Spectral properties of trapped two-level ions interacting with quantized fields
NASA Astrophysics Data System (ADS)
Yazdanpanah, N.; Tavassoly, M. K.
2017-06-01
In this paper we study the full quantum approach to the interaction of N trapped two-level ions with N quantized fields in such a way that each of the trapped ions separately interacts with one of the quantized fields. A semiclassical model of this type of interaction has been already studied, using classical laser fields instead of quantized fields, by Cirac and Zoller [Phys. Rev. Lett. 74, 4091 (1995), 10.1103/PhysRevLett.74.4091]. During each interaction, the excitation of a trapped ion occurs due to the occurrence of resonance between the trapped ion and one of the modes of multimode quantized field. In this way, we are able to find the quantized radiation field, which propagates from each excited trapped ion after its deexcitation. It is demonstrated that such a propagated field is a function of the position of ion within the trap, ion number, trapping and ionic transition frequencies, spontaneous emission rate, and time evolution of trapped ionic operators. In the continuation, to achieve the explicit form of such a field we propose a method to evaluate the temporal evolution of operators of the system by utilizing the Heisenberg operator approach. Via the propagated field of each trapped ion, the spectral properties such as intensities as well as power spectra of their radiations are evaluated. Furthermore, the quantum statistics of field and in particular, its photon antibunching and sub-Poissonian statistical properties are investigated. Finally, resonance spectroscopy of the trapped ions is obtained by which one can allocate a characteristic spectrum to each of them.
Self-adjointness of the Fourier expansion of quantized interaction field Lagrangians
Paneitz, S. M.; Segal, I. E.
1983-01-01
Regularity properties significantly stronger than were previously known are developed for four-dimensional non-linear conformally invariant quantized fields. The Fourier coefficients of the interaction Lagrangian in the interaction representation—i.e., evaluated after substitution of the associated quantized free field—is a densely defined operator on the associated free field Hilbert space K. These Fourier coefficients are with respect to a natural basis in the universal cosmos ˜M, to which such fields canonically and maximally extend from Minkowski space-time M0, which is covariantly a submanifold of ˜M. However, conformally invariant free fields over M0 and ˜M are canonically identifiable. The kth Fourier coefficient of the interaction Lagrangian has domain inclusive of all vectors in K to which arbitrary powers of the free hamiltonian in ˜M are applicable. Its adjoint in the rigorous Hilbert space sense is a-k in the case of a hermitian Lagrangian. In particular (k = 0) the leading term in the perturbative expansion of the S-matrix for a conformally invariant quantized field in M0 is a self-adjoint operator. Thus, e.g., if ϕ(x) denotes the free massless neutral scalar field in M0, then ∫M0:ϕ(x)4:d4x is a self-adjoint operator. No coupling constant renormalization is involved here. PMID:16593346
NASA Astrophysics Data System (ADS)
Shylau, A. A.; Zozoulenko, I. V.; Xu, H.; Heinzel, T.
2010-09-01
The effects of electron interaction on the magnetoconductance of graphene nanoribbons (GNRs) are studied within the Hartree approximation. We find that a perpendicular magnetic field leads to a suppression instead of an expected improvement of the quantization. This suppression is traced back to interaction-induced modifications of the band structure leading to the formation of compressible strips in the middle of GNRs. It is also shown that the hard-wall confinement combined with electron interaction generates overlaps between forward and backward propagating states, which may significantly enhance backscattering in realistic GNRs. The relation to available experiments is discussed.
Description of Atom-Field Interaction via Quantized Caldirola-Kanai Hamiltonian
NASA Astrophysics Data System (ADS)
Daneshmand, Roohollah; Tavassoly, Mohammad Kazem
2017-04-01
In this paper we outline an approach to the study of atom-field interacting systems, where the Hamiltonian of the field is simply inspired from the quantized Caldirola-Kanai Hamiltonian. As a simple physical realization of the model, the interaction between a two-level atom with such a single-mode field is studied. The explicit form of the atom-field entangled state associated with the considered system is analytically deduced and the dynamics of a few of its physical properties is numerically evaluated. To achieve the latter purposes, the temporal behavior of the degree of entanglement, atomic population inversion as well as sub-Poissonian statistics and quadrature squeezing of the field are evaluated. Moreover, the effects of the intensity of initial field and the damping parameter within the Caldirola-Kanai Hamiltonian on the above-mentioned criteria are investigated. As is shown, by adjusting the latter evolved parameters one can appropriately tune the discussed physical quantities.
Description of Atom-Field Interaction via Quantized Caldirola-Kanai Hamiltonian
NASA Astrophysics Data System (ADS)
Daneshmand, Roohollah; Tavassoly, Mohammad Kazem
2017-01-01
In this paper we outline an approach to the study of atom-field interacting systems, where the Hamiltonian of the field is simply inspired from the quantized Caldirola-Kanai Hamiltonian. As a simple physical realization of the model, the interaction between a two-level atom with such a single-mode field is studied. The explicit form of the atom-field entangled state associated with the considered system is analytically deduced and the dynamics of a few of its physical properties is numerically evaluated. To achieve the latter purposes, the temporal behavior of the degree of entanglement, atomic population inversion as well as sub-Poissonian statistics and quadrature squeezing of the field are evaluated. Moreover, the effects of the intensity of initial field and the damping parameter within the Caldirola-Kanai Hamiltonian on the above-mentioned criteria are investigated. As is shown, by adjusting the latter evolved parameters one can appropriately tune the discussed physical quantities.
Quantization as an emergent phenomenon due to matter-zeropoint field interaction
NASA Astrophysics Data System (ADS)
Cetto, A. M.; de la Peña, L.; Valdés-Hernández, A.
2012-05-01
Quantization is derived as an emergent phenomenon, resulting from the permanent interaction between matter and radiation field. The starting point for the derivation is the existence of the (continuous) random zero-point electromagnetic radiation field (zpf) of mean energy hslashω/2 per normal mode. A thermodynamic and statistical analysis leads unequivocally (and without quantum assumptions) to the Planck distribution law for the complete field in equilibrium. The problem of the quantization of matter is then approached from the same perspective: A detailed study of the dynamics of a particle embedded in the zpf shows that when the entire system eventually reaches a situation of energy balance thanks to the combined effect of diffusion and dissipation, the particle has acquired its characteristic quantum properties. To obtain the quantum-mechanical description it has been necessary to do a partial averaging and take the radiationless approximation. Consideration of the neglected radiative terms allows to establish contact with nonrelativistic quantum electrodynamics and derive the correct formulas for the first-order radiative corrections. Quantum mechanics emerges therefore as a partial, approximate and time-asymptotic description of a phenomenon that in its original (pre-quantum) description is entirely local and causal.
Deformation quantization of fermi fields
Galaviz, I. Garcia-Compean, H. Przanowski, M. Turrubiates, F.J.
2008-04-15
Deformation quantization for any Grassmann scalar free field is described via the Weyl-Wigner-Moyal formalism. The Stratonovich-Weyl quantizer, the Moyal *-product and the Wigner functional are obtained by extending the formalism proposed recently in [I. Galaviz, H. Garcia-Compean, M. Przanowski, F.J. Turrubiates, Weyl-Wigner-Moyal Formalism for Fermi Classical Systems, arXiv:hep-th/0612245] to the fermionic systems of infinite number of degrees of freedom. In particular, this formalism is applied to quantize the Dirac free field. It is observed that the use of suitable oscillator variables facilitates considerably the procedure. The Stratonovich-Weyl quantizer, the Moyal *-product, the Wigner functional, the normal ordering operator, and finally, the Dirac propagator have been found with the use of these variables.
NASA Astrophysics Data System (ADS)
Freyberger, Matthias; Vogel, Karl; Schleich, Wolfgang; O'Connell, Robert
The electromagnetic field appears almost everywhere in physics. Following the introduction of Maxwell's equations in 1864, Max Planck initiated quantum theory when he discovered h = 2πℏ in the laws of black-body radiation. In 1905 Albert Einstein explained the photoelectric effect on the hypothesis of a corpuscular nature of radiation and in 1917 this paradigm led to a description of the interaction between atoms and electromagnetic radiation.
