔX) at the lowest temperatures. In both cases, the thermal conductivity diverges at low temperatures.
Transport in a One-Dimensional Hyperconductor
NASA Astrophysics Data System (ADS)
Plamadeala, Eugeniu; Mulligan, Michael; Nayak, Chetan
We define a `hyperconductor' to be a material whose electrical and thermal DC conductivities are infinite at zero temperature. The low-temperature behavior of a hyperconductor is controlled by a quantum critical phase of interacting electrons that is stable to all potentially-gap-generating interactions and arbitrary potentially-localizing disorder. We compute the low-temperature DC and AC electrical and thermal conductivities in a one-dimensional hyperconductor, studied previously by the present authors, in the presence of both disorder and umklapp scattering. We identify the conditions under which the transport coefficients are finite, and exhibit examples of violations of the Wiedemann-Franz law. We show that the temperature dependence of the electrical conductivity is a power law, σ ~ 1 /T 1 - 2 (2 -ΔX) for ΔX >= 2 , down to zero temperature when the Fermi surface is commensurate with the lattice. In the incommensurate case with weak disorder, such scaling is seen at high-temperatures, followed by an exponential increase of the conductivity lnσ ~ 1 / T at intermediate temperatures and, finally, σ ~ 1 /T 2 - 2 (2 -ΔX) at the lowest temperatures. In both cases, the thermal conductivity diverges at low temperatures.
NASA Astrophysics Data System (ADS)
Cabrera, Ivelisse; Thompson, J. D.; Coldea, R.; Prabhakaran, D.; Bewley, R. I.; Guidi, T.; Rodriguez-Rivera, J. A.; Stock, C.
We report extensive single-crystal inelastic neutron scattering measurements of the magnetic excitations in the quasi 1D Ising ferromagnet CoNb2O6 in the quantum paramagnetic phase to characterize the effects of the finite interchain couplings. In this phase, we observe that excitations have a sharp, resolution-limited line shape at low energies and over most of the dispersion bandwidth, as expected for spin-flip quasiparticles. We map the full bandwidth along the strongly dispersive chain direction and resolve clear modulations of the dispersions in the plane normal to the chains, characteristic of frustrated interchain couplings in an antiferromagnetic isosceles triangular lattice. The dispersions can be well parametrized using a linear spin-wave model that includes interchain couplings and further neighbor exchanges. The observed dispersion bandwidth along the chain direction is smaller than that predicted by a linear spin-wave model using exchange values determined at zero field. We attribute this effect to quantum renormalization of the dispersion beyond the spin-wave approximation in fields slightly above the critical field, where quantum fluctuations are still significant. We acknowledge support from EPSRC Grant No. EP/H014934/1, the Oxford Clarendon Fund Scholarship and NSERC of Canada.
One-Dimensional Czedli-Type Islands
ERIC Educational Resources Information Center
Horvath, Eszter K.; Mader, Attila; Tepavcevic, Andreja
2011-01-01
The notion of an island has surfaced in recent algebra and coding theory research. Discrete versions provide interesting combinatorial problems. This paper presents the one-dimensional case with finitely many heights, a topic convenient for student research.
Cooling of a One-Dimensional Bose Gas
NASA Astrophysics Data System (ADS)
Rauer, B.; Grišins, P.; Mazets, I. E.; Schweigler, T.; Rohringer, W.; Geiger, R.; Langen, T.; Schmiedmayer, J.
2016-01-01
We experimentally study the dynamics of a degenerate one-dimensional Bose gas that is subject to a continuous outcoupling of atoms. Although standard evaporative cooling is rendered ineffective by the absence of thermalizing collisions in this system, we observe substantial cooling. This cooling proceeds through homogeneous particle dissipation and many-body dephasing, enabling the preparation of otherwise unexpectedly low temperatures. Our observations establish a scaling relation between temperature and particle number, and provide insights into equilibration in the quantum world.
Thermalization in a one-dimensional integrable system
Grisins, Pjotrs; Mazets, Igor E.
2011-11-15
We present numerical results demonstrating the possibility of thermalization of single-particle observables in a one-dimensional system, which is integrable in both the quantum and classical (mean-field) descriptions (a quasicondensate of ultracold, weakly interacting bosonic atoms are studied as a definite example). We find that certain initial conditions admit the relaxation of single-particle observables to the equilibrium state reasonably close to that corresponding to the Bose-Einstein thermal distribution of Bogoliubov quasiparticles.
One-dimensional Gromov minimal filling problem
Ivanov, Alexandr O; Tuzhilin, Alexey A
2012-05-31
The paper is devoted to a new branch in the theory of one-dimensional variational problems with branching extremals, the investigation of one-dimensional minimal fillings introduced by the authors. On the one hand, this problem is a one-dimensional version of a generalization of Gromov's minimal fillings problem to the case of stratified manifolds. On the other hand, this problem is interesting in itself and also can be considered as a generalization of another classical problem, the Steiner problem on the construction of a shortest network connecting a given set of terminals. Besides the statement of the problem, we discuss several properties of the minimal fillings and state several conjectures. Bibliography: 38 titles.
Heredity in one-dimensional quadratic maps
NASA Astrophysics Data System (ADS)
Romera, M.; Pastor, G.; Alvarez, G.; Montoya, F.
1998-12-01
In an iterative process, as is the case of a one-dimensional quadratic map, heredity has never been mentioned. In this paper we show that the pattern of a superstable orbit of a one-dimensional quadratic map can be expressed as the sum of the gene of the chaotic band where the pattern is to be found, and the ancestral path that joins all its ancestors. The ancestral path holds all the needed genetic information to calculate the descendants of the pattern. The ancestral path and successive descendant generations of the pattern constitute the family tree of the pattern, which is important to study and understand the orbit's ordering.
One-Dimensional Wavefront Sensor Analysis
1996-04-25
This software analyzes one-dimensional wavefront sensor data acquired with any of several data acquisition systems. It analyzes the data to determine centroids, wavefront slopes and overall wavefront error. The data can be displayed in many formats, with plots of various parameters vs time and position, including computer generated movies. Data can also be exported for use by other programs.
Hybrid Nanomaterials: One Dimensional Nanoparticle Assemblies
NASA Astrophysics Data System (ADS)
Sharma, Nikhil; Pochan, Darrin
2007-03-01
One-dimensional nanoparticle assemblies have potential applications in sensing, as plasmon and energy waveguides and in the conduction of novel signals such as phonons and spin states. Herein we present two strategies for the fabrication of such assemblies. Micro and meso-scale particle assemblies have been produced via a coaxial electrospinning process that results in assemblies of particles (silica and silver) encapsulated within a polymer nanofiber (polyethylene oxide). The method has been demonstrated successfully in the creation of 1D assemblies of differently sized silica particles. The effect of change in solution concentrations and relative flow rates in internal and external channels of the coaxial electrospinning apparatus on the structure of these assemblies has been investigated. Nano-scale assemblies of gold particles have been prepared by templating gold nanoparticles on a 20 amino acid peptide that displays laminated morphology. These assemblies are formed as laterally spaced one-dimensional nanoparticle assemblies.
Transient One-dimensional Pipe Flow Analyzer
1986-04-08
TOPAZ-SNLL, the Transient One- dimensional Pipe flow AnalyZer code, is a user-friendly computer program for modeling the heat transfer, fluid mechanics, and thermodynamics of multi-species gas transfer in arbitrary arrangements of pipes, valves, vessels, and flow branches. Although the flow conservation equations are assumed to be one-dimensional and transient, multidimensional features of internal fluid flow and heat transfer may be accounted for using the available quasi-steady flow correlations (e.g., Moody friction factor correlation and variousmore » form loss and heat transfer correlations). Users may also model the effects of moving system boundaries such as pistons, diaphragms, and bladders. The features of fully compressible flow are modeled, including the propagation of shocks and rarefaction waves, as well as the establishment of multiple choke points along the flow path.« less
Transient One-dimensional Pipe Flow Analyzer
1986-04-08
TOPAZ-SNLL, the Transient One- dimensional Pipe flow AnalyZer code, is a user-friendly computer program for modeling the heat transfer, fluid mechanics, and thermodynamics of multi-species gas transfer in arbitrary arrangements of pipes, valves, vessels, and flow branches. Although the flow conservation equations are assumed to be one-dimensional and transient, multidimensional features of internal fluid flow and heat transfer may be accounted for using the available quasi-steady flow correlations (e.g., Moody friction factor correlation and various form loss and heat transfer correlations). Users may also model the effects of moving system boundaries such as pistons, diaphragms, and bladders. The features of fully compressible flow are modeled, including the propagation of shocks and rarefaction waves, as well as the establishment of multiple choke points along the flow path.
Polarization transitions in one-dimensional arrays of interacting rings
NASA Astrophysics Data System (ADS)
Roostaei, Bahman; Mullen, Kieran J.; Rezakhani, A. T.
2008-08-01
Periodic nanostructures can display the dynamics of arrays of atoms while enabling the tuning of interactions in ways not normally possible in nature. We examine one-dimensional (1D) arrays of a “synthetic atom,” a one-dimensional ring with a nearest-neighbor Coulomb interaction. We consider the classical limit first, finding that arrays of singly charged rings possess antiferroelectric order at low temperatures when the charge is discrete, but that they do not order when the charge is treated as a continuous classical fluid. In the quantum limit Monte Carlo simulation suggests that the system undergoes a quantum phase transition as the interaction strength is increased. This is supported by mapping the system to the 1D transverse field Ising model. Finally, we examine the effect of magnetic fields. We find that a magnetic field can alter the electrostatic phase transition producing a ferroelectric ground state, solely through its effect of shifting the eigenenergies of the quantum problem.
Correlations in light propagation in one-dimensional waveguides
NASA Astrophysics Data System (ADS)
Javanainen, Juha; Ruostekoski, Janne
2016-05-01
We study light propagation between atoms in a one-dimensional waveguide both analytically and using numerical simulations. We employ classical electrodynamics, but in the limit of low light intensity the results are essentially exact also for quantum mechanics. We characterize the cooperative interactions between the atoms mediated by the electromagnetic field. The focus is on resonance shifts for various statistics of the positions of the atoms, such as statistically independent positions or atoms in a regular lattice. These shifts, potentially important if 1D waveguides are to be used in metrology, are different from the usual resonance shifts found in three spatial dimensions.
Cooling of a One-Dimensional Bose Gas.
Rauer, B; Grišins, P; Mazets, I E; Schweigler, T; Rohringer, W; Geiger, R; Langen, T; Schmiedmayer, J
2016-01-22
We experimentally study the dynamics of a degenerate one-dimensional Bose gas that is subject to a continuous outcoupling of atoms. Although standard evaporative cooling is rendered ineffective by the absence of thermalizing collisions in this system, we observe substantial cooling. This cooling proceeds through homogeneous particle dissipation and many-body dephasing, enabling the preparation of otherwise unexpectedly low temperatures. Our observations establish a scaling relation between temperature and particle number, and provide insights into equilibration in the quantum world. PMID:26849577
One-dimensional physics in the 21st century
NASA Astrophysics Data System (ADS)
Giamarchi, Thierry
2016-03-01
This paper presents a brief introduction to some of the systems and questions concerning one-dimensional interacting quantum systems. Historically, organic conductors and superconductors - a field extremely active in the "Laboratoire de physique des solides" in Orsay, in a good part thanks to the influence of Jacques Friedel, played a crucial role in this field. I will describe some of the aspects of this physics and also review some of the very exciting theoretical and experimental developments that took place in the 1D world in the last 15 years or so. xml:lang="fr"
Wave turbulence in one-dimensional models
NASA Astrophysics Data System (ADS)
Zakharov, V. E.; Guyenne, P.; Pushkarev, A. N.; Dias, F.
2001-05-01
A two-parameter nonlinear dispersive wave equation proposed by Majda, McLaughlin and Tabak is studied analytically and numerically as a model for the study of wave turbulence in one-dimensional systems. Our ultimate goal is to test the validity of weak turbulence theory. Although weak turbulence theory is independent on the sign of the nonlinearity of the model, the numerical results show a strong dependence on the sign of the nonlinearity. A possible explanation for this discrepancy is the strong influence of coherent structures - wave collapses and quasisolitons - in wave turbulence.
One-dimensional hypersonic phononic crystals.
Gomopoulos, N; Maschke, D; Koh, C Y; Thomas, E L; Tremel, W; Butt, H-J; Fytas, G
2010-03-10
We report experimental observation of a normal incidence phononic band gap in one-dimensional periodic (SiO(2)/poly(methyl methacrylate)) multilayer film at gigahertz frequencies using Brillouin spectroscopy. The band gap to midgap ratio of 0.30 occurs for elastic wave propagation along the periodicity direction, whereas for inplane propagation the system displays an effective medium behavior. The phononic properties are well captured by numerical simulations. The porosity in the silica layers presents a structural scaffold for the introduction of secondary active media for potential coupling between phonons and other excitations, such as photons and electrons. PMID:20141118
NASA Astrophysics Data System (ADS)
Vidal, A. J.; Astrakharchik, G. E.; Vranješ Markić, L.; Boronat, J.
2016-05-01
The ground-state properties of one-dimensional electron-spin-polarized hydrogen 1H, deuterium 2H, and tritium 3H are obtained by means of quantum Monte Carlo methods. The equations of state of the three isotopes are calculated for a wide range of linear densities. The pair correlation function and the static structure factor are obtained and interpreted within the framework of the Luttinger liquid theory. We report the density dependence of the Luttinger parameter and use it to identify different physical regimes: Bogoliubov Bose gas, super-Tonks–Girardeau gas, and quasi-crystal regimes for bosons; repulsive, attractive Fermi gas, and quasi-crystal regimes for fermions. We find that the tritium isotope is the one with the richest behavior. Our results show unambiguously the relevant role of the isotope mass in the properties of this quantum system.
Dislocation-mediated melting of one-dimensional Rydberg crystals
Sela, Eran; Garst, Markus; Punk, Matthias
2011-08-15
We consider cold Rydberg atoms in a one-dimensional optical lattice in the Mott regime with a single atom per site at zero temperature. An external laser drive with Rabi frequency {Omega} and laser detuning {Delta} creates Rydberg excitations whose dynamics is governed by an effective spin-chain model with (quasi) long-range interactions. This system possesses intrinsically a large degree of frustration resulting in a ground-state phase diagram in the ({Delta},{Omega}) plane with a rich topology. As a function of {Delta}, the Rydberg blockade effect gives rise to a series of crystalline phases commensurate with the optical lattice that form a so-called devil's staircase. The Rabi frequency {Omega}, on the other hand, creates quantum fluctuations that eventually lead to a quantum melting of the crystalline states. Upon increasing {Omega}, we find that generically a commensurate-incommensurate transition to a floating Rydberg crystal that supports gapless phonon excitations occurs first. For even larger {Omega}, dislocations within the floating Rydberg crystal start to proliferate and a second, Kosterlitz-Thouless-Nelson-Halperin-Young dislocation-mediated melting transition finally destroys the crystalline arrangement of Rydberg excitations. This latter melting transition is generic for one-dimensional Rydberg crystals and persists even in the absence of an optical lattice. The floating phase and the concomitant transitions can, in principle, be detected by Bragg scattering of light.
Aperiodicity in one-dimensional cellular automata
Jen, E.
1990-01-01
Cellular automata are a class of mathematical systems characterized by discreteness (in space, time, and state values), determinism, and local interaction. A certain class of one-dimensional, binary site-valued, nearest-neighbor automata is shown to generate infinitely many aperiodic temporal sequences from arbitrary finite initial conditions on an infinite lattice. The class of automaton rules that generate aperiodic temporal sequences are characterized by a particular form of injectivity in their interaction rules. Included are the nontrivial linear'' automaton rules (that is, rules for which the superposition principle holds); certain nonlinear automata that retain injectivity properties similar to those of linear automata; and a wider subset of nonlinear automata whose interaction rules satisfy a weaker form of injectivity together with certain symmetry conditions. A technique is outlined here that maps this last set of automata onto a linear automaton, and thereby establishes the aperiodicity of their temporal sequences. 12 refs., 3 figs.
Superfluid helium-4 in one dimensional channel
NASA Astrophysics Data System (ADS)
Kim, Duk Y.; Banavar, Samhita; Chan, Moses H. W.; Hayes, John; Sazio, Pier
2013-03-01
Superfluidity, as superconductivity, cannot exist in a strict one-dimensional system. However, the experiments employing porous media showed that superfluid helium can flow through the pores of nanometer size. Here we report a study of the flow of liquid helium through a single hollow glass fiber of 4 cm in length with an open id of 150 nm between 1.6 and 2.3 K. We found the superfluid transition temperature was suppressed in the hollow cylinder and that there is no flow above the transition. Critical velocity at temperature below the transition temperature was determined. Our results bear some similarity to that found by Savard et. al. studying the flow of helium through a nanohole in a silicon nitrite membrane. Experimental study at Penn State is supported by NSF Grants No. DMR 1103159.
One-Dimensional Photonic Crystal Superprisms
NASA Technical Reports Server (NTRS)
Ting, David
2005-01-01
Theoretical calculations indicate that it should be possible for one-dimensional (1D) photonic crystals (see figure) to exhibit giant dispersions known as the superprism effect. Previously, three-dimensional (3D) photonic crystal superprisms have demonstrated strong wavelength dispersion - about 500 times that of conventional prisms and diffraction gratings. Unlike diffraction gratings, superprisms do not exhibit zero-order transmission or higher-order diffraction, thereby eliminating cross-talk problems. However, the fabrication of these 3D photonic crystals requires complex electron-beam substrate patterning and multilayer thin-film sputtering processes. The proposed 1D superprism is much simpler in structural complexity and, therefore, easier to design and fabricate. Like their 3D counterparts, the 1D superprisms can exhibit giant dispersions over small spectral bands that can be tailored by judicious structure design and tuned by varying incident beam direction. Potential applications include miniature gas-sensing devices.
Three one-dimensional structural heating programs
NASA Technical Reports Server (NTRS)
Wing, L. D.
1978-01-01
Two computer programs for calculating profiles in a ten-element structure consisting of up to ten materials are presented, along with a third program for calculating the mean temperature for a payload container placed in an orbiting vehicle cargo bay. The three programs are related by the sharing of a common analytical technique; the energy balance is based upon one-dimensional heat transfer. The first program, NQLDW112, assumes a non-ablating surface. NQLDW117 is very similar but allows the outermost element to ablate. NQLDW040 calculates an average temperature profile through an idealized model of the real payload cannister and contents in the cargo bay of an orbiting vehicle.
One-dimensional immiscible displacement experiments
NASA Astrophysics Data System (ADS)
Thomson, N. R.; Graham, D. N.; Farquhar, G. J.
1992-08-01
In recent years, a great deal of attention has focused on the development of various methods to predict the fate of immiscible contaminants (NAPL's) in soils. In an attempt to satisfy this requirement, a host of numerical models has been developed. Unfortunately, there exist little experimental data to verify the assumptions used in the derivation of these immiscible flow models. One objective of this paper is to report on a non-destructive measurement technique which was used to capture the relative organic-phase saturation variations in a number of two-phase flow displacement experiments. The data obtained from these experiments were compared to results obtained from a one-dimensional, finite-element based, two-phase flow model. The experiments consisted of five separate trials using three different immiscible liquids (hydraulic oil, kerosene and hexane) in a water-saturated column. Irregular immiscible liquid infiltration fronts were observed in four of the five experiments, indicating that very small-scale heterogeneities control the infiltration of immiscible liquids into soil. Independent of the column experiments, saturation-capillary pressure curves were determined for the various liquids. In general, the simulated NAPL saturation vs. time profiles agreed very well with the observations for all five of the trials.
Probing the excitations of a one dimensional topological Bose insulator
NASA Astrophysics Data System (ADS)
Dalla Torre, Emanuele G.; Berg, Erez; Altman, Ehud
2008-03-01
We investigate the dynamic response of a system of ultracold dipolar atoms or molecules in the one dimensional Haldane Bose insulator phase. This phase, which was recently predicted theoretically [1], is characterized by non-local string order and its elementary excitations are domain walls in this order. We compute experimentally relevant response functions and we derive asymptotically exact expressions near the quantum critical points separating the Haldane insulator from the conventional Mott and density wave insulators. In particular, we predict a narrow absorption peak in Bragg spectroscopy experiments, due to the excitation of a single domain wall in the string order. [1] E.G. Dalla Torre, E. Berg, E. Altman, Phys. Rev Lett. 97, 260401 (2006)
Practical variational tomography for critical one-dimensional systems
NASA Astrophysics Data System (ADS)
Lee, Jong Yeon; Landon-Cardinal, Olivier
2015-06-01
We improve upon a recently introduced efficient quantum state reconstruction procedure targeted to states well approximated by the multiscale entanglement renormalization ansatz (MERA), e.g., ground states of critical models. We show how to numerically select a subset of experimentally accessible measurements which maximize information extraction about renormalized particles, thus dramatically reducing the required number of physical measurements. We numerically estimate the number of measurements required to characterize the ground state of the critical one-dimensional Ising (resp. XX) model and find that MERA tomography on 16-qubit (resp. 24-qubit) systems requires the same experimental effort as brute-force tomography on 8 qubits. We derive a bound computable from experimental data which certifies the distance between the experimental and reconstructed states.
Thermal transport in one-dimensional spin heterostructures
NASA Astrophysics Data System (ADS)
Arrachea, Liliana; Lozano, Gustavo S.; Aligia, A. A.
2009-07-01
We study heat transport in a one-dimensional inhomogeneous quantum spin-1/2 system. It consists of a finite-size XX spin chain coupled at its ends to semi-infinite XX and XY chains at different temperatures, which play the role of heat and spin reservoirs. After using the Jordan-Wigner transformation we map the original spin Hamiltonian into a fermionic Hamiltonian, which contains normal and pairing terms. We find the expressions for the heat currents and solve the problem with a nonequilibrium Green’s-function formalism. We analyze the behavior of the heat currents as functions of the model parameters. When finite magnetic fields are applied at the two reservoirs, the system exhibits rectifying effects in the heat flow.
Papp, E.; Micu, C.; Racolta, D.
2013-11-13
In this paper one deals with the theoretical derivation of energy bands and of related wavefunctions characterizing quasi 1D semiconductor heterostructures, such as InAs quantum wire models. Such models get characterized this time by equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions of dimensionless magnitude a under the influence of in-plane magnetic fields of magnitude B. We found that the orientations of the field can be selected by virtue of symmetry requirements. For this purpose one resorts to spin conservations, but alternative conditions providing sensible simplifications of the energy-band formula can be reasonably accounted for. Besides the wavenumber k relying on the 1D electron, one deals with the spin-like s=±1 factors in the front of the square root term of the energy. Having obtained the spinorial wavefunction, opens the way to the derivation of spin precession effects. For this purpose one resorts to the projections of the wavenumber operator on complementary spin states. Such projections are responsible for related displacements proceeding along the Ox-axis. This results in a 2D rotation matrix providing both the precession angle as well as the precession axis.
NASA Astrophysics Data System (ADS)
Papp, E.; Micu, C.; Racolta, D.
2013-11-01
In this paper one deals with the theoretical derivation of energy bands and of related wavefunctions characterizing quasi 1D semiconductor heterostructures, such as InAs quantum wire models. Such models get characterized this time by equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions of dimensionless magnitude a under the influence of in-plane magnetic fields of magnitude B. We found that the orientations of the field can be selected by virtue of symmetry requirements. For this purpose one resorts to spin conservations, but alternative conditions providing sensible simplifications of the energy-band formula can be reasonably accounted for. Besides the wavenumber k relying on the 1D electron, one deals with the spin-like s=±1 factors in the front of the square root term of the energy. Having obtained the spinorial wavefunction, opens the way to the derivation of spin precession effects. For this purpose one resorts to the projections of the wavenumber operator on complementary spin states. Such projections are responsible for related displacements proceeding along the Ox-axis. This results in a 2D rotation matrix providing both the precession angle as well as the precession axis.
NASA Astrophysics Data System (ADS)
Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Thomas, K. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.
We use a multiplexing scheme to measure the conductance properties of 95 split gates of 7 different gate dimensions fabricated on a GaAs/AlGaAs chip, in a single cool down. The number of devices for which conductance is accurately quantized reduces as the gate length increases. However, even the devices for which conductance is accurately quantized in units of 2e2 / h show no correlation between the length of electrostatic potential barrier in the channel and the gate length, using a saddle point model to estimate the barrier length. Further, the strength of coupling between the gates and the 1D channel does not increase with gate length beyond 0.7 μm. The background electrostatic profile appears as significant as the gate dimension in determining device behavior. We find a clear correlation between the curvature of the electrostatic barrier along the channel and the strength of the ``0.7 anomaly'' which identifies the electrostatic length of the channel as the principal factor governing the conductance of the 0.7 anomaly. Present address: Wisconsin Institute for Quantum Information, University of Wisconsin-Madison, Madison, WI.
Quasi-one-dimensional foam drainage
NASA Astrophysics Data System (ADS)
Grassia, P.; Cilliers, J. J.; Neethling, S. J.; Ventura-Medina, E.
Foam drainage is considered in a froth flotation cell. Air flow through the foam is described by a simple two-dimensional deceleration flow, modelling the foam spilling over a weir. Foam microstructure is given in terms of the number of channels (Plateau borders) per unit area, which scales as the inverse square of bubble size. The Plateau border number density decreases with height in the foam, and also decreases horizontally as the weir is approached. Foam drainage equations, applicable in the dry foam limit, are described. These can be used to determine the average cross-sectional area of a Plateau border, denoted A, as a function of position in the foam. Quasi-one-dimensional solutions are available in which A only varies vertically, in spite of the two-dimensional nature of the air flow and Plateau border number density fields. For such situations the liquid drainage relative to the air flow is purely vertical. The parametric behaviour of the system is investigated with respect to a number of dimensionless parameters: K (the strength of capillary suction relative to gravity), α (the deceleration of the air flow), and n and h (respectively, the horizontal and vertical variations of the Plateau border number density). The parameter K is small, implying the existence of boundary layer solutions: capillary suction is negligible except in thin layers near the bottom boundary. The boundary layer thickness (when converted back to dimensional variables) is independent of the height of the foam. The deceleration parameter α affects the Plateau border area on the top boundary: weaker decelerations give larger Plateau border areas at the surface. For weak decelerations, there is rapid convergence of the boundary layer solutions at the bottom onto ones with negligible capillary suction higher up. For strong decelerations, two branches of solutions for A are possible in the K=0 limit: one is smooth, and the other has a distinct kink. The full system, with small but non
Charge transport through one-dimensional Moiré crystals.
Bonnet, Roméo; Lherbier, Aurélien; Barraud, Clément; Della Rocca, Maria Luisa; Lafarge, Philippe; Charlier, Jean-Christophe
2016-01-01
Moiré superlattices were generated in two-dimensional (2D) van der Waals heterostructures and have revealed intriguing electronic structures. The appearance of mini-Dirac cones within the conduction and valence bands of graphene is one of the most striking among the new quantum features. A Moiré superstructure emerges when at least two periodic sub-structures superimpose. 2D Moiré patterns have been particularly investigated in stacked hexagonal 2D atomic lattices like twisted graphene layers and graphene deposited on hexagonal boron-nitride. In this letter, we report both experimentally and theoretically evidence of superlattices physics in transport properties of one-dimensional (1D) Moiré crystals. Rolling-up few layers of graphene to form a multiwall carbon nanotube adds boundaries conditions that can be translated into interference fringes-like Moiré patterns along the circumference of the cylinder. Such a 1D Moiré crystal exhibits a complex 1D multiple bands structure with clear and robust interband quantum transitions due to the presence of mini-Dirac points and pseudo-gaps. Our devices consist in a very large diameter (>80 nm) multiwall carbon nanotubes of high quality, electrically connected by metallic electrodes acting as charge reservoirs. Conductance measurements reveal the presence of van Hove singularities assigned to 1D Moiré superlattice effect and illustrated by electronic structure calculations. PMID:26786067
Charge transport through one-dimensional Moiré crystals
Bonnet, Roméo; Lherbier, Aurélien; Barraud, Clément; Rocca, Maria Luisa Della; Lafarge, Philippe; Charlier, Jean-Christophe
2016-01-01
Moiré superlattices were generated in two-dimensional (2D) van der Waals heterostructures and have revealed intriguing electronic structures. The appearance of mini-Dirac cones within the conduction and valence bands of graphene is one of the most striking among the new quantum features. A Moiré superstructure emerges when at least two periodic sub-structures superimpose. 2D Moiré patterns have been particularly investigated in stacked hexagonal 2D atomic lattices like twisted graphene layers and graphene deposited on hexagonal boron-nitride. In this letter, we report both experimentally and theoretically evidence of superlattices physics in transport properties of one-dimensional (1D) Moiré crystals. Rolling-up few layers of graphene to form a multiwall carbon nanotube adds boundaries conditions that can be translated into interference fringes-like Moiré patterns along the circumference of the cylinder. Such a 1D Moiré crystal exhibits a complex 1D multiple bands structure with clear and robust interband quantum transitions due to the presence of mini-Dirac points and pseudo-gaps. Our devices consist in a very large diameter (>80 nm) multiwall carbon nanotubes of high quality, electrically connected by metallic electrodes acting as charge reservoirs. Conductance measurements reveal the presence of van Hove singularities assigned to 1D Moiré superlattice effect and illustrated by electronic structure calculations. PMID:26786067
Dynamics of low dimensional model for weakly relativistic Zakharov equations for plasmas
Sahu, Biswajit; Pal, Barnali; Poria, Swarup; Roychoudhury, Rajkumar
2013-05-15
In the present paper, the nonlinear interaction between Langmuir waves and ion acoustic waves described by the one-dimensional Zakharov equations (ZEs) for relativistic plasmas are investigated formulating a low dimensional model. Equilibrium points of the model are found and it is shown that the existence and stability conditions of the equilibrium point depend on the relativistic parameter. Computational investigations are carried out to examine the effects of relativistic parameter and other plasma parameters on the dynamics of the model. Power spectrum analysis using fast fourier transform and also construction of first return map confirm that periodic, quasi-periodic, and chaotic type solution exist for both relativistic as well as in non-relativistic case. Existence of supercritical Hopf bifurcation is noted in the system for two critical plasmon numbers.
Conditions for one-dimensional supersonic flow of quantum gases
NASA Astrophysics Data System (ADS)
Giovanazzi, S.; Farrell, C.; Kiss, T.; Leonhardt, U.
2004-12-01
One can use transsonic Bose-Einstein condensates of alkali atoms to establish the laboratory analog of the event horizon and to measure the acoustic version of Hawking radiation. We determine the conditions for supersonic flow and the Hawking temperature for realistic condensates on waveguides where an external potential plays the role of a supersonic nozzle. The transition to supersonic speed occurs at the potential maximum and the Hawking temperature is entirely determined by the curvature of the potential.
Computer Simulation of a Particle in a One-Dimensional Double or Triple Potential Well.
ERIC Educational Resources Information Center
Humberston, J. W.; And Others
1983-01-01
A computer program was written for a model system in quantum mechanics (particle in a one-dimensional finite square well potential). Described is a major extension of the single-well program to treat problem of a particle in a double/triple finite square potential well. Technical/educational features of the program are considered. (Author/JN)
A disorder-enhanced quasi-one-dimensional superconductor.
Petrović, A P; Ansermet, D; Chernyshov, D; Hoesch, M; Salloum, D; Gougeon, P; Potel, M; Boeri, L; Panagopoulos, C
2016-01-01
A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2-δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials. PMID:27448209
A disorder-enhanced quasi-one-dimensional superconductor
Petrović, A. P.; Ansermet, D.; Chernyshov, D.; Hoesch, M.; Salloum, D.; Gougeon, P.; Potel, M.; Boeri, L.; Panagopoulos, C.
2016-01-01
A powerful approach to analysing quantum systems with dimensionality d>1 involves adding a weak coupling to an array of one-dimensional (1D) chains. The resultant quasi-1D (q1D) systems can exhibit long-range order at low temperature, but are heavily influenced by interactions and disorder due to their large anisotropies. Real q1D materials are therefore ideal candidates not only to provoke, test and refine theories of strongly correlated matter, but also to search for unusual emergent electronic phases. Here we report the unprecedented enhancement of a superconducting instability by disorder in single crystals of Na2−δMo6Se6, a q1D superconductor comprising MoSe chains weakly coupled by Na atoms. We argue that disorder-enhanced Coulomb pair-breaking (which usually destroys superconductivity) may be averted due to a screened long-range Coulomb repulsion intrinsic to disordered q1D materials. Our results illustrate the capability of disorder to tune and induce new correlated electron physics in low-dimensional materials. PMID:27448209
Berry phase oscillations in a one-dimensional Dirac comb
NASA Astrophysics Data System (ADS)
Hodge, William; Cassera, Nicholas; Rave, Matthew
In quantum mechanics, the Berry phase is a geometric phase acquired by a wave function over the course of a cycle, when subjected to adiabatic processes. In general, this phase is due to the geometry of the underlying parameter space and thus depends only on the path taken. In any system described by a periodic potential, the torus topology of the Brillouin zone itself can lead to such a phase. In this work, we numerically calculate the Berry phase for a one-dimensional Dirac comb described by N distinct wells per unit cell. As expected, the resulting Berry phase exhibits a rich band-dependence. In the case where N = 2 , we find that the Berry phase corresponding to the nth energy band oscillates such that γn (x) =An sin (πx) cos [ (2 n - 1) πx ] , where An is a band-dependent constant and 0 < x < 1 is the relative position of the two wells. This expression, obtained using perturbation theory, gives excellent agreement with exact numerical results, even at low energy levels. The Berry phase exhibits a similar behavior for cases where N > 2 .
Topological phase in one-dimensional Rashba wire
NASA Astrophysics Data System (ADS)
Sa-Ke, Wang; Jun, Wang; Jun-Feng, Liu
2016-07-01
We study the possible topological phase in a one-dimensional (1D) quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap. Project supported by the National Natural Science Foundation of China (Grant Nos. 115074045 and 11204187) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20131284).
Interspecies tunneling in one-dimensional Bose mixtures
Pflanzer, Anika C.; Zoellner, Sascha; Schmelcher, Peter
2010-02-15
We study the ground-state properties and quantum dynamics of few-boson mixtures with strong interspecies repulsion in one-dimensional traps. If one species localizes at the center, e.g., due to a very large mass compared to the other component, it represents an effective barrier for the latter, and the system can be mapped onto identical bosons in a double well. For weaker localization, the barrier atoms begin to respond to the light component, leading to an induced attraction between the mobile atoms that may even outweigh their bare intraspecies repulsion. To explain the resulting effects, we derive an effective Hubbard model for the lighter species accounting for the back action of the barrier in correction terms to the lattice parameters. Also the tunneling is drastically affected: by varying the degree of localization of the 'barrier' atoms, the dynamics of intrinsically noninteracting bosons can change from Rabi oscillations to effective pair tunneling. For identical fermions (or fermionized bosons), this leads to the tunneling of attractively bound pairs.
Electrical transport in doped one-dimensional nanostructures.
Li, Tan; Wang, Jianning; Zhang, Yumin
2005-09-01
Mobility and noise are two important issues for electronic devices, and they have many new features in one-dimensional (1D) doped nanostructures. For the convenience of readers the background of solid state physics is reviewed first, and then the transport process in 3D crystal material is introduced. Velocity saturation is an important phenomenon in modern electronic devices, and it is analyzed in an intuitive approach. It is predicted FinFET will be the next generation MOSFET, and its structure and characteristics are introduced. With the reduction of device dimensions the mesoscopic phenomena begin to show up. A simple way to treat transport problem in this domain is the Landauer-Büttiker formula, and the basic equation is derived. Finally the 1D quantum wire structure grown from a bottom-up approach is reviewed. Owing to the good material quality the scattering is very weak, and the wave properties of the coherent transport are discussed. Engineering applications of nanostructures in electronic information processing that manipulates time varying signals often involve device characterizations in the time domain. Since carrier transport in nanostructures is inherently a random process and it causes random fluctuations in quantities like current and voltage, so background knowledge in the microscopic origins of noise and other related practical issues is important to identify enough noise margins for reliable system design. This subject is the focus of the second part of the review article. PMID:16193956
Thermal transport in disordered one-dimensional spin chains
NASA Astrophysics Data System (ADS)
Poboiko, Igor; Feigel'man, Mikhail
2015-12-01
We study a one-dimensional anisotropic XXZ Heisenberg spin-1/2 chain with weak random fields hizSiz by means of Jordan-Wigner transformation to spinless Luttinger liquid with disorder and bosonization technique. First, we reinvestigate the phase diagram of the system in terms of dimensionless disorder γ =
Trapped Atoms in One-Dimensional Photonic Crystals
NASA Astrophysics Data System (ADS)
Kimble, H.
2013-05-01
I describe one-dimensional photonic crystals that support a guided mode suitable for atom trapping within a unit cell, as well as a second probe mode with strong atom-photon interactions. A new hybrid trap is analyzed that combines optical and Casimir-Polder forces to form stable traps for neutral atoms in dielectric nanostructures. By suitable design of the band structure, the atomic spontaneous emission rate into the probe mode can exceed the rate into all other modes by more than tenfold. The unprecedented single-atom reflectivity r0 ~= 0 . 9 for the guided probe field could create new scientific opportunities, including quantum many-body physics for 1 D atom chains with photon-mediated interactions and high-precision studies of vacuum forces. Towards these goals, my colleagues and I are pursuing numerical simulation, device fabrication, and cold-atom experiments with nanoscopic structures. Funding is provided by by the IQIM, an NSF PFC with support of the Moore Foundation, by the AFOSR QuMPASS MURI, by the DoD NSSEFF program (HJK), and by NSF Grant PHY0652914 (HJK). DEC acknowledges funding from Fundacio Privada Cellex Barcelona.
Localization of carriers in a one-dimensional electron system over liquid helium
NASA Astrophysics Data System (ADS)
Gladchenko, S. P.; Kovdrya, Yu. Z.; Nikolaenko, V. A.
2000-07-01
The mobility of carriers in a one-dimensional electron system over liquid helium has been measured at the temperature 0.5-1.7 K and for different values of linear electron density. Profiled nylon substrates with some quantity of charge deposited were used for the realization of a one-dimensional electron system. It is shown that electron mobility is dependent on the quantity of the charge on a substrate. Effects observed are explained by the localization of electrons moving in the random potential created by the substrates charge. It is supposed that at low temperatures the movement of carriers is determined by quantum effects.
Topological states in one dimensional solids and photonic crystals
NASA Astrophysics Data System (ADS)
Atherton, Timothy; Mathur, Harsh
2011-03-01
We show that the band structure of a one-dimensional solid with particle-hole symmetry may be characterized by a topological index that owes its existence to the non-trivial homotopy of the space of non-degenerate real symmetric matrices. Moreover we explicitly demonstrate a theorem linking the topological index to the existence of bound states on the surface of a semi-infinite one dimensional solid. Our analysis is a one-dimensional analogue of the analysis of topological insulators in two and three dimensions by Balents and Moore; our results may be relevant to long molecules that are the one dimensional analogue of topological insulators. We propose the realization of this physics in a one-dimensional photonic crystal. In this case the topology of the bandstructure reveals itself not as a bound surface state but as a Lorentzian feature in the time delay of light that is otherwise perfectly reflected by the photonic crystal.
The one-dimensional Gross-Pitaevskii equation and its some excitation states
Prayitno, T. B.
2015-04-16
We have derived some excitation states of the one-dimensional Gross-Pitaevskii equation coupled by the gravitational potential. The methods that we have used here are taken by pursuing the recent work of Kivshar et. al. by considering the equation as a macroscopic quantum oscillator. To obtain the states, we have made the appropriate transformation to reduce the three-dimensional Gross-Pitaevskii equation into the one-dimensional Gross-Pitaevskii equation and applying the time-independent perturbation theory in the general solution of the one-dimensional Gross-Pitaevskii equation as a linear superposition of the normalized eigenfunctions of the Schrödinger equation for the harmonic oscillator potential. Moreover, we also impose the condition by assuming that some terms in the equation should be so small in order to preserve the use of the perturbation method.
Gigantic optical nonlinearity in one-dimensional Mott-Hubbard insulators
Kishida; Matsuzaki; Okamoto; Manabe; Yamashita; Taguchi; Tokura
2000-06-22
The realization of all-optical switching, modulating and computing devices is an important goal in modern optical technology. Nonlinear optical materials with large third-order nonlinear susceptibilities (chi(3)) are indispensable for such devices, because the magnitude of this quantity dominates the device performance. A key strategy in the development of new materials with large nonlinear susceptibilities is the exploration of quasi-one-dimensional systems, or 'quantum wires'--the quantum confinement of electron-hole motion in one-dimensional space can enhance chi(3). Two types of chemically synthesized quantum wires have been extensively studied: the band insulators of silicon polymers, and Peierls insulators of pi-conjugated polymers and platinum halides. In these systems, chi(3) values of 10(-12) to 10(-7) e.s.u. (electrostatic system of units) have been reported. Here we demonstrate an anomalous enhancement of the third-order nonlinear susceptibility in a different category of quantum wires: one-dimensional Mott insulators of 3d transition-metal oxides and halides. By analysing the electroreflectance spectra of these compounds, we measure chi(3) values in the range 10(-8) to 10(-5) e.s.u. The anomalous enhancement results from a large dipole moment between the lowest two excited states of these systems. PMID:10879529
Coulomb drag between one-dimensional electron systems
NASA Astrophysics Data System (ADS)
Muhammad, Mustafa
We have measured Coulomb drag (CD) between two spatially separated and electrically isolated one-dimensional (1D) wires to study the Luttinger liquid (LL) state in 1D systems. We have fabricated dual-wire CD devices with long quantum wires (≥ 1 microm) and short quantum wires (≤ 500 nm) with respect to the thermal lengths. The devices are made from high-mobility (≅10 6cm2/Vs) two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures, using high-resolution e-beam lithography, combined with metal deposition by e-beam evaporation to form surface Schottky gates. Peak in drag voltage occurs when the subband bottoms of the lowest energy subbands of the drive and the drag wires line up with each other and the Fermi level. We have observed drag on 1 microm device at 22 mK temperature which is found to be reminiscent of the drag observed earlier on a 2 microm device. An extensive reanalysis of the drag results obtained on the 2 microm device indicates a power-law temperature dependence of drag for both identical and non-identical wires. Also drag is found to decay exponentially with the mismatch between the wires. These properties indicate the existence of Luttinger liquid (LL) state in the long wire device. We have observed positive and negative drags on short wire devices. The observed temperature dependence of drag resistance, for both positive and negative drags, shows first an increase, followed by a constant plateau and finally a decrease as the temperature is increased. This is in line with the predictions of the Fermi--Luttinger liquid (FLL) forward momentum transfer theory. This is the first experimental observation of 1D Coulomb drag due to forward momentum transfer between wires. A negative drag between same type of carriers (holes or electrons) may conceivably result from forward momentum transfer or forward scattering if the band curvature of the drag wire at or near the Fermi point is negative. Negative band curvature may result from asymmetry
Coulomb drag between one-dimensional electron systems
NASA Astrophysics Data System (ADS)
Muhammad, Mustafa
We have measured Coulomb drag (CD) between two spatially separated and electrically isolated one-dimensional (1D) wires to study the Luttinger liquid (LL) state in 1D systems. We have fabricated dual-wire CD devices with long quantum wires (≥ 1 mum) and short quantum wires (≤ 500 nm) with respect to the thermal lengths. The devices are made from high-mobility (≅106cm2/Vs) two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures, using high-resolution e-beam lithography, combined with metal deposition by e-beam evaporation to form surface Schottky gates. Peak in drag voltage occurs when the subband bottoms of the lowest energy subbands of the drive and the drag wires line up with each other and the Fermi level. We have observed drag on 1 mum device at 22 mK temperature which is found to be reminiscent of the drag observed earlier on a 2 mum device. An extensive reanalysis of the drag results obtained on the 2 mum device indicates a power-law temperature dependence of drag for both identical and non-identical wires. Also drag is found to decay exponentially with the mismatch between the wires. These properties indicate the existence of Luttinger liquid (LL) state in the long wire device. We have observed positive and negative drags on short wire devices. The observed temperature dependence of drag resistance, for both positive and negative drags, shows first an increase, followed by a constant plateau and finally a decrease as the temperature is increased. This is in line with the predictions of the Fermi-Luttinger liquid (FLL) forward momentum transfer theory. This is the first experimental observation of 1D Coulomb drag due to forward momentum transfer between wires. A negative drag between same type of carriers (holes or electrons) may conceivably result from forward momentum transfer or forward scattering if the band curvature of the drag wire at or near the Fermi point is negative. Negative band curvature may result from asymmetry in the wire
Extending the Analysis of One-Dimensional Motion.
ERIC Educational Resources Information Center
Canderle, Luis H.
1999-01-01
Proposes that introductory physics courses extend the analysis of one-dimensional motion to a more sophisticated level. Gives four experimental setups and graphical analysis of the distance, velocity, and acceleration in the vertical and horizontal directions. (WRM)
Asymptotic formula for eigenvalues of one dimensional Dirac system
NASA Astrophysics Data System (ADS)
Ulusoy, Ismail; Penahlı, Etibar
2016-06-01
In this paper, we study the spectral problem for one dimensional Dirac system with Dirichlet boundary conditions. By using Counting lemma, we give an asymptotic formulas of eigenvalues of Dirac system.
Synthetic magnetic fluxes and topological order in one-dimensional spin systems
NASA Astrophysics Data System (ADS)
Graß, Tobias; Muschik, Christine; Celi, Alessio; Chhajlany, Ravindra W.; Lewenstein, Maciej
2015-06-01
Engineering topological quantum order has become a major field of physics. Many advances have been made by synthesizing gauge fields in cold atomic systems. Here we carry over these developments to other platforms which are extremely well suited for quantum engineering, namely, trapped ions and nano-trapped atoms. Since these systems are typically one-dimensional, the action of artificial magnetic fields has so far received little attention. However, exploiting the long-range nature of interactions, loops with nonvanishing magnetic fluxes become possible even in one-dimensional settings. This gives rise to intriguing phenomena, such as fractal energy spectra, flat bands with localized edge states, and topological many-body states. We elaborate on a simple scheme for generating the required artificial fluxes by periodically driving an XY spin chain. Concrete estimates demonstrating the experimental feasibility for trapped ions and atoms in wave guides are given.
Superfluid–insulator transition in strongly disordered one-dimensional systems
NASA Astrophysics Data System (ADS)
Yao, Zhiyuan; Pollet, Lode; Prokof’ev, N.; Svistunov, B.
2016-04-01
We present an asymptotically exact renormalization-group theory of the superfluid–insulator transition in one-dimensional (1D) disordered systems, with emphasis on an accurate description of the interplay between the Giamarchi–Schulz (instanton–anti-instanton) and weak-link (scratched-XY) criticalities. Combining the theory with extensive quantum Monte Carlo simulations allows us to shed new light on the ground-state phase diagram of the 1D disordered Bose–Hubbard model at unit filling.
Strong-coupling ansatz for the one-dimensional Fermi gas in a harmonic potential
Levinsen, Jesper; Massignan, Pietro; Bruun, Georg M.; Parish, Meera M.
2015-01-01
A major challenge in modern physics is to accurately describe strongly interacting quantum many-body systems. One-dimensional systems provide fundamental insights because they are often amenable to exact methods. However, no exact solution is known for the experimentally relevant case of external confinement. We propose a powerful ansatz for the one-dimensional Fermi gas in a harmonic potential near the limit of infinite short-range repulsion. For the case of a single impurity in a Fermi sea, we show that our ansatz is indistinguishable from numerically exact results in both the few- and many-body limits. We furthermore derive an effective Heisenberg spin-chain model corresponding to our ansatz, valid for any spin-mixture, within which we obtain the impurity eigenstates analytically. In particular, the classical Pascal’s triangle emerges in the expression for the ground-state wave function. As well as providing an important benchmark for strongly correlated physics, our results are relevant for emerging quantum technologies, where a precise knowledge of one-dimensional quantum states is paramount. PMID:26601220
Studying non-equilibrium many-body dynamics using one-dimensional Bose gases
Langen, Tim; Gring, Michael; Kuhnert, Maximilian; Rauer, Bernhard; Geiger, Remi; Mazets, Igor; Smith, David Adu; Schmiedmayer, Jörg; Kitagawa, Takuya; Demler, Eugene
2014-12-04
Non-equilibrium dynamics of isolated quantum many-body systems play an important role in many areas of physics. However, a general answer to the question of how these systems relax is still lacking. We experimentally study the dynamics of ultracold one-dimensional (1D) Bose gases. This reveals the existence of a quasi-steady prethermalized state which differs significantly from the thermal equilibrium of the system. Our results demonstrate that the dynamics of non-equilibrium quantum many-body systems is a far richer process than has been assumed in the past.
The nature of one-dimensional carbon: polyynic versus cumulenic.
Neiss, Christian; Trushin, Egor; Görling, Andreas
2014-08-25
A question of both fundamental as well as practical importance is the nature of one-dimensional carbon, in particular whether a one-dimensional carbon allotrope is polyynic or cumulenic, that is, whether bond-length alternation occurs or not. By combining the concept of aromaticity and antiaromaticity with the rule of Peierls distortion, the occurrence and magnitude of bond-length alternation in carbon chains with periodic boundary conditions and corresponding carbon rings as a function of the chain or ring length can be explained. The electronic properties of one-dimensional carbon depend crucially on the bond-length alternation. Whereas it is generally accepted that carbon chains in the limit of infinite length have a polyynic structure at the minimum of the potential energy surface with bond-length alternation, we show here that zero-point vibrations lead to an effective equalization of all carbon-carbon bond lengths and thus to a cumulenic structure. PMID:24962252
One-dimensional rainbow technique using Fourier domain filtering.
Wu, Yingchun; Promvongsa, Jantarat; Wu, Xuecheng; Cen, Kefa; Grehan, Gerard; Saengkaew, Sawitree
2015-11-16
Rainbow refractometry can measure the refractive index and the size of a droplet simultaneously. The refractive index measurement is extracted from the absolute rainbow scattering angle. Accordingly, the angular calibration is vital for accurate measurements. A new optical design of the one-dimensional rainbow technique is proposed by using a one-dimensional spatial filter in the Fourier domain. The relationship between the scattering angle and the CCD pixel of a recorded rainbow image can be accurately determined by a simple calibration. Moreover, only the light perpendicularly incident on the lens in the angle (φ) direction is selected, which exactly matches the classical inversion algorithm used in rainbow refractometry. Both standard and global one-dimensional rainbow techniques are implemented with the proposed optical design, and are successfully applied to measure the refractive index and the size of a line of n-heptane droplets. PMID:26698532
One-Dimensional Quasicrystals from Incommensurate Charge Order
NASA Astrophysics Data System (ADS)
Flicker, Felix; van Wezel, Jasper
2015-12-01
Artificial quasicrystals are nowadays routinely manufactured, yet only two naturally occurring examples are known. We present a class of systems with the potential to be realized both artificially and in nature, in which the lowest energy state is a one-dimensional quasicrystal. These systems are based on incommensurately charge-ordered materials, in which the quasicrystalline phase competes with the formation of a regular array of discommensurations as a way of interpolating between incommensurate charge order at high temperatures and commensurate order at low temperatures. The nonlocal correlations characteristic of the quasicrystalline state emerge from a free-energy contribution localized in reciprocal space. We present a theoretical phase diagram showing that the required material properties for the appearance of such a ground state allow for one-dimensional quasicrystals to form in real materials. The result is a potentially wide class of one-dimensional quasicrystals.
One dimensional speckle fields generated by three phase level diffusers
NASA Astrophysics Data System (ADS)
Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.
2015-02-01
Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged.
Pose estimation for one-dimensional object with general motion
NASA Astrophysics Data System (ADS)
Liu, Jinbo; Song, Ge; Zhang, Xiaohu
2014-11-01
Our primary interest is in real-time one-dimensional object's pose estimation. In this paper, a method to estimate general motion one-dimensional object's pose, that is, the position and attitude parameters, using a single camera is proposed. Centroid-movement is necessarily continuous and orderly in temporal space, which means it follows at least approximately certain motion law in a short period of time. Therefore, the centroid trajectory in camera frame can be described as a combination of temporal polynomials. Two endpoints on one-dimensional object, A and B, at each time are projected on the corresponding image plane. With the relationship between A, B and centroid C, we can obtain a linear equation system related to the temporal polynomials' coefficients, in which the camera has been calibrated and the image coordinates of A and B are known. Then in the cases that object moves continuous in natural temporal space within the view of a stationary camera, the position of endpoints on the one-dimensional object can be located and also the attitude can be estimated using two end points. Moreover the position of any other point aligned on one-dimensional object can also be solved. Scene information is not needed in the proposed method. If the distance between the endpoints is not known, a scale factor between the object's real positions and the estimated results will exist. In order to improve the algorithm's performance from accuracy and robustness, we derive a pain of linear and optimal algorithms. Simulations' and experiments' results show that the method is valid and robust with respect to various Gaussian noise levels. The paper's work contributes to making self-calibration algorithms using one-dimensional objects applicable to practice. Furthermore, the method can also be used to estimate the pose and shape parameters of parallelogram, prism or cylinder objects.
Fabrication, device assembly, and application of one-dimensional chalcogenides nanostructures
NASA Astrophysics Data System (ADS)
Kum, Maxwell Chun Man
Nanotechnology has received a tremendous amount of research interests ever since the first discovery of carbon nanotubes. One-dimensional nanostructures, such as nanorods, nanowires, nanobelts as well as nanotubes, are of significant interest because of their potential application as interconnects and functional units in nanoscale electrical, optoelectronic, electrochemical, electromechanical, thermoelectric, spintronic, photovoltaic, and sensory devices. Nanoscale one-dimensional devices promise to deliver improved performance, to miniaturize bulky devices, to enable higher density nanoscale devices, and to lower energy consumption. As the radius of these one-dimensional nanostructures fall below the exciton Bohr radius of their respective materials, the structural morphology and size effectively modulates the fundamental electrical, optical, and magnetic properties due to quantum confinement effect. In addition, the high surface to volume ratio of one-dimensional nanostructures enables the device properties to be extremely sensitivity to the environment which is particularly attractive for sensing application. Currently, the focuses of nanotechnology research are (1) the fabrication technique with control over the composition, crystal structure, morphology, and size, (2) the device assembly of nanostructures into complex functional devices, and (3) the characterization and application of these nanoscale devices. There are a multitude of fabrication techniques for one-dimensional nanostructures, including but not exclusively, vapor-solid, vapor-liquid-solid, colloidal, solution-liquid-solid, self-assembly, and template directed electrodeposition. As one-dimensional nanostructures are produced, several techniques are available to assemble them into functional complex nanoscale devices, including but not exclusively, electron beam lithography, focus ion beam, magnetic assembly, and AC dielectrophoretic alignment. In this work, one-dimensional cadmium telluride (Cd
Hybrid surface-relief/volume one dimensional holographic gratings
NASA Astrophysics Data System (ADS)
Lucchetta, D. E.; Spegni, P.; Di Donato, A.; Simoni, F.; Castagna, R.
2015-04-01
Many one dimensional optically patterned photopolymers exist as surface relief or volume phase gratings. However, as far as we know, holographically recorded acrylate-based gratings in which both configurations are present are not described in literature. In this work we report a two steps fabrication process in which a large-area high-resolution hybrid volume/surface relief grating phase gratings is created in a thin film of multiacrylate material spinned on a proper designed substrate. Optical and morphological investigations, made on the optically patterned area, confirm the presence of a one dimensional double (surface relief and Bragg volume phase) periodic structure.
Lateral electronic screening in quasi-one-dimensional plasmons.
Lichtenstein, T; Tegenkamp, C; Pfnür, H
2016-09-01
The properties of one-dimensional (1D) plasmons are rather unexplored. We investigated the plasmonic collective excitations, measured as one-dimensional plasmon dispersions with electron energy loss spectroscopy, highly resolved both in energy and lateral momentum, for both phases of Au induced chains on stepped Si(553) substrates. We observe 1D dispersions that are strongly influenced by the lateral chain width and by the interchain coupling. Indications for the existence of two different plasmons originating from two surface bands of the systems are given for the low coverage phase. PMID:27384978
Lateral electronic screening in quasi-one-dimensional plasmons
NASA Astrophysics Data System (ADS)
Lichtenstein, T.; Tegenkamp, C.; Pfnür, H.
2016-09-01
The properties of one-dimensional (1D) plasmons are rather unexplored. We investigated the plasmonic collective excitations, measured as one-dimensional plasmon dispersions with electron energy loss spectroscopy, highly resolved both in energy and lateral momentum, for both phases of Au induced chains on stepped Si(553) substrates. We observe 1D dispersions that are strongly influenced by the lateral chain width and by the interchain coupling. Indications for the existence of two different plasmons originating from two surface bands of the systems are given for the low coverage phase.
Explicit solutions of one-dimensional total variation problem
NASA Astrophysics Data System (ADS)
Makovetskii, Artyom; Voronin, Sergei; Kober, Vitaly
2015-09-01
This work deals with denosing of a one-dimensional signal corrupted by additive white Gaussian noise. A common way to solve the problem is to utilize the total variation (TV) method. Basically, the TV regularization minimizes a functional consisting of the sum of fidelity and regularization terms. We derive explicit solutions of the one-dimensional TV regularization problem that help us to restore noisy signals with a direct, non-iterative algorithm. Computer simulation results are provided to illustrate the performance of the proposed algorithm for restoration of noisy signals.
Photon transport in a one-dimensional nanophotonic waveguide QED system
NASA Astrophysics Data System (ADS)
Liao, Zeyang; Zeng, Xiaodong; Nha, Hyunchul; Zubairy, M. Suhail
2016-06-01
The waveguide quantum electrodynamics (QED) system may have important applications in quantum device and quantum information technology. In this article we review the methods being proposed to calculate photon transport in a one-dimensional (1D) waveguide coupled to quantum emitters. We first introduce the Bethe ansatz approach and the input–output formalism to calculate the stationary results of a single photon transport. Then we present a dynamical time-dependent theory to calculate the real-time evolution of the waveguide QED system. In the longtime limit, both the stationary theory and the dynamical calculation give the same results. Finally, we also briefly discuss the calculations of the multiphoton transport problems.
Compressed simulation of thermal and excited states of the one-dimensional X Y model
NASA Astrophysics Data System (ADS)
Boyajian, W. L.; Kraus, B.
2015-09-01
Since several years, the preparation and manipulation of a small number of quantum systems in a controlled and coherent way is feasible in many experiments. In fact, these experiments are nowadays commonly used for quantum simulation and quantum computation. As recently shown, such a system can, however, also be utilized to simulate specific behaviors of exponentially larger systems. That is, certain quantum computations can be performed by an exponentially smaller quantum computer. This compressed quantum computation can be employed to observe, for instance, the quantum phase transition of the one-dimensional (1D) X Y model using very few qubits. We extend here this notion to simulate the behavior of thermal as well as excited states of the 1D X Y model. In particular, we consider the 1D X Y model of a spin chain of n qubits and derive a quantum circuit processing only log(n ) qubits which simulates the original system. We demonstrate how the behavior of thermal as well as any eigenstate of the system can be efficiently simulated in this compressed fashion and present a quantum circuit on log(n ) qubits to measure the magnetization, the number of kinks, and correlations occurring in the thermal as well as any excited state of the original systems. Moreover, we derive compressed circuits to study time evolutions.
Minimum critical length for superconductivity in one-dimensional wires
Chi, C.C.; Santhanam, P.; Wind, S.J.; Brady, M.J.; Bucchignano, J.J. )
1994-08-01
We have experimentally studied the superconducting behavior of one-dimensional aluminum wires of various lengths. Each wire had much wider two-dimensional contact pads on both sides. At a temperature [ital T] below [ital T][sub [ital c
Underwater striling engine design with modified one-dimensional model
NASA Astrophysics Data System (ADS)
Li, Daijin; Qin, Kan; Luo, Kai
2015-09-01
Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs) is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA). The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.
Underwater striling engine design with modified one-dimensional model
NASA Astrophysics Data System (ADS)
Li, Daijin; Qin, Kan; Luo, Kai
2015-05-01
Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs) is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA). The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.
Approximate Approaches to the One-Dimensional Finite Potential Well
ERIC Educational Resources Information Center
Singh, Shilpi; Pathak, Praveen; Singh, Vijay A.
2011-01-01
The one-dimensional finite well is a textbook problem. We propose approximate approaches to obtain the energy levels of the well. The finite well is also encountered in semiconductor heterostructures where the carrier mass inside the well (m[subscript i]) is taken to be distinct from mass outside (m[subscript o]). A relevant parameter is the mass…
A difference characteristic for one-dimensional deterministic systems
NASA Astrophysics Data System (ADS)
Shahverdian, A. Yu.; Apkarian, A. V.
2007-06-01
A numerical characteristic for one-dimensional deterministic systems reflecting its higher order difference structure is introduced. The comparison with Lyapunov exponent is given. A difference analogy for Eggleston theorem as well as an estimate for Hausdorff dimension of the difference attractor, formulated in terms of the new characteristic is proved.
Teaching Module for One-Dimensional, Transient Conduction.
ERIC Educational Resources Information Center
Ribando, Robert J.; O'Leary, Gerald W.
1998-01-01
Describes a PC-based teaching module designed to instruct engineering students in transient one-dimensional conduction heat transfer analysis. The discussion considers problem formulation, nondimensionalization, discretization, numerical stability and the time-step restriction, program operation, and program verification. (MES)
Synchronization of One-Dimensional Stochastically Coupled Cellular Automata
NASA Astrophysics Data System (ADS)
Mrowinski, Maciej J.; Kosinski, Robert A.
In this work the authors study synchronization resulting from the asymmetric stochastic coupling between two one-dimensional chaotic cellular automata and provide a simple analytical model to explain this phenomenon. The authors also study synchronization in a more general case, using sets of rules with a different number of states and different values of Langton's parameter λ.
The Long Decay Model of One-Dimensional Projectile Motion
ERIC Educational Resources Information Center
Lattery, Mark Joseph
2008-01-01
This article introduces a research study on student model formation and development in introductory mechanics. As a point of entry, I present a detailed analysis of the Long Decay Model of one-dimensional projectile motion. This model has been articulated by Galileo ("in De Motu") and by contemporary students. Implications for instruction are…
Transition density of one-dimensional diffusion with discontinuous drift
NASA Technical Reports Server (NTRS)
Zhang, Weijian
1990-01-01
The transition density of a one-dimensional diffusion process with a discontinuous drift coefficient is studied. A probabilistic representation of the transition density is given, illustrating the close connections between discontinuities of the drift and Brownian local times. In addition, some explicit results are obtained based on the trivariate density of Brownian motion, its occupation, and local times.
One-Dimensional Ising Model with "k"-Spin Interactions
ERIC Educational Resources Information Center
Fan, Yale
2011-01-01
We examine a generalization of the one-dimensional Ising model involving interactions among neighbourhoods of "k" adjacent spins. The model is solved by exploiting a connection to an interesting computational problem that we call ""k"-SAT on a ring", and is shown to be equivalent to the nearest-neighbour Ising model in the absence of an external…
Sandia One-Dimensional Direct and Inverse Thermal Code
1995-02-27
SODDIT is a reliable tool for solving a wide variety of one-dimensional transient heat conduction problems. Originally developed in 1972 to predict the ablation of graphite/carbon bodies reentering the earth''s atmosphere, it has since been modified by the authors to extend its capabilities well beyond its original scope.
Zero-n gap in one dimensional photonic crystal
NASA Astrophysics Data System (ADS)
Chobey, Mahesh K.; Suthar, B.
2016-05-01
We study a one-dimensional (1-D) photonic crystal composed of Double Positive (DPS) and Double Negative (DNG) material. This structure shows omnidirectional photonic bandgap, which is insensitive with angle of incidence and polarization. To study the effect of structural parameters on the photonic band structure, we have calculated photonic band gap at various thicknesses of DPS and DNG.
Exact Results for One Dimensional Fluids Through Functional Integration
NASA Astrophysics Data System (ADS)
Fantoni, Riccardo
2016-06-01
We review some of the exactly solvable one dimensional continuum fluid models of equilibrium classical statistical mechanics under the unified setting of functional integration in one dimension. We make some further developments and remarks concerning fluids with penetrable particles. We then apply our developments to the study of the Gaussian core model for which we are unable to find a well defined thermodynamics.
Reflection properties of one dimensional plasma photonic crystal
NASA Astrophysics Data System (ADS)
Kumar, Arun; Khundrakpam, Pinky; Sharma, Priyanka
2013-06-01
In this paper band structure and reflection properties of on one-dimensional plasma photonic crystal (PPC) containing alternate layers of dielectric and micro-plasma have been presented. For the purpose of computation, transfer matrix method has been used. It is found that width of the forbidden band gap(s) can be increased by increasing the thickness of plasma layers.
PREMIXED ONE-DIMENSIONAL FLAME (PROF) CODE USER'S MANUAL
The report is a user's manual that describes the problems that can be treated by the Premixed One-dimensional Flame (PROF) code. It also describes the mathematical models and solution procedures applied to these problems. Complete input instructions and a description of output ar...
One-Dimensional SO2 Predictions for Duct Injection
1993-10-05
DIAN1D is a one-dimensional model that predicts SO2 absorption by slurry droplets injected into a flue gas stream with two-fluid atomizers. DIANUI is an interactive user interface for DIAN1D. It prepares the input file for DIAN1D from plant design specifications and process requirements.
Toward precise solution of one-dimensional velocity inverse problems
Gray, S.; Hagin, F.
1980-01-01
A family of one-dimensional inverse problems are considered with the goal of reconstructing velocity profiles to reasonably high accuracy. The travel-time variable change is used together with an iteration scheme to produce an effective algorithm for computation. Under modest assumptions the scheme is shown to be convergent.
NASA Astrophysics Data System (ADS)
Seadawy, Aly R.
2015-12-01
The propagation of dust-ion-acoustic waves with high-energy electrons and positrons in three-dimensional is considered. The Zakharov-Kuznetsov-Burgers (ZKB) equations for the dust-ion-acoustic waves in dusty plasmas is obtained. The conservations laws and integrals of motion for the ZKB equation are deduced. In the present study, by applying the modified direct algebraic method, we found the electric field potential, electric field and quantum statistical pressure in form water wave solutions for three-dimensional ZKB equation. The solutions for the ZKB equation are obtained precisely and efficiency of the method can be demonstrated. The stability of the obtained solutions and the movement role of the waves by making the graphs of the exact solutions are discussed and analyzed.
Reformulating the Schroedinger equation as a Shabat-Zakharov system
Boonserm, Petarpa; Visser, Matt
2010-02-15
We reformulate the second-order Schroedinger equation as a set of two coupled first-order differential equations, a so-called 'Shabat-Zakharov system' (sometimes called a 'Zakharov-Shabat' system). There is considerable flexibility in this approach, and we emphasize the utility of introducing an 'auxiliary condition' or 'gauge condition' that is used to cut down the degrees of freedom. Using this formalism, we derive the explicit (but formal) general solution to the Schroedinger equation. The general solution depends on three arbitrarily chosen functions, and a path-ordered exponential matrix. If one considers path ordering to be an 'elementary' process, then this represents complete quadrature, albeit formal, of the second-order linear ordinary differential equation.
Properties of one-dimensional molybdenum nanowires in a confined environment
Sumpter, Bobby G; Meunier, Vincent; Muramatsu, H; Hayashi, T; Kim, Y A; Shimamoto, Daisuke; Terrones Maldonado, Humberto; Dresselhaus, M; Terrones Maldonado, Mauricio; Endo, M
2009-01-01
The atomistic mechanism for the self-assembly of molybdenum into one-dimensional metallic nanowires in a confined environment such as a carbon nanotube is investigated using quantum mechanical calculations. We find that Mo does not organize into linear chains but rather prefers to form four atom per unit-cell nanowires that consist of a subunit of a Mo-BCC crystal. Our model explains the 0.3 nm separation between features measured by high-resolution transmission electron microscopy and why the nanotube diameter must be in the 0.70 - 1.0 nm range to accommodate the smallest stable one-dimensional wire. We also computed the electronic band-structure of the Mo wires inside a nanotube and found significant hybridization with the nanotube states, thereby explaining the experimentally observed quenching of fluorescence and the damping of the radial breathing modes as well as an increased resistance to oxidation.
Scattering of two coherent photons inside a one-dimensional coupled-resonator waveguide
Alexanian, Moorad
2010-01-15
We consider the coherent propagation of n photons in a one-dimensional coupled-resonator waveguide for n=2,3,4.... The scattering by a three-level atom, which resides in one of the resonators of the waveguide and gives rise to only two-photon transitions, results in a perfect quantum switch that allows either total reflection or total transmission. This is to be contrasted to the case of a single photon inside a one-dimensional resonant waveguide scattered by a two-level system with single-photon transitions where only total reflection can be accomplished; viz. the system behaves only as a perfect mirror but not as an ideal, transparent medium.
All-optical electromagnetically induced transparency using one-dimensional coupled microcavities.
Naweed, Ahmer; Goldberg, David; Menon, Vinod M
2014-07-28
We report the first experimental realization of all-optical electromagnetically induced transparency (EIT) via a pair of coherently interacting SiO2 microcavities in a one-dimensional SiO2/Si3N4 photonic crystal consisting of a distributed Bragg reflector (DBR). The electromagnetic interactions between the coupled microcavities (CMCs), which possess distinct Q-factors, are controlled by varying the number of embedded SiO2/Si3N4 bilayers in the coupling DBR. In case of weak microcavity interactions, the reflectivity spectrum reveals an all-optical EIT resonance which splits into an Autler-Townes-like resonance under condition of strong microcavity coupling. Our results open up the way for implementing optical analogs of quantum coherence in much simpler one-dimensional structures. We also discuss potential applications of CMCs. PMID:25089499
Song, Hongwei; Pan, Guohui; Bai, Xue; Li, Suwen; Yu, Hongquan; Zhang, Hui
2008-03-01
One-dimensional nanosized phosphors demonstrate special structural and photoluminescence properties, which have application potential in some optical fields. In this article, we present our recent progress on preparation and luminescence properties of some one-dimensional rare earth compounds and complexes, the core-shell oxide nanowires prepared by a two-step hydrothermal route, the nanowires of some inorganic compounds doped with rare earths and rare earth complexes/PVP composites prepared by the electrospinning method, and the rare earth complexes in the SBA-15 mesoporous molecule sieves. In these systems, some novel or improved photoluminescence properties are observed such as improved luminescence quantum yield, thermal stability and/or photostability, and depressed thermal effect in upconversion luminescence. PMID:18468146
Zakharov simulations of beam-induced turbulence in the auroral ionosphere
NASA Astrophysics Data System (ADS)
Akbari, H.; Guio, P.; Hirsch, M. A.; Semeter, J. L.
2016-05-01
Recent detections of strong incoherent scatter radar echoes from the auroral F region, which have been explained as the signature of naturally produced Langmuir turbulence, have motivated us to revisit the topic of beam-generated Langmuir turbulence via simulation. Results from one-dimensional Zakharov simulations are used to study the interaction of ionospheric electron beams with the background plasma at the F region peak. A broad range of beam parameters extending by more than 2 orders of magnitude in average energy and electron number density is considered. A range of wave interaction processes, from a single parametric decay, to a cascade of parametric decays, to formation of stationary density cavities in the condensate region, and to direct collapse at the initial stages of turbulence, is observed as we increase the input energy to the system. The effect of suprathermal electrons, produced by collisional interactions of auroral electrons with the neutral atmosphere, on the dynamics of Langmuir turbulence is also investigated. It is seen that the enhanced Landau damping introduced by the suprathermal electrons significantly weakens the turbulence and truncates the cascade of parametric decays.
Statistics of extreme waves in the framework of one-dimensional Nonlinear Schrodinger Equation
NASA Astrophysics Data System (ADS)
Agafontsev, Dmitry; Zakharov, Vladimir
2013-04-01
time. In case of the cnoidal wave initial condition we observe severely non-Rayleigh PDFs for the classical NLS equation (1) with the regions corresponding to 2-, 3- and so on soliton collisions clearly seen of the PDFs. Addition of six-wave interactions in Eq. (2) for condensate initial condition results in appearance of non-Rayleigh addition to the PDFs that increase with six-wave interaction constant α and disappears with the absence of six-wave interactions α = 0. References: [1] D.S. Agafontsev, V.E. Zakharov, Rogue waves statistics in the framework of one-dimensional Generalized Nonlinear Schrodinger Equation, arXiv:1202.5763v3.
Excitonic condensation in spatially separated one-dimensional systems
Abergel, D. S. L.
2015-05-25
We show theoretically that excitons can form from spatially separated one-dimensional ground state populations of electrons and holes, and that the resulting excitons can form a quasicondensate. We describe a mean-field Bardeen-Cooper-Schrieffer theory in the low carrier density regime and then focus on the core-shell nanowire giving estimates of the size of the excitonic gap for InAs/GaSb wires and as a function of all the experimentally relevant parameters. We find that optimal conditions for pairing include small overlap of the electron and hole bands, large effective mass of the carriers, and low dielectric constant of the surrounding media. Therefore, one-dimensional systems provide an attractive platform for the experimental detection of excitonic quasicondensation in zero magnetic field.
Pairing correlations in a trapped one-dimensional Fermi gas
NASA Astrophysics Data System (ADS)
Kudla, Stephen; Gautreau, Dominique M.; Sheehy, Daniel E.
2015-04-01
We use a BCS-type variational wave function to study attractively interacting quasi-one-dimensional fermionic atomic gases, motivated by cold-atom experiments that access the one-dimensional regime using an anisotropic harmonic trapping potential (with trapping frequencies ωx=ωy≫ωz ) that confines the gas to a cigar-shaped geometry. To handle the presence of the trap along the z direction, we construct our variational wave function from the harmonic oscillator Hermite functions, which are the eigenstates of the single-particle problem. Using an analytic determination of the effective interaction among harmonic oscillator states along with a numerical solution of the resulting variational equations, we make specific experimental predictions for how pairing correlations would be revealed in experimental probes, such as the local density and the momentum correlation function.
Scaling properties of one-dimensional driven-dissipative condensates
NASA Astrophysics Data System (ADS)
He, Liang; Sieberer, Lukas M.; Altman, Ehud; Diehl, Sebastian
2015-10-01
We numerically investigate the scaling properties of a one-dimensional driven-dissipative condensate described by a stochastic complex Ginzburg-Landau equation (SCGLE). We directly extract the static and dynamical scaling exponents from the dynamics of the condensate's phase field, and find that both coincide with the ones of the one-dimensional Kardar-Parisi-Zhang (KPZ) equation. We furthermore calculate the spatial and the temporal two-point correlation functions of the condensate field itself. The decay of the temporal two-point correlator assumes a stretched-exponential form, providing further quantitative evidence for an effective KPZ description. Moreover, we confirm the observability of this nonequilibrium scaling for typical current experimental setups with exciton-polariton systems, if cavities with a reduced Q factor are used.
Dynamics of one-dimensional Kerr cavity solitons.
Leo, François; Gelens, Lendert; Emplit, Philippe; Haelterman, Marc; Coen, Stéphane
2013-04-01
We present an experimental observation of an oscillating Kerr cavity soliton, i.e., a time-periodic oscillating one-dimensional temporally localized structure excited in a driven nonlinear fiber cavity with a Kerr-type nonlinearity. More generally, these oscillations result from a Hopf bifurcation of a (spatially or temporally) localized state in the generic class of driven dissipative systems close to the 1 : 1 resonance tongue. Furthermore, we theoretically analyze dynamical instabilities of the one-dimensional cavity soliton, revealing oscillations and different chaotic states in previously unexplored regions of parameter space. As cavity solitons are closely related to Kerr frequency combs, we expect these dynamical regimes to be highly relevant for the field of microresonator-based frequency combs. PMID:23572006
Spatial coherence properties of one dimensional exciton-polariton condensates.
Fischer, J; Savenko, I G; Fraser, M D; Holzinger, S; Brodbeck, S; Kamp, M; Shelykh, I A; Schneider, C; Höfling, S
2014-11-14
In this work, we combine a systematic experimental investigation of the power- and temperature-dependent evolution of the spatial coherence function, g^{(1)}(r), in a one dimensional exciton-polariton channel with a modern microscopic numerical theory based on a stochastic master equation approach. The spatial coherence function g^{(1)}(r) is extracted via high-precision Michelson interferometry, which allows us to demonstrate that in the regime of nonresonant excitation, the dependence g^{(1)}(r) reaches a saturation value with a plateau, which is determined by the intensity of the pump and effective temperature of the crystal lattice. The theory, which was extended to allow for treating incoherent excitation in a stochastic frame, matches the experimental data with good qualitative and quantitative agreement. This allows us to verify the prediction that the decay of the off-diagonal long-range order can be almost fully suppressed in one dimensional condensate systems. PMID:25432043
One-dimensional Hubbard-Luttinger model for carbon nanotubes
NASA Astrophysics Data System (ADS)
Ishkhanyan, H. A.; Krainov, V. P.
2015-06-01
A Hubbard-Luttinger model is developed for qualitative description of one-dimensional motion of interacting Pi-conductivity-electrons in carbon single-wall nanotubes at low temperatures. The low-lying excitations in one-dimensional electron gas are described in terms of interacting bosons. The Bogolyubov transformation allows one to describe the system as an ensemble of non-interacting quasi-bosons. Operators of Fermi excitations and Green functions of fermions are introduced. The electric current is derived as a function of potential difference on the contact between a nanotube and a normal metal. Deviations from Ohm law produced by electron-electron short-range repulsion as well as by the transverse quantization in single-wall nanotubes are discussed. The results are compared with experimental data.