Quantization of higher spin fields
Wagenaar, J. W.; Rijken, T. A
2009-11-15
In this article we quantize (massive) higher spin (1{<=}j{<=}2) fields by means of Dirac's constrained Hamilton procedure both in the situation were they are totally free and were they are coupled to (an) auxiliary field(s). A full constraint analysis and quantization is presented by determining and discussing all constraints and Lagrange multipliers and by giving all equal times (anti)commutation relations. Also we construct the relevant propagators. In the free case we obtain the well-known propagators and show that they are not covariant, which is also well known. In the coupled case we do obtain covariant propagators (in the spin-3/2 case this requires b=0) and show that they have a smooth massless limit connecting perfectly to the massless case (with auxiliary fields). We notice that in our system of the spin-3/2 and spin-2 case the massive propagators coupled to conserved currents only have a smooth limit to the pure massless spin-propagator, when there are ghosts in the massive case.
Nascimento, Daniel R.; DePrince, A. Eugene
2015-12-07
We present a combined cavity quantum electrodynamics/ab initio electronic structure approach for simulating plasmon-molecule interactions in the time domain. The simple Jaynes-Cummings-type model Hamiltonian typically utilized in such simulations is replaced with one in which the molecular component of the coupled system is treated in a fully ab initio way, resulting in a computationally efficient description of general plasmon-molecule interactions. Mutual polarization effects are easily incorporated within a standard ground-state Hartree-Fock computation, and time-dependent simulations carry the same formal computational scaling as real-time time-dependent Hartree-Fock theory. As a proof of principle, we apply this generalized method to the emergence of a Fano-like resonance in coupled molecule-plasmon systems; this feature is quite sensitive to the nanoparticle-molecule separation and the orientation of the molecule relative to the polarization of the external electric field.
Mitra, Arnab; Vyas, Reeta; Erenso, Daniel
2007-11-15
The generation of entanglement between two identical, interacting quantum dots - initially in ground states--by a coherent field and the subsequent time evolution of the entanglement are studied by calculating the concurrence between the two dots. The results predict that while it is possible to generate entanglement (or entanglement of formation, as defined for a mixed state) between the two dots, at no time do the dots become fully entangled to each other or is a maximally entangled Bell state ever achieved. We also observe that the degree of entanglement increases with an increase in the photon number inside the cavity and a decrease in the dot-photon coupling. The behavior of the two-dot system, initially prepared in an entangled state and interacting with thermal light, is also studied.
Quantization of Electromagnetic Fields in Cavities
NASA Technical Reports Server (NTRS)
Kakazu, Kiyotaka; Oshiro, Kazunori
1996-01-01
A quantization procedure for the electromagnetic field in a rectangular cavity with perfect conductor walls is presented, where a decomposition formula of the field plays an essential role. All vector mode functions are obtained by using the decomposition. After expanding the field in terms of the vector mode functions, we get the quantized electromagnetic Hamiltonian.
NASA Astrophysics Data System (ADS)
Ghasemian, E.; Tavassoly, M. K.
2016-09-01
In this paper, we consider a model in which N two-level atoms in a Bose-Einstein condensate (BEC) interact with a single-mode quantized laser field. Our goal is to investigate the quantum dynamics of atoms in the BEC in the presence of interatom interactions. To achieve the purpose, at first, using the collective angular momentum operators, we try to reduce the dynamical Hamiltonian of the system to a well-known Jaynes-Cummings like model (JCM). We also use the Dicke model to construct the state of atomic subsystem, by which the analytical solution of the system may be obtained. Then, we analyze the atomic population inversion, the degree of entanglement between the "atoms in BEC" and the "field" as well as the Mandel parameter. Numerical results show that, the atomic population inversion, atom-field entanglement and quantum statistics of photons are very sensitive to the evolved parameters in the model (and so can be well-adjusted), such as the number of atoms in BEC, the intensity of initial field, the interatom coupling constant and detuning. To investigate the entanglement properties, we pay attention to the entropy and linear entropy. It is shown that, oscillations in the two entropy criteria may be seen, with some maxima of entanglement at some moments of time. Finally, looking for the quantum statistics, we evaluate the Mandel parameter, by which we demonstrate the sub-Poissonian statistics and so the nonclassical characteristics of the field state of system. Collapse-revival phenomenon, which is a distinguishable nonclassical characteristic of the system, can be apparently observed in the atomic population inversion and the Mandel parameter.
Zhang, Zhen-Lu; Huang, Yong-Chang
2014-03-15
Quantization theory gives rise to transverse phonons for the traditional Coulomb gauge condition and to scalar and longitudinal photons for the Lorentz gauge condition. We describe a new approach to quantize the general singular QED system by decomposing a general gauge potential into two orthogonal components in general field theory, which preserves scalar and longitudinal photons. Using these two orthogonal components, we obtain an expansion of the gauge-invariant Lagrangian density, from which we deduce the two orthogonal canonical momenta conjugate to the two components of the gauge potential. We then obtain the canonical Hamiltonian in the phase space and deduce the inherent constraints. In terms of the naturally deduced gauge condition, the quantization results are exactly consistent with those in the traditional Coulomb gauge condition and superior to those in the Lorentz gauge condition. Moreover, we find that all the nonvanishing quantum commutators are permanently gauge-invariant. A system can only be measured in physical experiments when it is gauge-invariant. The vanishing longitudinal vector potential means that the gauge invariance of the general QED system cannot be retained. This is similar to the nucleon spin crisis dilemma, which is an example of a physical quantity that cannot be exactly measured experimentally. However, the theory here solves this dilemma by keeping the gauge invariance of the general QED system. -- Highlights: •We decompose the general gauge potential into two orthogonal parts according to general field theory. •We identify a new approach for quantizing the general singular QED system. •The results obtained are superior to those for the Lorentz gauge condition. •The theory presented solves dilemmas such as the nucleon spin crisis.
Path integral representation for polymer quantized scalar fields
NASA Astrophysics Data System (ADS)
Kajuri, Nirmalya
2015-12-01
According to loop quantum gravity, matter fields must be quantized in a background-independent manner. For scalar fields, such a background-independent quantization is called polymer quantization and is inequivalent to the standard Schrödinger quantization. It is therefore important to obtain predictions from the polymer quantized scalar field theory and compare with the standard results. As a step towards this, we develop a path integral representation for the polymer quantized scalar field. We notice several crucial differences from the path integral for the Schrödinger quantized scalar field. One important difference is the appearance of an extra summation at each point in the path integral for the polymer quantized theory. A second crucial difference is the loss of manifest Lorentz symmetry for a polymer quantized theory on Minkowski space.
Quantized vortices in interacting gauge theories
NASA Astrophysics Data System (ADS)
Butera, Salvatore; Valiente, Manuel; Ohberg, Patrik
2015-05-01
We consider a two-dimensional weakly interacting ultracold Bose gas whose constituents are two-level atoms. We study the effects of a synthetic density-dependent gauge field that arises from laser-matter coupling in the adiabatic limit with a laser configuration such that the single-particle vector potential corresponds to a constant synthetic magnetic field. We find a new type of current non-linearity in the Gross-Pitaevskii equation which affects the dynamics of the order parameter of the condensate. We investigate on the physical conditions that make the nucleation of a quantized vortex in the system energetically favourable with respect to the non rotating solution. Two different physical interpretations can be given to this new non linearity: firstly it can be seen as a local modification of the mean field coupling constant, whose value depends on the angular momentum of the condensate. Secondly, it can be interpreted as a density modulated angular velocity given to the cloud. We analyze the physical conditions that make a single vortex state energetically favourable. In the Thomas-Fermi limit, we show that the effect of the new nonlinearity is to induce a rotation to the condensate, where the transition from non-rotating to rotating depends on the density of the cloud. The authors acknowledge support from CM-DTC and EPSRC.
Quantized vortices in interacting gauge theories
NASA Astrophysics Data System (ADS)
Butera, Salvatore; Valiente, Manuel; Öhberg, Patrik
2016-01-01
We consider a two-dimensional weakly interacting ultracold Bose gas whose constituents are two-level atoms. We study the effects of a synthetic density-dependent gauge field that arises from laser-matter coupling in the adiabatic limit with a laser configuration such that the single-particle zeroth-order vector potential corresponds to a constant synthetic magnetic field. We find a new exotic type of current nonlinearity in the Gross-Pitaevskii equation which affects the dynamics of the order parameter of the condensate. We investigate the rotational properties of this system in the Thomas-Fermi limit, focusing in particular on the physical conditions that make the existence of a quantized vortex in the system energetically favourable with respect to the non-rotating solution. We point out that two different physical interpretations can be given to this new nonlinearity: firstly it can be seen as a local modification of the mean field coupling constant, whose value depends on the angular momentum of the condensate. Secondly, it can be interpreted as a density modulated angular velocity given to the cloud. Looking at the problem from both of these viewpoints, we show that the effect of the new nonlinearity is to induce a rotation to the condensate, where the transition from non-rotating to rotating states depends on the density of the cloud.