Versatile hydrothermal synthesis of one-dimensional composite structures
NASA Astrophysics Data System (ADS)
Luo, Yonglan
2008-12-01
In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.
Assessing the inherent uncertainty of one-dimensional diffusions
NASA Astrophysics Data System (ADS)
Eliazar, Iddo; Cohen, Morrel H.
2013-01-01
In this paper we assess the inherent uncertainty of one-dimensional diffusion processes via a stochasticity classification which provides an à la Mandelbrot categorization into five states of uncertainty: infra-mild, mild, borderline, wild, and ultra-wild. Two settings are considered. (i) Stopped diffusions: the diffusion initiates from a high level and is stopped once it first reaches a low level; in this setting we analyze the inherent uncertainty of the diffusion's maximal exceedance above its initial high level. (ii) Stationary diffusions: the diffusion is in dynamical statistical equilibrium; in this setting we analyze the inherent uncertainty of the diffusion's equilibrium level. In both settings general closed-form analytic results are established, and their application is exemplified by stock prices in the stopped-diffusions setting, and by interest rates in the stationary-diffusions setting. These results provide a highly implementable decision-making tool for the classification of uncertainty in the context of one-dimensional diffusions.
One-dimensional XY model: Ergodic properties and hydrodynamic limit
NASA Astrophysics Data System (ADS)
Shuhov, A. G.; Suhov, Yu. M.
1986-11-01
We prove theorems on convergence to a stationary state in the course of time for the one-dimensional XY model and its generalizations. The key point is the well-known Jordan-Wigner transformation, which maps the XY dynamics onto a group of Bogoliubov transformations on the CAR C *-algebra over Z 1. The role of stationary states for Bogoliubov transformations is played by quasifree states and for the XY model by their inverse images with respect to the Jordan-Wigner transformation. The hydrodynamic limit for the one-dimensional XY model is also considered. By using the Jordan-Wigner transformation one reduces the problem to that of constructing the hydrodynamic limit for the group of Bogoliubov transformations. As a result, we obtain an independent motion of "normal modes," which is described by a hyperbolic linear differential equation of second order. For the XX model this equation reduces to a first-order transfer equation.
Improving the One Dimensional Schr"odinger Equation
NASA Astrophysics Data System (ADS)
Schorer, Bradley; Bricher, Stephen; Murray, Joelle
2009-05-01
The simple harmonic oscillator (SHO) model is a useful approach for approximating energies close to the ground state in a one dimensional hydrogen atom. According to empirical evidence, the actual potential results in an asymmetric equilibrium point and exhibits and exhibits asymptotic behavior at large distances from the nucleus. This creates a problem in the SHO model, as it does not possess such characteristics, and as a result, has energy values that do not match do not agree with the known energy levels very well. We propose a new one dimensional potential that more accurately fits the empirical data than the SHO model. We test our model by comparing the Schr"odinger equation's energy states to accepted energy levels of the hydrogen atom. Possible other uses for this model include the description of energy levels of atoms other than the hydrogen atom.
Entanglement vs. gap for one-dimensional spin systems
Hastings, Matthew; Aharonov, Dorit; Gottesman, Daniel
2008-01-01
We study the relationship between entanglement and spectral gap for local Hamiltonians in one dimension. The area law for a one-dimensional system states that for the ground state, the entanglement of any interval is upper-bounded by a constant independent of the size of the interval. However, the possible dependence of the upper bound on the spectral gap {Delta} is not known, as the best known general upper bound is asymptotically much larger than the largest possible entropy of any model system previously constructed for small {Delta}. To help resolve this asymptotic behavior, we construct a family of one-dimensional local systems for which some intervals have entanglement entropy which is polynomial in 1/{Delta}, whereas previously studied systems had the entropy of all intervals bounded by a constant times log(1/{Delta}).
Defects in a nonlinear pseudo one-dimensional solid
NASA Astrophysics Data System (ADS)
Blanchet, Graciela B.; Fincher, C. R., Jr.
1985-03-01
These infrared studies of acetanilide together with the existence of two equivalent structures for the hydrogen-bonded chain suggest the possibility of a topological defect state rather than a Davydov soliton as suggested previously. Acetanilide is an example of a class of one-dimensional materials where solitons are a consequence of a twofold degenerate structure and the nonlinear dynamics of the hydrogen-bonded network.
Nonequilibrium statistical mechanics in one-dimensional bose gases
NASA Astrophysics Data System (ADS)
Baldovin, F.; Cappellaro, A.; Orlandini, E.; Salasnich, L.
2016-06-01
We study cold dilute gases made of bosonic atoms, showing that in the mean-field one-dimensional regime they support stable out-of-equilibrium states. Starting from the 3D Boltzmann–Vlasov equation with contact interaction, we derive an effective 1D Landau–Vlasov equation under the condition of a strong transverse harmonic confinement. We investigate the existence of out-of-equilibrium states, obtaining stability criteria similar to those of classical plasmas.
Superlensing properties of one-dimensional dielectric photonic crystals
NASA Astrophysics Data System (ADS)
Savo, Salvatore; di Gennaro, Emiliano; Andreone, Antonello
2009-10-01
We present the experimental observation of the superlensing effect in a slab of a one-dimensional photonic crystal made of tilted dielectric elements. We show that this flat lens can achieve subwavelength resolution in different frequency bands. We also demonstrate that the introduction of a proper corrugation on the lens surface can dramatically improve both the transmission and the resolution of the imaged signal.
Many-body Anderson localization in one-dimensional systems
NASA Astrophysics Data System (ADS)
Delande, Dominique; Sacha, Krzysztof; Płodzień, Marcin; Avazbaev, Sanat K.; Zakrzewski, Jakub
2013-04-01
We show, using quasi-exact numerical simulations, that Anderson localization in a disordered one-dimensional potential survives in the presence of attractive interaction between particles. The localization length of the particles' center of mass—computed analytically for weak disorder—is in good agreement with the quasi-exact numerical observations using the time evolving block decimation algorithm. Our approach allows for simulation of the entire experiment including the final measurement of all atom positions.
Topological modes in one-dimensional solids and photonic crystals
NASA Astrophysics Data System (ADS)
Atherton, Timothy J.; Butler, Celia A. M.; Taylor, Melita C.; Hooper, Ian R.; Hibbins, Alastair P.; Sambles, J. Roy; Mathur, Harsh
2016-03-01
It is shown theoretically that a one-dimensional crystal with time-reversal and particle-hole symmetries is characterized by a topological invariant that predicts the existence or otherwise of edge states. This is confirmed experimentally through the construction and simulation of a photonic crystal analog in the microwave regime. It is shown that the edge mode couples to modes external to the photonic crystal via a Fano resonance.
Cloud pumping in a one-dimensional photochemical model
NASA Technical Reports Server (NTRS)
Costen, Robert C.; Tennille, Geoffrey M.; Levine, Joel S.
1988-01-01
Cloud pumping data based on tropical maritime updraft statistics are incorporated in a one-dimensional steady-state eddy diffusive photochemical model of the troposphere. It is suggested that regions with weaker convection, such as the midlatitudes, may also experience substantial effects from cloud pumping. The direct effects of cloud pumping on CO were found to be more significant than implied by sensitivity studies. The (CH3)2S profile computed with cloud pumping agrees well with previous data.
Growth of one-dimensional single-crystalline hydroxyapatite nanorods
NASA Astrophysics Data System (ADS)
Ren, Fuzeng; Ding, Yonghui; Ge, Xiang; Lu, Xiong; Wang, Kefeng; Leng, Yang
2012-06-01
A facile, effective and template/surfactant-free hydrothermal route in the presence of sodium bicarbonate was developed to synthesize highly uniform single-crystalline hydroxyapatite (HA) nanorods with the lengths of several hundred nanometers and aspect ratio up to ˜20. One dimensional (1-D) growth and aspect ratio could be controlled by hydrothermal reaction time and temperature. The longitudinal axis, also the growth direction of the nanorods, is parallel to the [001] direction of HA hexagonal crystal structure.
Quasi-Dirac points in one-dimensional graphene superlattices
NASA Astrophysics Data System (ADS)
Chen, C. H.; Tseng, P.; Hsueh, W. J.
2016-08-01
Quasi-Dirac points (QDPs) with energy different from the traditional Dirac points (TDPs) have been found for the first time in one-dimensional graphene superlattices. The angular-averaged conductance reaches a minimum value at the QDPs, at which the Fano factor approaches 1/3. Surprisingly, the minimum conductance at these QDPs may be lower than that at the TDPs under certain conditions. This is remarkable as the minimum conductance attainable in graphene superlattices was believed to appear at TDPs.
On numerical modeling of one-dimensional geothermal histories
Haugerud, R.A.
1989-01-01
Numerical models of one-dimensional geothermal histories are one way of understanding the relations between tectonics and transient thermal structure in the crust. Such models can be powerful tools for interpreting geochronologic and thermobarometric data. A flexible program to calculate these models on a microcomputer is available and examples of its use are presented. Potential problems with this approach include the simplifying assumptions that are made, limitations of the numerical techniques, and the neglect of convective heat transfer. ?? 1989.
Species segregation in one-dimensional granular-system simulations.
Pantellini, F; Landi, S
2008-02-01
We present one-dimensional molecular dynamics simulations of a two-species, initially uniform, freely evolving granular system. Colliding particles swap their relative position with a 50% probability allowing for the initial spatial ordering of the particles to evolve in time and frictional forces to operate. Unlike one-dimensional systems of identical particles, two-species one-dimensional systems of quasi-elastic particles are ergodic and the particles' velocity distributions tend to evolve towards Maxwell-Boltzmann distributions. Under such conditions, standard fluid equations with merely an additional sink term in the energy equation, reflecting the non-elasticity of the interparticle collisions, provide an excellent means to investigate the system's evolution. According to the predictions of fluid theory we find that the clustering instability is dominated by a non-propagating mode at a wavelength of the order 10 pi L/N epsilon , where N is the total number of particles, L the spatial extent of the system and epsilon the inelasticity coefficient. The typical fluid velocities at the time of inelastic collapse are seen to be supersonic, unless N epsilon
Cryptography using multiple one-dimensional chaotic maps
NASA Astrophysics Data System (ADS)
Pareek, N. K.; Patidar, Vinod; Sud, K. K.
2005-10-01
Recently, Pareek et al. [Phys. Lett. A 309 (2003) 75] have developed a symmetric key block cipher algorithm using a one-dimensional chaotic map. In this paper, we propose a symmetric key block cipher algorithm in which multiple one-dimensional chaotic maps are used instead of a one-dimensional chaotic map. However, we also use an external secret key of variable length (maximum 128-bits) as used by Pareek et al. In the present cryptosystem, plaintext is divided into groups of variable length (i.e. number of blocks in each group is different) and these are encrypted sequentially by using randomly chosen chaotic map from a set of chaotic maps. For block-by-block encryption of variable length group, number of iterations and initial condition for the chaotic maps depend on the randomly chosen session key and encryption of previous block of plaintext, respectively. The whole process of encryption/decryption is governed by two dynamic tables, which are updated time to time during the encryption/decryption process. Simulation results show that the proposed cryptosystem requires less time to encrypt the plaintext as compared to the existing chaotic cryptosystems and further produces the ciphertext having flat distribution of same size as the plaintext.
Correlated few-photon transport in one-dimensional waveguides: Linear and nonlinear dispersions
Roy, Dibyendu
2011-04-15
We address correlated few-photon transport in one-dimensional waveguides coupled to a two-level system (TLS), such as an atom or a quantum dot. We derive exactly the single-photon and two-photon current (transmission) for linear and nonlinear (tight-binding sinusoidal) energy-momentum dispersion relations of photons in the waveguides and compare the results for the different dispersions. A large enhancement of the two-photon current for the sinusoidal dispersion has been seen at a certain transition energy of the TLS away from the single-photon resonances.
Full counting statistics of laser excited Rydberg aggregates in a one-dimensional geometry.
Schempp, H; Günter, G; Robert-de-Saint-Vincent, M; Hofmann, C S; Breyel, D; Komnik, A; Schönleber, D W; Gärttner, M; Evers, J; Whitlock, S; Weidemüller, M
2014-01-10
We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional atomic gas. We measure asymmetric excitation spectra and increased second and third order statistical moments of the Rydberg number distribution, from which we determine the average aggregate size. Estimating rates for different excitation processes we conclude that the aggregates grow sequentially around an initial grain. Direct comparison with numerical simulations confirms this conclusion and reveals the presence of liquidlike spatial correlations. Our findings demonstrate the importance of dephasing in strongly correlated Rydberg gases and introduce a way to study spatial correlations in interacting many-body quantum systems without imaging. PMID:24483893
Two-Point Phase Correlations of a One-Dimensional Bosonic Josephson Junction
Betz, T.; Manz, S.; Buecker, R.; Berrada, T.; Koller, Ch.; Schmiedmayer, J.; Kazakov, G.; Mazets, I. E.; Stimming, H.-P.; Perrin, A.; Schumm, T.
2011-01-14
We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation. Comparison to a stochastic model allows us to measure the coupling strength and temperature and hence a full characterization of the system.
Barrier dependent electron tunneling lifetime in one-dimensional device structures
NASA Astrophysics Data System (ADS)
Li, Hui; Gong, Jian; Hu, Xing; Zhang, Rui-Qin
2010-11-01
The tunneling times of electrons in one-dimensional potential structures were studied using a projected Green function (PGF) method. The approach was applied to cases with potentials with one barrier, two barriers, and three barriers at the right side of a quantum well where the electron is located at the initial time. Our results include the effects of well width and barrier thickness on the tunneling time, and also show the impact on the tunneling time of splitting a single barrier into more barriers. This study confirms not only the validity of the PGF method but also reveals the impact of the potential structure on the operation speed of resonant tunneling devices.
Two-point phase correlations of a one-dimensional bosonic Josephson junction.
Betz, T; Manz, S; Bücker, R; Berrada, T; Koller, Ch; Kazakov, G; Mazets, I E; Stimming, H-P; Perrin, A; Schumm, T; Schmiedmayer, J
2011-01-14
We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation. Comparison to a stochastic model allows us to measure the coupling strength and temperature and hence a full characterization of the system. PMID:21405210
One-dimensional Bose gas in optical lattices of arbitrary strength
NASA Astrophysics Data System (ADS)
Astrakharchik, Grigory E.; Krutitsky, Konstantin V.; Lewenstein, Maciej; Mazzanti, Ferran
2016-02-01
One-dimensional Bose gas with contact interaction in optical lattices at zero temperature is investigated by means of the exact diffusion Monte Carlo algorithm. The results obtained from the fundamental continuous model are compared with those obtained from the lattice (discrete) Bose-Hubbard model, using exact diagonalization, and from the quantum sine-Gordon model. We map out the complete phase diagram of the continuous model and determine the regions of applicability of the Bose-Hubbard model. Various physical quantities characterizing the systems are calculated, and it is demonstrated that the sine-Gordon model used for shallow lattices is inaccurate.
Dimerized ground state in the one-dimensional spin-1 boson Hubbard model
Apaja, Vesa; Syljuaasen, Olav F.
2006-09-15
We have investigated the one-dimensional spin-1 boson Hubbard model with antiferromagnetic interactions using quantum Monte Carlo methods. We obtain the shapes of the two lowest Mott lobes and show that the ground state within the lowest Mott lobe is dimerized. The results presented here are relevant for optically trapped antiferromagnetic spin-1 bosons. An experimental signature of the dimerized ground state is modulated Bragg peaks in the noise distribution of the atomic cloud obtained after switching off the trap. These Bragg peaks are located at wave vectors corresponding to half-integer multiples of the reciprocal wave vector of the optical lattice.
Kocia, Lucas Heller, Eric J.
2014-11-14
A simplification of the Heller-Herman-Kluk-Kay (HK) propagator is presented that does not suffer from the need for an increasing number of trajectories with dimensions of the system under study. This is accomplished by replacing HK’s uniformizing integral over all of phase space by a one-dimensional curve that is appropriately selected to lie along the fastest growing manifold of a defining trajectory. It is shown that this modification leads to eigenspectra of quantum states in weakly anharmonic systems that can outperform the comparatively computationally cheap thawed Gaussian approximation method and frequently approach the accuracy of spectra obtained with the full HK propagator.
NASA Astrophysics Data System (ADS)
Kocia, Lucas; Heller, Eric J.
2014-11-01
A simplification of the Heller-Herman-Kluk-Kay (HK) propagator is presented that does not suffer from the need for an increasing number of trajectories with dimensions of the system under study. This is accomplished by replacing HK's uniformizing integral over all of phase space by a one-dimensional curve that is appropriately selected to lie along the fastest growing manifold of a defining trajectory. It is shown that this modification leads to eigenspectra of quantum states in weakly anharmonic systems that can outperform the comparatively computationally cheap thawed Gaussian approximation method and frequently approach the accuracy of spectra obtained with the full HK propagator.
An interpolatory ansatz captures the physics of one-dimensional confined Fermi systems
Andersen, M. E. S.; Dehkharghani, A. S.; Volosniev, A. G.; Lindgren, E. J.; Zinner, N. T.
2016-01-01
Interacting one-dimensional quantum systems play a pivotal role in physics. Exact solutions can be obtained for the homogeneous case using the Bethe ansatz and bosonisation techniques. However, these approaches are not applicable when external confinement is present. Recent theoretical advances beyond the Bethe ansatz and bosonisation allow us to predict the behaviour of one-dimensional confined systems with strong short-range interactions, and new experiments with cold atomic Fermi gases have already confirmed these theories. Here we demonstrate that a simple linear combination of the strongly interacting solution with the well-known solution in the limit of vanishing interactions provides a simple and accurate description of the system for all values of the interaction strength. This indicates that one can indeed capture the physics of confined one-dimensional systems by knowledge of the limits using wave functions that are much easier to handle than the output of typical numerical approaches. We demonstrate our scheme for experimentally relevant systems with up to six particles. Moreover, we show that our method works also in the case of mixed systems of particles with different masses. This is an important feature because these systems are known to be non-integrable and thus not solvable by the Bethe ansatz technique. PMID:27324113
Entanglement pre-thermalization in a one-dimensional Bose gas
NASA Astrophysics Data System (ADS)
Kaminishi, Eriko; Mori, Takashi; Ikeda, Tatsuhiko N.; Ueda, Masahito
2015-12-01
An isolated quantum system often shows relaxation to a quasi-stationary state before reaching thermal equilibrium. Such a pre-thermalized state was observed in recent experiments in a one-dimensional Bose gas after it had been coherently split into two. Although the existence of local conserved quantities is usually considered to be the key ingredient of pre-thermalization, the question of whether non-local correlations between the subsystems can influence pre-thermalization of the entire system has remained unanswered. Here we study the dynamics of coherently split one-dimensional Bose gases and find that the initial entanglement combined with energy degeneracy due to parity and translation invariance strongly affects the long-term behaviour of the system. The mechanism of this entanglement pre-thermalization is quite general and not restricted to one-dimensional Bose gases. In view of recent experiments with a small and well-defined number of ultracold atoms, our predictions based on exact few-body calculations could be tested in experiments.
An interpolatory ansatz captures the physics of one-dimensional confined Fermi systems.
Andersen, M E S; Dehkharghani, A S; Volosniev, A G; Lindgren, E J; Zinner, N T
2016-01-01
Interacting one-dimensional quantum systems play a pivotal role in physics. Exact solutions can be obtained for the homogeneous case using the Bethe ansatz and bosonisation techniques. However, these approaches are not applicable when external confinement is present. Recent theoretical advances beyond the Bethe ansatz and bosonisation allow us to predict the behaviour of one-dimensional confined systems with strong short-range interactions, and new experiments with cold atomic Fermi gases have already confirmed these theories. Here we demonstrate that a simple linear combination of the strongly interacting solution with the well-known solution in the limit of vanishing interactions provides a simple and accurate description of the system for all values of the interaction strength. This indicates that one can indeed capture the physics of confined one-dimensional systems by knowledge of the limits using wave functions that are much easier to handle than the output of typical numerical approaches. We demonstrate our scheme for experimentally relevant systems with up to six particles. Moreover, we show that our method works also in the case of mixed systems of particles with different masses. This is an important feature because these systems are known to be non-integrable and thus not solvable by the Bethe ansatz technique. PMID:27324113
An interpolatory ansatz captures the physics of one-dimensional confined Fermi systems
NASA Astrophysics Data System (ADS)
Andersen, M. E. S.; Dehkharghani, A. S.; Volosniev, A. G.; Lindgren, E. J.; Zinner, N. T.
2016-06-01
Interacting one-dimensional quantum systems play a pivotal role in physics. Exact solutions can be obtained for the homogeneous case using the Bethe ansatz and bosonisation techniques. However, these approaches are not applicable when external confinement is present. Recent theoretical advances beyond the Bethe ansatz and bosonisation allow us to predict the behaviour of one-dimensional confined systems with strong short-range interactions, and new experiments with cold atomic Fermi gases have already confirmed these theories. Here we demonstrate that a simple linear combination of the strongly interacting solution with the well-known solution in the limit of vanishing interactions provides a simple and accurate description of the system for all values of the interaction strength. This indicates that one can indeed capture the physics of confined one-dimensional systems by knowledge of the limits using wave functions that are much easier to handle than the output of typical numerical approaches. We demonstrate our scheme for experimentally relevant systems with up to six particles. Moreover, we show that our method works also in the case of mixed systems of particles with different masses. This is an important feature because these systems are known to be non-integrable and thus not solvable by the Bethe ansatz technique.
One-Dimensional Scanning Approach to Shock Sensing
NASA Technical Reports Server (NTRS)
Tokars, Roger; Adamovsky, Girgory; Floyd, Bertram
2009-01-01
Measurement tools for high speed air flow are sought both in industry and academia. Particular interest is shown in air flows that exhibit aerodynamic shocks. Shocks are accompanied by sudden changes in density, pressure, and temperature. Optical detection and characterization of such shocks can be difficult because the medium is normally transparent air. A variety of techniques to analyze these flows are available, but they often require large windows and optical components as in the case of Schlieren measurements and/or large operating powers which precludes their use for in-flight monitoring and applications. The one-dimensional scanning approach in this work is a compact low power technique that can be used to non-intrusively detect shocks. The shock is detected by analyzing the optical pattern generated by a small diameter laser beam as it passes through the shock. The optical properties of a shock result in diffraction and spreading of the beam as well as interference fringes. To investigate the feasibility of this technique a shock is simulated by a 426 m diameter optical fiber. Analysis of results revealed a direct correlation between the optical fiber or shock location and the beam s diffraction pattern. A plot of the width of the diffraction pattern vs. optical fiber location reveals that the width of the diffraction pattern was maximized when the laser beam is directed at the center of the optical fiber. This work indicates that the one-dimensional scanning approach may be able to determine the location of an actual shock. Near and far field effects associated with a small diameter laser beam striking an optical fiber used as a simulated shock are investigated allowing a proper one-dimensional scanning beam technique.
One-dimensional intense laser pulse solitons in a plasma
Sudan, R.N.; Dimant, Y.S.; Shiryaev, O.B.
1997-05-01
A general analytical framework is developed for the nonlinear dispersion relations of a class of large amplitude one-dimensional isolated envelope solitons for modulated light pulse coupled to electron plasma waves, previously investigated numerically [Kozlov {ital et al.}, Zh. Eksp. Teor. Fiz. {bold 76}, 148 (1979); Kaw {ital et al.}, Phys. Rev. Lett. {bold 68}, 3172 (1992)]. The analytical treatment of weakly nonlinear solitons [Kuehl and Zhang, Phys. Rev. E {bold 48}, 1316 (1993)] is extended to the strongly nonlinear limit. {copyright} {ital 1997 American Institute of Physics.}
Programmers manual for a one-dimensional Lagrangian transport model
Schoellhamer, D.H.; Jobson, H.E.
1986-01-01
A one-dimensional Lagrangian transport model for simulating water-quality constituents such as temperature, dissolved oxygen , and suspended sediment in rivers is presented in this Programmers Manual. Lagrangian transport modeling techniques, the model 's subroutines, and the user-written decay-coefficient subroutine are discussed in detail. Appendices list the program codes. The Programmers Manual is intended for the model user who needs to modify code either to adapt the model to a particular need or to use reaction kinetics not provided with the model. (Author 's abstract)
Dynamical Structure Factors of quasi-one-dimensional antiferromagnets
NASA Astrophysics Data System (ADS)
Hagemans, Rob; Caux, Jean-Sébastien; Maillet, Jean Michel
2007-03-01
For a long time it has been impossible to accurately calculate the dynamical structure factors (spin-spin correlators as a function of momentum and energy) of quasi-one-dimensional antiferromagnets. For integrable Heisenberg chains, the recently developed ABACUS method (a first-principles computational approach based on the Bethe Ansatz) now yields highly accurate (over 99% of the sum rule) results for the DSF for finite chains, allowing for a very precise description of neutron-scattering data over the full momentum and energy range. We show remarkable agreement between results obtained with ABACUS and experiment.
Discrete breathers in one-dimensional diatomic granular crystals.
Boechler, N; Theocharis, G; Job, S; Kevrekidis, P G; Porter, Mason A; Daraio, C
2010-06-18
We report the experimental observation of modulational instability and discrete breathers in a one-dimensional diatomic granular crystal composed of compressed elastic beads that interact via Hertzian contact. We first characterize their effective linear spectrum both theoretically and experimentally. We then illustrate theoretically and numerically the modulational instability of the lower edge of the optical band. This leads to the dynamical formation of long-lived breather structures, whose families of solutions we compute throughout the linear spectral gap. Finally, we experimentally observe the manifestation of the modulational instability and the resulting generation of localized breathing modes with quantitative characteristics that agree with our numerical results. PMID:20867305
A one-dimensional basic oscillator model of the vircator
NASA Astrophysics Data System (ADS)
Biswas, Debabrata
2009-06-01
A one-dimensional model of the virtual cathode oscillator (vircator) is proposed keeping only the essential physical processes. The basic model consists of a radiating charge in an oscillating electric field. Using parameters from (realistic) particle-in-cell simulations such as the charge Q and amplitude E1 of the oscillating electric field, the model correctly predicts the amplitude of virtual cathode oscillation and the power radiated. The basic model is then extended to incorporate beam-cavity interaction and the resonance effect.
One-dimensional image transformation in white light
NASA Astrophysics Data System (ADS)
Bartelt, H.
1981-08-01
A method for linear, one-dimensional transformations in white light is described. In the case of discrete object and transformation functions, this operation may also be called a matrix multiplication. The method uses the multiplexing facility of the wavelength coordinate. This fact allows an image quality corresponding to the full spatial resolution of the optical system to be achieved. Any type of positive basis functions can be introduced into the optical system. The only restriction is caused by the use of temporally incoherent light. Therefore, bipolar basis functions of a transformation must be split into positive parts. As an application, a Walsh-Hadamard transformation has been performed.
Parallel solution of sparse one-dimensional dynamic programming problems
NASA Technical Reports Server (NTRS)
Nicol, David M.
1989-01-01
Parallel computation offers the potential for quickly solving large computational problems. However, it is often a non-trivial task to effectively use parallel computers. Solution methods must sometimes be reformulated to exploit parallelism; the reformulations are often more complex than their slower serial counterparts. We illustrate these points by studying the parallelization of sparse one-dimensional dynamic programming problems, those which do not obviously admit substantial parallelization. We propose a new method for parallelizing such problems, develop analytic models which help us to identify problems which parallelize well, and compare the performance of our algorithm with existing algorithms on a multiprocessor.
One-dimensional electron system over liquid helium
NASA Astrophysics Data System (ADS)
Kovdrya, Yu. Z.; Nikolaenko, V. A.; Gladchenko, S. P.
2000-07-01
A system close to a one-dimensional (1D) electron system on superfluid helium is realized in the experiments. A profiled substrate with a small dielectric constant is used to create a set of parallel channels on the surface of liquid helium. The mobility of carriers was measured in this system in the temperature range 0.5-1.8 K. For clean substrates the electron mobility increases with decreasing temperature and reaches high values at low temperatures. The results of experiments are found to be in a good agreement with the existing theory.
Coupling Identical one-dimensional Many-Body Localized Systems
NASA Astrophysics Data System (ADS)
Bordia, Pranjal; Lüschen, Henrik P.; Hodgman, Sean S.; Schreiber, Michael; Bloch, Immanuel; Schneider, Ulrich
2016-04-01
We experimentally study the effects of coupling one-dimensional many-body localized systems with identical disorder. Using a gas of ultracold fermions in an optical lattice, we artificially prepare an initial charge density wave in an array of 1D tubes with quasirandom on-site disorder and monitor the subsequent dynamics over several thousand tunneling times. We find a strikingly different behavior between many-body localization and Anderson localization. While the noninteracting Anderson case remains localized, in the interacting case any coupling between the tubes leads to a delocalization of the entire system.
One-dimensional hydrodynamic model generating a turbulent cascade
NASA Astrophysics Data System (ADS)
Matsumoto, Takeshi; Sakajo, Takashi
2016-05-01
As a minimal mathematical model generating cascade analogous to that of the Navier-Stokes turbulence in the inertial range, we propose a one-dimensional partial-differential-equation model that conserves the integral of the squared vorticity analog (enstrophy) in the inviscid case. With a large-scale random forcing and small viscosity, we find numerically that the model exhibits the enstrophy cascade, the broad energy spectrum with a sizable correction to the dimensional-analysis prediction, peculiar intermittency, and self-similarity in the dynamical system structure.
An improved lambda-scheme for one-dimensional flows
NASA Technical Reports Server (NTRS)
Moretti, G.; Dipiano, M. T.
1983-01-01
A code for the calculation of one-dimensional flows is presented, which combines a simple and efficient version of the lambda-scheme with tracking of discontinuities. The latter is needed to identify points where minor departures from the basic integration scheme are applied to prevent infiltration of numerical errors. Such a tracking is obtained via a systematic application of Boolean algebra. It is, therefore, very efficient. Fifteen examples are presented and discussed in detail. The results are exceptionally good. All discontinuites are captured within one mesh interval.
Solution methods for one-dimensional viscoelastic problems
NASA Technical Reports Server (NTRS)
Stubstad, John M.; Simitses, George J.
1987-01-01
A recently developed differential methodology for solution of one-dimensional nonlinear viscoelastic problems is presented. Using the example of an eccentrically loaded cantilever beam-column, the results from the differential formulation are compared to results generated using a previously published integral solution technique. It is shown that the results obtained from these distinct methodologies exhibit a surprisingly high degree of correlation with one another. A discussion of the various factors affecting the numerical accuracy and rate of convergence of these two procedures is also included. Finally, the influences of some 'higher order' effects, such as straining along the centroidal axis are discussed.
A statistical formulation of one-dimensional electron fluid turbulence
NASA Technical Reports Server (NTRS)
Fyfe, D.; Montgomery, D.
1977-01-01
A one-dimensional electron fluid model is investigated using the mathematical methods of modern fluid turbulence theory. Non-dissipative equilibrium canonical distributions are determined in a phase space whose co-ordinates are the real and imaginary parts of the Fourier coefficients for the field variables. Spectral densities are calculated, yielding a wavenumber electric field energy spectrum proportional to k to the negative second power for large wavenumbers. The equations of motion are numerically integrated and the resulting spectra are found to compare well with the theoretical predictions.
Functional One-Dimensional Lipid Bilayers on Carbon Nanotube Templates
Artyukhin, A; Shestakov, A; Harper, J; Bakajin, O; Stroeve, P; Noy, A
2004-07-23
We present one-dimensional (1-D) lipid bilayer structures that integrate carbon nanotubes with a key biological environment-phospholipid membrane. Our structures consist of lipid bilayers wrapped around carbon nanotubes modified with a hydrophilic polymer cushion layer. Despite high bilayer curvature, the lipid membrane maintains its fluidity and can sustain repeated damage-recovery cycles. We also present the first evidence of spontaneous insertion of pore-forming proteins into 1-D lipid bilayers. These structures could lead to the development of new classes of biosensors and bioelectronic devices.
Accuracy of differential sensitivity for one-dimensional shock problems
Henninger, R.J.; Maudlin, P.J.; Rightley, M.L.
1998-07-01
The technique called Differential Sensitivity has been applied to the system of Eulerian continuum mechanics equations solved by a hydrocode. Differential Sensitivity uses forward and adjoint techniques to obtain output response sensitivity to input parameters. Previous papers have described application of the technique to two-dimensional, multi-component problems. Inaccuracies in the adjoint solutions have prompted us to examine our numerical techniques in more detail. Here we examine one-dimensional, one material shock problems. Solution accuracy is assessed by comparison to sensitivities obtained by automatic differentiation and a code-based adjoint differentiation technique. {copyright} {ital 1998 American Institute of Physics.}
Evaluation of one dimensional analytical models for vegetation canopies
NASA Technical Reports Server (NTRS)
Goel, Narendra S.; Kuusk, Andres
1992-01-01
The SAIL model for one-dimensional homogeneous vegetation canopies has been modified to include the specular reflectance and hot spot effects. This modified model and the Nilson-Kuusk model are evaluated by comparing the reflectances given by them against those given by a radiosity-based computer model, Diana, for a set of canopies, characterized by different leaf area index (LAI) and leaf angle distribution (LAD). It is shown that for homogeneous canopies, the analytical models are generally quite accurate in the visible region, but not in the infrared region. For architecturally realistic heterogeneous canopies of the type found in nature, these models fall short. These shortcomings are quantified.
Computer model of one-dimensional equilibrium controlled sorption processes
Grove, D.B.; Stollenwerk, K.G.
1984-01-01
A numerical solution to the one-dimensional solute-transport equation with equilibrium-controlled sorption and a first-order irreversible-rate reaction is presented. The computer code is written in FORTRAN language, with a variety of options for input and output for user ease. Sorption reactions include Langmuir, Freundlich, and ion-exchange, with or without equal valance. General equations describing transport and reaction processes are solved by finite-difference methods, with nonlinearities accounted for by iteration. Complete documentation of the code, with examples, is included. (USGS)
Time delay in simple one-dimensional systems
NASA Astrophysics Data System (ADS)
van Dijk, W.; Kiers, K. A.
1992-06-01
The time delay or the time advance in the scattering of simple one-dimensional systems can be evaluated in a straightforward manner for certain potential models. It is found that when the interacting potential is attractive and has a strength such that it nearly supports an additional bound state, the time delay at small scattering energy is very large. On the other hand, if the potential supports a bound state with nearly zero binding energy, the time advance near threshold is anomalously large. The behavior of a wave packet scattering from the double delta-function potential is also investigated.
Strongly coupled slow-light polaritons in one-dimensional disordered localized states
Gao, Jie; Combrie, Sylvain; Liang, Baolai; Schmitteckert, Peter; Lehoucq, Gaelle; Xavier, Stephane; Xu, XinAn; Busch, Kurt; Huffaker, Diana L.; De Rossi, Alfredo; Wong, Chee Wei
2013-01-01
Cavity quantum electrodynamics advances the coherent control of a single quantum emitter with a quantized radiation field mode, typically piecewise engineered for the highest finesse and confinement in the cavity field. This enables the possibility of strong coupling for chip-scale quantum processing, but till now is limited to few research groups that can achieve the precision and deterministic requirements for these polariton states. Here we observe for the first time coherent polariton states of strong coupled single quantum dot excitons in inherently disordered one-dimensional localized modes in slow-light photonic crystals. Large vacuum Rabi splittings up to 311 μeV are observed, one of the largest avoided crossings in the solid-state. Our tight-binding models with quantum impurities detail these strong localized polaritons, spanning different disorder strengths, complementary to model-extracted pure dephasing and incoherent pumping rates. Such disorder-induced slow-light polaritons provide a platform towards coherent control, collective interactions, and quantum information processing. PMID:23771242
One dimensional wavefront sensor development for tomographic flow measurements
Neal, D.; Pierson, R.; Chen, E.
1995-08-01
Optical diagnostics are extremely useful in fluid mechanics because they generally have high inherent bandwidth, and are non-intrusive. However, since optical probe measurements inherently integrate all information along the optical path, it is often difficult to isolate out-of-plane components in 3-dimensional flow events. It is also hard to make independent measurements of internal flow structure. Using an arrangement of one-dimensional wavefront sensors, we have developed a system that uses tomographic reconstruction to make two-dimensional measurements in an arbitrary flow. These measurements provide complete information in a plane normal to the flow. We have applied this system to the subsonic free jet because of the wide range of flow scales available. These measurements rely on the development of a series of one-dimensional wavefront sensors that are used to measure line-integral density variations in the flow of interest. These sensors have been constructed using linear CCD cameras and binary optics lenslet arrays. In designing these arrays, we have considered the coherent coupling between adjacent lenses and have made comparisons between theory and experimental noise measurements. The paper will present examples of the wavefront sensor development, line-integral measurements as a function of various experimental parameters, and sample tomographic reconstructions.
One-Dimensional Electrical Contact to Molybdenum Disulfide
NASA Astrophysics Data System (ADS)
Yang, Zheng; Ra, Changho; Ahmed, Faisal; Lee, Daeyeong; Choi, Minsup; Liu, Xiaochi; Qu, Deshun; Yoo, Won Jong; Nano Device Processing Lab Team
Molybdenum disulfide (MoS2) is one of the promising two-dimensional materials for future application in nano electronics, which has high carrier mobility, very good stability under atmosphere, proper band gap, etc. However, its application to electronic switching devices is hindered by Fermi level pinning at metal-MoS2 interfaces. Here, we experimentally demonstrate one-dimensional electrical contact to MoS2 formed via controllable plasma etching. We fabricated Al/MoS2 FET (n-type), Mo/MoS2 FET (n-type), and Pd/MoS2 FET (ambipolar). For Mo/MoS2 FET (n-type), on/off current ratio is around 108 and mobility is around 104 cm2/(Vs). By contrast, for Pd/MoS2 FET (ambipolar), on/off current ratio is around 108, hole mobility is ranged from 350 to 650 cm2/(Vs), and the mean free path of holes at 9K is around 23 nm. All the measured mobilities are evaluated by using two-terminal field-effect configuration. We can also achieve complementary logic gates with intrinsic MoS2/metal one-dimensional electrical contact.
Constraint and gauge shocks in one-dimensional numerical relativity
Reimann, Bernd; Alcubierre, Miguel; Nunez, Dario; Gonzalez, Jose A.
2005-03-15
We study how different types of blowups can occur in systems of hyperbolic evolution equations of the type found in general relativity. In particular, we discuss two independent criteria that can be used to determine when such blowups can be expected. One criteria is related to the so-called geometric blowup leading to gradient catastrophes, while the other is based upon the ODE-mechanism leading to blowups within finite time. We show how both mechanisms work in the case of a simple one-dimensional wave equation with a dynamic wave speed and sources, and later explore how those blowups can appear in one-dimensional numerical relativity. In the latter case we recover the well known 'gauge shocks' associated with Bona-Masso-type slicing conditions. However, a crucial result of this study has been the identification of a second family of blowups associated with the way in which the constraints have been used to construct a hyperbolic formulation. We call these blowups 'constraint shocks' and show that they are formulation specific, and that choices can be made to eliminate them or at least make them less severe.