Entropic quantization of scalar fields
Ipek, Selman; Caticha, Ariel
2015-01-13
Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation.
NASA Astrophysics Data System (ADS)
Ghasemian, E.; Tavassoly, M. K.
2017-09-01
In this paper we consider a system consisting of a number of two-level atoms in a Bose-Einstein condensate (BEC) and a single-mode quantized field, which interact with each other in the presence of two different damping sources, i.e. cavity and atomic reservoirs. The reservoirs which we consider here are thermal and squeezed vacuum ones corresponding to field and atom modes. Strictly speaking, by considering both types of reservoirs for each of the atom and field modes, we investigate the quantum dynamics of the interacting bosons in the system. Then, via solving the quantum Langevin equations for such a dissipative BEC system, we obtain analytical expressions for the time dependence of atomic population inversion, mean atom as well as photon number and quadrature squeezing in the field and atom modes. Our investigations demonstrate that for modeling the real physical systems, considering the dissipation effects is essential. Also, numerical calculations which are presented show that the atomic population inversion, the mean number of atoms in the BEC and the photons in the cavity possess damped oscillatory behavior due to the presence of reservoirs. In addition, non-classical squeezing effects in the field quadrature can be observed especially when squeezed vacuum reservoirs are taken into account. As an outstanding property of this model, we may refer to the fact that one can extract the atom-field coupling constant from the frequency of oscillations in the mentioned quantities such as atomic population inversion.
Features of multiphoton-stimulated bremsstrahlung in a quantized field
NASA Astrophysics Data System (ADS)
Burenkov, Ivan A.; Tikhonova, Olga V.
2010-12-01
The process of absorption and emission of external field quanta by a free electron during the scattering on a potential centre is investigated in the case of interaction with a quantized electromagnetic field. The analytical expression for differential cross-sections and probabilities of different multiphoton channels are obtained. We demonstrate that in the case of a non-classical 'squeezed vacuum' initial field state the probability for the electron to absorb a large number of photons appears to be larger by several orders of magnitude in comparison to the classical field and leads to the formation of the high-energy plateau in the electron energy spectrum. The generalization of the Marcuse effect to the case of the quantized field is worked out. The total probability of energy absorption by electron from the non-classical light is analysed.
Phase-space quantization of field theory.
Curtright, T.; Zachos, C.
1999-04-20
In this lecture, a limited introduction of gauge invariance in phase-space is provided, predicated on canonical transformations in quantum phase-space. Exact characteristic trajectories are also specified for the time-propagating Wigner phase-space distribution function: they are especially simple--indeed, classical--for the quantized simple harmonic oscillator. This serves as the underpinning of the field theoretic Wigner functional formulation introduced. Scalar field theory is thus reformulated in terms of distributions in field phase-space. This is a pedagogical selection from work published and reported at the Yukawa Institute Workshop ''Gauge Theory and Integrable Models'', 26-29 January, 1999.
NASA Astrophysics Data System (ADS)
Hassani Nadiki, M.; Tavassoly, M. K.
2016-12-01
In this paper the interaction of a three-level atom in V-configuration with a two-mode quantized field in cavity optomechanics is studied. To achieve the purpose, we first deduce the effective Hamiltonian and evaluate the explicit time-dependent form of the state vector of the whole system by choosing special initial conditions for atom, field and the oscillatory mirror. Interestingly, we can obtain the time evolution of atomic linear entropy, population inversion, quantum statistics and squeezing, both analytically and numerically. The results show that the entanglement between the atom and the subsystem of field and mirror, and all above-mentioned physical quantities can be appropriately controlled by the initial atom-field state condition, the parameters of cavity optomechanics as well as atom-field coupling strengths. In particular, the appearance of collapse-revival phenomenon in the entanglement and quantum photon statistics, also the full sub-Poissonian statistics in the two modes of field as well as in the mechanical mode of optomechanical system are noticeable features of the work.
Alternate Light Front Quantization Procedure for Scalar Fields
NASA Astrophysics Data System (ADS)
Przeszowski, Jerzy A.
2017-03-01
The novel procedure for the light-front (LF) quantization is formulated and applied for models of free scalar fields. The expected well-known results are rediscovered for a single field and new results are obtained for the two fields model. We use fields smeared with a test function on the LF hypersurface as the basic ingredient of our novel quantization procedure.
Field quantization for open optical cavities
NASA Astrophysics Data System (ADS)
Viviescas, Carlos; Hackenbroich, Gregor
2003-01-01
We study the quantum properties of the electromagnetic field in optical cavities coupled to an arbitrary number of escape channels. We consider both inhomogeneous dielectric resonators with a scalar dielectric constant ɛ(r) and cavities defined by mirrors of arbitrary shape. Using the Feshbach projector technique we quantize the field in terms of a set of resonator and bath modes. We rigorously show that the field Hamiltonian reduces to the system-and-bath Hamiltonian of quantum optics. The field dynamics is investigated using the input-output theory of Gardiner and Collet. In the case of strong coupling to the external radiation field we find spectrally overlapping resonator modes. The mode dynamics is coupled due to the damping and noise inflicted by the external field. For wave chaotic resonators the mode dynamics is determined by a non-Hermitean random matrix. Upon including an amplifying medium, our dynamics of open-resonator modes may serve as a starting point for a quantum theory of random lasing.
Precise quantization of anomalous Hall effect near zero magnetic field
NASA Astrophysics Data System (ADS)
Bestwick, Andrew; Fox, Eli; Kou, Xufeng; Pan, Lei; Wang, Kang; Goldhaber-Gordon, David
2015-03-01
The quantum anomalous Hall effect (QAHE) has recently been of great interest due to its recent experimental realization in thin films of Cr-doped (Bi, Sb)2Te3, a ferromagnetic 3D topological insulator. The presence of ferromagnetic exchange breaks time-reversal symmetry, opening a gap in the surface states, but gives rise to dissipationless chiral conduction at the edge of a magnetized film. Ideally, this leads to vanishing longitudinal resistance and Hall resistance quantized to h /e2 , where h is Planck's constant and e is the electron charge, but perfect quantization has so far proved elusive. Here, we study the QAHE in the limit of zero applied magnetic field, and measure Hall resistance quantized to within one part per 10,000. Deviation from quantization is due primarily to thermally activated carriers, which can be nearly eliminated through adiabatic demagnetization cooling. This result demonstrates an important step toward dissipationless electron transport in technologically relevant conditions.
Polymer-Fourier quantization of the scalar field revisited
NASA Astrophysics Data System (ADS)
Garcia-Chung, Angel; Vergara, J. David
2016-10-01
The polymer quantization of the Fourier modes of the real scalar field is studied within algebraic scheme. We replace the positive linear functional of the standard Poincaré invariant quantization by a singular one. This singular positive linear functional is constructed as mimicking the singular limit of the complex structure of the Poincaré invariant Fock quantization. The resulting symmetry group of such polymer quantization is the subgroup SDiff(ℝ4) which is a subgroup of Diff(ℝ4) formed by spatial volume preserving diffeomorphisms. In consequence, this yields an entirely different irreducible representation of the canonical commutation relations, nonunitary equivalent to the standard Fock representation. We also compared the Poincaré invariant Fock vacuum with the polymer Fourier vacuum.
Potential scattering of electrons in a quantized radiation field
NASA Astrophysics Data System (ADS)
Bergou, J.; Ehlotzky, F.
1986-05-01
Potential scattering of electrons in a strong laser field is reconsidered. The laser beam is described by a quantized single-mode plane-wave field with a finite number of quanta in the mode. The scattering amplitude is expanded in powers of the potential, and the first two Born terms are considered. It is shown that in the limit of an infinite number of field quanta, the Kroll-Watson approximation is recovered. Additional insight is gained into the validity of this low-frequency theorem. The approach rests on the introduction of electron-dressed quantized-field states. Relations to earlier work are indicated.
Electromagnetic Field Quantization in Time-Dependent Linear Media
Pedrosa, I. A.; Rosas, Alexandre
2009-07-03
We present a quantization scheme for the electromagnetic field in time-dependent homogeneous nondispersive conducting and nonconducting linear media without sources. Using the Coulomb gauge, we demonstrate this quantization can be mapped into a damped (attenuated) time-dependent quantum harmonic oscillator. Remarkably, we find that the time dependence of the permittivity, for epsilon>0, gives rise to an attenuation of the radiation field. Afterwards, we obtain the exact wave functions for this problem and consider an exponential time accretion of the permittivity as a particular case.