Lattice Boltzmann method for one-dimensional vector radiative transfer.
Zhang, Yong; Yi, Hongliang; Tan, Heping
2016-02-01
A one-dimensional vector radiative transfer (VRT) model based on lattice Boltzmann method (LBM) that considers polarization using four Stokes parameters is developed. The angular space is discretized by the discrete-ordinates approach, and the spatial discretization is conducted by LBM. LBM has such attractive properties as simple calculation procedure, straightforward and efficient handing of boundary conditions, and capability of stable and accurate simulation. To validate the performance of LBM for vector radiative transfer, four various test problems are examined. The first case investigates the non-scattering thermal-emitting atmosphere with no external collimated solar. For the other three cases, the external collimated solar and three different scattering types are considered. Particularly, the LBM is extended to solve VRT in the atmospheric aerosol system where the scattering function contains singularities and the hemisphere space distributions for the Stokes vector are presented and discussed. The accuracy and computational efficiency of this algorithm are discussed. Numerical results show that the LBM is accurate, flexible and effective to solve one-dimensional polarized radiative transfer problems. PMID:26906779
Generating arbitrary one-dimensional dose profiles using rotational therapy
NASA Astrophysics Data System (ADS)
Zhuang, Tingliang; Wu, Qiuwen
2010-10-01
Conformal radiation therapy can be delivered using several methods: intensity-modulated radiotherapy (IMRT) at fixed gantry angles, through the continuous gantry rotation of linac (rotational arc therapy), or by a dedicated treatment unit such as tomotherapy. The recently developed volumetric modulated arc therapy (VMAT), a form of rotational arc therapy, has attracted lots of attention from investigators to explore its capability of generating highly conformal dose to the target. The main advanced features of VMAT are the variable dose rate and gantry rotation speed. In this paper, we present a theoretical framework of generating arbitrary one-dimensional dose profiles using rotational arc therapy to further explore the new degree of freedom of the VMAT technique. This framework was applied to design a novel technique for total body irradiation (TBI) treatment, where the desired dose distribution can be simplified by a one-dimensional profile. The technique was validated using simulations and experimental measurements. The preliminary results demonstrated that the new TBI technique using either dynamic MLC only, variable dose rate only, or a combination of dynamic MLC and variable dose rate can achieve arbitrary dose distribution in one dimension, such as uniform dose to target and lower dose to critical organ. This technique does not require the use of customized compensators, nor large treatment rooms as in the conventional extended SSD technique.
Design and fabrication of one-dimensional and two- dimensional photonic bandgap devices
NASA Astrophysics Data System (ADS)
Lim, Kuo-Yi
1999-10-01
One-dimensional and two-dimensional photonic bandgap devices have been designed and fabricated using III-V compound semiconductors. The one-dimensional photonic bandgap devices consist of monorail and air-bridge waveguide microcavities, while the two-dimensional photonic bandgap devices consist of light-emitting devices with enhanced extraction efficiency. Fabrication techniques such as gas source molecular beam epitaxy, direct-write electron-beam lithography, reactive ion etching and thermal oxidation of AlxGa1- xAs have been employed. The III-V thermal oxide, in particular, is used as an index confinement material, as a sacrificial material for micromechanical fabrication of the air-bridge microcavity, and in the realization of a wide-bandwidth distributed Bragg reflector. The one-dimensional photonic bandgap waveguide microcavities have been designed to operate in the wavelength regimes of 4.5 m m and 1.55 m m. The devices designed to operate in the 1.55 m m wavelength regime have been optically characterized. The transmission spectra exhibit resonances at around 1.55 m m and cavity quality factors (Q's) ranging from 136 to 334. The resonant modal volume is calculated to be about 0.056 m m3. Tunability in the resonance wavelengths has also been demonstrated by changing the size of the defect in the one-dimensional photonic crystal. The two-dimensional photonic bandgap light-emitting device consists of a In0.51Ga0.49P/In0.2Ga0.8As/In 0.51Ga0.49P quantum well emitting at 980nm with a triangular photonic lattice of holes in the top cladding layer of the quantum well. The photonic crystal prohibits the propagation of guided modes in the semiconductor, thus enhancing the extraction of light vertical to the light-emitting device. A wide-bandwidth GaAs/AlxOy distributed Bragg reflector mirror under the quantum well structure further enhances the extraction of light from the devices. The extraction efficiency of the two-dimensional photonic bandgap light-emitting device
The full Zakharov equations in nonextensive q-plasma
Liu, Xiao-Lan; Li, Xiao-Qing
2014-02-15
The wave-wave interactions among electromagnetic mode, Langmuir and ion-sound modes are theoretically investigated in a nonextensive plasma, with the help of the two-fluid theory and the two-scale method. The full Zakharov equations for the nonextensive distribution are derived and analyzed numerically. The results show that the collapsing of the three waves would be affected by the nonextensive parameter q. When q increasing, the collapsing would become faster and the rate of density perturbation would be greater. And the localized density structure would form a plasma channel much easier.
Coupling of a dipolar emitter into one-dimensional surface plasmon
Barthes, Julien; Bouhelier, Alexandre; Dereux, Alain; Francs, Gérard Colas des
2013-01-01
Quantum plasmonics relies on a new paradigm for light–matter interaction. It benefits from strong confinement of surface plasmon polaritons (SPP) that ensures efficient coupling at a deep subwavelength scale, instead of working with a long lifetime cavity polariton that increases the duration of interaction. The large bandwidth and the strong confinement of one dimensional SPP enable controlled manipulation of a nearby quantum emitter. This paves the way to ultrafast nanooptical devices. However, the large SPP bandwidth originates from strong losses so that a clear understanding of the coupling process is needed. In this report, we investigate in details the coupling between a single emitter and a plasmonic nanowire, but also SPP mediated coupling between two emitters. We notably clarify the role of losses in the Purcell factor, unavoidable to achieve nanoscale confinement down to 10−4(λ/n)3. Both the retarded and band-edge quasi-static regimes are discussed. PMID:24061164
Restoring phase coherence in a one-dimensional superconductor using power-law electron hopping
NASA Astrophysics Data System (ADS)
Lobos, Alejandro M.; Tezuka, Masaki; García-García, Antonio M.
2013-10-01
In a one-dimensional (1D) superconductor, zero-temperature quantum fluctuations destroy phase coherence. Here we put forward a mechanism which can restore phase coherence: power-law hopping. We study a 1D attractive-U Hubbard model with power-law hopping using Abelian bosonization and density-matrix renormalization group (DMRG) techniques. The parameter that controls the hopping decay acts as the effective, noninteger spatial dimensionality deff. For real-valued hopping amplitudes we identify analytically a range of parameters for which power-law hopping suppresses fluctuations and restores superconducting long-range order for any deff>1, at zero temperature. A detailed DMRG analysis fully supports these findings. These results are also of direct relevance to quantum magnetism as our model can be mapped onto an S=1/2 XXZ spin chain with power-law decaying couplings, which can be studied experimentally with cold-ion-trap techniques.
Dimerized phase and entanglement in the one-dimensional spin-1 bilinear biquadratic model
NASA Astrophysics Data System (ADS)
Chen, Ai Min; Su, Yao Heng; Wang, Honglei
2015-10-01
Dimerized phase and quantum entanglement are investigated in the one-dimensional spin-1 bilinear biquadratic model. Employing the infinite matrix product state representation, groundstate wavefunctions are numerically obtained by using the infinite time evolving block decimation method in the infinite lattice system. From a bipartite entanglement measure of the groundstates, i.e., von Neumann entropy, the phase transition points can be clearly extracted. Moreover, the even-bond and odd-bond von Neumann entropies show two different values in the spontaneous dimerized phase. It implies that the quantum entanglement can distinguish the two degenerate groundstates. Then, we define a dimer entropy in the spontaneous dimerized phase. Comparing to the dimer order parameter, the dimer entropy can play a role of a local order parameter to characterize the spontaneous dimerized phase.
Exponential and nonexponential localization of the one-dimensional periodically kicked Rydberg atom
Yoshida, S.; Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6373 ; Reinhold, C. O.; Kristoefel, P.; Burgdoerfer, J.; Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6373; Institute for Theoretical Physics, Vienna University of Technology, A1040 Vienna,
2000-08-01
We investigate the quantum localization of the one-dimensional Rydberg atom subject to a unidirectional periodic train of impulses. For high frequencies of the train the classical system becomes chaotic and leads to fast ionization. By contrast, the quantum system is found to be remarkably stable. We identify for this system the coexistence of different localization mechanisms associated with resonant and nonresonant diffusion. We find for the suppression of nonresonant diffusion an exponential localization whose localization length can be related to the classical dynamics in terms of the ''scars'' of the unstable periodic orbits. We show that the localization length is determined by the energy excursion along the periodic orbits. The suppression of resonant diffusion along the sequence of photonic peaks is found to be nonexponential due to the presence of high harmonics in the driving force. (c) 2000 The American Physical Society.
Quasiparticle breakdown in the quasi-one-dimensional Ising ferromagnet CoNb2O6
NASA Astrophysics Data System (ADS)
Robinson, Neil J.; Essler, Fabian H. L.; Cabrera, Ivelisse; Coldea, Radu
2014-11-01
We present experimental and theoretical evidence that an interesting quantum many-body effect—quasiparticle breakdown—occurs in the quasi-one-dimensional spin-1/2 Ising-like ferromagnet CoNb2O6 in its paramagnetic phase at high transverse field as a result of explicit breaking of spin inversion symmetry. We propose a quantum spin Hamiltonian capturing the essential one-dimensional physics of CoNb2O6 and determine the exchange parameters of this model by fitting the calculated single-particle dispersion to the one observed experimentally in applied transverse magnetic fields [1]. We present high-resolution inelastic neutron scattering measurements of the single-particle dispersion which observe "anomalous broadening" effects over a narrow energy range at intermediate energies. We propose that this effect originates from the decay of the one particle mode into two-particle states. This decay arises from (i) a finite overlap between the one-particle dispersion and the two-particle continuum in a narrow energy-momentum range and (ii) a small misalignment of the applied field away from the direction perpendicular to the Ising axis in the experiments, which allows for nonzero matrix elements for decay by breaking the Z2 spin inversion symmetry of the Hamiltonian.
Semiclassical investigation of the revival phenomena in a one-dimensional system
NASA Astrophysics Data System (ADS)
Wang, Zhe-xian; Heller, Eric J.
2009-07-01
In a quantum revival, a localized wave packet re-forms or 'revives' into a compact reincarnation of itself long after it has spread in an unruly fashion over a region restricted only by the potential energy. This is a purely quantum phenomenon, which has no classical analog. Quantum revival and Anderson localization are members of a small class of subtle interference effects resulting in a quantum distribution radically different from the classical after long time evolution under classically nonlinear evolution. However, it is not clear that semiclassical methods, which start with the classical density and add interference effects, are in fact capable of capturing the revival phenomenon. Here we investigate two different one-dimensional systems, the infinite square well and Morse potential. In both the cases, after a long time the underlying classical manifolds are spread rather uniformly over phase space and are correspondingly spread in coordinate space, yet the semiclassical amplitudes are able to destructively interfere over most of coordinate space and constructively interfere in a small region, correctly reproducing a quantum revival. Further implications of this ability are discussed.
Béguin, J-B; Bookjans, E M; Christensen, S L; Sørensen, H L; Müller, J H; Polzik, E S; Appel, J
2014-12-31
We demonstrate preparation and detection of an atom number distribution in a one-dimensional atomic lattice with the variance -14 dB below the Poissonian noise level. A mesoscopic ensemble containing a few thousand atoms is trapped in the evanescent field of a nanofiber. The atom number is measured through dual-color homodyne interferometry with a pW-power shot noise limited probe. Strong coupling of the evanescent probe guided by the nanofiber allows for a real-time measurement with a precision of ±8 atoms on an ensemble of some 10(3) atoms in a one-dimensional trap. The method is very well suited for generating collective atomic entangled or spin-squeezed states via a quantum nondemolition measurement as well as for tomography of exotic atomic states in a one-dimensional lattice. PMID:25615331
Properties of surface modes in one dimensional plasma photonic crystals
Shukla, S.; Prasad, S. Singh, V.
2015-02-15
Properties of surface modes supported at the interface of air and a semi-infinite one dimensional plasma photonic crystal are analyzed. The surface mode equation is obtained by using transfer matrix method and applying continuity conditions of electric fields and its derivatives at the interface. It is observed that with increase in the width of cap layer, frequencies of surface modes are shifted towards lower frequency side, whereas increase in tangential component of wave-vector increases the mode frequency and total energy carried by the surface modes. With increase in plasma frequency, surface modes are found to shift towards higher frequency side. The group velocity along interface is found to control by cap layer thickness.
Experiment and simulation on one-dimensional plasma photonic crystals
Zhang, Lin; Ouyang, Ji-Ting
2014-10-15
The transmission characteristics of microwaves passing through one-dimensional plasma photonic crystals (PPCs) have been investigated by experiment and simulation. The PPCs were formed by a series of discharge tubes filled with argon at 5 Torr that the plasma density in tubes can be varied by adjusting the discharge current. The transmittance of X-band microwaves through the crystal structure was measured under different discharge currents and geometrical parameters. The finite-different time-domain method was employed to analyze the detailed properties of the microwaves propagation. The results show that there exist bandgaps when the plasma is turned on. The properties of bandgaps depend on the plasma density and the geometrical parameters of the PPCs structure. The PPCs can perform as dynamical band-stop filter to control the transmission of microwaves within a wide frequency range.
Strongly-Refractive One-Dimensional Photonic Crystal Prisms
NASA Technical Reports Server (NTRS)
Ting, David Z. (Inventor)
2004-01-01
One-dimensional (1D) photonic crystal prisms can separate a beam of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a ID photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1 D photonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The ID photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.
Unexpected photoluminescence properties from one-dimensional molecular chains
NASA Astrophysics Data System (ADS)
Yuan, Ye; Yao, Mingguang; Chen, Shuanglong; Liu, Shijie; Yang, Xigui; Zhang, Weiwei; Yao, Zhen; Liu, Ran; Liu, Bo; Liu, Bingbing
2016-01-01
Unlike bulk iodine, iodine molecular chains formed inside one dimensional (1D) nanochannels of AlPO4-5 (AFI) single crystals show unexpected PL behavior. Thanks to its unique 1D structure, the PL exhibits obvious polarization both in excitation and emission, by changing the angle between the c-axis of the channels and the polarization direction of the incident laser. As pressure increases, the PL intensity increases obviously due to the population increase of (I2)n chains upon compression. In contrast, the breaking of the (I2)n chain at high temperature leads to the decrease of PL intensity. Our theoretical calculation further points out that the PL may arise from the intrinsic band structure of (I2)n chains.
One-Dimensional Analysis Techniques for Pulsed Blowing Distribution
NASA Astrophysics Data System (ADS)
Chambers, Frank
2005-11-01
Pulsed blowing offers reductions in bleed air requirements for aircraft flow control. Efficient pulsed blowing systems require careful design to minimize bleed air use while distributing blowing to multiple locations. Pulsed blowing systems start with a steady flow supply and process it to generate a pulsatile flow. The fluid-acoustic dynamics of the system play an important role in overall effectiveness. One-dimensional analysis techniques that in the past have been applied to ventilation systems and internal combustion engines have been adapted to pulsed blowing. Pressure wave superposition and reflection are used with the governing equations of continuity, momentum and energy to determine particle velocities and pressures through the flow field. Simulations have been performed to find changes in the amplitude and wave shape as pulses are transmitted through a simple pulsed blowing system. A general-purpose code is being developed to simulate wave transmission and allow the determination of blowing system dynamic parameters.
Localization of wave packets in one-dimensional random potentials
NASA Astrophysics Data System (ADS)
Valdes, Juan Pablo Ramírez; Wellens, Thomas
2016-06-01
We study the expansion of an initially strongly confined wave packet in a one-dimensional weak random potential with short correlation length. At long times, the expansion of the wave packet comes to a halt due to destructive interferences leading to Anderson localization. We develop an analytical description for the disorder-averaged localized density profile. For this purpose, we employ the diagrammatic method of Berezinskii which we extend to the case of wave packets, present an analytical expression of the Lyapunov exponent which is valid for small as well as for high energies, and, finally, develop a self-consistent Born approximation in order to analytically calculate the energy distribution of our wave packet. By comparison with numerical simulations, we show that our theory describes well the complete localized density profile, not only in the tails but also in the center.
Anyon Hubbard Model in One-Dimensional Optical Lattices.
Greschner, Sebastian; Santos, Luis
2015-07-31
Raman-assisted hopping may be used to realize the anyon Hubbard model in one-dimensional optical lattices. We propose a feasible scenario that significantly improves the proposal of T. Keilmann et al. [Nat. Commun. 2, 361 (2011)], allowing as well for an exact realization of the two-body hard-core constraint, and for controllable effective interactions without the need of Feshbach resonances. We show that the combination of anyonic statistics and two-body hard-core constraint leads to a rich ground-state physics, including Mott insulators with attractive interactions, pair superfluids, dimer phases, and multicritical points. Moreover, the anyonic statistics results in a novel two-component superfluid of holon and doublon dimers, characterized by a large but finite compressibility and a multipeaked momentum distribution, which may be easily revealed experimentally. PMID:26274417
Users manual for a one-dimensional Lagrangian transport model
Schoellhamer, D.H.; Jobson, H.E.
1986-01-01
A Users Manual for the Lagrangian Transport Model (LTM) is presented. The LTM uses Lagrangian calculations that are based on a reference frame moving with the river flow. The Lagrangian reference frame eliminates the need to numerically solve the convective term of the convection-diffusion equation and provides significant numerical advantages over the more commonly used Eulerian reference frame. When properly applied, the LTM can simulate riverine transport and decay processes within the accuracy required by most water quality studies. The LTM is applicable to steady or unsteady one-dimensional unidirectional flows in fixed channels with tributary and lateral inflows. Application of the LTM is relatively simple and optional capabilities improve the model 's convenience. Appendices give file formats and three example LTM applications that include the incorporation of the QUAL II water quality model 's reaction kinetics into the LTM. (Author 's abstract)
Periodic transmission peak splitting in one dimensional disordered photonic structures
NASA Astrophysics Data System (ADS)
Kriegel, Ilka; Scotognella, Francesco
2016-08-01
In the present paper we present ways to modulate the periodic transmission peaks arising in disordered one dimensional photonic structures with hundreds of layers. Disordered structures in which the optical length nd (n is the refractive index and d the layer thickness) is the same for each layer show regular peaks in their transmission spectra. A proper variation of the optical length of the layers leads to a splitting of the transmission peaks. Notably, the variation of the occurrence of high and low refractive index layers, gives a tool to tune also the width of the peaks. These results are of highest interest for optical application, such as light filtering, where the manifold of parameters allows a precise design of the spectral transmission ranges.
Quasi one dimensional transport in individual electrospun composite nanofibers
Avnon, A. Datsyuk, V.; Trotsenko, S.; Wang, B.; Zhou, S.
2014-01-15
We present results of transport measurements of individual suspended electrospun nanofibers Poly(methyl methacrylate)-multiwalled carbon nanotubes. The nanofiber is comprised of highly aligned consecutive multiwalled carbon nanotubes. We have confirmed that at the range temperature from room temperature down to ∼60 K, the conductance behaves as power-law of temperature with an exponent of α ∼ 2.9−10.2. The current also behaves as power law of voltage with an exponent of β ∼ 2.3−8.6. The power-law behavior is a footprint for one dimensional transport. The possible models of this confined system are discussed. Using the model of Luttinger liquid states in series, we calculated the exponent for tunneling into the bulk of a single multiwalled carbon nanotube α{sub bulk} ∼ 0.06 which agrees with theoretical predictions.
Reprint of : Absorbing/Emitting Phonons with one dimensional MOSFETs
NASA Astrophysics Data System (ADS)
Bosisio, Riccardo; Gorini, Cosimo; Fleury, Geneviève; Pichard, Jean-Louis
2016-08-01
We consider nanowires in the field effect transistor device configuration. Modeling each nanowire as a one dimensional lattice with random site potentials, we study the heat exchanges between the nanowire electrons and the substrate phonons, when electron transport is due to phonon-assisted hops between localized states. Shifting the nanowire conduction band with a metallic gate induces different behaviors. When the Fermi potential is located near the band center, a bias voltage gives rise to small local heat exchanges which fluctuate randomly along the nanowire. When it is located near one of the band edges, the bias voltage yields heat currents which flow mainly from the substrate towards the nanowire near one boundary of the nanowire, and in the opposite direction near the other boundary. This opens interesting perspectives for heat management at submicron scales: arrays of parallel gated nanowires could be used for a field control of phonon emission/absorption.
Growth of One-Dimensional MnO2 Nanostructure
NASA Astrophysics Data System (ADS)
Lu, Pai; Xue, Dongfeng
Large scale MnO2 nanorods were controllably synthesized from the inexpensive precursors (e.g., manganese acetate, ammonium persulfate) via a facile one-step low temperature hydrothermal strategy. The crystal phase and microscopic morphology of the as-prepared MnO2 nanorods were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). Through investigating the morphology evolution of MnO2 products in the whole synthesis process, a novel growth mechanism of these MnO2 nanorods was proposed, which may be efficiently extended to other material systems as a general approach towards one-dimensional nanostructures. The obtained MnO2 nanorods may have potential applications in Li-ion batteries and supercapacitors.
Moving perturbation in a one-dimensional Fermi gas
NASA Astrophysics Data System (ADS)
Visuri, A.-M.; Kim, D.-H.; Kinnunen, J. J.; Massel, F.; Törmä, P.
2014-11-01
We simulate a balanced attractively interacting two-component Fermi gas in a one-dimensional lattice perturbed with a moving potential well or barrier. Using the time-evolving block decimation (TEBD) method, we study different velocities of the perturbation and distinguish two velocity regimes based on clear differences in the time evolution of particle densities and the pair correlation function. We show that, in the slow regime, the densities deform as particles are either attracted by the potential well or repelled by the barrier, and a wave front of hole or particle excitations propagates at the maximum group velocity. Simultaneously, the initial pair correlations are broken and coherence over different sites is lost. In contrast, in the fast regime, the densities are not considerably deformed and the pair correlations are preserved.
Topological phase transition in quasi-one dimensional organic conductors
Ye, Xiao-Shan; Liu, Yong-Jun; Zeng, Xiang-Hua; Wu, Guoqing
2015-01-01
We explore topological phase transition, which involves the energy spectra of field-induced spin-density-wave (FISDW) states in quasi-one dimensional (Q1D) organic conductors, using an extended Su-Schrieffer-Heeger (SSH) model. We show that, in presence of half magnetic-flux FISDW state, the system exhibits topologically nontrivial phases, which can be characterized by a nonzero Chern number. The nontrivial evolution of the bulk bands with chemical potential in a topological phase transition is discussed. We show that the system can have a similar phase diagram which is discussed in the Haldane’s model. We suggest that the topological feature should be tested experimentally in this organic system. These studies enrich the theoretical research on topologically nontrivial phases in the Q1D lattice system as compared to the Haldane topological phase appearing in the two-dimensional lattices. PMID:26612317
Pseudo-one-dimensional nucleation in dilute polymer solutions
NASA Astrophysics Data System (ADS)
Zhang, Lingyun; Schmit, Jeremy D.
2016-06-01
Pathogenic protein fibrils have been shown in vitro to have nucleation-dependent kinetics despite the fact that one-dimensional structures do not have the size-dependent surface energy responsible for the lag time in classical theory. We present a theory showing that the conformational entropy of the peptide chains creates a free-energy barrier that is analogous to the translational entropy barrier in higher dimensions. We find that the dynamics of polymer rearrangement make it very unlikely for nucleation to succeed along the lowest free-energy trajectory, meaning that most of the nucleation flux avoids the free-energy saddle point. We use these results to construct a three-dimensional model for amyloid nucleation that accounts for conformational entropy, backbone H bonds, and side-chain interactions to compute nucleation rates as a function of concentration.
CHARGE ORDER FLUCTUATIONS IN ONE-DIMENSIONAL SILICIDES
Zeng, Changgan; Kent, P. R.C.; Kim, Tae-Hwan; Li, An-Ping; Weitering, Hanno H.
2014-01-01
Metallic nanowires are of great interest as interconnects in future nanoelectronic circuits. They also represent important systems for understanding the complexity of electronic interactions and conductivity in one-dimension. We have fabricated exceptionally long and uniform YSi2 nanowires via self-assembly of yttrium atoms on Si(001). The thinnest wires represent one of the closest realizations of the isolated Peierls chain, exhibiting van-Hove type singularities in the one-dimensional density of states and charge order fluctuations below 150 K. The structure of the wire was determined though a detailed comparison of scanning tunneling microscopy data and first-principles calculations. Sporadic broadenings of the wires’ cross section imply the existence of a novel metal-semiconductor junction whose electronic properties are governed by the finite-size- and temperature-scaling of the charge ordering correlation. PMID:18552849
Size Dependent Heat Conduction in One-Dimensional Diatomic Lattices
NASA Astrophysics Data System (ADS)
Tejal, N. Shah; P. N., Gajjar
2016-04-01
We study the size dependency of heat conduction in one-dimensional diatomic FPU-β lattices and establish that for low dimensional material, contribution from optical phonons is found more effective to the thermal conductivity and enhance heat transport in the thermodynamic limit N → ∞. For the finite size, thermal conductivity of 1D diatomic lattice is found to be lower than 1D monoatomic chain of the same size made up of the constituent particle of the diatomic chain. For the present 1D diatomic chain, obtained value of power divergent exponent of thermal conductivity 0.428±0.001 and diffusion exponent 1.2723 lead to the conclusions that increase in the system size, increases the thermal conductivity and existence of anomalous energy diffusion. Existing numerical data supports our findings.
Majorana fermion exchange in strictly one-dimensional structures
NASA Astrophysics Data System (ADS)
Chiu, Ching-Kai; Vazifeh, M. M.; Franz, M.
2015-04-01
It is generally thought that the adiabatic exchange of two identical particles is impossible in one spatial dimension. Here we describe a simple protocol that permits the adiabatic exchange of two Majorana fermions in a one-dimensional topological superconductor wire. The exchange relies on the concept of “Majorana shuttle” whereby a π domain wall in the superconducting order parameter which hosts a pair of ancillary majoranas delivers one zero mode across the wire while the other one tunnels in the opposite direction. The method requires some tuning of parameters and does not, therefore, enjoy full topological protection. The resulting exchange statistics, however, remain non-Abelian for a wide range of parameters that characterize the exchange.
Erosion by a one-dimensional random walk
NASA Astrophysics Data System (ADS)
Chisholm, Rebecca H.; Hughes, Barry D.; Landman, Kerry A.
2014-08-01
We consider a model introduced by Baker et al. [Phys. Rev. E 88, 042113 (2013), 10.1103/PhysRevE.88.042113] of a single lattice random walker moving on a domain of allowed sites, surrounded by blocked sites. The walker enlarges the allowed domain by eroding the boundary at its random encounters with blocked boundary sites: attempts to step onto blocked sites succeed with a given probability and convert these sites to allowed sites. The model interpolates continuously between the Pólya random walker on the one-dimensional lattice and a "blind" walker who attempts freely, but always aborts, moves to blocked sites. We obtain some exact results about the walker's location and the rate of erosion.
Topological phase transition in quasi-one dimensional organic conductors.
Ye, Xiao-Shan; Liu, Yong-Jun; Zeng, Xiang-Hua; Wu, Guoqing
2015-01-01
We explore topological phase transition, which involves the energy spectra of field-induced spin-density-wave (FISDW) states in quasi-one dimensional (Q1D) organic conductors, using an extended Su-Schrieffer-Heeger (SSH) model. We show that, in presence of half magnetic-flux FISDW state, the system exhibits topologically nontrivial phases, which can be characterized by a nonzero Chern number. The nontrivial evolution of the bulk bands with chemical potential in a topological phase transition is discussed. We show that the system can have a similar phase diagram which is discussed in the Haldane's model. We suggest that the topological feature should be tested experimentally in this organic system. These studies enrich the theoretical research on topologically nontrivial phases in the Q1D lattice system as compared to the Haldane topological phase appearing in the two-dimensional lattices. PMID:26612317
Topological phase transition in quasi-one dimensional organic conductors
NASA Astrophysics Data System (ADS)
Ye, Xiao-Shan; Liu, Yong-Jun; Zeng, Xiang-Hua; Wu, Guoqing
2015-11-01
We explore topological phase transition, which involves the energy spectra of field-induced spin-density-wave (FISDW) states in quasi-one dimensional (Q1D) organic conductors, using an extended Su-Schrieffer-Heeger (SSH) model. We show that, in presence of half magnetic-flux FISDW state, the system exhibits topologically nontrivial phases, which can be characterized by a nonzero Chern number. The nontrivial evolution of the bulk bands with chemical potential in a topological phase transition is discussed. We show that the system can have a similar phase diagram which is discussed in the Haldane’s model. We suggest that the topological feature should be tested experimentally in this organic system. These studies enrich the theoretical research on topologically nontrivial phases in the Q1D lattice system as compared to the Haldane topological phase appearing in the two-dimensional lattices.
A Reduced Order, One Dimensional Model of Joint Response
DOHNER,JEFFREY L.
2000-11-06
As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.
Polaron and bipolaron of uniaxially strained one dimensional zigzag ladder
NASA Astrophysics Data System (ADS)
Yavidov, B. Ya.
2016-09-01
An influence of the uniaxial strains in one dimensional zigzag ladder (1DZL) on the properties of polarons and bipolarons is considered. It is shown that strain changes all the parameters of the system, in particular, spectrum, existing bands and the masses of charge carriers. Numerical results obtained by taking into an account the Poisson effect clearly indicate that the properties of the (bi)polaronic system can be tuned via strain. Mass of bipolaron can be manipulated by the strain too which in turn leads to the way of tuning Bose-Einstein condensation temperature TBEC of bipolarons. It is shown that TBEC of bipolarons in strained 1DZL reasonably correlates with the values of critical temperature of superconductivity of certain perovskites.
One-dimensional Electron Gases at Oxide Interfaces
NASA Astrophysics Data System (ADS)
Cao, Yanwei; Zhong, Zhicheng; Shafer, P.; Liu, Xiaoran; Kareev, M.; Middey, S.; Meyers, D.; Arenholz, E.; Chakhalian, Jak
Emergence of two-dimensional electron gases (2DEG) at the oxide interfaces of two dissimilar insulators is a remarkable manifestation of interface engineering. With continuously reduced dimensionality, it arises an interesting question: could one-dimensional electron gases (1DEG) be designed at oxide interfaces? So far there is no report on this. Here, we report on the formation of 1DEG at the carefully engineered titanate heterostructures. Combined resonant soft X-ray linear dichroism with electrical transport and the first-principles calculations have confirmed the formation of 1DEG driven by the interfacial symmetry breaking. Our findings provide a route to engineer new electronic and magnetic states. This work was supported by Gordon and Betty Moore Foundation, DODARO, DOE, and the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy.
One-dimensional vertical dust strings in a glass box
Kong, Jie; Hyde, Truell W.; Matthews, Lorin; Qiao Ke; Zhang Zhuanhao; Douglass, Angela
2011-07-15
The oscillation spectrum of a one-dimensional vertical dust string formed inside a glass box on top of the lower electrode in a gaseous electronics conference (GEC) reference cell was studied. A mechanism for creating a single vertical dust string is described. It is shown that the oscillation amplitudes, resonance frequencies, damping coefficients, and oscillation phases of the dust particles separate into two distinct groups. One group exhibits low damping coefficients, increasing amplitudes, and decreasing resonance frequencies for dust particles closer to the lower electrode. The other group shows high damping coefficients but anomalous resonance frequencies and amplitudes. At low oscillation frequencies, the two groups are also separated by a {pi} phase difference. One possible cause for the difference in behavior between the two groups is discussed.
One-Dimensional Time to Explosion (Thermal Sensitivity) of ANPZ
Hsu, P.; Hust, G.; McClelland, M.; Gresshoff, M.
2014-11-12
Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the recent ODTX experimental data and modeling results for 2,6-diamino-3,5-dintropyrazine (ANPZ).
Novel superconducting phenomena in quasi-one-dimensional Bechgaard salts
NASA Astrophysics Data System (ADS)
Jerome, Denis; Yonezawa, Shingo
2016-03-01
It is the saturation of the transition temperature Tc in the range of 24 K for known materials in the late sixties that triggered the search for additional materials offering new coupling mechanisms leading in turn to higher Tc's. As a result of this stimulation, superconductivity in organic matter was discovered in tetramethyl-tetraselenafulvalene-hexafluorophosphate, (TMTSF)2PF6, in 1979, in the laboratory founded at Orsay by Professor Friedel and his colleagues in 1962. Although this conductor is a prototype example for low-dimensional physics, we mostly focus in this article on the superconducting phase of the ambient-pressure superconductor (TMTSF)2ClO4, which has been studied most intensively among the TMTSF salts. We shall present a series of experimental results supporting nodal d-wave symmetry for the superconducting gap in these prototypical quasi-one-dimensional conductors. xml:lang="fr"
Superconducting cosmic strings and one dimensional extended supersymmetric algebras
Oikonomou, V.K.
2014-11-15
In this article we study in detail the supersymmetric structures that underlie the system of fermionic zero modes around a superconducting cosmic string. Particularly, we extend the analysis existing in the literature on the one dimensional N=2 supersymmetry and we find multiple N=2, d=1 supersymmetries. In addition, compact perturbations of the Witten index of the system are performed and we find to which physical situations these perturbations correspond. More importantly, we demonstrate that there exists a much more rich supersymmetric structure underlying the system of fermions with N{sub f} flavors and these are N-extended supersymmetric structures with non-trivial topological charges, with “N” depending on the fermion flavors.
Excitations of one-dimensional supersolids with optical lattices
NASA Astrophysics Data System (ADS)
Hsueh, C.-H.; Tsai, Y.-C.; Wu, W. C.
2016-06-01
Based on mean-field Gross-Pitaevskii and Bogoliubov-de Gennes approaches, we investigate excitations of a one-dimensional soft-core interacting ultracold Bose gas under the effect of an optical lattice. It is found that no matter how deep the lattice is, at q →0 the lowest mode corresponds to a gapless phonon, ω12=v12q2 , whereas the second lowest mode corresponds to a gapped optical phonon, ω22=Δ2±v22q2 . Determination of the velocities v1,v2 , the gap Δ , and the possible sign change in ω2 upon the change of lattice depth can give decisive measures to the transitions across various supersolid and solid states. The power law v1˜(fs) 1 /2 with fs the superfluid fraction is identified in the present system at the tight-binding regime.
Loschmidt echo in one-dimensional interacting Bose gases
Lelas, K.; Seva, T.; Buljan, H.
2011-12-15
We explore Loschmidt echo in two regimes of one-dimensional interacting Bose gases: the strongly interacting Tonks-Girardeau (TG) regime, and the weakly interacting mean-field regime. We find that the Loschmidt echo of a TG gas decays as a Gaussian when small (random and time independent) perturbations are added to the Hamiltonian. The exponent is proportional to the number of particles and the magnitude of a small perturbation squared. In the mean-field regime the Loschmidt echo shows richer behavior: it decays faster for larger nonlinearity, and the decay becomes more abrupt as the nonlinearity increases; it can be very sensitive to the particular realization of the noise potential, especially for relatively small nonlinearities.
Wigner quantization of some one-dimensional Hamiltonians
Regniers, G.; Van der Jeugt, J.
2010-12-15
Recently, several papers have been dedicated to the Wigner quantization of different Hamiltonians. In these examples, many interesting mathematical and physical properties have been shown. Among those we have the ubiquitous relation with Lie superalgebras and their representations. In this paper, we study two one-dimensional Hamiltonians for which the Wigner quantization is related with the orthosymplectic Lie superalgebra osp(1|2). One of them, the Hamiltonian H=xp, is popular due to its connection with the Riemann zeros, discovered by Berry and Keating on the one hand and Connes on the other. The Hamiltonian of the free particle, H{sub f}=p{sup 2}/2, is the second Hamiltonian we will examine. Wigner quantization introduces an extra representation parameter for both of these Hamiltonians. Canonical quantization is recovered by restricting to a specific representation of the Lie superalgebra osp(1|2).
Bandgap characteristics of one-dimensional plasma photonic crystal
Yin Yan; Ma Yanyun; Tian Chenglin; Shao Fuqiu; Xu Han; Zhuo Hongbin; Yu, M. Y.
2009-10-15
When two pump laser pulses intersect in an underdense plasma, plasma Bragg grating (PBG) is induced by the slow-varying ponderomotive force [Z. M. Sheng et al., Appl. Phys. B: Lasers Opt. 77, 673 (2003)]. Such a PBG can be considered as a one-dimensional (1D) plasma photonic crystal (PPC). Here the bandgap characteristic of 1D PPC composed of plasma layers of different densities is investigated theoretically and numerically. It is found that when the maximum density is lower than the critical density of the pump laser, there is only one normal-incidence bandgap. When the maximum density is higher than the critical density of the pump laser, high-order bandgaps are found. The theoretical results are verified by 1D particle-in-cell simulations.
One-dimensional photonic crystal fishbone hybrid nanocavity with nanoposts
Lu, Tsan-Wen; Lin, Pin-Tso; Lee, Po-Tsung
2014-05-12
We propose and investigate a one-dimensional photonic crystal (PhC) fishbone (FB) hybrid nanocavity lying on silver substrate with a horizontal air slot. With very few PhC periods, the confined transverse-magnetic, TM{sub 10} hybrid mode concentrated within the air slot shows high quality factor over effective mode volume ratio larger than 10{sup 5}λ{sup −3}. Most importantly, this FB hybrid nanocavity allows formation of low-index nanoposts within the air slot without significantly affecting the mode properties. These nanoposts guarantee the structural stabilities under different environmental perturbations. Furthermore, capabilities of our proposed design in serving as optical sensors and tweezers for bio-sized nanoparticles are also investigated.
One-dimensional disk model simulation for klystron design
Yonezawa, H.; Okazaki, Y.
1984-05-01
In 1982, one of the authors (Okazaki), of Toshiba Corporation, wrote a one-dimensional, rigid-disk model computer program <1> to serve as a reliable design tool for the 150 MW klystron development project. This is an introductory note for the users of this program. While reviewing the so-called disk programs presently available, hypotheses such as gridded interaction gaps, a linear relation between phase and position, and so on, were found. These hypotheses bring serious limitations and uncertainties into the computational results. JPNDISK was developed to eliminate these defects, to follow the equations of motion as rigorously as possible, and to obtain self-consistent solutions for the gap voltages and the electron motion. Although some inaccuracy may be present in the relativistic region, JPNDISK, in its present form, seems a most suitable tool for klystron design; it is both easy and inexpensive to use.
Pseudo-one-dimensional nucleation in dilute polymer solutions.