Quantization of gauge fields, graph polynomials and graph homology
Kreimer, Dirk; Sars, Matthias; Suijlekom, Walter D. van
2013-09-15
We review quantization of gauge fields using algebraic properties of 3-regular graphs. We derive the Feynman integrand at n loops for a non-abelian gauge theory quantized in a covariant gauge from scalar integrands for connected 3-regular graphs, obtained from the two Symanzik polynomials. The transition to the full gauge theory amplitude is obtained by the use of a third, new, graph polynomial, the corolla polynomial. This implies effectively a covariant quantization without ghosts, where all the relevant signs of the ghost sector are incorporated in a double complex furnished by the corolla polynomial–we call it cycle homology–and by graph homology. -- Highlights: •We derive gauge theory Feynman from scalar field theory with 3-valent vertices. •We clarify the role of graph homology and cycle homology. •We use parametric renormalization and the new corolla polynomial.
The Quantization of Classical Fields Equations and the Cyclic Universe
NASA Astrophysics Data System (ADS)
Guo, Zhu Ho
2011-03-01
Basically nothing is known definitely about the early universe. Einstein gravity field equation, based on general relativity and the grand unified field theories, has been employed for the study of the early universe but has not provided definitive answers. As detailed in this article, for understanding the enormous energy of the early universe, classical field equations, including general relativity, must be quantized. The quantization of general relativity by using Feynman's formulation has also faced difficulties. Unified Field theory also needs quantization of Einstein equation for studying the universe. New interpretations of the uncertainty principles indicates that physical quantities should have both lower and upper limits. Physical quantities form pairs, couple and complement to each other performing cyclic process. Their limits should overcome the limits of coupling formulae. In this article, cyclic universe theories are reviewed and limits coupling formulae are derived for pairs of physical quantities. By means of these limits coupling formulae, most of the classical field equations, including Einstein equation, are quantized. The equations derived are used successfully to describe quantitatively the whole development of our cyclic universe. Some long-standing questions in cosmology may be answered with this approach, such as the origin of quasar and the existence of other universes.
The Theory of Quantized Fields. II
DOE R&D Accomplishments Database
Schwinger, J.
1951-01-01
The arguments leading to the formulation of the Action Principle for a general field are presented. In association with the complete reduction of all numerical matrices into symmetrical and anti-symmetrical parts, the general field is decomposed into two sets, which are identified with Bose-Einstein and Fermi-Dirac fields. The spin restriction on the two kinds of fields is inferred from the time reflection invariance requirement. The consistency of the theory is verified in terms of a criterion involving the various generators of infinitesimal transformations. Following a discussion of charged fields, the electromagnetic field is introduced to satisfy the postulate of general gauge invariance. As an aspect of the latter, it is recognized that the electromagnetic field and charged fields are not kinematically independent. After a discussion of the field-strength commutation relations, the independent dynamical variable of the electromagnetic field are exhibited in terms of a special gauge.
Gravity quantized: Loop quantum gravity with a scalar field
Domagala, Marcin; Kaminski, Wojciech; Giesel, Kristina; Lewandowski, Jerzy
2010-11-15
...''but we do not have quantum gravity.'' This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational field coupled to (scalar) fields for which the quantization procedure can be completed using loop quantum gravity techniques. The model we present in this paper consists of the gravitational field coupled to a scalar field. The result has similar structure to the loop quantum cosmology models, except that it involves all the local degrees of freedom of the gravitational field because no symmetry reduction has been performed at the classical level.
Novel properties of the q-analogue quantized radiation field
NASA Technical Reports Server (NTRS)
Nelson, Charles A.
1993-01-01
The 'classical limit' of the q-analog quantized radiation field is studied paralleling conventional quantum optics analyses. The q-generalizations of the phase operator of Susskind and Glogower and that of Pegg and Barnett are constructed. Both generalizations and their associated number-phase uncertainty relations are manifestly q-independent in the n greater than g number basis. However, in the q-coherent state z greater than q basis, the variance of the generic electric field, (delta(E))(sup 2) is found to be increased by a factor lambda(z) where lambda(z) greater than 1 if q not equal to 1. At large amplitudes, the amplitude itself would be quantized if the available resolution of unity for the q-analog coherent states is accepted in the formulation. These consequences are remarkable versus the conventional q = 1 limit.
The Theory of Quantized Fields. III
DOE R&D Accomplishments Database
Schwinger, J.
1953-05-01
In this paper we discuss the electromagnetic field, as perturbed by a prescribed current. All quantities of physical interest in various situations, eigenvalues, eigenfunctions, and transformation probabilities, are derived from a general transformation function which is expressed in a non-Hermitian representation. The problems treated are: the determination of the energy-momentum eigenvalues and eigenfunctions for the isolated electromagnetic field, and the energy eigenvalues and eigenfunctions for the field perturbed by a time-independent current that departs from zero only within a finite time interval, and for a time-dependent current that assumes non-vanishing time-independent values initially and finally. The results are applied in a discussion of the intra-red catastrophe and of the adiabatic theorem. It is shown how the latter can be exploited to give a uniform formulation for all problems requiring the evaluation of transition probabilities or eigenvalue displacements.
Quantum paradoxes, entanglement and their explanation on the basis of quantization of fields
NASA Astrophysics Data System (ADS)
Melkikh, A. V.
2017-01-01
Quantum entanglement is discussed as a consequence of the quantization of fields. The inclusion of quantum fields self-consistently explains some quantum paradoxes (EPR and Hardy’s paradox). The definition of entanglement was introduced, which depends on the maximum energy of the interaction of particles. The destruction of entanglement is caused by the creation and annihilation of particles. On this basis, an algorithm for quantum particle evolution was formulated.
Precise quantization of anomalous Hall effect near zero magnetic field
Bestwick, A. J.; Fox, E. J.; Kou, Xufeng; Pan, Lei; Wang, Kang L.; Goldhaber-Gordon, D.
2015-05-04
In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.
Quantization of fields in a Fabry-Perot cavity.
NASA Astrophysics Data System (ADS)
Ezawa, H.
A Fabry-Perot cavity, which consists of two highly reflective but slightly transmissive mirrors facing each other, is used as an interferometer in the gravitational wave detectors now being developed in Tokyo and elsewhere. The sensitive mirrors are suspended freely in order to respond to the weak, incoming waves; the quantum fluctuations of the radiation pressure can be a source of noise to the mirrors. This paper examines the orthogonality and the completeness of the eigenmodes of the radiation field in the cavity as constructed by Ley and Loundon (1987) for the purpose of field quantization.
Direct Images, Fields of Hilbert Spaces, and Geometric Quantization
NASA Astrophysics Data System (ADS)
Lempert, László; Szőke, Róbert
2014-04-01
Geometric quantization often produces not one Hilbert space to represent the quantum states of a classical system but a whole family H s of Hilbert spaces, and the question arises if the spaces H s are canonically isomorphic. Axelrod et al. (J. Diff. Geo. 33:787-902, 1991) and Hitchin (Commun. Math. Phys. 131:347-380, 1990) suggest viewing H s as fibers of a Hilbert bundle H, introduce a connection on H, and use parallel transport to identify different fibers. Here we explore to what extent this can be done. First we introduce the notion of smooth and analytic fields of Hilbert spaces, and prove that if an analytic field over a simply connected base is flat, then it corresponds to a Hermitian Hilbert bundle with a flat connection and path independent parallel transport. Second we address a general direct image problem in complex geometry: pushing forward a Hermitian holomorphic vector bundle along a non-proper map . We give criteria for the direct image to be a smooth field of Hilbert spaces. Third we consider quantizing an analytic Riemannian manifold M by endowing TM with the family of adapted Kähler structures from Lempert and Szőke (Bull. Lond. Math. Soc. 44:367-374, 2012). This leads to a direct image problem. When M is homogeneous, we prove the direct image is an analytic field of Hilbert spaces. For certain such M—but not all—the direct image is even flat; which means that in those cases quantization is unique.
Noise suppression in three-level atomic system driven by quantized field
NASA Astrophysics Data System (ADS)
Gelman, A.; Mironov, V.
2010-02-01
Numerically by the Monte-Carlo wave function (MCWF) method and analytically by the Heisenberg-Langevin method the interaction of three-level atom with quantized electromagnetic field is investigated in the conditions of electromagnetically induced transparency (EIT) conditions. A possibility of noise suppression in atomic system by means of quantum features of squeezed light is examined in detail. The characteristics of atomic system responsible for relaxation processes and noise in EIT are found.