Zhang, Lingyun; Schmit, Jeremy D
2016-06-01
Pathogenic protein fibrils have been shown in vitro to have nucleation-dependent kinetics despite the fact that one-dimensional structures do not have the size-dependent surface energy responsible for the lag time in classical theory. We present a theory showing that the conformational entropy of the peptide chains creates a free-energy barrier that is analogous to the translational entropy barrier in higher dimensions. We find that the dynamics of polymer rearrangement make it very unlikely for nucleation to succeed along the lowest free-energy trajectory, meaning that most of the nucleation flux avoids the free-energy saddle point. We use these results to construct a three-dimensional model for amyloid nucleation that accounts for conformational entropy, backbone H bonds, and side-chain interactions to compute nucleation rates as a function of concentration. PMID:27415194
Switching synchronization in one-dimensional memristive networks
NASA Astrophysics Data System (ADS)
Slipko, Valeriy A.; Shumovskyi, Mykola; Pershin, Yuriy V.
2015-11-01
We report on a switching synchronization phenomenon in one-dimensional memristive networks, which occurs when several memristive systems with different switching constants are switched from the high- to low-resistance state. Our numerical simulations show that such a collective behavior is especially pronounced when the applied voltage slightly exceeds the combined threshold voltage of memristive systems. Moreover, a finite increase in the network switching time is found compared to the average switching time of individual systems. An analytical model is presented to explain our observations. Using this model, we have derived asymptotic expressions for memory resistances at short and long times, which are in excellent agreement with results of our numerical simulations.
Switching synchronization in one-dimensional memristive networks.
Slipko, Valeriy A; Shumovskyi, Mykola; Pershin, Yuriy V
2015-11-01
We report on a switching synchronization phenomenon in one-dimensional memristive networks, which occurs when several memristive systems with different switching constants are switched from the high- to low-resistance state. Our numerical simulations show that such a collective behavior is especially pronounced when the applied voltage slightly exceeds the combined threshold voltage of memristive systems. Moreover, a finite increase in the network switching time is found compared to the average switching time of individual systems. An analytical model is presented to explain our observations. Using this model, we have derived asymptotic expressions for memory resistances at short and long times, which are in excellent agreement with results of our numerical simulations. PMID:26651772
Sonic black holes in a one-dimensional relativistic flow
NASA Astrophysics Data System (ADS)
Carbonaro, P.
2015-09-01
The analogy between sound propagation in a fluid background and light propagation in a curved spacetime, discovered by Unruh in 1981, does not work in general when considering the motion of a fluid which is confined in one spatial dimension being unable in (1+1) dimensions to introduce in a coherent manner an effective acoustic metric, barring some exceptional cases. In this paper a relativistic fluid is considered and the general condition for the existence of an acoustic metric in strictly one-dimensional systems is found. Attention is also paid to the physical meaning of the equations of state characterizing such systems and to the remarkable symmetry of structure taken by the basic equations. Finally the Hawking temperature is calculated in an artificial de Laval nozzle.
Magnons in one-dimensional k-component Fibonacci structures
Costa, C. H.; Vasconcelos, M. S.
2014-05-07
We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: S{sub n}{sup (k)}=S{sub n−1}{sup (k)}S{sub n−k}{sup (k)} (n≥k=0,1,2,…), where S{sub n}{sup (k)} is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.
One-dimensional Ising model with multispin interactions
NASA Astrophysics Data System (ADS)
Turban, Loïc
2016-09-01
We study the spin-1/2 Ising chain with multispin interactions K involving the product of m successive spins, for general values of m. Using a change of spin variables the zero-field partition function of a finite chain is obtained for free and periodic boundary conditions and we calculate the two-spin correlation function. When placed in an external field H the system is shown to be self-dual. Using another change of spin variables the one-dimensional Ising model with multispin interactions in a field is mapped onto a zero-field rectangular Ising model with first-neighbour interactions K and H. The 2D system, with size m × N/m, has the topology of a cylinder with helical BC. In the thermodynamic limit N/m\\to ∞ , m\\to ∞ , a 2D critical singularity develops on the self-duality line, \\sinh 2K\\sinh 2H=1.
One-dimensional Kondo lattice model at quarter filling
NASA Astrophysics Data System (ADS)
Xavier, J. C.; Miranda, E.
2008-10-01
We revisit the problem of the quarter-filled one-dimensional Kondo lattice model, for which the existence of a dimerized phase and a nonzero charge gap had been reported by Xavier [Phys. Rev. Lett. 90, 247204 (2003)]. Recently, some objections were raised claiming that the system is neither dimerized nor has a charge gap. In the interest of clarifying this important issue, we show that these objections are based on results obtained under conditions in which the dimer order is artificially suppressed. We use the incontrovertible dimerized phase of the Majumdar-Ghosh point of the J1-J2 Heisenberg model as a paradigm with which to illustrate this artificial suppression. Finally, by means of extremely accurate density-matrix renormalization-group calculations, we show that the charge gap is indeed nonzero in the dimerized phase.
Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization
NASA Astrophysics Data System (ADS)
Pu, Shi; Roy, Victor; Rezzolla, Luciano; Rischke, Dirk H.
2016-04-01
We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a nonzero magnetization. First, we assume a constant magnetic susceptibility χm and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with χm>0 ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with χm<0 ), the energy density decays faster because it feeds energy into the magnetic field. Furthermore, when the magnetic field is taken to be external and to decay in proper time τ with a power law ˜τ-a, two distinct solutions can be found depending on the values of a and χm. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the nonvanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. It is only for magnetic fields about an order of magnitude larger than expected for heavy-ion collisions that the system is substantially reheated and the lifetime of the quark phase might be extended.
A One-Dimensional Synthetic-Aperture Microwave Radiometer
NASA Technical Reports Server (NTRS)
Doiron, Terence; Piepmeier, Jeffrey
2010-01-01
A proposed one-dimensional synthetic- aperture microwave radiometer could serve as an alternative to either the two-dimensional synthetic-aperture radiometer described in the immediately preceding article or to a prior one-dimensional one, denoted the Electrically Scanned Thinned Array Radiometer (ESTAR), mentioned in that article. The proposed radiometer would operate in a pushbroom imaging mode, utilizing (1) interferometric cross-track scanning to obtain cross-track resolution and (2) the focusing property of a reflector for along-track resolution. The most novel aspect of the proposed system would be the antenna (see figure), which would include a cylindrical reflector of offset parabolic cross section. The reflector could be made of a lightweight, flexible material amenable to stowage and deployment. Other than a stowage/deployment mechanism, the antenna would not include moving parts, and cross-track scanning would not entail mechanical rotation of the antenna. During operation, the focal line, parallel to the cylindrical axis, would be oriented in the cross-track direction, so that placement of receiving/radiating elements at the focal line would afford the desired along-track resolution. The elements would be microwave feed horns sparsely arrayed along the focal line. The feed horns would be oriented with their short and long cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis to obtain fan-shaped beams having their broad and narrow cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis. The interference among the beams would be controlled in the same manner as in the ESTAR to obtain along-cylindrical- axis (cross-track) resolution and cross-track scanning.
Magnetic properties of manganese based one-dimensional spin chains.
Asha, K S; Ranjith, K M; Yogi, Arvind; Nath, R; Mandal, Sukhendu
2015-12-14
We have correlated the structure-property relationship of three manganese-based inorganic-organic hybrid structures. Compound 1, [Mn2(OH-BDC)2(DMF)3] (where BDC = 1,4-benzene dicarboxylic acid and DMF = N,N'-dimethylformamide), contains Mn2O11 dimers as secondary building units (SBUs), which are connected by carboxylate anions forming Mn-O-C-O-Mn chains. Compound 2, [Mn2(BDC)2(DMF)2], contains Mn4O20 clusters as SBUs, which also form Mn-O-C-O-Mn chains. In compound 3, [Mn3(BDC)3(DEF)2] (where DEF = N,N'-diethylformamide), the distorted MnO6 octahedra are linked to form a one-dimensional chain with Mn-O-Mn connectivity. The magnetic properties were investigated by means of magnetization and heat capacity measurements. The temperature dependent magnetic susceptibility of all the three compounds could be nicely fitted using a one-dimensional S = 5/2 Heisenberg antiferromagnetic chain model and the value of intra-chain exchange coupling (J/k(B)) between Mn(2+) ions was estimated to be ∼1.1 K, ∼0.7 K, and ∼0.46 K for compounds 1, 2, and 3, respectively. Compound 1 does not undergo any magnetic long-range-order down to 2 K while compounds 2 and 3 undergo long-range magnetic order at T(N) ≈ 4.2 K and ≈4.3 K, respectively, which are of spin-glass type. From the values of J/k(B) and T(N) the inter-chain coupling (J(⊥)/k(B)) was calculated to be about 0.1J/k(B) for both compounds 2 and 3, respectively. PMID:26455515
One-dimensional cloud fluid model for propagating star formation
NASA Technical Reports Server (NTRS)
Titus, Timothy N.; Struck-Marcell, Curtis
1990-01-01
The aim of this project was to study the propagation of star formation (SF) with a self-consistent deterministic model for the interstellar gas. The questions of under what conditions does star formation propagate in this model and what are the mechanisms of the propagation are explored. Here, researchers used the deterministic Oort-type cloud fluid model of Scalo and Struck-Marcell (1984, also see the review of Struck-Marcell, Scalo and Appleton 1987). This cloud fluid approach includes simple models for the effects of cloud collisional coalescence or disruption, collisional energy dissipation, and cloud disruption and acceleration as the result of young star winds, HII regions and supernovae. An extensive one-zone parameter study is presented in Struck-Marcell and Scalo (1987). To answer the questions above, researchers carried out one-dimensional calculations for an annulus within a galactic disk, like the so-called solar neighborhood of the galactic chemical evolution. In the calculations the left-hand boundary is set equal to the right hand boundary. The calculation is obviously idealized; however, it is computationally convenient to study the first order effects of propagating star formation. The annulus was treated as if it were at rest, i.e., in the local rotating frame. This assumption may remove some interesting effects of a supersonic gas flow, but was necessary to maintain a numerical stability in the annulus. The results on the one-dimensional propagation of SF in the Oort cloud fluid model follow: (1) SF is propagated by means of hydrodynamic waves, which can be generated by external forces or by the pressure generated by local bursts. SF is not effectively propagated via diffusion or variation in cloud interaction rates without corresponding density and velocity changes. (2) The propagation and long-range effects of SF depend on how close the gas density is to the critical threshold value, i.e., on the susceptibility of the medium.
NASA Astrophysics Data System (ADS)
Liu, Wen-Cheng; Cai, Wei
2008-03-01
One-dimensional (1D) and quasi-1D ZnO nanostructures have been fabricated by a kind of new spray-pyrolysis-assisted thermal evaporation method. Pure ZnO powder serves as an evaporation source. Thus-obtained products have been characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM). The room temperature photoluminescence spectrum of these ZnO nanostructures is presented. The results show that as-grown ZnO nanomaterials have a hexagonal wurtzite crystalline structure. Besides nanosaws, nanobelts and nanowires, complex ZnO nanotrees have also been observed in synthesized products. The study provides a new simple route to construct 1D and quasi-1D ZnO nanomaterials, which can probably be extended to fabricate other oxide nanomaterials with high melting point and doped oxide nanomaterials.
An adaptive grid algorithm for one-dimensional nonlinear equations
NASA Technical Reports Server (NTRS)
Gutierrez, William E.; Hills, Richard G.
1990-01-01
Richards' equation, which models the flow of liquid through unsaturated porous media, is highly nonlinear and difficult to solve. Step gradients in the field variables require the use of fine grids and small time step sizes. The numerical instabilities caused by the nonlinearities often require the use of iterative methods such as Picard or Newton interation. These difficulties result in large CPU requirements in solving Richards equation. With this in mind, adaptive and multigrid methods are investigated for use with nonlinear equations such as Richards' equation. Attention is focused on one-dimensional transient problems. To investigate the use of multigrid and adaptive grid methods, a series of problems are studied. First, a multigrid program is developed and used to solve an ordinary differential equation, demonstrating the efficiency with which low and high frequency errors are smoothed out. The multigrid algorithm and an adaptive grid algorithm is used to solve one-dimensional transient partial differential equations, such as the diffusive and convective-diffusion equations. The performance of these programs are compared to that of the Gauss-Seidel and tridiagonal methods. The adaptive and multigrid schemes outperformed the Gauss-Seidel algorithm, but were not as fast as the tridiagonal method. The adaptive grid scheme solved the problems slightly faster than the multigrid method. To solve nonlinear problems, Picard iterations are introduced into the adaptive grid and tridiagonal methods. Burgers' equation is used as a test problem for the two algorithms. Both methods obtain solutions of comparable accuracy for similar time increments. For the Burgers' equation, the adaptive grid method finds the solution approximately three times faster than the tridiagonal method. Finally, both schemes are used to solve the water content formulation of the Richards' equation. For this problem, the adaptive grid method obtains a more accurate solution in fewer work units and
Manifestations of one-dimensional electronic correlations in higher-dimensional systems
NASA Astrophysics Data System (ADS)
Saha, Ronojoy
In this work we have studied the fundamental aspects of transport and thermodynamic properties of a one-dimensional (1D) electron system, and have shown that these 1D correlations play an important role in understanding the physics of higher-dimensional systems. The first system we studied is a three-dimensional (3D) metal subjected to a strong magnetic field that confines the electrons to the lowest Landau level. We investigated the effect of dilute impurities in the transport properties of this system. We showed that the nature of electron transport is one dimensional due to the reduced effective dimensionality induced by the magnetic field. The localization behavior in this system was shown to be intermediate, between a 1D and a 3D system. The interaction corrections to the conductivity exhibit power law scaling, sigma ∝ Talpha with a field dependent exponent. Next we studied the thermodynamic properties of a one-dimensional interacting system, where we showed that the next-to-leading terms in the specific heat and spin susceptibility are nonanalytic, in the same way as they are for higher-dimensional (D = 2,3) systems. We obtained the nonanalytic, T lnT term in the specific heat in 1D and showed that although the nonanalytic corrections in all dimensions arise from the same source, there are subtle differences in the magnitude of the effect in different dimensions. In the final part of this work we analyzed the nonanalytic corrections to the spin susceptibility (chis(H)) in higher dimensional systems. We showed that, although there were contributions from non-1D scattering in these nonanalytic terms, the dominant contribution came from 1D scattering. We also showed that the second order ferromagnetic quantum phase transition is unstable both in 2D and 3D, with a tendency towards a first order transition.
Causality and relativistic localization in one-dimensional Hamiltonians
Wagner, R. E.; Shields, B. T.; Ware, M. R.; Su, Q.; Grobe, R.
2011-06-15
We compare the relativistic time evolution of an initially localized quantum particle obtained from the relativistic Schroedinger, the Klein-Gordon and the Dirac equations. By computing the amount of the spatial probability density that evolves outside the light cone we quantify the amount of causality violation for the relativistic Schroedinger Hamiltonian. We comment on the relationship between quantum field theoretical transition amplitudes, commutators of the fields and their bilinear combinations outside the light cone as indicators of a possible causality violation. We point out the relevance of the relativistic localization problem to this discussion and comment on ideas about the supposed role of quantum field theory as a vehicle of making a theory causal by introducing antiparticles.
Decay of Bogoliubov excitations in one-dimensional Bose gases
NASA Astrophysics Data System (ADS)
Ristivojevic, Zoran; Matveev, K. A.
2016-07-01
We study the decay of Bogoliubov quasiparticles in one-dimensional Bose gases. Starting from the hydrodynamic Hamiltonian, we develop a microscopic theory that enables one to systematically study both the excitations and their decay. At zero temperature, the leading mechanism of decay of a quasiparticle is disintegration into three others. We find that low-energy quasiparticles (phonons) decay with the rate that scales with the seventh power of momentum, whereas the rate of decay of the high-energy quasiparticles does not depend on momentum. In addition, our approach allows us to study analytically the quasiparticle decay in the whole crossover region between the two limiting cases. When applied to integrable models, including the Lieb-Liniger model of bosons with contact repulsion, our theory confirms the absence of the decay of quasiparticle excitations. We account for two types of integrability-breaking perturbations that enable finite decay: three-body interaction between the bosons and two-body interaction of finite range.
Evolution of a One-dimensional, Two Component, Universe
NASA Astrophysics Data System (ADS)
Shiozawa, Yui; Miller, Bruce; Rouet, Jean-Louis
2015-03-01
While the universe we observe today exhibits local filament-like structures, with stellar clusters and large voids between them, the primordial universe is believed to have been nearly homogeneous with slight variations in matter density. To understand how the observed hierarchical structure was formed, researchers have developed a one-dimensional analogue of the universe that can simulate the evolution of a large number of matter particles. Investigations to date demonstrate that this model reveals structure formation that shares essential features with the three-dimensional observations. In the present work, we have expanded on this concept to include two species of matter, specifically dark matter and luminous matter. In our simulation, luminous matter is treated in a way that loses energy in interaction with itself. The results of the simulations clearly show the formation of a Cantor set like multifractal pattern over time in configuration space as well as in phase space. In contrast with most earlier studies, mass-oriented methods for computing the multifractal dimensions were performed on various subsets of the matter distribution in order to understand the bottom-up structure formation.
Fractal analysis in a one-dimensional universe
NASA Astrophysics Data System (ADS)
Shiozawa, Yui
2014-09-01
While the universe we observe today exhibits local filament-like structures, with stellar clusters and large voids between them, the primordial universe is believed to have been nearly homogeneous with slight variations in matter density. To understand how the observed hierarchical structure was formed, researchers have developed a one-dimensional analogue of the universe that can simulate the evolution of a large number of matter particles. Investigations to date demonstrate that this model reveals structure formation that shares essential features with the three-dimensional observations. In the present work, we have expanded on this concept to include two species of matter, specifically dark matter and luminous matter. In our simulation, luminous matter is treated in a way that loses energy in interaction. The results of the simulations clearly show the formation of a Cantor set like multifractal pattern over time. In contrast with most earlier studies, mass-oriented methods for computing multifractal dimensions were applied to analyze the bottom-up structure formation.
Automated quantification of one-dimensional nanostructure alignment on surfaces.
Dong, Jianjin; Goldthorpe, Irene A; Abukhdeir, Nasser Mohieddin
2016-06-10
A method for automated quantification of the alignment of one-dimensional (1D) nanostructures from microscopy imaging is presented. Nanostructure alignment metrics are formulated and shown to be able to rigorously quantify the orientational order of nanostructures within a two-dimensional domain (surface). A complementary image processing method is also presented which enables robust processing of microscopy images where overlapping nanostructures might be present. Scanning electron microscopy (SEM) images of nanowire-covered surfaces are analyzed using the presented methods and it is shown that past single parameter alignment metrics are insufficient for highly aligned domains. Through the use of multiple parameter alignment metrics, automated quantitative analysis of SEM images is shown to be possible and the alignment characteristics of different samples are able to be quantitatively compared using a similarity metric. The results of this work provide researchers in nanoscience and nanotechnology with a rigorous method for the determination of structure/property relationships, where alignment of 1D nanostructures is significant. PMID:27119552
Carbyne with finite length: The one-dimensional sp carbon
Pan, Bitao; Xiao, Jun; Li, Jiling; Liu, Pu; Wang, Chengxin; Yang, Guowei
2015-01-01
Carbyne is the one-dimensional allotrope of carbon composed of sp-hybridized carbon atoms. Definitive evidence for carbyne has remained elusive despite its synthesis and preparation in the laboratory. Given the remarkable technological breakthroughs offered by other allotropes of carbon, including diamond, graphite, fullerenes, carbon nanotubes, and graphene, interest in carbyne and its unusual potential properties remains intense. We report the first synthesis of carbyne with finite length, which is clearly composed of alternating single bonds and triple bonds, using a novel process involving laser ablation in liquid. Spectroscopic analyses confirm that the product is the structure of sp hybridization with alternating carbon-carbon single bonds and triple bonds and capped by hydrogen. We observe purple-blue fluorescence emissions from the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of carbyne. Condensed-phase carbyne crystals have a hexagonal lattice and resemble the white crystalline powder produced by drying a carbyne solution. We also establish that the combination of gold and alcohol is crucial to carbyne formation because carbon-hydrogen bonds can be cleaved with the help of gold catalysts under the favorable thermodynamic environment provided by laser ablation in liquid and because the unique configuration of two carbon atoms in an alcohol molecule matches the elementary entity of carbyne. This laboratory synthesis of carbyne will enable the exploration of its properties and applications. PMID:26601318
Carbyne with finite length: The one-dimensional sp carbon.
Pan, Bitao; Xiao, Jun; Li, Jiling; Liu, Pu; Wang, Chengxin; Yang, Guowei
2015-10-01
Carbyne is the one-dimensional allotrope of carbon composed of sp-hybridized carbon atoms. Definitive evidence for carbyne has remained elusive despite its synthesis and preparation in the laboratory. Given the remarkable technological breakthroughs offered by other allotropes of carbon, including diamond, graphite, fullerenes, carbon nanotubes, and graphene, interest in carbyne and its unusual potential properties remains intense. We report the first synthesis of carbyne with finite length, which is clearly composed of alternating single bonds and triple bonds, using a novel process involving laser ablation in liquid. Spectroscopic analyses confirm that the product is the structure of sp hybridization with alternating carbon-carbon single bonds and triple bonds and capped by hydrogen. We observe purple-blue fluorescence emissions from the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of carbyne. Condensed-phase carbyne crystals have a hexagonal lattice and resemble the white crystalline powder produced by drying a carbyne solution. We also establish that the combination of gold and alcohol is crucial to carbyne formation because carbon-hydrogen bonds can be cleaved with the help of gold catalysts under the favorable thermodynamic environment provided by laser ablation in liquid and because the unique configuration of two carbon atoms in an alcohol molecule matches the elementary entity of carbyne. This laboratory synthesis of carbyne will enable the exploration of its properties and applications. PMID:26601318
Topological water wave states in a one-dimensional structure
Yang, Zhaoju; Gao, Fei; Zhang, Baile
2016-01-01
Topological concepts have been introduced into electronic, photonic, and phononic systems, but have not been studied in surface-water-wave systems. Here we study a one-dimensional periodic resonant surface-water-wave system and demonstrate its topological transition. By selecting three different water depths, we can construct different types of water waves - shallow, intermediate and deep water waves. The periodic surface-water-wave system consists of an array of cylindrical water tanks connected with narrow water channels. As the width of connecting channel varies, the band diagram undergoes a topological transition which can be further characterized by Zak phase. This topological transition holds true for shallow, intermediate and deep water waves. However, the interface state at the boundary separating two topologically distinct arrays of water tanks can exhibit different bands for shallow, intermediate and deep water waves. Our work studies for the first time topological properties of water wave systems, and paves the way to potential management of water waves. PMID:27373982
Weak lasing in one-dimensional polariton superlattices
Zhang, Long; Xie, Wei; Wang, Jian; Poddubny, Alexander; Lu, Jian; Wang, Yinglei; Gu, Jie; Liu, Wenhui; Xu, Dan; Shen, Xuechu; Rubo, Yuri G.; Altshuler, Boris L.; Kavokin, Alexey V.; Chen, Zhanghai
2015-01-01
Bosons with finite lifetime exhibit condensation and lasing when their influx exceeds the lasing threshold determined by the dissipative losses. In general, different one-particle states decay differently, and the bosons are usually assumed to condense in the state with the longest lifetime. Interaction between the bosons partially neglected by such an assumption can smear the lasing threshold into a threshold domain—a stable lasing many-body state exists within certain intervals of the bosonic influxes. This recently described weak lasing regime is formed by the spontaneously symmetry breaking and phase-locking self-organization of bosonic modes, which results in an essentially many-body state with a stable balance between gains and losses. Here we report, to our knowledge, the first observation of the weak lasing phase in a one-dimensional condensate of exciton–polaritons subject to a periodic potential. Real and reciprocal space photoluminescence images demonstrate that the spatial period of the condensate is twice as large as the period of the underlying periodic potential. These experiments are realized at room temperature in a ZnO microwire deposited on a silicon grating. The period doubling takes place at a critical pumping power, whereas at a lower power polariton emission images have the same periodicity as the grating. PMID:25787253
One-dimensional surface phonon polaritons in boron nitride nanotubes.
Xu, Xiaoji G; Ghamsari, Behnood G; Jiang, Jian-Hua; Gilburd, Leonid; Andreev, Gregory O; Zhi, Chunyi; Bando, Yoshio; Golberg, Dmitri; Berini, Pierre; Walker, Gilbert C
2014-01-01
Surface polaritons, which are electromagnetic waves coupled to material charge oscillations, have enabled applications in concentrating, guiding and harvesting optical energy below the diffraction limit. Surface plasmon polaritons involve oscillations of electrons and are accessible in noble metals at visible and near-infrared wavelengths, whereas surface phonon polaritons (SPhPs) rely on phonon resonances in polar materials, and are active in the mid-infrared. Noble metal surface plasmon polaritons have limited applications in the mid-infrared. SPhPs at flat interfaces normally possess long polariton wavelengths and provide modest field confinement/enhancement. Here we demonstrate propagating SPhPs in a one-dimensional material consisting of a boron nitride nanotube at mid-infrared wavelengths. The observed SPhP exhibits high field confinement and enhancement, and a very high effective index (neff~70). We show that the modal and propagation length characteristics of the SPhPs may be controlled through the nanotube size and the supporting substrates, enabling mid-infrared applications. PMID:25154586
Topological water wave states in a one-dimensional structure
NASA Astrophysics Data System (ADS)
Yang, Zhaoju; Gao, Fei; Zhang, Baile
2016-07-01
Topological concepts have been introduced into electronic, photonic, and phononic systems, but have not been studied in surface-water-wave systems. Here we study a one-dimensional periodic resonant surface-water-wave system and demonstrate its topological transition. By selecting three different water depths, we can construct different types of water waves - shallow, intermediate and deep water waves. The periodic surface-water-wave system consists of an array of cylindrical water tanks connected with narrow water channels. As the width of connecting channel varies, the band diagram undergoes a topological transition which can be further characterized by Zak phase. This topological transition holds true for shallow, intermediate and deep water waves. However, the interface state at the boundary separating two topologically distinct arrays of water tanks can exhibit different bands for shallow, intermediate and deep water waves. Our work studies for the first time topological properties of water wave systems, and paves the way to potential management of water waves.
Using the NASA GRC Sectored-One-Dimensional Combustor Simulation
NASA Technical Reports Server (NTRS)
Paxson, Daniel E.; Mehta, Vishal R.
2014-01-01
The document is a user manual for the NASA GRC Sectored-One-Dimensional (S-1-D) Combustor Simulation. It consists of three sections. The first is a very brief outline of the mathematical and numerical background of the code along with a description of the non-dimensional variables on which it operates. The second section describes how to run the code and includes an explanation of the input file. The input file contains the parameters necessary to establish an operating point as well as the associated boundary conditions (i.e. how it is fed and terminated) of a geometrically configured combustor. It also describes the code output. The third section describes the configuration process and utilizes a specific example combustor to do so. Configuration consists of geometrically describing the combustor (section lengths, axial locations, and cross sectional areas) and locating the fuel injection point and flame region. Configuration requires modifying the source code and recompiling. As such, an executable utility is included with the code which will guide the requisite modifications and insure that they are done correctly.
Solitary Wave in One-dimensional Buckyball System at Nanoscale
Xu, Jun; Zheng, Bowen; Liu, Yilun
2016-01-01
We have studied the stress wave propagation in one-dimensional (1-D) nanoscopic buckyball (C60) system by molecular dynamics (MD) simulation and quantitative modeling. Simulation results have shown that solitary waves are generated and propagating in the buckyball system through impacting one buckyball at one end of the buckyball chain. We have found the solitary wave behaviors are closely dependent on the initial temperature and impacting speed of the buckyball chain. There are almost no dispersion and dissipation of the solitary waves (stationary solitary wave) for relatively low temperature and high impacting speed. While for relatively high temperature and low impacting speed the profile of the solitary waves is highly distorted and dissipated after propagating several tens of buckyballs. A phase diagram is proposed to describe the effect of the temperature and impacting speed on the solitary wave behaviors in buckyball system. In order to quantitatively describe the wave behavior in buckyball system, a simple nonlinear-spring model is established, which can describe the MD simulation results at low temperature very well. The results presented in this work may lay a solid step towards the further understanding and manipulation of stress wave propagation and impact energy mitigation at nanoscale. PMID:26891624
One-dimensional simulation of lanthanide isotachophoresis using COMSOL.
Dixon, Derek R; Clark, Sue B; Ivory, Cornelius F
2012-03-01
Electrokinetic separations can be used to quickly separate rare earth metals to determine their forensic signature. In this work, we simulate the concentration and separation of trivalent lanthanide cations by isotachophoresis. A one-dimensional simulation is developed using COMSOL v4.0a, a commercial finite element simulator, to represent the isotachophoretic separation of three lanthanides: lanthanum, terbium, and lutetium. The binding ligand chosen for complexation with the lanthanides is α-hydroxyisobutyric acid (HIBA) and the buffer system includes acetate, which also complexes with the lanthanides. The complexes formed between the three lanthanides, HIBA, and acetate are all considered in the simulation. We observe that the presence of only lanthanide:HIBA complexes in a buffer system with 10 mM HIBA causes the slowest lanthanide peak (lutetium) to split from the other analytes. The addition of lanthanide:acetate complexes into the simulation of the same buffer system eliminates this splitting. Decreasing the concentration of HIBA in the buffer to 7 mM causes the analyte stack to migrate faster through the capillary. PMID:22522543
Characterization of Thermal Transport in One-dimensional Solid Materials
Liu, Guoqing; Lin, Huan; Tang, Xiaoduan; Bergler, Kevin; Wang, Xinwei
2014-01-01
The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including conductive, semi-conductive or nonconductive one-dimensional structures. This technique broadens the measurement scope of materials (conductive and nonconductive) and improves the accuracy and stability. If the sample (especially biomaterials, such as human head hair, spider silk, and silkworm silk) is not conductive, it will be coated with a gold layer to make it electronically conductive. The effect of parasitic conduction and radiative losses on the thermal diffusivity can be subtracted during data processing. Then the real thermal conductivity can be calculated with the given value of volume-based specific heat (ρcp), which can be obtained from calibration, noncontact photo-thermal technique or measuring the density and specific heat separately. In this work, human head hair samples are used to show how to set up the experiment, process the experimental data, and subtract the effect of parasitic conduction and radiative losses. PMID:24514072
Transmission properties of one-dimensional ternary plasma photonic crystals
NASA Astrophysics Data System (ADS)
Shiveshwari, Laxmi; Awasthi, S. K.
2015-09-01
Omnidirectional photonic band gaps (PBGs) are found in one-dimensional ternary plasma photonic crystals (PPC) composed of single negative metamaterials. The band characteristics and transmission properties are investigated through the transfer matrix method. We show that the proposed structure can trap light in three-dimensional space due to the elimination of Brewster's angle transmission resonance allowing the existence of complete PBG. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material, and number of unit cells (N) for TE and TM polarizations. It is seen that PBG characteristics is apparent even in an N ≥ 2 system, which is weakly sensitive to the incident angle and completely insensitive to the polarization. Finite PPC could be used for multichannel transmission filter without introducing any defect in the geometry. We show that the locations of the multichannel transmission peaks are in the allowed band of the infinite structure. The structure can work as a single or multichannel filter by varying the number of unit cells. Binary PPC can also work as a polarization sensitive tunable filter.
Weak lasing in one-dimensional polariton superlattices.
Zhang, Long; Xie, Wei; Wang, Jian; Poddubny, Alexander; Lu, Jian; Wang, Yinglei; Gu, Jie; Liu, Wenhui; Xu, Dan; Shen, Xuechu; Rubo, Yuri G; Altshuler, Boris L; Kavokin, Alexey V; Chen, Zhanghai
2015-03-31
Bosons with finite lifetime exhibit condensation and lasing when their influx exceeds the lasing threshold determined by the dissipative losses. In general, different one-particle states decay differently, and the bosons are usually assumed to condense in the state with the longest lifetime. Interaction between the bosons partially neglected by such an assumption can smear the lasing threshold into a threshold domain--a stable lasing many-body state exists within certain intervals of the bosonic influxes. This recently described weak lasing regime is formed by the spontaneously symmetry breaking and phase-locking self-organization of bosonic modes, which results in an essentially many-body state with a stable balance between gains and losses. Here we report, to our knowledge, the first observation of the weak lasing phase in a one-dimensional condensate of exciton-polaritons subject to a periodic potential. Real and reciprocal space photoluminescence images demonstrate that the spatial period of the condensate is twice as large as the period of the underlying periodic potential. These experiments are realized at room temperature in a ZnO microwire deposited on a silicon grating. The period doubling takes place at a critical pumping power, whereas at a lower power polariton emission images have the same periodicity as the grating. PMID:25787253
Is there hope for spintronics in one dimensional realistic systems?
NASA Astrophysics Data System (ADS)
Rocha, Alexandre; Martins, Thiago; Fazzio, Adalberto; da Silva, Antônio J. R.
2010-03-01
The use of the electron spin as the ultimate logic bit can lead to a novel way of thinking about information flow. At the same time graphene, a gapless semiconductor, has been the subject of intense research due to its fundamental properties and its potential application in electronics. Defects are usually seen as having deleterious effects on the spin polarization of devices and thus they would tend to hinder the applicability of spintronics in realistic devices. Here we use a ab initio methods to simulate the electronic transport properties of graphene nanoribbons up to 450 nm long containing a large number of randomly distributed impurities. We will demonstrate that it is possible to obtain perfect spin selectivity in these nanoribbons which can be explained in terms of different localization lengths for each spin channel. This together with the well know exponential dependence of the conductance on the length of the device leads to a new mechanism for the spin filtering effect that is in fact driven by disorder. Furthermore, we demonstrate that this is an effect that does not depend on the underlying system itself and could be observed in carbon nanotubes and nanowires or any other one-dimensional device.
One-dimensional flows of an imperfect diatomic gas
NASA Technical Reports Server (NTRS)
1959-01-01
With the assumptions that Berthelot's equation of state accounts for molecular size and intermolecular force effects, and that changes in the vibrational heat capacities are given by a Planck term, expressions are developed for analyzing one-dimensional flows of a diatomic gas. The special cases of flow through normal and oblique shocks in free air at sea level are investigated. It is found that up to a Mach number 10 pressure ratio across a normal shock differs by less than 6 percent from its ideal gas value; whereas at Mach numbers above 4 the temperature rise is considerable below and hence the density rise is well above that predicted assuming ideal gas behavior. It is further shown that only the caloric imperfection in air has an appreciable effect on the pressures developed in the shock process considered. The effects of gaseous imperfections on oblique shock-flows are studied from the standpoint of their influence on the life and pressure drag of a flat plate operating at Mach numbers of 10 and 20. The influence is found to be small. (author)
One-Dimensional Random Walks with One-Step Memory
NASA Astrophysics Data System (ADS)
Piaskowski, Kevin; Nolan, Michael
2016-03-01
Formalized studies of random walks have been done dating back to the early 20th century. Since then, well-defined conclusions have been drawn, specifically in the case of one and two-dimensional random walks. An important theorem was formulated by George Polya in 1912. He stated that for a one or two-dimensional lattice random walk with infinite number of steps, N, the probability that the walker will return to its point of origin is unity. The work done in this particular research explores Polya's theorem for one-dimensional random walks that are non-isotropic and have the property of one-step memory, i.e. the probability of moving in any direction is non-symmetric and dependent on the previous step. The key mathematical construct used in this research is that of a generating function. This helps compute the return probability for an infinite N. An explicit form of the generating function was devised and used to calculate return probabilities for finite N. Return probabilities for various memory parameters were explored analytically and via simulations. Currently, further analysis is being done to try and find a relationship between memory parameters and number of steps, N.
Dynamical spin structure factor of one-dimensional interacting fermions
NASA Astrophysics Data System (ADS)
Zyuzin, Vladimir A.; Maslov, Dmitrii L.
2015-02-01
We revisit the dynamic spin susceptibility χ (q ,ω ) of one-dimensional interacting fermions. To second order in the interaction, backscattering results in a logarithmic correction to χ (q ,ω ) at q ≪kF , even if the single-particle spectrum is linearized near the Fermi points. Consequently, the dynamic spin structure factor Im χ (q ,ω ) is nonzero at frequencies above the single-particle continuum. In the boson language, this effect results from the marginally irrelevant backscattering operator of the sine-Gordon model. Away from the threshold, the high-frequency tail of Im χ (q ,ω ) due to backscattering is larger than that due to finite mass by a factor of kF/q . We derive the renormalization group equations for the coupling constants of the g -ology model at finite ω and q and find the corresponding expression for χ (q ,ω ) , valid to all orders in the interaction but not in the immediate vicinity of the continuum boundary, where the finite-mass effects become dominant.
Dynamic response of one-dimensional bosons in a trap
Golovach, Vitaly N.; Minguzzi, Anna; Glazman, Leonid I.
2009-10-15
We calculate the dynamic structure factor S(q,{omega}) of a one-dimensional (1D) interacting Bose gas confined in a harmonic trap. The effective interaction depends on the strength of the confinement enforcing the (1D) motion of atoms; interaction may be further enhanced by superimposing an optical lattice on the trap potential. In the compressible state, we find that the smooth variation in the gas density around the trap center leads to softening of the singular behavior of S(q,{omega}) at the first Lieb excitation mode compared to the behavior predicted for homogeneous 1D systems. Nevertheless, the density-averaged response S(q,{omega}) remains a nonanalytic function of q and {omega} at the first Lieb excitation mode in the limit of weak trap confinement. The exponent of the power-law nonanalyticity is modified due to the inhomogeneity in a universal way and thus bears unambiguously the information about the (homogeneous) Lieb-Liniger model. A strong optical lattice causes formation of Mott phases. Deep in the Mott regime, we predict a semicircular peak in S(q,{omega}) centered at the on-site repulsion energy, {omega}=U. Similar peaks of smaller amplitudes exist at multiples of U as well. We explain the suppression of the dynamic response with entering into the Mott regime, observed recently by Clement et al. [Phys. Rev. Lett. 102, 155301 (2009)], based on an f-sum rule for the Bose-Hubbard model.
One-dimensional nanoferroic rods; synthesis and characterization
NASA Astrophysics Data System (ADS)
Ahmed, M. A.; Seddik, U.; Okasha, N.; Imam, N. G.
2015-11-01
One-dimensional nanoferroic rods of BaTiO3 were synthesized by improved citrate auto-combustion technology using tetrabutyl titanate. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize the prepared sample. The results indicated that the crystal structure of BaTiO3 is tetragonal phase with an average crystallite size of 47 nm. SEM image gives a cauliflower-like morphology of the agglomerated nanorods. The stoichiometry of the chemical composition of the BaTiO3 ceramic was confirmed by EDX. TEM micrograph exhibited that BaTiO3 nanoparticles have rod-like shape with an average length of 120 nm and width of 43 nm. AFM was used to investigate the surface topography and its roughness. The topography image in 3D showed that the BaTiO3 particles have a rod shape with an average particle size of 116 nm which in agreement with 3D TEM result.