Noise suppression in three-level atomic system driven by quantized field
NASA Astrophysics Data System (ADS)
Gelman, A.; Mironov, V.
2009-10-01
Numerically by the Monte-Carlo wave function (MCWF) method and analytically by the Heisenberg-Langevin method the interaction of three-level atom with quantized electromagnetic field is investigated in the conditions of electromagnetically induced transparency (EIT) conditions. A possibility of noise suppression in atomic system by means of quantum features of squeezed light is examined in detail. The characteristics of atomic system responsible for relaxation processes and noise in EIT are found.
q-bosons and the q-analogue quantized field
NASA Technical Reports Server (NTRS)
Nelson, Charles A.
1995-01-01
The q-analogue coherent states are used to identify physical signatures for the presence of a 1-analogue quantized radiation field in the q-CS classical limits where the absolute value of z is large. In this quantum-optics-like limit, the fractional uncertainties of most physical quantities (momentum, position, amplitude, phase) which characterize the quantum field are O(1). They only vanish as O(1/absolute value of z) when q = 1. However, for the number operator, N, and the N-Hamiltonian for a free q-boson gas, H(sub N) = h(omega)(N + 1/2), the fractional uncertainties do still approach zero. A signature for q-boson counting statistics is that (Delta N)(exp 2)/ (N) approaches 0 as the absolute value of z approaches infinity. Except for its O(1) fractional uncertainty, the q-generalization of the Hermitian phase operator of Pegg and Barnett, phi(sub q), still exhibits normal classical behavior. The standard number-phase uncertainty-relation, Delta(N) Delta phi(sub q) = 1/2, and the approximate commutation relation, (N, phi(sub q)) = i, still hold for the single-mode q-analogue quantized field. So, N and phi(sub q) are almost canonically conjugate operators in the q-CS classical limit. The q-analogue CS's minimize this uncertainty relation for moderate (absolute value of z)(exp 2).
NASA Astrophysics Data System (ADS)
Iqbal, M. J.; Masood, W.; Shah, H. A.; Tsintsadze, N. L.
2017-01-01
In the present work, we have investigated the effect of trapping as a microscopic phenomenon on the formation of solitary structures in the presence of a quantizing magnetic field in an electron-positron-ion (e-p-i) plasma having degenerate electrons and positrons, whereas ions are taken to be classical and cold. We have found that positron concentration, quantizing magnetic field, and finite electron temperature effects not only affect the linear dispersion characteristics of the electrostatic waves under consideration but also have a significant bearing on the propagation of solitary structures in the nonlinear regime. Importantly, the system under consideration has been found to allow the formation of compressive solitary structures only. The work presented here may be beneficial to understand the propagation of nonlinear electrostatic structures in dense astrophysical environments and in intense-laser plasma interactions.
Casimir effect for a scalar field via Krein quantization
Pejhan, H.; Tanhayi, M.R.; Takook, M.V.
2014-02-15
In this work, we present a rather simple method to study the Casimir effect on a spherical shell for a massless scalar field with Dirichlet boundary condition by applying the indefinite metric field (Krein) quantization technique. In this technique, the field operators are constructed from both negative and positive norm states. Having understood that negative norm states are un-physical, they are only used as a mathematical tool for renormalizing the theory and then one can get rid of them by imposing some proper physical conditions. -- Highlights: • A modification of QFT is considered to address the vacuum energy divergence problem. • Casimir energy of a spherical shell is calculated, through this approach. • In this technique, it is shown, the theory is automatically regularized.
NASA Astrophysics Data System (ADS)
Kaliteevski, M. A.; Gubaydullin, A. R.; Ivanov, K. A.; Mazlin, V. A.
2016-09-01
We have developed a rigorous self-consistent approach for the quantization of electromagnetic field in inhomogeneous structures. The approach is based on utilization of the scattering matrix of the system. Instead of the use of standard periodic Born-Karman boundary conditions, we use the quantization condition implying equating eigenvalues of the scattering matrix (S-matrix) of the system to unity (S-quantization). In the trivial case of uniform medium boundary condition for S-quantization is nothing but periodic boundary condition. S-quantization allows calculating modification of the spontaneous emission rate for arbitrary inhomogeneous structure and direction of the emitted radiation. S-quantization solves the long-standing problem coupled to normalization of the quasi-stationary electromagnetic modes. Examples of application of S-quantization for the calculation of spontaneous emission rate for the cases of Bragg reflector and microcavity are demonstrated.
Plasmon-photon interaction in metal nanoparticles: Second-quantization perturbative approach
NASA Astrophysics Data System (ADS)
Finazzi, Marco; Ciccacci, Franco
2012-07-01
We present a description of photon-plasmon interactions in metal nanoparticles based on the second quantization of electromagnetic fields and collective electron excitations. The quantum optical properties of nanostructured systems sustaining resonant charge oscillations will be derived by applying perturbation theory. The linear optical properties can be completely derived from the plasmon-photon coupling coefficients that apply to the particular particle material, environment, and geometry. Nonlinear electromagnetic phenomena such as second harmonic generation need instead to be described by explicitly accounting for the nonlinear corrections of the plasmon-photon interaction Hamiltonian.
q-bosons and the q-analogue quantized field
Nelson, C.A.
1994-12-31
The q-analogue coherent states {vert_bar}z >{sub q} are used to identify physical signatures for the presence of a q-analogue quantized radiation field in the {vert_bar} >{sub q} classical limit where {vert_bar}z{vert_bar} is large. In this quantum-optics-like limit, the fractional uncertainties of most physical quantities (momentum, position, amplitude, phase) which characterize the quantum field are O(1). They only vanish as O(1/{vert_bar}z{vert_bar}) when q = 1. However, for the number operator, N, and the N-Hamiltonian for a free q-boson gas, H{sub N} = {Dirac_h}{omega}(N + 1/2), the fractional uncertainties do still approach zero. A signature for q-boson counting statistics is that ({Delta}N){sup 2}/
Cotangent bundle quantization: entangling of metric and magnetic field
NASA Astrophysics Data System (ADS)
Karasev, M. V.; Osborn, T. A.
2005-10-01
For manifolds \\mathcal{M} of noncompact type endowed with an affine connection (for example, the Levi-Civita connection) and a closed 2-form (magnetic field), we define a Hilbert algebra structure in the space L^2(T^*\\!{\\mathcal{M}}) and construct an irreducible representation of this algebra in L^2(\\mathcal{M}) . This algebra is automatically extended to polynomial in momenta functions and distributions. Under some natural conditions, this algebra is unique. The non-commutative product over T^*\\!{\\mathcal{M}} is given by an explicit integral formula. This product is exact (not formal) and is expressed in invariant geometrical terms. Our analysis reveals that this product has a front, which is described in terms of geodesic triangles in \\mathcal{M} . The quantization of δ-functions induces a family of symplectic reflections in T^*\\!{\\mathcal{M}} and generates a magneto-geodesic connection Γ on T^*\\mathcal{M} . This symplectic connection entangles, on the phase space level, the original affine structure on \\mathcal{M} and the magnetic field. In the classical approximation, the planck2-part of the quantum product contains the Ricci curvature of Γ and a magneto-geodesic coupling tensor.
Anatomy of a deformed symmetry: Field quantization on curved momentum space
Arzano, Michele
2011-01-15
In certain scenarios of deformed relativistic symmetries relevant for noncommutative field theories particles exhibit a momentum space described by a non-Abelian group manifold. Starting with a formulation of phase space for such particles which allows for a generalization to include group-valued momenta we discuss quantization of the corresponding field theory. Focusing on the particular case of {kappa}-deformed phase space we construct the one-particle Hilbert space and show how curvature in momentum space leads to an ambiguity in the quantization procedure reminiscent of the ambiguities one finds when quantizing fields in curved space-times. The tools gathered in the discussion on quantization allow for a clear definition of the basic deformed field mode operators and two-point function for {kappa}-quantum fields.
Effective Field Theory of Fractional Quantized Hall Nematics
Mulligan, Michael; Nayak, Chetan; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC
2012-06-06
We present a Landau-Ginzburg theory for a fractional quantized Hall nematic state and the transition to it from an isotropic fractional quantum Hall state. This justifies Lifshitz-Chern-Simons theory - which is shown to be its dual - on a more microscopic basis and enables us to compute a ground state wave function in the symmetry-broken phase. In such a state of matter, the Hall resistance remains quantized while the longitudinal DC resistivity due to thermally-excited quasiparticles is anisotropic. We interpret recent experiments at Landau level filling factor {nu} = 7/3 in terms of our theory.