One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties
NASA Astrophysics Data System (ADS)
Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur
2016-11-01
Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.
Nucleation and growth of nanoscaled one-dimensional materials
NASA Astrophysics Data System (ADS)
Cui, Hongtao
Nanoscaled one-dimensional materials have attracted great interest due to their novel physical and chemical properties. The purpose of this dissertation is to study the nucleation and growth mechanisms of carbon nanotubes and silicon nitride nanowires with their field emission applications in mind. As a result of this research, a novel methodology has been developed to deposit aligned bamboo-like carbon nanotubes on substrates using a methane and ammonia mixture in microwave plasma enhanced chemical deposition. Study of growth kinetics suggests that the carbon diffusion through bulk catalyst particles controls growth in the initial deposition process. Microstructures of carbon nanotubes are affected by the growth temperature and carbon concentration in the gas phase. High-resolution transmission electron microscope confirms the existence of the bamboo-like structure. Electron diffraction reveals that the iron-based catalyst nucleates and sustains the growth of carbon nanotubes. A nucleation and growth model has been constructed based upon experimental data and observations. In the study of silicon nitride nanoneedles, a vapor-liquid-solid model is employed to explain the nucleation and growth processes. Ammonia plasma etching is proposed to reduce the size of the catalyst and subsequently produce the novel needle-like nanostructure. High-resolution transmission electron microscope shows the structure is well crystallized and composed of alpha-silicon nitride. Other observations in the structure are also explained.
One-dimensional transient radiative transfer by lattice Boltzmann method.
Zhang, Yong; Yi, Hongliang; Tan, Heping
2013-10-21
The lattice Boltzmann method (LBM) is extended to solve transient radiative transfer in one-dimensional slab containing scattering media subjected to a collimated short laser irradiation. By using a fully implicit backward differencing scheme to discretize the transient term in the radiative transfer equation, a new type of lattice structure is devised. The accuracy and computational efficiency of this algorithm are examined firstly. Afterwards, effects of the medium properties such as the extinction coefficient, the scattering albedo and the anisotropy factor, and the shapes of laser pulse on time-resolved signals of transmittance and reflectance are investigated. Results of the present method are found to compare very well with the data from the literature. For an oblique incidence, the LBM results in this paper are compared with those by Monte Carlo method generated by ourselves. In addition, transient radiative transfer in a two-Layer inhomogeneous media subjected to a short square pulse irradiation is investigated. At last, the LBM is further extended to study the transient radiative transfer in homogeneous medium with a refractive index discontinuity irradiated by the short pulse laser. Several trends on the time-resolved signals different from those for refractive index of 1 (i.e. refractive-index-matched boundary) are observed and analysed. PMID:24150298
Automated quantification of one-dimensional nanostructure alignment on surfaces
NASA Astrophysics Data System (ADS)
Dong, Jianjin; Goldthorpe, Irene A.; Mohieddin Abukhdeir, Nasser
2016-06-01
A method for automated quantification of the alignment of one-dimensional (1D) nanostructures from microscopy imaging is presented. Nanostructure alignment metrics are formulated and shown to be able to rigorously quantify the orientational order of nanostructures within a two-dimensional domain (surface). A complementary image processing method is also presented which enables robust processing of microscopy images where overlapping nanostructures might be present. Scanning electron microscopy (SEM) images of nanowire-covered surfaces are analyzed using the presented methods and it is shown that past single parameter alignment metrics are insufficient for highly aligned domains. Through the use of multiple parameter alignment metrics, automated quantitative analysis of SEM images is shown to be possible and the alignment characteristics of different samples are able to be quantitatively compared using a similarity metric. The results of this work provide researchers in nanoscience and nanotechnology with a rigorous method for the determination of structure/property relationships, where alignment of 1D nanostructures is significant.
Topological order in interacting one-dimensional Bose Systems
NASA Astrophysics Data System (ADS)
Grusdt, Fabian; Höning, Michael; Fleischhauer, Michael
2015-05-01
We discuss topological aspects of one-dimensional inversion-symmetric systems of interacting bosons, which can be implemented in current experiments with ultra cold atoms. We consider both integer and fractional fillings of a topologically non-trivial Bloch band. Our starting point is the chiral-symmetric Su-Schrieffer-Heeger (SSH) model of non-interacting fermions, which can be realized by hard-core bosons. When the hard-core constraint is removed, we obtain a bosonic system with inversion-symmetry protected topological order. Because the chiral symmetry is broken by finite interactions, the bulk-boundary correspondence of the SSH model is no longer valid. Nevertheless we show that the fractional part of the charge which is localized at the edge can distinguish topologically trivial- from non-trivial states. We generalize our analysis by including nearest neighbor interactions and present a topological classification of the resulting quarter-filling Mott insulating phase. In this case fractionally charged bulk excitations exist, which we identify in the grand-canonical phase diagram. F.G. acknowledges support from the Graduate School of Material Science MAINZ.
Scattering by infinitely rising one-dimensional potentials
NASA Astrophysics Data System (ADS)
Ferreira, E. M.; Sesma, J.
2015-12-01
Infinitely rising one-dimensional potentials constitute impenetrable barriers which reflect totally any incident wave. However, the scattering by such kind of potentials is not structureless: resonances may occur for certain values of the energy. Here we consider the problem of scattering by the members of a family of potentials Va(x) = - sgn(x) | x | a, where sgn represents the sign function and a is a positive rational number. The scattering function and the phase shifts are obtained from global solutions of the Schrödinger equation. For the determination of the Gamow states, associated to resonances, we exploit their close relation with the eigenvalues of the PT-symmetric Hamiltonians with potentials VaPT(x) = - i sgn(x) | x | a. Calculation of the time delay in the scattering at real energies is used to characterize the resonances. As an additional result, the breakdown of the PT-symmetry of the family of potentials VaPT for a < 3 may be conjectured.
Reentrant phase coherence in a quasi-one-dimensional superconductor
NASA Astrophysics Data System (ADS)
Ansermet, Diane; Petrovic, Alexander P.; He, Shikun; Chernyshov, Dmitri; Hoesch, Moritz; Salloum, Diala; Gougeon, Patrick; Potel, Michel; Boeri, Lilia; Andersen, Ole K.; Panagopoulos, Christos
Short coherence lengths characteristic of low-dimensional superconductors are related to high critical fields or temperatures. Fatally, such materials are often sensitive to disorder and suffer from phase fluctuations in the order parameter which diverge with temperature T, magnetic field H or current I. To solve synthesis and fluctuation problems, we propose to build superconductors from inhomogeneous composites of nanofilaments. Single crystals of quasi-one-dimensional Na2-δMo6Se6 featuring Na vacancy disorder (δ ~ 0 . 2) behave as percolative networks of superconducting nanowires. Long range order is established via transverse coupling between individual filaments, yet phase coherence is unstable to fluctuations and localization in the zero-(T, H, I) limit. A region of reentrant phase coherence develops upon raising (T, H, I) and is attributed to an enhancement of the transverse coupling due to electron delocalization. The observed reentrance in the electronic transport coincides with a peak in the Josephson energy EJ at non-zero (T, H, I). Na2-δMo6Se6 is a blueprint for a new generation of low dimensional superconductors with resilience to phase fluctuations at high (T, H, I). This work was supported by the National Research Foundation, Singapore, through Grant NRF-CRP4-2008-04.
Validation and Comparison of One-Dimensional Graound Motion Methodologies
B. Darragh; W. Silva; N. Gregor
2006-06-28
Both point- and finite-source stochastic one-dimensional ground motion models, coupled to vertically propagating equivalent-linear shear-wave site response models are validated using an extensive set of strong motion data as part of the Yucca Mountain Project. The validation and comparison exercises are presented entirely in terms of 5% damped pseudo absolute response spectra. The study consists of a quantitative analyses involving modeling nineteen well-recorded earthquakes, M 5.6 to 7.4 at over 600 sites. The sites range in distance from about 1 to about 200 km in the western US (460 km for central-eastern US). In general, this validation demonstrates that the stochastic point- and finite-source models produce accurate predictions of strong ground motions over the range of 0 to 100 km and for magnitudes M 5.0 to 7.4. The stochastic finite-source model appears to be broadband, producing near zero bias from about 0.3 Hz (low frequency limit of the analyses) to the high frequency limit of the data (100 and 25 Hz for response and Fourier amplitude spectra, respectively).
Thermodynamics of trajectories of the one-dimensional Ising model
NASA Astrophysics Data System (ADS)
Loscar, Ernesto S.; Mey, Antonia S. J. S.; Garrahan, Juan P.
2011-12-01
We present a numerical study of the dynamics of the one-dimensional Ising model by applying the large-deviation method to describe ensembles of dynamical trajectories. In this approach trajectories are classified according to a dynamical order parameter and the structure of ensembles of trajectories can be understood from the properties of large-deviation functions, which play the role of dynamical free-energies. We consider both Glauber and Kawasaki dynamics, and also the presence of a magnetic field. For Glauber dynamics in the absence of a field we confirm the analytic predictions of Jack and Sollich about the existence of critical dynamical, or space-time, phase transitions at critical values of the 'counting' field s. In the presence of a magnetic field the dynamical phase diagram also displays first order transition surfaces. We discuss how these non-equilibrium transitions in the 1d Ising model relate to the equilibrium ones of the 2d Ising model. For Kawasaki dynamics we find a much simpler dynamical phase structure, with transitions reminiscent of those seen in kinetically constrained models.
Numerical method of characteristics for one-dimensional blood flow
NASA Astrophysics Data System (ADS)
Acosta, Sebastian; Puelz, Charles; Rivière, Béatrice; Penny, Daniel J.; Rusin, Craig G.
2015-08-01
Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the utility of the proposed method by implementing it on small and large arterial networks of vessels whose elastic and geometrical parameters are physiologically relevant.
Energy transport in one-dimensional disordered granular solids
NASA Astrophysics Data System (ADS)
Achilleos, V.; Theocharis, G.; Skokos, Ch.
2016-02-01
We investigate the energy transport in one-dimensional disordered granular solids by extensive numerical simulations. In particular, we consider the case of a polydisperse granular chain composed of spherical beads of the same material and with radii taken from a random distribution. We start by examining the linear case, in which it is known that the energy transport strongly depends on the type of initial conditions. Thus, we consider two sets of initial conditions: an initial displacement and an initial momentum excitation of a single bead. After establishing the regime of sufficiently strong disorder, we focus our study on the role of nonlinearity for both sets of initial conditions. By increasing the initial excitation amplitudes we are able to identify three distinct dynamical regimes with different energy transport properties: a near linear, a weakly nonlinear, and a highly nonlinear regime. Although energy spreading is found to be increasing for higher nonlinearities, in the weakly nonlinear regime no clear asymptotic behavior of the spreading is found. In this regime, we additionally find that energy, initially trapped in a localized region, can be eventually detrapped and this has a direct influence on the fluctuations of the energy spreading. We also demonstrate that in the highly nonlinear regime, the differences in energy transport between the two sets of initial conditions vanish. Actually, in this regime the energy is almost ballistically transported through shocklike excitations.
Energy Models of One-Dimensional Multi-Propagative Systems
NASA Astrophysics Data System (ADS)
Ichchou, M. N.; Le Bot, A.; Jezequel, L.
1997-04-01
For a number of years, a model well suited to medium and high frequencies in structures, and called Energy Flow analysis, has been studied in order to generalize Statistical Energy Analysis. This model is based on a thermal analogy: a law analogous to Fourier's law for heat flow is involved. This relationship, which relates the energy flow to the energy density, leads to a differential equation similar to the heat conduction equation in steady state conditions. The aim of this study is to generalize previous works on one-dimensional structures. A wave approach is adopted, It is shown that Fourier's law is valid for one symmetric propagation mode (one group velocity). However this law has to be modified for non-symmetric propagation modes or multi-mode propagation. In each case, the wave approach determines the relationship between energy density and energy flow. Finally, the theoretical models are illustrated with several examples of waveguides: an Euler-Bernoulli beam on an elastic support, pipes carrying moving fluid and a Timoshenko beam.
Transmission properties of one-dimensional ternary plasma photonic crystals
Shiveshwari, Laxmi; Awasthi, S. K.
2015-09-15
Omnidirectional photonic band gaps (PBGs) are found in one-dimensional ternary plasma photonic crystals (PPC) composed of single negative metamaterials. The band characteristics and transmission properties are investigated through the transfer matrix method. We show that the proposed structure can trap light in three-dimensional space due to the elimination of Brewster's angle transmission resonance allowing the existence of complete PBG. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material, and number of unit cells (N) for TE and TM polarizations. It is seen that PBG characteristics is apparent even in an N ≥ 2 system, which is weakly sensitive to the incident angle and completely insensitive to the polarization. Finite PPC could be used for multichannel transmission filter without introducing any defect in the geometry. We show that the locations of the multichannel transmission peaks are in the allowed band of the infinite structure. The structure can work as a single or multichannel filter by varying the number of unit cells. Binary PPC can also work as a polarization sensitive tunable filter.
Solitary Wave in One-dimensional Buckyball System at Nanoscale.
Xu, Jun; Zheng, Bowen; Liu, Yilun
2016-01-01
We have studied the stress wave propagation in one-dimensional (1-D) nanoscopic buckyball (C60) system by molecular dynamics (MD) simulation and quantitative modeling. Simulation results have shown that solitary waves are generated and propagating in the buckyball system through impacting one buckyball at one end of the buckyball chain. We have found the solitary wave behaviors are closely dependent on the initial temperature and impacting speed of the buckyball chain. There are almost no dispersion and dissipation of the solitary waves (stationary solitary wave) for relatively low temperature and high impacting speed. While for relatively high temperature and low impacting speed the profile of the solitary waves is highly distorted and dissipated after propagating several tens of buckyballs. A phase diagram is proposed to describe the effect of the temperature and impacting speed on the solitary wave behaviors in buckyball system. In order to quantitatively describe the wave behavior in buckyball system, a simple nonlinear-spring model is established, which can describe the MD simulation results at low temperature very well. The results presented in this work may lay a solid step towards the further understanding and manipulation of stress wave propagation and impact energy mitigation at nanoscale. PMID:26891624
One-dimensional surface phonon polaritons in boron nitride nanotubes
NASA Astrophysics Data System (ADS)
Xu, Xiaoji G.; Ghamsari, Behnood G.; Jiang, Jian-Hua; Gilburd, Leonid; Andreev, Gregory O.; Zhi, Chunyi; Bando, Yoshio; Golberg, Dmitri; Berini, Pierre; Walker, Gilbert C.
2014-08-01
Surface polaritons, which are electromagnetic waves coupled to material charge oscillations, have enabled applications in concentrating, guiding and harvesting optical energy below the diffraction limit. Surface plasmon polaritons involve oscillations of electrons and are accessible in noble metals at visible and near-infrared wavelengths, whereas surface phonon polaritons (SPhPs) rely on phonon resonances in polar materials, and are active in the mid-infrared. Noble metal surface plasmon polaritons have limited applications in the mid-infrared. SPhPs at flat interfaces normally possess long polariton wavelengths and provide modest field confinement/enhancement. Here we demonstrate propagating SPhPs in a one-dimensional material consisting of a boron nitride nanotube at mid-infrared wavelengths. The observed SPhP exhibits high field confinement and enhancement, and a very high effective index (neff~70). We show that the modal and propagation length characteristics of the SPhPs may be controlled through the nanotube size and the supporting substrates, enabling mid-infrared applications.
One-dimensional extended Hubbard model in the atomic limit
NASA Astrophysics Data System (ADS)
Mancini, F.; Mancini, F. P.
2008-06-01
We present the exact solution of the one-dimensional extended Hubbard model in the atomic limit within the Green’s function and equations of motion formalism. We provide a comprehensive and systematic analysis of the model by considering all the relevant response and correlation functions as well as thermodynamic quantities in the whole parameters space. At zero temperature we identify four phases in the plane (U,n) ( U is the on-site potential and n is the filling) and relative phase transitions as well as different types of charge ordering. These features are endorsed by investigating at T=0 the chemical potential and pertinent local correlators, the particle and double occupancy correlation functions, the entropy, and by studying the behavior in the limit T→0 of the charge and spin susceptibilities. A detailed study of the thermodynamic quantities is also presented at finite temperature. This study evidences that a finite-range order persists for a wide range of the temperature, as shown by the behavior of the correlation functions and by the two-peak structure exhibited by the charge susceptibility and by the entropy. Moreover, the equations of motion formalism, together with the use of composite operators, allows us to exactly determine the set of elementary excitations. As a result, the density of states can be determined and a detailed analysis of the specific heat allows for identifying the excitations and for ascribing its two-peak structure to a redistribution of the charge density.
Reflectometry as a fluctuation diagnostic: A one-dimensional simulation
Chou, A.E.; Luhmann, N.C. Jr.; Peebles, W.A.; Rhodes, T.L. )
1992-10-01
Reflectometry is currently employed to characterize turbulence in fusion plasmas worldwide and is expected to be a major diagnostic on the next generation of machines (e.g., ITER). Until recently, little was known about the response of a reflectometer to fluctuations (degree of localization of the signal, sensitivity to fluctuation wave number, dependence on density scale length, etc.). To elucidate these properties, we have been modeling reflectometer behavior with a code based on solution of a one-dimensional full wave equation. The code models an infinite plane plasma with density gradient in the {ital x} direction and solves the full wave equation to find the electric field of the reflectometer's electromagnetic wave. It can simulate stationary and moving density perturbations with arbitrary waveforms and wave numbers in plasmas with arbitrary density profiles. We present results of test cases comparing computational results to known analytic solutions for linear and 1{minus}{alpha}{sup 2}/{ital x}{sup 2} plasma density profiles, which show very good agreement.
Electronic effects of defects in one-dimensional channels
NASA Astrophysics Data System (ADS)
Fuller, Elliot J.; Pan, Deng; Corso, Brad L.; Gul, O. Tolga; Collins, Philip G.
2013-09-01
As electronic devices shrink to the one-dimensional limit, unusual device physics can result, even at room temperature. Nanoscale conductors like single-walled carbon nanotubes (SWNTs) are particularly useful tools for experimentally investigating these effects. Our characterization of point defects in SWNTs has focused on these electronic consequences. A single scattering site in an otherwise quasi-ballistic SWNT introduces resistance, transconductance, and chemical sensitivity, and here we investigate these contributions using a combination of transport and scanning probe techniques. The transport measurements determine the two-terminal contributions over a wide range of bias, temperature, and environmental conditions, while the scanning probe work provides complementary confirmation that the effects originate at a particular site along the conduction path in a SWNT. Together, the combination proves that single point defects behave like scattering barriers having Poole-Frenkel transport characteristics. The Poole-Frenkel barriers have heights of 10 - 30 meV and gate-dependent widths that grow as large as 1 μm due to the uniquely poor screening in one dimension. Poole-Frenkel characteristics suggest that the barriers contain at least one localized electronic state, and that this state primarily contributes to conduction under high bias or high temperature conditions. Because these localized states vary from one device to another, we hypothesize that each might be unique to a particular defect's chemical type.
One-dimensional consolidation in unsaturated soils under cyclic loading
NASA Astrophysics Data System (ADS)
Lo, Wei-Cheng; Sposito, Garrison; Lee, Jhe-Wei; Chu, Hsiuhua
2016-05-01
The one-dimensional consolidation model of poroelasticity of Lo et al. (2014) for an unsaturated soil under constant loading is generalized to include an arbitrary time-dependent loading. A closed-form solution for the pore water and air pressures along with the total settlement is derived by employing a Fourier series representation in the spatial domain and a Laplace transformation in the time domain. This solution is illustrated for the important example of a fully-permeable soil cylinder with an undrained initial condition acted upon by a periodic stress. Our results indicate that, in terms of a dimensionless time scale, the transient solution decays to zero most slowly in a water-saturated soil, whereas for an unsaturated soil, the time for the transient solution to die out is inversely proportional to the initial water saturation. The generalization presented here shows that the diffusion time scale for pore water in an unsaturated soil is orders of magnitude greater than that in a water-saturated soil, mainly because of the much smaller hydraulic conductivity of the former.
A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals
Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin
2015-01-01
To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g−1 with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics. PMID:26689375
Dynamic response of one-dimensional bosons in a trap
NASA Astrophysics Data System (ADS)
Golovach, Vitaly N.; Minguzzi, Anna; Glazman, Leonid I.
2009-10-01
We calculate the dynamic structure factor S(q,ω) of a one-dimensional (1D) interacting Bose gas confined in a harmonic trap. The effective interaction depends on the strength of the confinement enforcing the (1D) motion of atoms; interaction may be further enhanced by superimposing an optical lattice on the trap potential. In the compressible state, we find that the smooth variation in the gas density around the trap center leads to softening of the singular behavior of S(q,ω) at the first Lieb excitation mode compared to the behavior predicted for homogeneous 1D systems. Nevertheless, the density-averaged response S¯(q,ω) remains a nonanalytic function of q and ω at the first Lieb excitation mode in the limit of weak trap confinement. The exponent of the power-law nonanalyticity is modified due to the inhomogeneity in a universal way and thus bears unambiguously the information about the (homogeneous) Lieb-Liniger model. A strong optical lattice causes formation of Mott phases. Deep in the Mott regime, we predict a semicircular peak in S(q,ω) centered at the on-site repulsion energy, ω=U . Similar peaks of smaller amplitudes exist at multiples of U as well. We explain the suppression of the dynamic response with entering into the Mott regime, observed recently by Clément [Phys. Rev. Lett. 102, 155301 (2009)], based on an f -sum rule for the Bose-Hubbard model.
Nonequilibrium electronic transport in a one-dimensional Mott insulator
Heidrich-Meisner, F.; Gonzalez, Ivan; Al-Hassanieh, K. A.; Feiguin, A. E.; Rozenberg, M. J.; Dagotto, Elbio R
2010-01-01
We calculate the nonequilibrium electronic transport properties of a one-dimensional interacting chain at half filling, coupled to noninteracting leads. The interacting chain is initially in a Mott insulator state that is driven out of equilibrium by applying a strong bias voltage between the leads. For bias voltages above a certain threshold we observe the breakdown of the Mott insulator state and the establishment of a steady-state elec- tronic current through the system. Based on extensive time-dependent density-matrix renormalization-group simulations, we show that this steady-state current always has the same functional dependence on voltage, independent of the microscopic details of the model and we relate the value of the threshold to the Lieb-Wu gap. We frame our results in terms of the Landau-Zener dielectric breakdown picture. Finally, we also discuss the real-time evolution of the current, and characterize the current-carrying state resulting from the breakdown of the Mott insulator by computing the double occupancy, the spin structure factor, and the entanglement entropy.
One-dimensional particle models for heat transfer analysis
NASA Astrophysics Data System (ADS)
Bufferand, H.; Ciraolo, G.; Ghendrih, Ph; Tamain, P.; Bagnoli, F.; Lepri, S.; Livi, R.
2010-11-01
For a better understanding of Spitzer-Härm closure restrictions and for estimating the relevancy of this expression when collisionnality decreases, an effort is done in developing simple models that aim at catching the physics of the transition from conductive to free-streaming heat flux. In that perspective, one-dimensional particle models are developed to study heat transfer properties in the direction parallel to the magnetic field in tokamaks. These models are based on particles that carry energy at a specific velocity and that can interact with each other or with heat sources. By adjusting the particle dynamics and particle interaction properties, it is possible to generate a broad range of models of growing complexity. The simplest models can be solved analytically and are used to link particle behavior to general macroscopic heat transfer properties. In particular, some configurations recover Fourier's law and make possible to investigate the dependance of thermal conductivity on temperature. Besides, some configurations where local balance is lost require defining non local expression for heat flux. These different classes of models could then be linked to different plasma configurations and used to study transition from collisional to non-collisional plasma.
Screw dislocation-driven growth of one-dimensional nanomaterials
NASA Astrophysics Data System (ADS)
Meng, Fei
Nanoscience and nanotechnology are impacting our lives in many ways, from electronic and photonic devices to biosensors. They also hold the promise of tackling the renewable energy challenges facing us. However, one limiting scientific challenge is the effective and efficient bottom-up synthesis of nanomaterials. In this thesis, we discuss the fundamental theories of screw dislocation-driven growth of various nanostructures including one-dimensional nanowires and nanotubes, two-dimensional nanoplates, and three-dimensional hierarchical tree-like nanostructures. We then introduce the transmission electron microscopy (TEM) techniques to structurally characterize the dislocation-driven nanomaterials for future searching and identifying purposes. We summarize the guidelines for rationally designing the dislocation-driven growth and discuss specific examples to illustrate how to implement the guidelines. We also show that dislocation growth is a general and versatile mechanism that can be used to grow a variety of nanomaterials via distinct reaction chemistry and synthetic methods. The fundamental investigation and development of dislocation-driven growth of nanomaterials will create a new dimension to the rational design and synthesis of increasingly complex nanomaterials.
Digital noise generators using one-dimensional chaotic maps
Martínez-Ñonthe, J. A; Palacios-Luengas, L.; Cruz-Irisson, M.; Vazquez Medina, R.; Díaz Méndez, J. A.
2014-05-15
This work shows how to improve the statistical distribution of signals produced by digital noise generators designed with one-dimensional (1-D) chaotic maps. It also shows that in a digital electronic design the piecewise linear chaotic maps (PWLCM) should be considered because they do not have stability islands in its chaotic behavior region, as it occurs in the case of the logistic map, which is commonly used to build noise generators. The design and implementation problems of the digital noise generators are analyzed and a solution is proposed. This solution relates the output of PWLCM, usually defined in the real numbers' domain, with a codebook of S elements, previously defined. The proposed solution scheme produces digital noise signals with a statistical distribution close to a uniform distribution. Finally, this work shows that it is possible to have control over the statistical distribution of the noise signal by selecting the control parameter of the PWLCM and using, as a design criterion, the bifurcation diagram.
Theoretical modelling of one dimensional photonic crystal based optical demultiplexer
NASA Astrophysics Data System (ADS)
Sharma, Gaurav; Kumar, Sushil; Prasad, Surendra; Singh, Vivek
2016-05-01
An optical demultiplexer through one-dimensional Si-SiO2 photonic crystal structure in the presence of air cavity with a single crystal PMN-0.38PT material is presented. The transmittance of this structure is obtained using the transfer matrix method. The transmittance of this structure shows a sharp passband in the band gap region. It is observed that by introducing PMN-0.38PT layer in both sides of the air cavity, the existing band gap region of Si-SiO2 structure is slightly increased. Here, PMN-0.38PT material is working as a tunable element for passband. By applying some external potential on PMN-0.38PT crystal, the thickness of cavity layer can be tuned and the passband can be placed at any desired wavelength in the band gap region. Since the photonic band gap region contains a range of wavelengths which are not allowed to pass through the structure can be considered as a multiplex signal for the proposed demultiplexer. Therefore, any optical signal that lies in the band gap region of the structure can be separated into its components as a pass band. Hence, the proposed structure will work as an optical demultiplexer.
A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals
NASA Astrophysics Data System (ADS)
Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin
2015-12-01
To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g-1 with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics.
Benchmarking the variational cluster approach by means of the one-dimensional Bose-Hubbard model
Knap, Michael; Arrigoni, Enrico; Linden, Wolfgang von der
2010-06-15
Convergence properties of the variational cluster approach with respect to the variational parameter space, cluster size, and boundary conditions of the reference system are investigated and discussed for bosonic many-body systems. Specifically, the variational cluster approach is applied to the one-dimensional Bose-Hubbard model, which exhibits a quantum phase transition from Mott to superfluid phase. In order to benchmark the variational cluster approach, results for the phase boundary delimiting the first Mott lobe are compared with essentially exact density matrix renormalization group data. Furthermore, static quantities, such as the ground state energy and the one-particle density matrix are compared with high-order strong coupling perturbation theory results. For reference systems with open boundary conditions the variational parameter space is extended by an additional variational parameter which allows for a more uniform particle density on the reference system and thus drastically improves the results. It turns out that the variational cluster approach yields accurate results with relatively low-computational effort for both the phase boundary as well as the static properties of the one-dimensional Bose-Hubbard model, even at the tip of the first Mott lobe where correlation effects are most pronounced.
Xu, Renjing; Zhang, Shuang; Wang, Fan; Yang, Jiong; Wang, Zhu; Pei, Jiajie; Myint, Ye Win; Xing, Bobin; Yu, Zongfu; Fu, Lan; Qin, Qinghua; Lu, Yuerui
2016-02-23
We report a trion (charged exciton) binding energy of ∼162 meV in few-layer phosphorene at room temperature, which is nearly 1-2 orders of magnitude larger than those in two-dimensional (2D) transition metal dichalcogenide semiconductors (20-30 meV) and quasi-2D quantum wells (∼1-5 meV). Such a large binding energy has only been observed in truly one-dimensional (1D) materials such as carbon nanotubes, whose optoelectronic applications have been severely hindered by their intrinsically small optical cross sections. Phosphorene offers an elegant way to overcome this hurdle by enabling quasi-1D excitonic and trionic behaviors in a large 2D area, allowing optoelectronic integration. We experimentally validated the quasi-1D nature of excitonic and trionic dynamics in phospherene by demonstrating completely linearly polarized light emission from excitons and trions in few-layer phosphorene. The implications of the extraordinarily large trion binding energy in a higher-than-one-dimensional material are far-reaching. It provides a room-temperature 2D platform to observe the fundamental many-body interactions in the quasi-1D region. PMID:26713882
Magnetotransport in a quasi-one-dimensional electron system on superfluid helium
NASA Astrophysics Data System (ADS)
Nikolaenko, B. A.; Kovdrya, Yu. Z.; Gladchenko, S. P.
2002-11-01
Magnetotransport in a nondegenerate quasi-one-dimensional electron system on superfluid helium is investigated experimentally. The measurements are performed in perpendicular magnetic fields B⩽2.6 T in the temperature range 0.48-2.05 K with 100-400 nm wide conducting channels. In the region where the carriers are scattered by the helium atoms in the vapor (T>0.9 K) and in the region where the electrons are scattered by ripplons (T<0.9 K) the longitudinal component ρxx of the magnetoresistance of the conducting channels predominantly increases with B. The experimental data in the region of carrier scattering by helium atoms in the vapor agree with the classical Drude law, and in the quantum transport regime with ωcτ>1 (ωc is the cyclotron frequency and τ is the relaxation time of the electron system) the self-consistent Born approximation for a 2D electron system above helium gives a qualitative explanation of the data. It is conjectured that the quantitative differences between the experimental data and the theoretical calculations are due to the difference of the specific features between the experimentally studied and theoretically analyzed systems. The experimental values of the electron mobilities at low temperatures and in weak magnetic fields agree with theoretical calculations for a quasi-one-dimensional system. Weak carrier localization in the experimental electron system explains the negative magnetoresistance of the conducting channels, which was observed in the gas and ripplon carrier scattering regions.
NASA Astrophysics Data System (ADS)
Zakrzewski, Jakub; Delande, Dominique
2008-11-01
The quantum phase transition point between the insulator and the superfluid phase at unit filling factor of the infinite one-dimensional Bose-Hubbard model is numerically computed with a high accuracy. The method uses the infinite system version of the time evolving block decimation algorithm, here tested in a challenging case. We provide also the accurate estimate of the phase transition point at double occupancy.
Kamenev, Yu E; Masalov, S A; Filimonova, A A
2005-04-30
A method is proposed and a device is described for determining the electrodynamic parameters of one-dimensional wire gratings in the submillimetre range. The grating under study was used as the output mirror of the laser. The transmission coefficient and the phase shift are determined experimentally for several gratings with different parameters at a wavelength of 337 {mu}m. (laser applications and other topics in quantum electronics)
Heterolayered, one-dimensional nanobuilding block mat batteries.
Choi, Keun-Ho; Cho, Sung-Ju; Chun, Sang-Jin; Yoo, Jong Tae; Lee, Chang Kee; Kim, Woong; Wu, Qinglin; Park, Sang-Bum; Choi, Don-Ha; Lee, Sun-Young; Lee, Sang-Young
2014-10-01
The rapidly approaching smart/wearable energy era necessitates advanced rechargeable power sources with reliable electrochemical properties and versatile form factors. Here, as a unique and promising energy storage system to address this issue, we demonstrate a new class of heterolayered, one-dimensional (1D) nanobuilding block mat (h-nanomat) battery based on unitized separator/electrode assembly (SEA) architecture. The unitized SEAs consist of wood cellulose nanofibril (CNF) separator membranes and metallic current collector-/polymeric binder-free electrodes comprising solely single-walled carbon nanotube (SWNT)-netted electrode active materials (LiFePO4 (cathode) and Li4Ti5O12 (anode) powders are chosen as model systems to explore the proof of concept for h-nanomat batteries). The nanoporous CNF separator plays a critical role in securing the tightly interlocked electrode-separator interface. The SWNTs in the SEAs exhibit multifunctional roles as electron conductive additives, binders, current collectors and also non-Faradaic active materials. This structural/physicochemical uniqueness of the SEAs allows significant improvements in the mass loading of electrode active materials, electron transport pathways, electrolyte accessibility and misalignment-proof of separator/electrode interface. As a result, the h-nanomat batteries, which are easily fabricated by stacking anode SEA and cathode SEA, provide unprecedented advances in the electrochemical performance, shape flexibility and safety tolerance far beyond those achievable with conventional battery technologies. We anticipate that the h-nanomat batteries will open 1D nanobuilding block-driven new architectural design/opportunity for development of next-generation energy storage systems. PMID:25226349
One dimensional blood flow in a planetocentric orbit
NASA Astrophysics Data System (ADS)
Haranas, Ioannis; Gkigkitzis, Ioannis
2012-05-01
All life on earth is accustomed to the presence of gravity. When gravity is altered, biological processes can go awry. It is of great importance to ensure safety during a spaceflight. Long term exposure to microgravity can trigger detrimental physiological responses in the human body. Fluid redistribution coupled with fluid loss is one of the effects. In particular, in microgravity blood volume is shifted towards the thorax and head. Sympathetic nervous system-induced vasoconstriction is needed to maintain arterial pressure, while venoconstriction limits venous pooling of blood prevents further reductions in venous return of blood to the heart. In this paper, we modify an existing one dimensional blood flow model with the inclusion of the hydrostatic pressure gradient that further depends on the gravitational field modified by the oblateness and rotation of the Earth. We find that the velocity of the blood flow VB is inversely proportional to the blood specific volume d, also proportional to the oblateness harmonic coefficient J2, the angular velocity of the Earth ωE, and finally proportional to an arbitrary constant c. For c = -0.39073 and ξH = -0.5 mmHg, all orbits result to less blood flow velocities than that calculated on the surface of the Earth. From all considered orbits, elliptical polar orbit of eccentricity e = 0.2 exhibit the largest flow velocity VB = 1.031 m/s, followed by the orbits of inclination i = 45°and 0°. The Earth's oblateness and its rotation contribute a 0.7% difference to the blood flow velocity.
Spatial modes in one-dimensional models for capillary jets
NASA Astrophysics Data System (ADS)
Guerrero, J.; González, H.; García, F. J.
2016-03-01
One-dimensional (1D) models are widely employed to simplify the analysis of axisymmetric capillary jets. These models postulate that, for slender deformations of the free surface, the radial profile of the axial velocity can be approximated as uniform (viscous slice, averaged, and Cosserat models) or parabolic (parabolic model). In classical works on spatial stability analysis with 1D models, considerable misinterpretation was generated about the modes yielded by each model. The already existing physical analysis of three-dimensional (3D) axisymmetric spatial modes enables us to relate these 1D spatial modes to the exact 3D counterparts. To do so, we address the surface stimulation problem, which can be treated as linear, by considering the effect of normal and tangential stresses to perturb the jet. A Green's function for a spatially local stimulation having a harmonic time dependence provides the general formalism to describe any time-periodic stimulation. The Green's function of this signaling problem is known to be a superposition of the spatial modes, but in fact these modes are of fundamental nature, i.e., not restricted to the surface stimulation problem. The smallness of the wave number associated with each mode is the criterion to validate or invalidate the 1D approaches. The proposed axial-velocity profiles (planar or parabolic) also have a remarkable influence on the outcomes of each 1D model. We also compare with the classical 3D results for (i) conditions for absolute instability, and (ii) the amplitude of the unstable mode resulting from both normal and tangential surface stress stimulation. Incidentally, as a previous task, we need to re-deduce 1D models in order to include eventual stresses of various possible origins (electrohydrodynamic, thermocapillary, etc.) applied on the free surface, which were not considered in the previous general formulations.
Stereo correspondence in one-dimensional Gabor stimuli.
Prince, S J; Eagle, R A
2000-01-01
Previous data [Prince, S.J.D., & Eagle, R.A., (1999). Size-disparity correlation in human binocular depth perception. Proceedings of the Royal Society of London B, 266, 1361-1365] have demonstrated that the upper disparity limit for stereopsis (DMax) is considerably smaller in filtered noise stereograms than in isolated Gabor patches of the same spatial frequency. This discrepancy is not currently understood. Here, the solution of the correspondence problem for bandpass stereograms was further examined. On each trial observers were presented with two one-dimensional Gabor stimuli containing disparities of equal magnitude but opposite sign. Subjects were required to indicate which interval contained the crossed disparity stimulus. It was found that matching behaviour changed as a function of Gabor envelope size. As a function of disparity magnitude, performance cycled between mostly correct and mostly incorrect at large envelope sizes but was always correct at small envelope sizes. At intermediate envelope sizes performance was cyclical at small disparities but always correct at large disparities. The critical envelope size at which performance changed from mostly correct to mostly incorrect at 270 degrees phase disparity was used as a measure of the matching performance as other parameters of the Gabor were varied. Both absolute and relative contrast were shown to influence the perceived sign of matches. Critical envelope size was also found to decrease as a function of spatial frequency, but more slowly than a phase-based limit would predict. These data cannot be predicted by current models of stereopsis, and can be used to constrain future models. PMID:10720662
Two dimensionality in quasi-one-dimensional cobalt oxides
NASA Astrophysics Data System (ADS)
Sugiyama, J.; Nozaki, H.; Brewer, J. H.; Ansaldo, E. J.; Morris, G. D.; Takami, T.; Ikuta, H.; Mizutani, U.
2006-03-01
Magnetism of quasi-one-dimensional (1D) cobalt oxides ACoO ( A=Ca, Sr and Ba, n=1-5 and ∞) was investigated by μ+SR using polycrystalline samples, at temperatures from 300 K down to 1.8 K. The wTF- μ+SR experiments showed the existence of a magnetic transition in all six samples investigated. The onset temperature of the transition (Tcon) was found to decrease with n; that is, 100±25, 90±10, 85±10, 65±10 50±10, and 15±1 K for n=1-5, and ∞, respectively. In particular, for the samples with n=2-5, Tcon was detected only by the present μ+SR measurements. A muon spin oscillation was clearly observed in both Ca 3Co 2O 6(n=1) and BaCoO 3(n=∞), whereas only a fast relaxation is apparent even at 1.8 K in the other four samples ( n=2-5). Taking together with the fact that the paramagnetic Curie temperature ranges from -150 to -200 K for the compound with n=2 and 3, the μ+SR result indicates that a two-dimensional (2D) short-range antiferromagnetic (AF) order, which has been thought to be unlikely to exist at high T due to a relatively strong 1D F interaction, appears below Tcon for all compounds with n=1-5; but quasi-static long-range AF order formed only in Ca 3Co 2O 6, below 25 K. For BaCoO 3(n=∞), as T decreased from 300 K, 1D F order appeared below 53 K, and a sharp 2D AF transition occurred at 15 K.