The Indispensability of Ghost Fields in the Light-Cone Gauge Quantization of Gauge Fields
NASA Astrophysics Data System (ADS)
Nakawaki, Y.; McCartor, G.
1999-07-01
We continue McCartor and Robertson's recent demonstration of the indispensability of ghost fields in the light-cone gauge quantization of gauge fields. It is shown that the ghost fields are indispensable in deriving well-defined antiderivatives and in regularizing the most singular component of the gauge field propagator. To this end it is sufficient to confine ourselves to noninteracting abelian fields. Furthermore, to circumvent dealing with constrained systems, we construct the temporal gauge canonical formulation of the free electromagnetic field in auxiliary coordinates xμ=(x-, x+, x1, x2), where x- = x0 cos {θ}-x3 sin θ x+ = x0 sin θ +x3 cos θ and x- plays the role of time. In so doing we can quantize the fields canonically without any constraints, unambiguously introduce ``static ghost fields" as residual gauge degrees of freedom and construct the light-cone gauge solution in the light-cone representation by simply taking the light-cone limit (θ --> (π / 4) ). As a by product we find that, with a suitable choice of vacuum, the Mandelstam-Leibbrandt form of the propagator can be derived in the θ=0 case (the temporal gauge formulation in the equal-time representation).
Quantized Conductance in InSb nanowires at zero magnetic field
NASA Astrophysics Data System (ADS)
Kammhuber, Jakob; Cassidy, Maja; Zhang, Hao; Gül, Önder; Pei, Fei; de Moor, Michiel; Watanabe, Kenji; Taniguchi, Takashi; Car, Diana; Bakkers, Erik; Kouwenhoven, Leo
We present measurements of InSb nanowires in the ballistic transport regime. In 1D materials such as nanowires, electron scattering has an increased chance of back-reflection, obscuring the observation of quantized conductance at low magnetic fields. By improving the contacts to the nanowire as well as its dielectric environment backscattering events are minimized and conductance quantization is observable at zero magnetic field with high device yield. We study the evolution of individual sub-bands in an external magnetic field, observing a degeneracy between the 2nd and 3rd sub-band when the magnetic field is orientated perpendicular to the nanowire axis.
NASA Astrophysics Data System (ADS)
De, Sanchari; Chakrabarty, Somenath
2017-01-01
Using Thomas-Fermi (TF) and Thomas-Fermi-Dirac (TFD) models, we have investigated the properties of electron gas inside two-dimensional (2D) Wigner-Seitz (WS) cells in presence of a strong orthogonal quantizing magnetic field. The electron-electron Coulomb exchange interaction in quasi-2D case is obtained. The exact form of exchange term in 2D is derived making the width of the system tending to zero. Further, using the exchange term, the Thomas-Fermi-Dirac equation in 2D is established. It has been observed that only the ionized WS cell can have finite radius in the Thomas-Fermi model, even in presence of a strong quantizing magnetic field. On the other hand, in the Thomas-Fermi-Dirac model a neutral WS cell can have finite radius.
Conductance Quantization at Zero Magnetic Field in InSb Nanowires
NASA Astrophysics Data System (ADS)
Kammhuber, Jakob; Cassidy, Maja C.; Zhang, Hao; Gül, Önder; Pei, Fei; de Moor, Michiel W. A.; Nijholt, Bas; Watanabe, Kenji; Taniguchi, Takashi; Car, Diana; Plissard, Sébastien R.; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.
2016-06-01
Ballistic electron transport is a key requirement for existence of a topological phase transition in proximitized InSb nanowires. However, measurements of quantized conductance as direct evidence of ballistic transport have so far been obscured due to the increased chance of backscattering in one dimensional nanowires. We show that by improving the nanowire-metal interface as well as the dielectric environment we can consistently achieve conductance quantization at zero magnetic field. Additionally, studying the sub-band evolution in a rotating magnetic field reveals an orbital degeneracy between the second and third sub-bands for perpendicular fields above 1T.
A unique Fock quantization for fields in non-stationary spacetimes
NASA Astrophysics Data System (ADS)
Cortez, Jerónimo; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.
2010-10-01
In curved spacetimes, the lack of criteria for the construction of a unique quantization is a fundamental problem undermining the significance of the predictions of quantum field theory. Inequivalent quantizations lead to different physics. Recently, however, some uniqueness results have been obtained for fields in non-stationary settings. In particular, for vacua that are invariant under the background symmetries, a unitary implementation of the classical evolution suffices to pick up a unique Fock quantization in the case of Klein-Gordon fields with time-dependent mass, propagating in a static spacetime whose spatial sections are three-spheres. In fact, the field equation can be reinterpreted as describing the propagation in a Friedmann-Robertson-Walker spacetime after a suitable scaling of the field by a function of time. For this class of fields, we prove here an even stronger result about the Fock quantization: the uniqueness persists when one allows for linear time-dependent transformations of the field in order to account for a scaling by background functions. In total, paying attention to the dynamics, there exists a preferred choice of quantum field, and only one SO(4)-invariant Fock representation for it that respects the standard probabilistic interpretation along the evolution. The result has relevant implications e.g. in cosmology.
On the magnetotransport of 3D systems in quantizing magnetic field
NASA Astrophysics Data System (ADS)
Cheremisin, M. V.
2014-12-01
The resistivity components of 3D electron gas placed in quantizing magnetic field are calculated taking into account the correction caused by combined action of the Peltier and Seebeck thermoelectric effects. The longitudinal, transverse and the Hall magnetoresistivities exhibit familiar 1/B-period oscillations being universal functions of magnetic field and temperature.
Thermoelectric power of n-InSb in a transverse quantizing magnetic field
Gadzhialiev, M. M. Bashirov, R. R.; Pirmagomedov, Z. Sh.; Efendieva, T. N.; Mädge, H.; Filar, K.
2015-07-15
The thermoelectric power of electronic InSb is investigated in a transverse magnetic field up to 14 T at 80 K. It is established that the experimental results for a quantizing magnetic field agree with theoretical data obtained without accounting for spin splitting of the Landau levels.
Conductance Quantization at Zero Magnetic Field in InSb Nanowires.
Kammhuber, Jakob; Cassidy, Maja C; Zhang, Hao; Gül, Önder; Pei, Fei; de Moor, Michiel W A; Nijholt, Bas; Watanabe, Kenji; Taniguchi, Takashi; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Kouwenhoven, Leo P
2016-06-08
Ballistic electron transport is a key requirement for existence of a topological phase transition in proximitized InSb nanowires. However, measurements of quantized conductance as direct evidence of ballistic transport have so far been obscured due to the increased chance of backscattering in one-dimensional nanowires. We show that by improving the nanowire-metal interface as well as the dielectric environment we can consistently achieve conductance quantization at zero magnetic field. Additionally we study the contribution of orbital effects to the sub-band dispersion for different orientation of the magnetic field, observing a near-degeneracy between the second and third sub-bands.
Effects of quantized scalar fields in cosmological spacetimes with big rip singularities
Bates, Jason D.; Anderson, Paul R.
2010-07-15
Effects of quantized free scalar fields in cosmological spacetimes with big rip singularities are investigated. The energy densities for these fields are computed at late times when the expansion is very rapid. For the massless minimally coupled field it is shown that an attractor state exists in the sense that, for a large class of states, the energy density of the field asymptotically approaches the energy density it would have if it was in the attractor state. Results of numerical computations of the energy density for the massless minimally coupled field and for massive fields with minimal and conformal couplings to the scalar curvature are presented. For the massive fields the energy density is seen to always asymptotically approach that of the corresponding massless field. The question of whether the energy densities of quantized fields can be large enough for backreaction effects to remove the big rip singularity is addressed.
Phase space quantization, noncommutativity, and the gravitational field
NASA Astrophysics Data System (ADS)
Chatzistavrakidis, Athanasios
2014-07-01
In this paper we study the structure of the phase space in noncommutative geometry in the presence of a nontrivial frame. Our basic assumptions are that the underlying space is a symplectic and parallelizable manifold. Furthermore, we assume the validity of the Leibniz rule and the Jacobi identities. We consider noncommutative spaces due to the quantization of the symplectic structure and determine the momentum operators that guarantee a set of canonical commutation relations, appropriately extended to include the nontrivial frame. We stress the important role of left vs right acting operators and of symplectic duality. This enables us to write down the form of the full phase space algebra on these noncommutative spaces, both in the noncompact and in the compact case. We test our results against the class of four-dimensional and six-dimensional symplectic nilmanifolds, thus presenting a large set of nontrivial examples that realizes the general formalism.
Quantization of a free particle interacting linearly with a harmonic oscillator.
Mainiero, Thomas; Porter, Mason A
2007-12-01
We investigate the quantization of a free particle coupled linearly to a harmonic oscillator. This system, whose classical counterpart has clearly separated regular and chaotic regions, provides an ideal framework for studying the quantization of mixed systems. We identify key signatures of the classically chaotic and regular portions in the quantum system by constructing Husimi distributions and investigating avoided level crossings of eigenvalues as functions of the strength and range of the interaction between the system's two components. We show, in particular, that the Husimi structure becomes mixed and delocalized as the classical dynamics becomes more chaotic.
Quantized photonic spin Hall effect in graphene
NASA Astrophysics Data System (ADS)
Cai, Liang; Liu, Mengxia; Chen, Shizhen; Liu, Yachao; Shu, Weixing; Luo, Hailu; Wen, Shuangchun
2017-01-01
We examine the photonic spin Hall effect (SHE) in a graphene-substrate system with the presence of an external magnetic field. In the quantum Hall regime, we demonstrate that the in-plane and transverse spin-dependent splittings in the photonic SHE exhibit different quantized behaviors. The quantized SHE can be described as a consequence of a quantized geometric phase (Berry phase), which corresponds to the quantized spin-orbit interaction. Furthermore, an experimental scheme based on quantum weak value amplification is proposed to detect the quantized SHE in the terahertz frequency regime. By incorporating the quantum weak measurement techniques, the quantized photonic SHE holds great promise for detecting quantized Hall conductivity and the Berry phase. These results may bridge the gap between the electronic SHE and photonic SHE in graphene.
Response of a rotating detector coupled to a polymer quantized field
NASA Astrophysics Data System (ADS)
Jaffino Stargen, D.; Kajuri, Nirmalya; Sriramkumar, L.
2017-09-01
Assuming that high-energy effects may alter the standard dispersion relations governing quantized fields, the influence of such modifications on various phenomena has been studied extensively in the literature. In different contexts, it has generally been found that, while superluminal dispersion relations hardly affect the standard results, subluminal relations can lead to (even substantial) modifications to the conventional results. A polymer quantized scalar field is characterized by a series of modified dispersion relations along with suitable changes to the standard measure of the density of modes. Amongst the modified dispersion relations, one finds that the lowest in the series can behave subluminally over a small domain in wave numbers. In this work, we study the response of a uniformly rotating Unruh-DeWitt detector that is coupled to a polymer quantized scalar field. While certain subluminal dispersion relations can alter the response of the rotating detector considerably, in the case of polymer quantization, due to the specific nature of the dispersion relations, the modification to the transition probability rate of the detector does not prove to be substantial. We discuss the wider implications of the result.
Reformulation of the covering and quantizer problems as ground states of interacting particles
NASA Astrophysics Data System (ADS)
Torquato, S.
2010-11-01
It is known that the sphere-packing problem and the number-variance problem (closely related to an optimization problem in number theory) can be posed as energy minimizations associated with an infinite number of point particles in d -dimensional Euclidean space Rd interacting via certain repulsive pair potentials. We reformulate the covering and quantizer problems as the determination of the ground states of interacting particles in Rd that generally involve single-body, two-body, three-body, and higher-body interactions. This is done by linking the covering and quantizer problems to certain optimization problems involving the “void” nearest-neighbor functions that arise in the theory of random media and statistical mechanics. These reformulations, which again exemplify the deep interplay between geometry and physics, allow one now to employ theoretical and numerical optimization techniques to analyze and solve these energy minimization problems. The covering and quantizer problems have relevance in numerous applications, including wireless communication network layouts, the search of high-dimensional data parameter spaces, stereotactic radiation therapy, data compression, digital communications, meshing of space for numerical analysis, and coding and cryptography, among other examples. In the first three space dimensions, the best known solutions of the sphere-packing and number-variance problems (or their “dual” solutions) are directly related to those of the covering and quantizer problems, but such relationships may or may not exist for d≥4 , depending on the peculiarities of the dimensions involved. Our reformulation sheds light on the reasons for these similarities and differences. We also show that disordered saturated sphere packings provide relatively thin (economical) coverings and may yield thinner coverings than the best known lattice coverings in sufficiently large dimensions. In the case of the quantizer problem, we derive improved upper
NASA Astrophysics Data System (ADS)
Baulieu, Laurent
1996-02-01
We construct a framework which unifies in pairs the fields and anti-fields of the Batalin and Vilkovisky quantization method. We consider gauge theories of p-forms coupled to Yang-Mills fields. Our algorithm generates many topological models of the Chern-Simons type or of the Donaldson-Witten type. Some of these models can undergo a partial breaking of their topological symmetries. We investigate the properties of 2D gravity in the Batalin and Vilkovisky quantization scheme. We find a structure which satisfies the holomorphic factorization and also properties analogous to those existing in the topological theories of forms. New conformal fields are introduced with their invariant action.
Field quantization and squeezed states generation in resonators with time-dependent parameters
NASA Technical Reports Server (NTRS)
Dodonov, V. V.; Klimov, A. B.; Nikonov, D. E.
1992-01-01
The problem of electromagnetic field quantization is usually considered in textbooks under the assumption that the field occupies some empty box. The case when a nonuniform time-dependent dielectric medium is confined in some space region with time-dependent boundaries is studied. The basis of the subsequent consideration is the system of Maxwell's equations in linear passive time-dependent dielectric and magnetic medium without sources.
Uniqueness of the Fock quantization of scalar fields in spatially flat cosmological spacetimes
NASA Astrophysics Data System (ADS)
Castelló Gomar, Laura; Cortez, Jerónimo; Martín-de Blas, Daniel; Mena Marugán, Guillermo A.; Velhinho, José M.
2012-11-01
We study the Fock quantization of scalar fields in (generically) time dependent scenarios, focusing on the case in which the field propagation occurs in -either a background or effective- spacetime with spatial sections of flat compact topology. The discussion finds important applications in cosmology, like e.g. in the description of test Klein-Gordon fields and scalar perturbations in Friedmann-Robertson-Walker spacetime in the observationally favored flat case. Two types of ambiguities in the quantization are analyzed. First, the infinite ambiguity existing in the choice of a Fock representation for the canonical commutation relations, understandable as the freedom in the choice of inequivalent vacua for a given field. Besides, in cosmological situations, it is customary to scale the fields by time dependent functions, which absorb part of the evolution arising from the spacetime, which is treated classically. This leads to an additional ambiguity, this time in the choice of a canonical pair of field variables. We show that both types of ambiguities are removed by the requirements of (a) invariance of the vacuum under the symmetries of the three-torus, and (b) unitary implementation of the dynamics in the quantum theory. In this way, one arrives at a unique class of unitarily equivalent Fock quantizations for the system. This result provides considerable robustness to the quantum predictions and renders meaningful the confrontation with observation.
Uniqueness of the Fock quantization of scalar fields in spatially flat cosmological spacetimes
Gomar, Laura Castelló; Cortez, Jerónimo; Blas, Daniel Martín-de; Marugán, Guillermo A. Mena; Velhinho, José M. E-mail: jacq@ciencias.unam.mx E-mail: jvelhi@ubi.pt
2012-11-01
We study the Fock quantization of scalar fields in (generically) time dependent scenarios, focusing on the case in which the field propagation occurs in –either a background or effective– spacetime with spatial sections of flat compact topology. The discussion finds important applications in cosmology, like e.g. in the description of test Klein-Gordon fields and scalar perturbations in Friedmann-Robertson-Walker spacetime in the observationally favored flat case. Two types of ambiguities in the quantization are analyzed. First, the infinite ambiguity existing in the choice of a Fock representation for the canonical commutation relations, understandable as the freedom in the choice of inequivalent vacua for a given field. Besides, in cosmological situations, it is customary to scale the fields by time dependent functions, which absorb part of the evolution arising from the spacetime, which is treated classically. This leads to an additional ambiguity, this time in the choice of a canonical pair of field variables. We show that both types of ambiguities are removed by the requirements of (a) invariance of the vacuum under the symmetries of the three-torus, and (b) unitary implementation of the dynamics in the quantum theory. In this way, one arrives at a unique class of unitarily equivalent Fock quantizations for the system. This result provides considerable robustness to the quantum predictions and renders meaningful the confrontation with observation.
Perspectives of Light-Front Quantized Field Theory: Some New Results
Srivastava, Prem P.