Spectroscopy of one-dimensionally inhomogeneous media with quadratic nonlinearity
Golubkov, A A; Makarov, Vladimir A
2011-11-30
We present a brief review of the results of fifty years of development efforts in spectroscopy of one-dimensionally inhomogeneous media with quadratic nonlinearity. The recent original results obtained by the authors show the fundamental possibility of determining, from experimental data, the coordinate dependences of complex quadratic susceptibility tensor components of a onedimensionally inhomogeneous (along the z axis) medium with an arbitrary frequency dispersion, if the linear dielectric properties of the medium also vary along the z axis and are described by a diagonal tensor of the linear dielectric constant. It is assumed that the medium in question has the form of a plane-parallel plate, whose surfaces are perpendicular to the direction of the inhomogeneity. Using the example of several components of the tensors X{sup (2)}(z, {omega}{sub 1} {+-} {omega}{sub 2}; {omega}{sub 1}, {+-} {omega}{sub 2}), we describe two methods for finding their spatial profiles, which differ in the interaction geometry of plane monochromatic fundamental waves with frequencies {omega}{sub 1} and {omega}{sub 2}. The both methods are based on assessing the intensity of the waves propagating from the plate at the sum or difference frequency and require measurements over a range of angles of incidence of the fundamental waves. Such measurements include two series of additional estimates of the intensities of the waves generated under special conditions by using the test and additional reference plates, which eliminates the need for complicated phase measurements of the complex amplitudes of the waves at the sum (difference) frequency.
One dimensional time-to-explode (ODTX) in HMX spheres
Breshears, D.
1997-06-02
In a series of papers researchers at Lawrence Livermore National Laboratory (LLNL) have reported measurements of the time to explosion in spheres of various high explosives following a rapid, uniform increase in the surface temperature of the sphere. Due to the spherical symmetry, the time-dependent properties of the explosive (temperature, chemical composition, etc.) are functions of the radial spatial coordinate only; thus the name one-dimensional time-to-explosion (ODTX). The LLNL researchers also report an evolving series of computational modeling results for the ODTX experiments, culminating in those obtained using a sophisticated heat transfer code incorporating accurate descriptions of chemical reaction. Although the chemical reaction mechanism used to describe HMX decomposition is quite simple, the computational results agree very well with the experimental data. In addition to reproducing the magnitude and temperature dependence of the measured times to explosion, the computational results also agree with the results of post reaction visual inspection. The ODTX experiments offer a near-ideal example of a transport process (heat transfer in this case) tightly coupled with chemical reaction. The LLNL computational model clearly captures the important features of the ODTX experiments. An obvious question of interest is to what extent the model and/or its individual components (specifically the chemical reaction mechanism) are applicable to other experimental scenarios. Valid exploration of this question requires accurate understanding of (1) the experimental scenario addressed by the LLNL model and (2) details of the application of the model. The author reports here recent work addressing points (1) and (2).
Construction and optoelectronic properties of organic one-dimensional nanostructures.
Zhao, Yong Sheng; Fu, Hongbing; Peng, Aidong; Ma, Ying; Liao, Qing; Yao, Jiannian
2010-03-16
In the last 10 years, nanomaterials based on small organic molecules have attracted increasing attention. Such materials have unique optical and electronic properties, which could lead to new applications in nanoscale devices. Zero-dimensional (0D) organic nanoparticles with amorphous structures have been widely studied; however, the systematic investigation of crystalline one-dimensional (1D) organic nanostructures has only emerged in recent years. Researchers have used inorganic 1D nanomaterials, such as wires, tubes, and belts, as building blocks in optoelectronic nanodevices. We expect that their organic counterparts will also play an important role in this field. Because organic nanomaterials are composed of molecular units with weaker intermolecular interactions, they allow for higher structural tunability, reactivity, and processability. In addition, organic materials usually possess higher luminescence efficiency and can be grown on almost any solid substrate. In this Account, we describe recent progress in our group toward the construction of organic 1D nanomaterials and studies of their unique optical and electronic properties. First, we introduce the techniques for synthesizing 1D organic nanostructures. Because this strategy is both facile and reliable, liquid phase synthesis is most commonly used. More importantly, this method allows researchers to produce composite materials, including core/sheath and uniformly doped structures, which allow to investigate the interactions between different components in the nanomaterials, including fluorescent resonance energy transfer and photoinduced electron transfer. Physical vapor deposition allows for the synthesis of organic 1D nanomaterials with high crystallinity. Nanomaterials produced with this method offer improved charge transport properties and better optoelectronic performance in areas including multicolor emission, tunable emission, optical waveguide, and lasing. Although inorganic nanomaterials have
Boundary-induced dynamics in one-dimensional topological systems and memory effects of edge modes
NASA Astrophysics Data System (ADS)
He, Yan; Chien, Chih-Chun
2016-07-01
Dynamics induced by a change of boundary conditions reveals rate-dependent signatures associated with topological properties in one-dimensional Kitaev chain and SSH model. While the perturbation from a change of the boundary propagates into the bulk, the density of topological edge modes in the case of transforming to open boundary condition reaches steady states. The steady-state density depends on the transformation rate of the boundary and serves as an illustration of quantum memory effects in topological systems. Moreover, while a link is physically broken as the boundary condition changes, some correlation functions can remain finite across the broken link and keep a record of the initial condition. By testing those phenomena in the nontopological regimes of the two models, none of the interesting signatures of memory effects can be observed. Our results thus contrast the importance of topological properties in boundary-induced dynamics.
Non-thermal fixed points and solitons in a one-dimensional Bose gas
NASA Astrophysics Data System (ADS)
Schmidt, Maximilian; Erne, Sebastian; Nowak, Boris; Sexty, Dénes; Gasenzer, Thomas
2012-07-01
Single-particle momentum spectra for a dynamically evolving one-dimensional Bose gas are analysed in the semi-classical wave limit. Representing one of the simplest correlation functions, these provide information on a possible universal scaling behaviour. Motivated by the previously discovered connection between (quasi-) topological field configurations, strong wave turbulence and non-thermal fixed points of quantum field dynamics, soliton formation is studied with respect to the appearance of transient power-law spectra. A random-soliton model is developed for describing the spectra analytically, and the analogies and differences between the emerging power laws and those found in a field theory approach to strong wave turbulence are discussed. The results open a new perspective on solitary wave dynamics from the point of view of critical phenomena far from thermal equilibrium and the possibility of studying this dynamics by experiment without the need for detecting solitons in situ.
Hidden One-Dimensional Electronic Structure of η-Mo_4O_11
NASA Astrophysics Data System (ADS)
Gweon, G.-H.; Mo, S.-K.; Allen, J. W.; Höchst, H.; Sarrao, J. L.; Fisk, Z.
2002-03-01
η-Mo_4O_11 is a layered metal that undergoes two charge density wave (CDW) transitions at 109 K and 30 K, and is unique in showing a bulk quantum Hall effect. Research so far indicates that this material has a ``hidden one-dimensional'' (hidden-1d) Fermi surface (FS) in the normal state (T > 109 K), whose nesting property drives the 109 K CDW formation. Here, we directly confirm this picture by angle resolved photoemission spectroscopy (ARPES). We also observe a gap opening associated with the 109 K transition. Most interesting, this material shows the same ARPES line shape anomalies that suggest electron fractionalization in other hidden-1d materials like NaMo_6O_17 and KMo_6O_17. Studies of the 30 K transition are in progress.
Class of solitary wave solutions of the one-dimensional Gross-Pitaevskii equation
Atre, Rajneesh; Panigrahi, Prasanta K.; Agarwal, G. S.
2006-05-15
We present a large family of exact solitary wave solutions of the one-dimensional Gross-Pitaevskii equation, with time-varying scattering length and gain or loss, in both expulsive and regular parabolic confinement regimes. The consistency condition governing the soliton profiles is shown to map onto a linear Schroedinger eigenvalue problem, thereby enabling one to find analytically the effect of a wide variety of temporal variations in the control parameters, which are experimentally realizable. Corresponding to each solvable quantum mechanical system, one can identify a soliton configuration. These include soliton trains in close analogy to experimental observations of Strecker et al. [Nature (London) 417, 150 (2002)], spatiotemporal dynamics, solitons undergoing rapid amplification, collapse and revival of condensates, and analytical expression of two-soliton bound states, to name a few.
Class of solitary wave solutions of the one-dimensional Gross-Pitaevskii equation.
Atre, Rajneesh; Panigrahi, Prasanta K; Agarwal, G S
2006-05-01
We present a large family of exact solitary wave solutions of the one-dimensional Gross-Pitaevskii equation, with time-varying scattering length and gain or loss, in both expulsive and regular parabolic confinement regimes. The consistency condition governing the soliton profiles is shown to map onto a linear Schrödinger eigenvalue problem, thereby enabling one to find analytically the effect of a wide variety of temporal variations in the control parameters, which are experimentally realizable. Corresponding to each solvable quantum mechanical system, one can identify a soliton configuration. These include soliton trains in close analogy to experimental observations of Streckeret al. [Nature (London) 417, 150 (2002)], spatiotemporal dynamics, solitons undergoing rapid amplification, collapse and revival of condensates, and analytical expression of two-soliton bound states, to name a few. PMID:16803061
One-dimensional array of ion chains coupled to an optical cavity
NASA Astrophysics Data System (ADS)
Cetina, Marko; Bylinskii, Alexei; Karpa, Leon; Gangloff, Dorian; Beck, Kristin M.; Ge, Yufei; Scholz, Matthias; Grier, Andrew T.; Chuang, Isaac; Vuletić, Vladan
2013-05-01
We present a novel system where an optical cavity is integrated with a microfabricated planar-electrode ion trap. The trap electrodes produce a tunable periodic potential allowing the trapping of up to 50 separate ion chains aligned with the cavity and spaced by 160 μm in a one-dimensional array along the cavity axis. Each chain can contain up to 20 individually addressable Yb+ ions coupled to the cavity mode. We demonstrate deterministic distribution of ions between the sites of the electrostatic periodic potential and control of the ion-cavity coupling. The measured strength of this coupling should allow access to the strong collective coupling regime with ≲10 ions. The optical cavity could serve as a quantum information bus between ions or be used to generate a strong wavelength-scale periodic optical potential.
A rare-earth phosphor containing one-dimensional chains identified through combinatorial methods
Danielson; Devenney; Giaquinta; Golden; Haushalter; McFarland; Poojary; Reaves; Weinberg; Wu
1998-02-01
An unusual luminescent inorganic oxide, Sr2CeO4, was identified by parallel screening techniques from within a combinatorial library of more than 25,000 members prepared by automated thin-film synthesis. A bulk sample of single-phase Sr2CeO4 was prepared, and its structure, determined from powder x-ray diffraction data, reveals one-dimensional chains of edge-sharing CeO6 octahedra, with two terminal oxygen atoms per cerium center, that are isolated from one another by Sr2+ cations. The emission maximum at 485 nanometers appears blue-white and has a quantum yield of 0.48 +/- 0.02. The excited-state lifetime, electron spin resonance, magnetic susceptibility, and structural data all suggest that luminescence originates from a ligand-to-metal Ce4+ charge transfer. PMID:9452377
Phase structure of one-dimensional interacting Floquet systems. II. Symmetry-broken phases
NASA Astrophysics Data System (ADS)
von Keyserlingk, C. W.; Sondhi, S. L.
2016-06-01
Recent work suggests that a sharp definition of "phase of matter" can be given for periodically driven "Floquet" quantum systems exhibiting many-body localization. In this work, we propose a classification of the phases of interacting Floquet localized systems with (completely) spontaneously broken symmetries; we focus on the one-dimensional case, but our results appear to generalize to higher dimensions. We find that the different Floquet phases correspond to elements of Z (G ) , the center of the symmetry group in question. In a previous paper [C. W. von Keyserlingk and S. L. Sondhi, preceding paper, Phys. Rev. B 93, 245145 (2016)], 10.1103/PhysRevB.93.245145, we offered a companion classification of unbroken, i.e., paramagnetic phases.
NASA Astrophysics Data System (ADS)
von Keyserlingk, C. W.; Sondhi, S. L.
2016-06-01
Recent work suggests that a sharp definition of "phase of matter" can be given for some quantum systems out of equilibrium, first for many-body localized systems with time-independent Hamiltonians and more recently for periodically driven or Floquet localized systems. In this work, we propose a classification of the finite Abelian symmetry-protected phases of interacting Floquet localized systems in one dimension. We find that the different Floquet phases correspond to elements of ClG×AG , where ClG is the undriven interacting classification, and AG is a set of (twisted) one-dimensional representations corresponding to symmetry group G . We will address symmetry-broken phases in a subsequent paper C. W. von Keyserlingk and S. L. Sondhi, following paper, Phys. Rev. B 93, 245146 (2016), 10.1103/PhysRevB.93.245146.
Superfluid-insulator transition of ultracold bosons in disordered one-dimensional traps
NASA Astrophysics Data System (ADS)
Vosk, Ronen; Altman, Ehud
2012-01-01
We derive an effective quantum Josephson array model for a weakly interacting one-dimensional condensate that is fragmented into weakly coupled puddles by a disorder potential. The distribution of coupling constants, obtained from first principles, indicates that weakly interacting bosons in a disorder potential undergo a superfluid insulator transition controlled by a strong randomness fixed point [E. Altman , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.93.150402 93, 150402 (2004)]. We compute renormalization-group flows for concrete realizations of the disorder potential to facilitate finite size scaling of experimental results and allow comparison to the behavior dictated by the strong randomness fixed point. The phase diagram of the system is obtained with corrections to mean-field results.
NASA Astrophysics Data System (ADS)
Kawakami, Takuto; Hu, Xiao
2016-01-01
We investigate one-dimensional (1D) Majorana bound states (MBSs) realized in terms of the helical edge states of a 2D quantum spin-Hall insulator in a heterostructure with a superconducting substrate and two ferromagnetic insulators (FIs). By means of Bogoliubov-de Gennes approach we demonstrate that there is a helical spin texture in the MBS wave function with a pitch proportional to the Fermi momentum. Moreover, simultaneous detection on local density of states by scanning tunneling microscopy and spectroscopy at a position close to one FI edge and at the midpoint between the two FIs can not only map out the energy spectrum ±E cos(ϕ/2) where ϕ is the relative angle between the magnetizations of two FIs, but also prove experimentally that the two quasiparticle excitations do not mix with each other as protected by the parity conservation associated with the MBSs.
One-pot synthesis of one-dimensional CdTe-cystine nanocomposite for humidity sensing
NASA Astrophysics Data System (ADS)
Lu, Zhisong; Wang, Jing; Xie, Jiale; Li, Chang Ming
2014-03-01
Quantum dot (QD)-incorporated one-dimensional (1D) nanocomposites offer great application potential. However, a facile one-step synthesis of the nanocomposites and fabrication of their free-standing film for sensing has not been accomplished. Herein a rod-shaped nanocomposite is one-pot synthesized via an L-cysteine-assisted hydrothermal approach, in which synthesis parameters including L-cysteine amount, temperature and reaction duration are tailored to control the composite nanostructures. CdTe nanocrystals are incorporated into the L-cystine matrices to form the nanorods, which tangle each other to network an intact film structure via a simple drying process. The free-standing CdTe-cystine nanorod film is directly utilized as a humidity sensor. This work provides a one-pot synthesis approach to grow 1D CdTe incorporated nanocomposites, demonstrating their great potential in film sensing applications.
NASA Astrophysics Data System (ADS)
Jiang, Lei; Qu, Chunlei; Zhang, Chuanwei
2016-06-01
The recent experimental realization of one-dimensional (1D) equal Rashba-Dresselhaus spin-orbit coupling (ERD-SOC) for cold atoms provides a disorder-free and highly controllable platform for the implementation and observation of Majorana fermions (MFs), analogous to the broadly studied solid-state nanowire-superconductor heterostructures. However, the corresponding 1D chains of cold atoms possess strong quantum fluctuation, which may destroy the superfluids and MFs. In this paper, we show that such 1D topological chains with MFs may be on demand generated in a two- or three-dimensional nontopological optical lattice with 1D ERD-SOC by modifying local potentials on target locations using experimentally already implemented atomic gas microscopes or patterned (e.g., double- or triple-well) optical lattices. All ingredients in our scheme have been experimentally realized, and the combination of them may pave the way for the experimental observation of MFs in a clean system.
Decoherence-induced conductivity in the one-dimensional Anderson model
Stegmann, Thomas; Wolf, Dietrich E.; Ujsághy, Orsolya
2014-08-20
We study the effect of decoherence on the electron transport in the one-dimensional Anderson model by means of a statistical model [1, 2, 3, 4, 5]. In this model decoherence bonds are randomly distributed within the system, at which the electron phase is randomized completely. Afterwards, the transport quantity of interest (e.g. resistance or conductance) is ensemble averaged over the decoherence configurations. Averaging the resistance of the sample, the calculation can be performed analytically. In the thermodynamic limit, we find a decoherence-driven transition from the quantum-coherent localized regime to the Ohmic regime at a critical decoherence density, which is determined by the second-order generalized Lyapunov exponent (GLE) [4].
Intrinsic dephasing in one-dimensional ultracold atom interferometers.
Bistritzer, R; Altman, E
2007-06-12
Quantum-phase fluctuations prevent true long-range phase order from forming in interacting 1D condensates, even at zero temperature. Nevertheless, by dynamically splitting the condensate into two parallel decoupled tubes the system can be prepared with a macroscopic relative phase, facilitating interferometric measurement. Here, we describe a dephasing mechanism whereby the quantum-phase fluctuations, which are so effective in equilibrium, act to destroy the macroscopic relative phase that was imposed as a nonequilibrium initial condition. We show that the phase coherence between the condensates decays exponentially with a dephasing time that depends on intrinsic parameters: the interaction strength, sound velocity, and density. Interestingly, significant temperature dependence appears only above a cross-over scale T*. In contrast to the usual phase diffusion, which is essentially an effect of confinement and leads to Gaussian decay, the exponential dephasing caused by fluctuations is a bulk effect that survives the thermodynamic limit. PMID:17548834
An initial-boundary value problem for three-dimensional Zakharov-Kuznetsov equation
NASA Astrophysics Data System (ADS)
Faminskii, Andrei V.
2016-02-01
An initial-boundary value problem with homogeneous Dirichlet boundary conditions for three-dimensional Zakharov-Kuznetsov equation is considered. Results on global existence, uniqueness and large-time decay of weak solutions in certain weighted spaces are established.
Non-equilibrium dynamics around integrability in a one-dimensional two-component Bose gas
NASA Astrophysics Data System (ADS)
van Druten, Nicolaas; Wicke, Philipp; Whitlock, Shannon
2011-05-01
We investigate a one-dimensional two-component Bose gas near the point of state-independent interactions. At this specific point the system is integrable, in the sense that exact (thermodynamic) Bethe Ansatz solutions can be applied locally. In the experiments, we employ an atom chip and the magnetically trappable clock states in 87Rb. State-dependent potentials are generated by using the polarization dependence of radio-frequency dressing. We show that this allows us to continuously and dynamically tune both the local interactions and the global trapping potential. The experimentally accessible range in interactions includes the region around the integrability point. We study the spin motion that follows upon a sudden change in the system, a quantum quench. When starting from a low-temperature, quantum-degenerate gas in the weakly interacting regime, good agreement with a Gross-Pitaevskii description is found. The experiment allows exploring regimes that go beyond such a description and opens up a novel route to the study of the relation between non-equilibrium dynamics, thermalization and the making and breaking of integrability in quantum many-body physics. Supported by FOM, NWO and EU
Centini, M.; Sciscione, L.; Sibilia, C.; Bertolotti, M.; Perina, J. Jr.; Scalora, M.; Bloemer, M.J.
2005-09-15
A description of spontaneous parametric down-conversion in finite-length one-dimensional nonlinear photonic crystals is developed using semiclassical and quantum approaches. It is shown that if a suitable averaging is added to the semiclassical model, its results are in very good agreement with the quantum approach. We propose two structures made with GaN/AlN that generate both degenerate and nondegenerate entangled photon pairs. Both structures are designed so as to achieve a high efficiency of the nonlinear process.
NASA Astrophysics Data System (ADS)
Peng, Hsuan Tung; Ho, Yew Kam
2015-10-01
We have investigated quantum entanglement for two interacting ultracold bosonic atoms in one-dimensional harmonic traps. The effective potential is modeled by delta interaction. For this two-atom system, we have investigated quantum entanglement properties, such as von Neumann entropy and linear entropy for its ground state and excited states. Using a computational scheme that is different from previously employed, a total of the lowest 16 states are studied. Here we show the dependencies of entanglement properties under various interacting strengths. Comparisons for the ground state entanglement are made with earlier results in the literature. New results for the other 15 excited states are reported here.
One-dimensional fast migration of vacancy clusters in metals
Matsukawa, Yoshitaka; Zinkle, Steven J
2007-01-01
The migration of point defects, e.g. crystal lattice vacancies and self-interstitial atoms (SIAs), typically occurs through three-dimensional (3-D) random walk. However, when vacancies and SIAs agglomerate with like defects forming clusters, the migration mode may change. Recently, atomic-scale computer simulations using molecular dynamics (MD) codes have reported that nanometer-sized two-dimensional (2-D) clusters of SIAs exhibit one-dimensional (1-D) fast migration1-7. The 1-D migration mode transports the entire cluster containing several tens of SIAs with a mobility comparable to single SIAs3. This anisotropic migration of SIA clusters can have a significant impact on the evolution of a material fs neutron-irradiation damage microstructure, which dominates the material fs lifetime in nuclear reactor environments8-9. This is also proposed to be a key physical mechanism for the self-organization of nanometer-sized sessile vacancy cluster arrays10-13. Given these findings for SIA clusters, a fundamental question is whether the 1-D migration mode is also possible for 2-D clusters of vacancies. Preceding MD results predicted that 1-D migration of vacancy clusters is possible in body-centered cubic (bcc) iron, but not in face-centered cubic (fcc) copper2. Previous experimental studies have reported 1-D migration of SIA clusters14, but there have been no observations of 1-D vacancy cluster migration. Here we present the first experimental transmission electron microscopy (TEM) dynamic observation demonstrating the 1-D migration of vacancy clusters in fcc gold. It was found that the mobility of the vacancy clusters via the 1-D migration is much higher than single vacancies via 3-D random walk and comparable to single SIAs via 3-D random walk. Hence, the mobility of the glissile clusters is not associated with the character of their constituent point defects. Dynamic conversion of a planar vacancy loop into a 3-D stacking fault tetrahedron geometry was also observed.
Molecular Self-Assembly into One-Dimensional Nanostructures
PALMER, LIAM C.; STUPP, SAMUEL I.
2008-01-01
CONSPECTUS Self-assembly of small molecules into one-dimensional nanostructures offers many potential applications in electronically and biologically active materials. The recent advances discussed in this Account demonstrate how researchers can use the fundamental principles of supramolecular chemistry to craft the size, shape, and internal structure of nanoscale objects. In each system described here, we used atomic force microscopy (AFM) and transmission electron microscopy (TEM) to study the assembly morphology. Circular dichroism, nuclear magnetic resonance, infrared, and optical spectroscopy provided additional information about the self-assembly behavior in solution at the molecular level. Dendron rod–coil molecules self-assemble into flat or helical ribbons. They can incorporate electronically conductive groups and can be mineralized with inorganic semiconductors. To understand the relative importance of each segment in forming the supramolecular structure, we synthetically modified the dendron, rod, and coil portions. The self-assembly depended on the generation number of the dendron, the number of hydrogen-bonding functions, and the length of the rod and coil segments. We formed chiral helices using a dendron–rod–coil molecule prepared from an enantiomerically enriched coil. Because helical nanostructures are important targets for use in biomaterials, nonlinear optics, and stereoselective catalysis, researchers would like to precisely control their shape and size. Tripeptide-containing peptide lipid molecules assemble into straight or twisted nanofibers in organic solvents. As seen by AFM, the sterics of bulky end groups can tune the helical pitch of these peptide lipid nanofibers in organic solvents. Furthermore, we demonstrated the potential for pitch control using trans-to-cis photoisomerization of a terminal azobenzene group. Other molecules called peptide amphiphiles (PAs) are known to assemble in water into cylindrical nanostructures that
One-dimensional optical wave turbulence: Experiment and theory
NASA Astrophysics Data System (ADS)
Laurie, Jason; Bortolozzo, Umberto; Nazarenko, Sergey; Residori, Stefania
2012-05-01
We present a review of the latest developments in one-dimensional (1D) optical wave turbulence (OWT). Based on an original experimental setup that allows for the implementation of 1D OWT, we are able to show that an inverse cascade occurs through the spontaneous evolution of the nonlinear field up to the point when modulational instability leads to soliton formation. After solitons are formed, further interaction of the solitons among themselves and with incoherent waves leads to a final condensate state dominated by a single strong soliton. Motivated by the observations, we develop a theoretical description, showing that the inverse cascade develops through six-wave interaction, and that this is the basic mechanism of nonlinear wave coupling for 1D OWT. We describe theory, numerics and experimental observations while trying to incorporate all the different aspects into a consistent context. The experimental system is described by two coupled nonlinear equations, which we explore within two wave limits allowing for the expression of the evolution of the complex amplitude in a single dynamical equation. The long-wave limit corresponds to waves with wave numbers smaller than the electrical coherence length of the liquid crystal, and the opposite limit, when wave numbers are larger. We show that both of these systems are of a dual cascade type, analogous to two-dimensional (2D) turbulence, which can be described by wave turbulence (WT) theory, and conclude that the cascades are induced by a six-wave resonant interaction process. WT theory predicts several stationary solutions (non-equilibrium and thermodynamic) to both the long- and short-wave systems, and we investigate the necessary conditions required for their realization. Interestingly, the long-wave system is close to the integrable 1D nonlinear Schrödinger equation (NLSE) (which contains exact nonlinear soliton solutions), and as a result during the inverse cascade, nonlinearity of the system at low wave
Bioinspired one-dimensional materials for directional liquid transport.
Ju, Jie; Zheng, Yongmei; Jiang, Lei
2014-08-19
One-dimensional materials (1D) capable of transporting liquid droplets directionally, such as spider silks and cactus spines, have recently been gathering scientists' attention due to their potential applications in microfluidics, textile dyeing, filtration, and smog removal. This remarkable property comes from the arrangement of the micro- and nanostructures on these organisms' surfaces, which have inspired chemists to develop methods to prepare surfaces with similar directional liquid transport ability. In this Account, we report our recent progress in understanding how this directional transport works, as well our advances in the design and fabrication of bioinspired 1D materials capable of transporting liquid droplets directionally. To begin, we first discuss some basic theories on droplet directional movement. Then, we discuss the mechanism of directional transport of water droplets on natural spider silks. Upon contact with water droplets, the spider silk undergoes what is known as a wet-rebuilt, which forms periodic spindle-knots and joints. We found that the resulting gradient of Laplace pressure and surface free energy between the spindle-knots and joints account for the cooperative driving forces to transport water droplets directionally. Next, we discuss the directional transport of water droplets on desert cactus. The integration of multilevel structures of the cactus and the resulting integration of multiple functions together allow the cactus spine to transport water droplets continuously from tip to base. Based on our studies of natural spider silks and cactus spines, we have prepared a series of artificial spider silks (A-SSs) and artificial cactus spines (A-CSs) with various methods. By changing the surface roughness and chemical compositions of the artificial spider silks' spindle-knots, or by introducing stimulus-responsive molecules, such as thermal-responsive and photoresponsive molecules, onto the spindle-knots, we can reversibly manipulate
Quasi-One-Dimensional Modeling of Pulse Detonation Rocket Engines
NASA Technical Reports Server (NTRS)
Morris, Christopher I.
2002-01-01
. While such a nozzle is a considerable idealization, it is clear that nozzle design and optimization will play a critical role in whether the performance potential of PDREs can be effectively realized in practice. In order to study PDRE nozzle issues with greater accuracy, a quasi-one-dimensional, finite-rate chemistry CFD code has been developed by the author. Comparisons of the code with both the previous MOC model and experimental data from Stanford University are reported. The effect of constant-gamma and finite-rate chemistry assumptions on the flowfield and performance is examined. Parametric studies of the effect of nozzle throat size and expansion ratio, at various blowdown pressure ratios, are reported.
Analytical models of optical response in one-dimensional semiconductors
NASA Astrophysics Data System (ADS)
Pedersen, Thomas Garm
2015-09-01
The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron-hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed.
Polar Phase of One-dimensional Bosons with Large Spin
Tsvelik, A.M.; Shlyapnikov, G.
2011-06-20
Spinor ultracold gases in one dimension (1D) represent an interesting example of strongly correlated quantum fluids. They have a rich phase diagram and exhibit a variety of quantum phase transitions. We consider a 1D spinor gas of bosons with a large spin S. A particular example is the gas of chromium atoms (S = 3), where the dipolar collisions efficiently change the magnetization and make the system sensitive to the linear Zeeman effect. We argue that in 1D the most interesting effects come from the pairing interaction. If this interaction is negative, it gives rise to a (quasi)condensate of singlet bosonic pairs with an algebraic order at zero temperature, and for (2S+1) >> 1 the saddle point approximation leads to physically transparent results. Since in 1D one needs a finite energy to destroy a pair, the spectrum of spin excitations has a gap. Hence, in the absence of a magnetic field, there is only one gapless mode corresponding to phase fluctuations of the pair quasicondensate. Once the magnetic field exceeds the gap, another condensate emerges, namely the quasicondensate of unpaired bosons with spins aligned along the magnetic field. The spectrum then contains two gapless modes corresponding to the singlet-paired and spin-aligned unpaired Bose condensed particles, respectively. At T = 0, the corresponding phase transition is of the commensurate-incommensurate type.
Integrals of motion for one-dimensional Anderson localized systems
NASA Astrophysics Data System (ADS)
Modak, Ranjan; Mukerjee, Subroto; Yuzbashyan, Emil A.; Shastry, B. Sriram
2016-03-01
Anderson localization is known to be inevitable in one-dimension for generic disordered models. Since localization leads to Poissonian energy level statistics, we ask if localized systems possess ‘additional’ integrals of motion as well, so as to enhance the analogy with quantum integrable systems. We answer this in the affirmative in the present work. We construct a set of nontrivial integrals of motion for Anderson localized models, in terms of the original creation and annihilation operators. These are found as a power series in the hopping parameter. The recently found Type-1 Hamiltonians, which are known to be quantum integrable in a precise sense, motivate our construction. We note that these models can be viewed as disordered electron models with infinite-range hopping, where a similar series truncates at the linear order. We show that despite the infinite range hopping, all states but one are localized. We also study the conservation laws for the disorder free Aubry-Andre model, where the states are either localized or extended, depending on the strength of a coupling constant. We formulate a specific procedure for averaging over disorder, in order to examine the convergence of the power series. Using this procedure in the Aubry-Andre model, we show that integrals of motion given by our construction are well-defined in localized phase, but not so in the extended phase. Finally, we also obtain the integrals of motion for a model with interactions to lowest order in the interaction.
Applications of One-Dimensional Nanomaterials for Stretchable Electronics
NASA Astrophysics Data System (ADS)
Xu, Feng
Electronics that can be stretched and/or conformal to curvilinear surfaces has recently attracted broad attention. Success of stretchable electronics depends on the availability of electronic materials and structures that can be highly stretched, compressed, bent, and twisted. One-dimensional (1D) nanomaterials are expected to aid the development of the stretchable electronic systems by improving performance, expanding integration possibilities, and potentially lowering cost, due to their superior mechanical/electronic/optical properties, high aspect ratios, and compatibility with bulk synthesis. This dissertation is primarily focused on the application of 1D nanomaterials, including silicon nanowires (SiNWs), carbon nanotubes (CNTs) and silver nanowires (AgNWs) for stretchable electronics. The mechanical properties of SiNWs, grown by the vapor-liquid-solid process, were first studied with in situ tensile tests inside a scanning electron microscope (SEM). It was found that the fracture strain increased from 2.7% to about 12% when the NW diameter decreased from 60 to 15 nm. The Young's modulus decreased while the fracture strength increased up to 12.2 GPa, as the nanowire diameter decreased. The fracture strength also increased with the decrease of the side surface area. Repeated loading and unloading during tensile tests demonstrated that the nanowires are linear elastic until fracture without appreciable plasticity. Then, SiNW coils were fabricated on elastomeric substrates by a controlled buckling process. SiNWs were first transferred onto prestrained and ultraviolet/ozone (UVO)-treated poly(dimethylsiloxane) (PDMS) substrates and buckled upon release of the prestrain. Two buckling modes (the in-plane wavy mode and the three-dimensional coiled mode) were found; a transition between them was achieved by controlling the UVO treatment of PDMS. Structural characterization revealed that the NW coils were oval-shaped. The oval-shaped NW coils exhibited very large
One-dimensional Magnus-type platinum double salts
Hendon, Christopher H.; Walsh, Aron; Akiyama, Norinobu; Konno, Yosuke; Kajiwara, Takashi; Ito, Tasuku; Kitagawa, Hiroshi; Sakai, Ken
2016-01-01
Interest in platinum-chain complexes arose from their unusual oxidation states and physical properties. Despite their compositional diversity, isolation of crystalline chains has remained challenging. Here we report a simple crystallization technique that yields a series of dimer-based 1D platinum chains. The colour of the Pt2+ compounds can be switched between yellow, orange and blue. Spontaneous oxidation in air is used to form black Pt2.33+ needles. The loss of one electron per double salt results in a metallic state, as supported by quantum chemical calculations, and displays conductivity of 11 S cm−1 at room temperature. This behaviour may open up a new avenue for controllable platinum chemistry. PMID:27320502
Quasiparticle and excitonic gaps of one-dimensional carbon chains.
Mostaani, E; Monserrat, B; Drummond, N D; Lambert, C J
2016-06-01
We report diffusion quantum Monte Carlo (DMC) calculations of the quasiparticle and excitonic gaps of hydrogen-terminated oligoynes and extended polyyne. The electronic gaps are found to be very sensitive to the atomic structure in these systems. We have therefore optimised the geometry of polyyne by directly minimising the DMC energy with respect to the lattice constant and the Peierls-induced carbon-carbon bond-length alternation. We find the bond-length alternation of polyyne to be 0.136(2) Å and the excitonic and quasiparticle gaps to be 3.30(7) and 3.4(1) eV, respectively. The DMC zone-centre longitudinal optical phonon frequency of polyyne is 2084(5) cm(-1), which is consistent with Raman spectroscopic measurements for large oligoynes. PMID:27104222
One-dimensional Magnus-type platinum double salts.
Hendon, Christopher H; Walsh, Aron; Akiyama, Norinobu; Konno, Yosuke; Kajiwara, Takashi; Ito, Tasuku; Kitagawa, Hiroshi; Sakai, Ken
2016-01-01
Interest in platinum-chain complexes arose from their unusual oxidation states and physical properties. Despite their compositional diversity, isolation of crystalline chains has remained challenging. Here we report a simple crystallization technique that yields a series of dimer-based 1D platinum chains. The colour of the Pt(2+) compounds can be switched between yellow, orange and blue. Spontaneous oxidation in air is used to form black Pt(2.33+) needles. The loss of one electron per double salt results in a metallic state, as supported by quantum chemical calculations, and displays conductivity of 11 S cm(-1) at room temperature. This behaviour may open up a new avenue for controllable platinum chemistry. PMID:27320502
Integrals of motion for one-dimensional Anderson localized systems
Modak, Ranjan; Mukerjee, Subroto; Yuzbashyan, Emil A.; Shastry, B. Sriram
2016-03-02
Anderson localization is known to be inevitable in one-dimension for generic disordered models. Since localization leads to Poissonian energy level statistics, we ask if localized systems possess ‘additional’ integrals of motion as well, so as to enhance the analogy with quantum integrable systems. Weanswer this in the affirmative in the present work. We construct a set of nontrivial integrals of motion for Anderson localized models, in terms of the original creation and annihilation operators. These are found as a power series in the hopping parameter. The recently found Type-1 Hamiltonians, which are known to be quantum integrable in a precisemore » sense, motivate our construction.Wenote that these models can be viewed as disordered electron models with infinite-range hopping, where a similar series truncates at the linear order.Weshow that despite the infinite range hopping, all states but one are localized.Wealso study the conservation laws for the disorder free Aubry–Andre model, where the states are either localized or extended, depending on the strength of a coupling constant.Weformulate a specific procedure for averaging over disorder, in order to examine the convergence of the power series. Using this procedure in the Aubry–Andre model, we show that integrals of motion given by our construction are well-defined in localized phase, but not so in the extended phase. Lastly, we also obtain the integrals of motion for a model with interactions to lowest order in the interaction.« less
Nesting and lifetime effects in the FFLO state of quasi-one-dimensional imbalanced Fermi gases
NASA Astrophysics Data System (ADS)
Caldas, Heron; Continentino, Mucio A.
2013-07-01
Motivated by the recent experimental realization of a candidate to the Fulde-Ferrell (FF) and the Larkin-Ovchinnikov (LO) states in one-dimensional (1D) atomic Fermi gases, we study the quantum phase transitions in these enigmatic, finite-momentum-paired superfluids. We focus on the FF state and investigate the effects of the induced interaction on the stability of the FFLO phase in homogeneous spin-imbalanced quasi-1D Fermi gases at zero temperature. When this is taken into account, we find a direct transition from the fully polarized to the FFLO state in agreement with exact solutions. Also, we consider the effect of a finite lifetime of the quasi-particle states in the normal-superfluid instability. In the limit of long lifetimes, the lifetime effect is irrelevant and the transition is directly from the fully polarized to the FFLO state. We show, however, that for sufficiently short lifetimes, there is a quantum critical point, at a finite value of the mismatch of the Fermi wave-vectors of the different quasi-particles, that we fully characterize. In this case, the transition is from the FFLO phase to a normal partially polarized state with increasing mismatch.
One-Dimensional Liquid ^{4}He: Dynamical Properties beyond Luttinger-Liquid Theory.
Bertaina, G; Motta, M; Rossi, M; Vitali, E; Galli, D E
2016-04-01
We compute the zero-temperature dynamical structure factor of one-dimensional liquid ^{4}He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model. PMID:27081985
Sa de Melo, C.A.R.
1996-02-01
The thermodynamics of quasi-one-dimensional superconductors in the presence of large magnetic fields is studied. When the quantum effects of the magnetic field are taken into account, several reentrant superconducting phases persist at very high fields. In the last reentrant phase the free energy change, the specific heat jump and the excess magnetization are estimated near the critical temperature. In particular, the excess magnetization is found to be paramagnetic as opposed to diamagnetic in weak fields and its sign is controlled by the slope of H{sub c{sub 2}} (T). The authors further generalize this result to the entire phase diagram (including all quantum phases) and to different physical systems using general thermodynamic relations which show that the sign of the excess magnetization {Delta}M of the superconducting state near H{sub c{sub 2}}(T) follows dH{sub c{sub 2}}(T)/dT. These relations provide a scenario for the evolution of the sign of {Delta}M from weak fields to strong fields.
Numerical method for nonlinear steady-state transport in one-dimensional correlated conductors
NASA Astrophysics Data System (ADS)
Einhellinger, M.; Cojuhovschi, A.; Jeckelmann, E.
2012-06-01
We present a method for investigating the steady-state transport properties of one-dimensional correlated quantum systems. Using a procedure based on our analysis of finite-size effects in a related classical model (LC line) we show that stationary currents can be obtained from transient currents in finite systems driven out of equilibrium. The nonequilibrium dynamics of correlated quantum systems is calculated using the time-evolving block decimation method. To demonstrate our method we determine the full I-V characteristic of the spinless fermion model with nearest-neighbor hopping tH and interaction VH using two different setups to generate currents (turning on/off a potential bias). Our numerical results agree with exact results for noninteracting fermions (VH=0). For interacting fermions we find that in the linear regime eV≪4tH the current I is independent from the setup and our numerical data agree with the predictions of the Luttinger liquid theory combined with the Bethe Ansatz solution. For larger potentials V the steady-state current depends on the current-generating setup and as V increases we find a negative differential conductance with one setup while the currents saturate at finite values in the other one. Both effects are due to finite renormalized bandwidths.
Single-photon transport through an atomic chain coupled to a one-dimensional nanophotonic waveguide
NASA Astrophysics Data System (ADS)
Liao, Zeyang; Zeng, Xiaodong; Zhu, Shi-Yao; Zubairy, M. Suhail
2015-08-01
We study the dynamics of a single-photon pulse traveling through a linear atomic chain coupled to a one-dimensional (1D) single mode photonic waveguide. We derive a time-dependent dynamical theory for this collective many-body system which allows us to study the real time evolution of the photon transport and the atomic excitations. Our analytical result is consistent with previous numerical calculations when there is only one atom. For an atomic chain, the collective interaction between the atoms mediated by the waveguide mode can significantly change the dynamics of the system. The reflectivity of a photon can be tuned by changing the ratio of coupling strength and the photon linewidth or by changing the number of atoms in the chain. The reflectivity of a single-photon pulse with finite bandwidth can even approach 100 % . The spectrum of the reflected and transmitted photon can also be significantly different from the single-atom case. Many interesting physical phenomena can occur in this system such as the photonic band-gap effects, quantum entanglement generation, Fano-like interference, and superradiant effects. For engineering, this system may serve as a single-photon frequency filter, single-photon modulation, and may find important applications in quantum information.
Emergent quasi-one-dimensionality in a kagome magnet: A simple route to complexity
NASA Astrophysics Data System (ADS)
Gong, Shou-Shu; Zhu, Wei; Yang, Kun; Starykh, Oleg A.; Sheng, D. N.; Balents, Leon
2016-07-01
We study the ground-state phase diagram of the quantum spin-1 /2 Heisenberg model on the kagome lattice with first- (J1<0 ) , second- (J2<0 ) , and third-neighbor interactions (Jd>0 ) by means of analytical low-energy field theory and numerical density-matrix renormalization group (DMRG) studies. The results offer a consistent picture of the Jd-dominant regime in terms of three sets of spin chains weakly coupled by the ferromagnetic interchain interactions J1 ,2. When either J1 or J2 is much stronger than the other one, the model is found to support one of two cuboctohedral phases, cuboc1, and cuboc2. These cuboc states host noncoplanar long-ranged magnetic order and possess finite scalar spin chirality. However, in the compensated regime J1≃J2 , a valence bond crystal phase emerges between the two cuboc phases. We find excellent agreement between an analytical theory based on coupled spin chains and unbiased DMRG calculations, including at a very detailed level of comparison of the structure of the valence bond crystal state. To our knowledge, this is the first such comprehensive understanding of a highly frustrated two-dimensional quantum antiferromagnet. We find no evidence of either the one-dimensional gapless spin liquid or the chiral spin liquids, which were previously suggested by parton mean-field theories.
Equilibrium and off-equilibrium trap-size scaling in one-dimensional ultracold bosonic gases
Campostrini, Massimo; Vicari, Ettore
2010-12-15
We study some aspects of equilibrium and off-equilibrium quantum dynamics of dilute bosonic gases in the presence of a trapping potential. We consider systems with a fixed number of particles and study their scaling behavior with increasing the trap size. We focus on one-dimensional bosonic systems, such as gases described by the Lieb-Liniger model and its Tonks-Girardeau limit of impenetrable bosons, and gases constrained in optical lattices as described by the Bose-Hubbard model. We study their quantum (zero-temperature) behavior at equilibrium and off equilibrium during the unitary time evolution arising from changes of the trapping potential, which may be instantaneous or described by a power-law time dependence, starting from the equilibrium ground state for an initial trap size. Renormalization-group scaling arguments and analytical and numerical calculations show that the trap-size dependence of the equilibrium and off-equilibrium dynamics can be cast in the form of a trap-size scaling in the low-density regime, characterized by universal power laws of the trap size, in dilute gases with repulsive contact interactions and lattice systems described by the Bose-Hubbard model. The scaling functions corresponding to several physically interesting observables are computed. Our results are of experimental relevance for systems of cold atomic gases trapped by tunable confining potentials.
One-Dimensional Liquid 4He: Dynamical Properties beyond Luttinger-Liquid Theory
NASA Astrophysics Data System (ADS)
Bertaina, G.; Motta, M.; Rossi, M.; Vitali, E.; Galli, D. E.
2016-04-01
We compute the zero-temperature dynamical structure factor of one-dimensional liquid 4He by means of state-of-the-art quantum Monte Carlo and analytic continuation techniques. By increasing the density, the dynamical structure factor reveals a transition from a highly compressible critical liquid to a quasisolid regime. In the low-energy limit, the dynamical structure factor can be described by the quantum hydrodynamic Luttinger-liquid theory, with a Luttinger parameter spanning all possible values by increasing the density. At higher energies, our approach provides quantitative results beyond the Luttinger-liquid theory. In particular, as the density increases, the interplay between dimensionality and interaction makes the dynamical structure factor manifest a pseudo-particle-hole continuum typical of fermionic systems. At the low-energy boundary of such a region and moderate densities, we find consistency, within statistical uncertainties, with predictions of a power-law structure by the recently developed nonlinear Luttinger-liquid theory. In the quasisolid regime, we observe a novel behavior at intermediate momenta, which can be described by new analytical relations that we derive for the hard-rods model.
Fabrication and characterization of one dimensional zinc oxide nanostructures
NASA Astrophysics Data System (ADS)
Cheng, Chun
In this thesis, one dimensional (1D) ZnO nanostructures with controlled morphologies, defects and alignment have been fabricated by a simple vapor transfer method. The crystal structures, interfaces, growth mechanisms and optical properties of ZnO nanostructures have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. Great efforts have been devoted to the patterned growth and assembly of ZnO nanostructures as well as the stability of ZnO nanowires (NWs). Using carbonized photoresists, a simple and very effective method has been developed for fabricating and patterning high-quality ZnO NW arrays. ZnO NWs from this method show excellent alignment, crystal quality, and optical properties that are independent of the substrates. The carbonized photoresists provide perfect nucleation sites for the growth of aligned ZnO NWs and also perfectly connect to the NWs to form ideal electrodes. This approach is further extended to realize large area growth of different forms of ZnO NW arrays (e.g., the horizontal growth and multilayered ZnO NW arrays) on other kinds of carbon-based materials. In addition, the as-synthesized vertically aligned ZnO NW arrays show a low weighted reflectance (Rw) and can be used as antireflection coatings. Moreover, non c-axis growth of 1D ZnO nanostructures (e.g., nanochains, nanobrushes and nanobelts) and defect related 1D ZnO nanostructures (e.g., Y-shaped twinned nanobelts and hierarchical nanostructures decorated by flowers induced by screw dislocations) is also present. Using direct oxidization of pure Zn at high temperatures in air, uniformed ZnO NWs and tetrapods have been fabricated. The spatially-resolved PL study on these two kinds of nanostructures suggests that the defects leading to the green luminescence (GL) should originate from the structural changes along the legs of the tetrapods. Surface defects in these ZnO nanostructures play an unimportant
Guan, X. W.; Lee, J.-Y.; Batchelor, M. T.; Yin, X.-G.; Chen Shu
2010-08-15
A simple set of algebraic equations is derived for the exact low-temperature thermodynamics of one-dimensional multicomponent strongly attractive fermionic atoms with enlarged SU(N) spin symmetry and Zeeman splitting. Universal multicomponent Tomonaga-Luttinger liquid (TLL) phases are thus determined. For linear Zeeman splitting, the physics of the gapless phase at low temperatures belongs to the universality class of a two-component asymmetric TLL corresponding to spin-neutral N-atom composites and spin-(N-1)/2 single atoms. The equation of state which we obtained provides a precise description of multicomponent composite fermions and opens up the study of quantum criticality in one-dimensional systems of N-component Fermi gases with population imbalance.
Asymptotic Stability of High-dimensional Zakharov-Kuznetsov Solitons
NASA Astrophysics Data System (ADS)
Côte, Raphaël; Muñoz, Claudio; Pilod, Didier; Simpson, Gideon
2016-05-01
We prove that solitons (or solitary waves) of the Zakharov-Kuznetsov (ZK) equation, a physically relevant high dimensional generalization of the Korteweg-de Vries (KdV) equation appearing in Plasma Physics, and having mixed KdV and nonlinear Schrödinger (NLS) dynamics, are strongly asymptotically stable in the energy space. We also prove that the sum of well-arranged solitons is stable in the same space. Orbital stability of ZK solitons is well-known since the work of de Bouard [Proc R Soc Edinburgh 126:89-112, 1996]. Our proofs follow the ideas of Martel [SIAM J Math Anal 157:759-781, 2006] and Martel and Merle [Math Ann 341:391-427, 2008], applied for generalized KdV equations in one dimension. In particular, we extend to the high dimensional case several monotonicity properties for suitable half-portions of mass and energy; we also prove a new Liouville type property that characterizes ZK solitons, and a key Virial identity for the linear and nonlinear part of the ZK dynamics, obtained independently of the mixed KdV-NLS dynamics. This last Virial identity relies on a simple sign condition which is numerically tested for the two and three dimensional cases with no additional spectral assumptions required. Possible extensions to higher dimensions and different nonlinearities could be obtained after a suitable local well-posedness theory in the energy space, and the verification of a corresponding sign condition.
One-dimensional quasi-exactly solvable Schrödinger equations
NASA Astrophysics Data System (ADS)
Turbiner, Alexander V.
2016-06-01
Quasi-Exactly Solvable Schrödinger Equations occupy an intermediate place between exactly-solvable (e.g. the harmonic oscillator and Coulomb problems, etc.) and non-solvable ones. Mainly, they were discovered in the 1980s. Their major property is an explicit knowledge of several eigenstates while the remaining ones are unknown. Many of these problems are of the anharmonic oscillator type with a special type of anharmonicity. The Hamiltonians of quasi-exactly-solvable problems are characterized by the existence of a hidden algebraic structure but do not have any hidden symmetry properties. In particular, all known one-dimensional (quasi)-exactly-solvable problems possess a hidden sl(2, R) -Lie algebra. They are equivalent to the sl(2, R) Euler-Arnold quantum top in a constant magnetic field. Quasi-Exactly Solvable problems are highly non-trivial, they shed light on the delicate analytic properties of the Schrödinger Equations in coupling constant, they lead to a non-trivial class of potentials with the property of Energy-Reflection Symmetry. The Lie-algebraic formalism allows us to make a link between the Schrödinger Equations and finite-difference equations on uniform and/or exponential lattices, it implies that the spectra is preserved. This link takes the form of quantum canonical transformation. The corresponding isospectral problems for finite-difference operators are described. The underlying Fock space formalism giving rise to this correspondence is uncovered. For a quite general class of perturbations of unperturbed problems with the hidden Lie algebra property we can construct an algebraic perturbation theory, where the wavefunction corrections are of polynomial nature, thus, can be found by algebraic means. In general, Quasi-Exact-Solvability points to the existence of a hidden algebra formalism which ranges from quantum mechanics to 2-dimensional conformal field theories.
Sykes, Andrew G.; Davis, Matthew J.; Roberts, David C.
2009-08-21
The existence of frictionless flow below a critical velocity for obstacles moving in a superfluid is well established in the context of the mean-field Gross-Pitaevskii theory. We calculate the next order correction due to quantum and thermal fluctuations and find a nonzero force acting on a delta-function impurity moving through a quasi-one-dimensional Bose-Einstein condensate at all subcritical velocities and at all temperatures. The force occurs due to an imbalance in the Doppler shifts of reflected quantum fluctuations from either side of the impurity. Our calculation is based on a consistent extension of Bogoliubov theory to second order in the interaction strength, and finds new analytical solutions to the Bogoliubov-de Gennes equations for a gray soliton. Our results raise questions regarding the quantum dynamics in the formation of persistent currents in superfluids.
Non-Markovianity induced by a single-photon wave packet in a one-dimensional waveguide.
Valente, D; Arruda, M F Z; Werlang, T
2016-07-01
The concept of non-Markovianity (NM) in quantum dynamics is still an open debate. Understanding how to generate and measure NM in specific models may aid in this quest. In quantum optics, an engineered electromagnetic environment coupled to a single atom can induce NM. The most common scenario of structured electromagnetic environment is an optical cavity, composed by a pair of mirrors. Here, we show how to generate and measure NM on a two-level system coupled to a one-dimensional waveguide with no mirrors required. The origin of the non-Markovian behavior lies in the initial state of the field, prepared as a single-photon packet. NM is shown to depend on two experimentally controllable parameters, namely, the linewidth of the packet and its central frequency. We relate the presence of NM to quantum interference. We also show how the two output channels of the waveguide provide distinct signatures of NM, both experimentally accessible. PMID:27367118
One-dimensional edge state transport in a topological Kondo insulator
NASA Astrophysics Data System (ADS)
Nakajima, Yasuyuki; Syers, Paul; Wang, Xiangfeng; Wang, Renxiong; Paglione, Johnpierre
2016-03-01
Topological insulators, with metallic boundary states protected against time-reversal-invariant perturbations, are a promising avenue for realizing exotic quantum states of matter, including various excitations of collective modes predicted in particle physics, such as Majorana fermions and axions. According to theoretical predictions, a topological insulating state can emerge from not only a weakly interacting system with strong spin-orbit coupling, but also in insulators driven by strong electron correlations. The Kondo insulator compound SmB6 is an ideal candidate for realizing this exotic state of matter, with hybridization between itinerant conduction electrons and localized f-electrons driving an insulating gap and metallic surface states at low temperatures. Here we exploit the existence of surface ferromagnetism in SmB6 to investigate the topological nature of metallic surface states by studying magnetotransport properties at very low temperatures. We find evidence of one-dimensional surface transport with a quantized conductance value of e2/h originating from the chiral edge channels of ferromagnetic domain walls, providing strong evidence that topologically non-trivial surface states exist in SmB6.
van Vugt, Lambert K.; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh
2011-01-01
Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk. PMID:21628582
Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces.
Zhuang, Houlong L; Zhang, Lipeng; Xu, Haixuan; Kent, P R C; Ganesh, P; Cooper, Valentino R
2016-01-01
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the "polar catastrophe" mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified "polar catastrophe" model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first-principles calculations indicate that for nanowire heterostructures a robust one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity at LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density decays laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier dimensionality between 1D and 2D conductivity. Our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases. PMID:27151049
Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces
Zhuang, Houlong L.; Zhang, Lipeng; Xu, Haixuan; Kent, P. R. C.; Ganesh, P.; Cooper, Valentino R.
2016-01-01
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the “polar catastrophe” mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified “polar catastrophe” model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first-principles calculations indicate that for nanowire heterostructures a robust one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity at LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density decays laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier dimensionality between 1D and 2D conductivity. Our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases. PMID:27151049
Bloch Oscillation in a One-Dimensional Array of Small Josephson Junctions
NASA Astrophysics Data System (ADS)
Shimada, Hiroshi; Katori, Shunsuke; Gandrothula, Srinivas; Deguchi, Tomoaki; Mizugaki, Yoshinao
2016-07-01
A distinct Bloch nose was demonstrated in the current-voltage characteristics of a one-dimensional array of 20 small Josephson junctions. Arrays of direct-current superconducting quantum interference device (dc-SQUID) structures were used as leads to the array of junctions, and the environmental impedance was tuned with a magnetic field. The observed Bloch nose had a negative differential resistance of its magnitude of as large as 14.3 MΩ, a blockade voltage of 0.36 mV, and a decrease in voltage of 0.21 mV due to the Bloch oscillation, all of which are larger than those obtained in a single junction by more than one order. The observed Bloch oscillation was quantitatively described on the basis of the Bloch oscillation of each single junction in combination with the charge soliton model in a long array. Unexpected constant-current spikes, whose origin lay in the dc-SQUID in the leads, were also observed to be superposed on the current-voltage characteristics when the Coulomb blockade appeared.
Finite-temperature charge transport in the one-dimensional Hubbard model
NASA Astrophysics Data System (ADS)
Jin, F.; Steinigeweg, R.; Heidrich-Meisner, F.; Michielsen, K.; De Raedt, H.
2015-11-01
We study the charge conductivity of the one-dimensional repulsive Hubbard model at finite temperature using the method of dynamical quantum typicality, focusing at half filling. This numerical approach allows us to obtain current autocorrelation functions from systems with as many as 18 sites, way beyond the range of standard exact diagonalization. Our data clearly suggest that the charge Drude weight vanishes with a power law as a function of system size. The low-frequency dependence of the conductivity is consistent with a finite dc value and thus with diffusion, despite large finite-size effects. Furthermore, we consider the mass-imbalanced Hubbard model for which the charge Drude weight decays exponentially with system size, as expected for a nonintegrable model. We analyze the conductivity and diffusion constant as a function of the mass imbalance and we observe that the conductivity of the lighter component decreases exponentially fast with the mass-imbalance ratio. While in the extreme limit of immobile heavy particles, the Falicov-Kimball model, there is an effective Anderson-localization mechanism leading to a vanishing conductivity of the lighter species, we resolve finite conductivities for an inverse mass ratio of η ≳0.25 .
Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces
NASA Astrophysics Data System (ADS)
Zhuang, Houlong L.; Zhang, Lipeng; Xu, Haixuan; Kent, P. R. C.; Ganesh, P.; Cooper, Valentino R.
2016-05-01
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the “polar catastrophe” mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified “polar catastrophe” model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first-principles calculations indicate that for nanowire heterostructures a robust one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity at LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density decays laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier dimensionality between 1D and 2D conductivity. Our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases.
Loading and detecting a three-dimensional Fermi gas in a one-dimensional optical superlattice
NASA Astrophysics Data System (ADS)
Sheikhan, Ameneh; Kollath, Corinna
2015-04-01
We investigate the procedures of loading and detecting three-dimensional fermionic quantum gases in a one-dimensional optical superlattice potential subjected to a trapping potential. Additionally, we consider the relaxation dynamics after a sudden change of the superlattice potential. We numerically simulate the time-dependent evolution of the continuous system using exact diagonalization of noninteracting fermions. During the loading procedure we analyze the occupation of the instantaneous energy levels and compare the situation in a homogeneous system with the trapped one. Strong differences are found in particular in the evolution of excitations which we trace back to the distinct global density distribution. Starting from an imbalanced state in the superlattice potential, we consider the relaxation dynamics of fermions after a slow change of the superlattice potential and find a bimodal distribution of excitations. To be able to compare with the experimental results we also simulate the measurement sequence of the even and odd local density and find a strong dependence of the outcome on the actual ramp procedure. We suggest how the loading and detecting procedure can be optimized.
Topological pumping in the one-dimensional Bose-Hubbard model
NASA Astrophysics Data System (ADS)
Rossini, Davide; Gibertini, Marco; Giovannetti, Vittorio; Fazio, Rosario
2013-02-01
By means of time-dependent density-matrix renormalization-group calculations, we study topological quantum pumping in a strongly interacting system. The system under consideration is described by the Hamiltonian of a one-dimensional extended Bose-Hubbard model in the presence of a correlated hopping which breaks lattice inversion symmetry. This model has been predicted to support topological pumping [E. Berg, M. Levin, and E. Altman, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.110405 106, 110405 (2011)]. The pumped charge is quantized and of a topological nature. We provide a detailed analysis of the finite-size scaling behavior of the pumped charge and its deviations from the quantized value. Furthermore, we also analyze the nonadiabatic corrections due to the finite frequency of the modulation. We consider two configurations: a closed ring where the time dependence of the parameter induces a circulating current and a finite open-ended chain where particles are dragged from one edge to the opposite edge, due to the pumping mechanism induced by the bulk.
Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces
Zhang, Lipeng; Xu, Haixuan; Kent, Paul R. C.; Ganesh, Panchapakesan; Cooper, Valentino R.; Zhuang, Houlong L.
2016-05-06
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO over layers. This insulator-to-metal transition can be explained through the polar catastrophe mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified polar catastrophe" model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first principles calculations indicate that for nanowire heterostructuremore » geometries a one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity in LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density will decay laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier behavior between 1D and 2D conductivity. Furthermore, our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases.« less
van Vugt, Lambert K; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh
2011-06-21
Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk. PMID:21628582
NMR Signature of One-Dimensional Behavior of He3 in Nanopores
NASA Astrophysics Data System (ADS)
Yager, B.; Nyéki, J.; Casey, A.; Cowan, B. P.; Lusher, C. P.; Saunders, J.
2013-11-01
We have performed thermodynamic and NMR relaxation time measurements of He3 adsorbed in the pores of the mesoporous molecular sieve MCM-41 at temperatures down to 1.7 K and at a range of frequencies up to 240 kHz. The MCM-41 substrate comprises a uniform array of quasi-1D straight pores with a diameter of 2.3 nm. We preplated the pores with a monolayer of He4 to achieve an effective diameter of 1.6 nm at low temperatures. We made NMR measurements as a function of line density and frequency to investigate the spin dynamics and the effect of dimensionality. We observed T1∝ω1/2, which is characteristic of one-dimensional diffusion. At these temperatures this arises from a classical size effect in the narrow pores. Our results demonstrate the possibility to study the spin dynamics of a 1D Tomonaga-Luttinger liquid at lower temperatures, where the He3 liquid will constitute a quantum 1D system.
Tunable One-Dimensional Electron Gas Carrier Densities at Nanostructured Oxide Interfaces
Zhang, Lipeng; Xu, Haixuan; Kent, Paul R; Ganesh, Panchapakesan; Cooper, Valentino R
2016-01-01
The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO over layers. This insulator-to-metal transition can be explained through the polar catastrophe mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified polar catastrophe" model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first principles calculations indicate that for nanowire heterostructure geometries a one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity in LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density will decay laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier behavior between 1D and 2D conductivity. In essence, our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases.
Amo-Ochoa, Pilar; Castillo, Oscar; Gómez-García, Carlos J; Hassanein, Khaled; Verma, Sandeep; Kumar, Jitendra; Zamora, Félix
2013-10-01
Four new copper(II) coordination complexes, obtained by reaction of CuX2 (X = acetate or chloride) with thymine-1-acetic acid and uracil-1-propionic acid as ligands, of formulas [Cu(TAcO)2(H2O)4]·4H2O (1), [Cu(TAcO)2(H2O)2]n (2), [Cu3(TAcO)4(H2O)2(OH)2]n·4H2O (3), and [Cu3(UPrO)2Cl2(OH)2(H2O)2]n (4) (TAcOH = thymine-1-acetic acid, UPrOH = uracil-1-propionic acid) are described. While 1 is a discrete complex, 2-4 are one-dimensional coordination polymers. Complexes 2-4 present dc conductivity values between 10(-6) and 10(-9) S/cm(-1). The magnetic behavior of complex 2 is typical for almost isolated Cu(II) metal centers. Moderate-weak antiferromagnetic interactions have been found in complex 3, whereas a combination of strong and weak antiferromagnetic interactions have been found in complex 4. Quantum computational calculations have been done to estimate the individual "J" magnetic coupling constant for each superexchange pathway in complexes 3 and 4. Compounds 2-4 are the first known examples of semiconductor and magnetic coordination polymers containing nucleobases. PMID:24040754
Damping of confined excitation modes of one-dimensional condensates in an optical lattice
NASA Astrophysics Data System (ADS)
Trallero-Giner, C.; Santiago-Pérez, Darío G.; Chung, Ming-Chiang; Marques, G. E.; Cipolatti, R.
2015-10-01
We study the damping of the collective excitations of Bose-Einstein condensates in a harmonic trap potential loaded in an optical lattice. In the presence of a confining potential the system is inhomogeneous and the collective excitations are characterized by a set of discrete confined phononlike excitations. We derive a general convenient analytical description for the damping rate, which takes into account the trapping potential and the optical lattice for the Landau and Beliaev processes at any temperature T . At high temperature or weak spatial confinement, we show that both mechanisms display a linear dependence on T . In the quantum limit, we find that the Landau damping is exponentially suppressed at low temperatures and the total damping is independent of T . Our theoretical predictions for the damping rate under the thermal regime is in complete correspondence with the experimental values reported for the one-dimensional (1D) condensate of sodium atoms. We show that the laser intensity can tune the collision process, allowing a resonant effect for the condensate lifetime. Also, we study the influence of the attractive or repulsive nonlinear terms on the decay rate of the collective excitations. A general expression for the renormalized Goldstone frequency is obtained as a function of the 1D nonlinear self-interaction parameter, laser intensity, and temperature.
Upper critical magnetic fields in quasi-one-dimensional layered superconductors
NASA Astrophysics Data System (ADS)
Sepper, Otar
This thesis presents a theoretical analysis of upper critical magnetic fields in quasi-one-dimensional (Q1D), layered superconductors with highly anisotropic electron spectra. It is shown quantitatively how the temperature dependence and spacial orientation of the upper critical magnetic fields, Hc2(T), can reveal important microscopic properties of such superconductors, including the nature of their pairing symmetry. The results obtained show that highly anisotropic, layered compounds can possess exotic superconducting properties such as: non-analytical angular dependence in the upper critical fields at low temperature, the rare spin-triplet Cooper pairing, and a novel quantum limit reentrant superconducting phase occurring in Q1D compounds under ultra-high magnetic fields. For this purpose, two unconventional superconductors are examined: the highly anisotropic Q1D organic superconductor (DMET)2I3, and the layered transition metal oxide superconductor Li0.9Mo6O 17. In the first case, an angular dependence of H c2 that varies as theta3/2 is predicted in (DMET) 2I3 for small angles and low temperatures, in contrast to the well-established (Ginzburg-Landau) quadratic angular dependence near the transition temperature. For Li0.9Mo6O17, spin-triplet pairing is shown to be the most likely scenario, supported by theoretical analysis of the recent experimental data on H c2(T when the field is aligned parallel to the most conducting axis. Furthermore, in Li0.9Mo6O17, a novel quantum limit (QL) superconducting phase is theoretically predicted as a consequence of dimensional crossover in ultra-high magnetic field. If confirmed experimentally, the QL phase would be the first example of existence of superconductivity in magnetic fields greater than 100 Tesla, and in addition would unequivocally confirm spin-triplet Cooper pairing in Li0.9Mo 6O17.
The IVP for the Benjamin-Ono-Zakharov-Kuznetsov equation in low regularity Sobolev spaces
NASA Astrophysics Data System (ADS)
Cunha, Alysson; Pastor, Ademir
2016-08-01
In this paper we study the initial-value problem associated with the Benjamin-Ono-Zakharov-Kuznetsov equation. Such equation appears as a two-dimensional generalization of the Benjamin-Ono equation when transverse effects are included via weak dispersion of Zakharov-Kuznetsov type. We prove that the initial-value problem is locally well-posed in the usual L2 (R2)-based Sobolev spaces Hs (R2), s > 11 / 8, and in some weighted Sobolev spaces. To obtain our results, most of the arguments are accomplished taking into account the ones for the Benjamin-Ono equation.
Symmetry reductions, exact solutions, and conservation laws of the generalized Zakharov equations
NASA Astrophysics Data System (ADS)
Buhe, Eerdun; Bluman, George W.
2015-10-01
In this paper, the generalized Zakharov equations, which describe interactions between high- and low-frequency waves in plasma physics are studied from the perspective of Lie symmetry analysis and conservation laws. Based on some subalgebras of symmetries, several reductions and numerous new exact solutions are obtained. All of these solutions represent modified traveling waves. The obtained solutions include expressions involving Airy functions, Bessel functions, Whittaker functions, and generalized hypergeometric functions. Previously unknown conservation laws are constructed for the generalized Zakharov equations using the direct method. Profiles are presented for some of these new solutions.
Comparisons between thermodynamic and one-dimensional combustion models of spark-ignition engines
NASA Technical Reports Server (NTRS)
Ramos, J. I.
1986-01-01
Results from a one-dimensional combustion model employing a constant eddy diffusivity and a one-step chemical reaction are compared with those of one-zone and two-zone thermodynamic models to study the flame propagation in a spark-ignition engine. One-dimensional model predictions are found to be very sensitive to the eddy diffusivity and reaction rate data. The average mixing temperature found using the one-zone thermodynamic model is higher than those of the two-zone and one-dimensional models during the compression stroke, and that of the one-dimensional model is higher than those predicted by both thermodynamic models during the expansion stroke. The one-dimensional model is shown to predict an accelerating flame even when the front approaches the cold cylinder wall.
Correlated two-photon transport in a one-dimensional waveguide side-coupled to a nonlinear cavity
Liao Jieqiao; Law, C. K.
2010-11-15
We investigate the transport properties of two photons inside a one-dimensional waveguide side-coupled to a single-mode nonlinear cavity. The cavity is filled with a nonlinear Kerr medium. Based on the Laplace transform method, we present an analytic solution for the quantum states of the two transmitted and reflected photons, which are initially prepared in a Lorentzian wave packet. The solution reveals how quantum correlation between the two photons emerges after the scattering by the nonlinear cavity. In particular, we show that the output wave function of the two photons in position space can be localized in relative coordinates, which is a feature that might be interpreted as a two-photon bound state in this waveguide-cavity system.
Suppression of 2π phase slip due to hidden zero modes in one-dimensional topological superconductors
NASA Astrophysics Data System (ADS)
Pekker, David; Hou, Chang-Yu; Bergman, Doron L.; Goldberg, Sam; Adagideli, İnanç; Hassler, Fabian
2013-02-01
We study phase slips in one-dimensional topological superconducting wires. These wires have been proposed as building blocks for topologically protected qubits in which the quantum information is distributed over the length of the device and thus is immune to local sources of decoherence. However, phase slips are nonlocal events that can result in decoherence. Phase slips in topological superconductors are peculiar for the reason that they occur in multiples of 4π (instead of 2π in conventional superconductors). We reestablish this fact via a beautiful analogy to the particle physics concept of dynamic symmetry breaking by explicitly finding a “hidden” zero mode in the fermion spectrum computed in the background of a 2π phase slip. Armed with the understanding of phase slips in topological superconductors, we propose a simple experimental setup with which the predictions can be tested by monitoring the tunneling rate of a superconducting flux quantum through a topological superconducting wire.
Balabanyan, Karén G; Prokof'ev, Nikolay; Svistunov, Boris
2005-07-29
We study the nature of the superfluid-insulator quantum phase transition in a one-dimensional system of lattice bosons with off-diagonal disorder in the limit of a large integer filling factor. Monte Carlo simulations of two strongly disordered models show that the universality class of the transition in question is the same as that of the superfluid-Mott-insulator transition in a pure system. This result can be explained by disorder self-averaging in the superfluid phase and the applicability of the standard quantum hydrodynamic action. We also formulate the necessary conditions which should be satisfied by the stong-randomness universality class, if one exists. PMID:16090888
Song, Bin; Zhong, Yiling; Wu, Sicong; Chu, Binbin; Su, Yuanyuan; He, Yao
2016-04-13
We herein report a kind of one-dimensional biocompatible fluorescent silicon nanorods (SiNRs) with tunable lengths ranging ∼100-250 nm, which can be facilely prepared through one-pot microwave synthesis. In addition to the strong fluorescence (quantum yield value: ∼15%) and negligible toxicity, the resultant SiNRs exhibit excitation wavelength-dependent photoluminescence whose maximum emission wavelength ranges from ∼450 to ∼600 nm under serial excitation wavelengths from 390 to 560 nm, providing feasibility for multicolor biological imaging. More significantly, the SiNRs are ultrahighly photostable, preserving strong and nearly unchanged fluorescence under 400 min high-power UV irradiation, which is in sharp contrast to severe fluorescence quenching of organic dyes (e.g., FITC) or II-VI quantum dots (QDs) (e.g., CdTe QDs and CdSe/ZnS QDs) within 15 or 160 min UV treatment under the same experiment conditions, respectively. Taking advantage of these attractive merits, we further exploit the SiNRs as a novel type of color converters for the construction of white light-emitting diodes (LED), which is the first proof-of-concept demonstration of LED device fabricated using the one-dimensional fluorescent silicon nanostructures. PMID:27010956
NASA Astrophysics Data System (ADS)
Liu, Guangkun; Kaushal, Nitin; Li, Shaozhi; Bishop, Christopher B.; Wang, Yan; Johnston, Steve; Alvarez, Gonzalo; Moreo, Adriana; Dagotto, Elbio
2016-06-01
A recently introduced one-dimensional three-orbital Hubbard model displays orbital-selective Mott phases with exotic spin arrangements such as spin block states [J. Rincón et al., Phys. Rev. Lett. 112, 106405 (2014), 10.1103/PhysRevLett.112.106405]. In this publication we show that the constrained-path quantum Monte Carlo (CPQMC) technique can accurately reproduce the phase diagram of this multiorbital one-dimensional model, paving the way to future CPQMC studies in systems with more challenging geometries, such as ladders and planes. The success of this approach relies on using the Hartree-Fock technique to prepare the trial states needed in CPQMC. We also study a simplified version of the model where the pair-hopping term is neglected and the Hund coupling is restricted to its Ising component. The corresponding phase diagrams are shown to be only mildly affected by the absence of these technically difficult-to-implement terms. This is confirmed by additional density matrix renormalization group and determinant quantum Monte Carlo calculations carried out for the same simplified model, with the latter displaying only mild fermion sign problems. We conclude that these methods are able to capture quantitatively the rich physics of the several orbital-selective Mott phases (OSMP) displayed by this model, thus enabling computational studies of the OSMP regime in higher dimensions, beyond static or dynamic mean-field approximations.
Liu, Guangkun; Kaushal, Nitin; Li, Shaozhi; Bishop, Christopher B; Wang, Yan; Johnston, Steve; Alvarez, Gonzalo; Moreo, Adriana; Dagotto, Elbio
2016-06-01
A recently introduced one-dimensional three-orbital Hubbard model displays orbital-selective Mott phases with exotic spin arrangements such as spin block states [J. Rincón et al., Phys. Rev. Lett. 112, 106405 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.106405]. In this publication we show that the constrained-path quantum Monte Carlo (CPQMC) technique can accurately reproduce the phase diagram of this multiorbital one-dimensional model, paving the way to future CPQMC studies in systems with more challenging geometries, such as ladders and planes. The success of this approach relies on using the Hartree-Fock technique to prepare the trial states needed in CPQMC. We also study a simplified version of the model where the pair-hopping term is neglected and the Hund coupling is restricted to its Ising component. The corresponding phase diagrams are shown to be only mildly affected by the absence of these technically difficult-to-implement terms. This is confirmed by additional density matrix renormalization group and determinant quantum Monte Carlo calculations carried out for the same simplified model, with the latter displaying only mild fermion sign problems. We conclude that these methods are able to capture quantitatively the rich physics of the several orbital-selective Mott phases (OSMP) displayed by this model, thus enabling computational studies of the OSMP regime in higher dimensions, beyond static or dynamic mean-field approximations. PMID:27415393
Liu, Guangkun; Kaushal, Nitin; Liu, Shaozhi; Bishop, Christopher B.; Wang, Yan; Johnston, Steve; Alvarez, Gonzalo; Moreo, Adriana; Dagotto, Elbio R.
2016-06-24
A recently introduced one-dimensional three-orbital Hubbard model displays orbital-selective Mott phases with exotic spin arrangements such as spin block states [J. Rincón et al., Phys. Rev. Lett. 112, 106405 (2014)]. In this paper we show that the constrained-path quantum Monte Carlo (CPQMC) technique can accurately reproduce the phase diagram of this multiorbital one-dimensional model, paving the way to future CPQMC studies in systems with more challenging geometries, such as ladders and planes. The success of this approach relies on using the Hartree-Fock technique to prepare the trial states needed in CPQMC. In addition, we study a simplified version of themore » model where the pair-hopping term is neglected and the Hund coupling is restricted to its Ising component. The corresponding phase diagrams are shown to be only mildly affected by the absence of these technically difficult-to-implement terms. This is confirmed by additional density matrix renormalization group and determinant quantum Monte Carlo calculations carried out for the same simplified model, with the latter displaying only mild fermion sign problems. Lastly, we conclude that these methods are able to capture quantitatively the rich physics of the several orbital-selective Mott phases (OSMP) displayed by this model, thus enabling computational studies of the OSMP regime in higher dimensions, beyond static or dynamic mean-field approximations.« less
A Note on Exact Travelling Wave Solutions for the Klein-Gordon- Zakharov Equations
NASA Astrophysics Data System (ADS)
Zhang, Zai-Yun; Zhang, Ying-Hui; Gan, Xiang-Yang; Yu, De-Ming
2012-04-01
In this paper, we investigate the travelling wave solutions for the Klein-Gordon-Zakharov equations by using the modified trigonometric function series method benefited to the ideas of Z. Y. Zhang, Y. X. Li, Z. H. Liu, and X. J. Miao, Commun. Nonlin. Sci. Numer. Simul. , 3097 (2011). Exact travelling wave solutions are obtained
Various methods for solving time fractional KdV-Zakharov-Kuznetsov equation
NASA Astrophysics Data System (ADS)
Guner, Ozkan; Aksoy, Esin; Bekir, Ahmet; Cevikel, Adem C.
2016-06-01
This paper presents the exact analytical solution of the (3+1)-dimensional time fractional KdV-Zakharov-Kuznetsov (KdV-ZK) equation with the help of the Kudryashov method, the exp-function method and the functional variable method. The fractional derivatives are described in Jumarie's sense.