1999-08-13
A review of some basic topics in the light-front (LF) quantization of relativistic field theory is made. It is argued that the LF quantization is equally appropriate as the conventional one and that they lead, assuming the microcausality principle, to the same physical content. This is confirmed in the studies on the LF of the spontaneous symmetry breaking (SSB), of the degenerate vacua in Schwinger model (SM) and Chiral SM (CSM), of the chiral boson theory, and of the QCD in covariant gauges among others. The discussion on the LF is more economical and more transparent than that found in the conventional equal-time quantized theory. The removal of the constraints on the LF phase space by following the Dirac method, in fact, results in a substantially reduced number of independent dynamical variables. Consequently, the descriptions of the physical Hilbert space and the vacuum structure, for example, become more tractable. In the context of the Dyson-Wick perturbation theory the relevant propagators in the front form theory are causal. The Wick rotation can then be performed to employ the Euclidean space integrals in momentum space. The lack of manifest covariance becomes tractable, and still more so if we employ, as discussed in the text, the Fourier transform of the fermionic field based on a special construction of the LF spinor. The fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of the hyperbolic partial differential equation is found irrelevant in the quantized theory; it seems sufficient to quantize the theory on one of the characteristic hyperplanes.
Markov Random Fields, Stochastic Quantization and Image Analysis
1990-01-01
Markov random fields based on the lattice Z2 have been extensively used in image analysis in a Bayesian framework as a-priori models for the...of Image Analysis can be given some fundamental justification then there is a remarkable connection between Probabilistic Image Analysis , Statistical Mechanics and Lattice-based Euclidean Quantum Field Theory.
Obliquely propagating ion acoustic solitary structures in the presence of quantized magnetic field
NASA Astrophysics Data System (ADS)
Iqbal Shaukat, Muzzamal
2017-10-01
The effect of linear and nonlinear propagation of electrostatic waves have been studied in degenerate magnetoplasma taking into account the effect of electron trapping and finite temperature with quantizing magnetic field. The formation of solitary structures has been investigated by employing the small amplitude approximation both for fully and partially degenerate quantum plasma. It is observed that the inclusion of quantizing magnetic field significantly affects the propagation characteristics of the solitary wave. Importantly, the Zakharov-Kuznetsov equation under consideration has been found to allow the formation of compressive solitary structures only. The present investigation may be beneficial to understand the propagation of nonlinear electrostatic structures in dense astrophysical environments such as those found in white dwarfs.
The study of relatively low density stellar matter in presence of strong quantizing magnetic field
Nag, Nandini; Ghosh, Sutapa; Chakrabarty, Somenath
2009-03-15
The effect of strong quantizing magnetic field on the equation of state of matter at the outer crust region of magnetars is studied. The density of such matter is low enough compared to the matter density at the inner crust or outer core region. Based on the relativistic version of semi-classical Thomas-Fermi-Dirac model in presence of strong quantizing magnetic field a formalism is developed to investigate this specific problem. The equation of state of such low density crustal matter is obtained by replacing the compressed atoms/ions by Wigner-Seitz cells with nonuniform electron density. The results are compared with other possible scenarios. The appearance of Thomas-Fermi induced electric charge within each Wigner-Seitz cell is also discussed.
Equivalence of the Langevin and auxiliary-field quantization methods for absorbing dielectrics
NASA Astrophysics Data System (ADS)
Tip, A.; Knöll, L.; Scheel, S.; Welsch, D.-G.
2001-04-01
Recently two methods have been developed for the quantization of the electromagnetic field in general dispersing and absorbing linear dielectrics. The first is based upon the introduction of a quantum Langevin current in Maxwell's equations [T. Gruner and D.-G. Welsch, Phys. Rev. A 53, 1818 (1996); Ho Trung Dung, L. Knöll, and D.-G. Welsch, Phys. Rev. A 57, 3931 (1998); S. Scheel, L. Knöll, and D.-G. Welsch, Phys. Rev. A 58, 700 (1998)], whereas the second makes use of a set of auxiliary fields, followed by a canonical quantization procedure [A. Tip, Phys. Rev. A 57, 4818 (1998)]. We show that both approaches are equivalent.
Surface photocurrent in an electron gas over liquid He subjected to a quantizing magnetic field
NASA Astrophysics Data System (ADS)
Magarill, L. I.; Entin, M. V.
2015-06-01
The photogalvanic effect is studied in electron gas over the liquid He surface with the presence of quantizing magnetic field. The gas is affected by the weak alternating microwave electric field tilted towards the surface normal. Both linear and circular photogalvanic effects are studied. The current occurs via indirect phototransition with the participation of ripplons emission or absorption. The photogalvanic tensor has strong resonances at the microwave frequency ω approaching to the frequencies of transitions between size-quantized subbands. The resonances are symmetric or antisymmetric, depending on a tensor component. Other resonances appear at ω ≈ nω c , where n being integer and ω c is the cyclotron frequency. It is found that the latter resonances split to two peaks connected with emission or absorption of ripplons. The calculated photogalvanic coefficients are in accord with the experimental observed values.
Quantization of massive scalar fields over static black string backgrounds
Fernandez Piedra, Owen Pavel; Montes de Oca, Alejandro Cabo
2007-05-15
The renormalized mean value of the corresponding components of the energy-momentum tensor for massive scalar fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the energy-momentum tensor in the particular background of the black-string space-time. In the case of the black string considered in this work, we prove that a violation of the weak energy condition occurs at the horizon of the space-time for values of the coupling constant, which include as particular cases the most interesting of minimal and conformal coupling.
Quantized scalar field as DM: the axion's case
Barranco, J.; Bernal, A.
2008-12-04
We derive a rough estimation of the radius and the mass of a self-gravitating system made of axions. The system is a stationary solution of the Einstein-Klein-Gordon equations with a source term given by the vacuum expectation value of the energy-momentum operator constructed from the axion field. We found that such system would have masses of the order of asteroids ({approx}10{sup -10} M{sub {center_dot}}) and radius of the order of few centimeters. Some implications of such type of objects are discussed.
Improved conductance quantization in gold point contacts in high magnetic fields
NASA Astrophysics Data System (ADS)
Manders, F.; Geim, A. K.; Maan, J. C.
2001-01-01
We have studied the influence of magnetic field on room-temperature quantization in normal-metal point contacts by measuring the transient conductance during a mechanical break of the electric contact between two macroscopic pieces of Au. It is found that, with increasing the magnetic field parallel to the movement of a sharp tip retracted from a mechanical contact with a large Au plate, the conductance steps become increasingly better defined. We attribute this observation to a micro-mechanical force caused by magnetic field and acting on the atomic wires drawn by the tip at the final stages of the breaking process.
NASA Astrophysics Data System (ADS)
Daneshmand, R. N.; Tavassoly, M. K.
2015-05-01
Following the approach of Solano et al (2003 Phys. Rev. Lett. 90 027903) we propose a scheme for a generation of a few classes of entangled (nonlinear) coherent states. To achieve this purpose, the interaction of a spatially narrow collection of two-level atoms with a quantized field in a high-Q factor cavity in the presence of a strong-driving classical field is studied. We perform appropriate Hamiltonians describing the atom-field interaction by focusing on two particular forms of intensity-dependent functions which are directly related to su(1, 1) and su(2) Lie algebras. It is shown that the dynamical evolution of the considered systems can generate bipartite, tripartite (nonlinear) and more complicated entangled states corresponding to the mentioned groups depending on the number of atoms in the cavity. In the processes of the abovementioned generation schemes, even and odd nonlinear coherent states are produced. In the end, in a particular circumstance with the two-mode quantized field we can turn easily from Jaynes-Cummings to anti-Jaynes-Cummings interactions which brings us to the maximally entangled number state. Finally, to quantify the degree of entanglement of the produced states, the measures of von Neumann and linear entropies are applied.
Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field
NASA Astrophysics Data System (ADS)
Das, Praloy; Pramanik, Souvik; Ghosh, Subir
2016-11-01
Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac's Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein-Brillouin-Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr-Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.
Field-induced diverse quantizations in monolayer and bilayer black phosphorus
NASA Astrophysics Data System (ADS)
Wu, Jhao-Ying; Chen, Szu-Chao; Gumbs, Godfrey; Lin, Ming-Fa
2017-03-01
This report provides a comprehensive understanding of the magnetic quantization effects in phosphorene with the use of the generalized tight-binding model. Especially for bilayer systems, a composite magnetic and electric field can induce the feature-rich LL spectrum. We demonstrate the existence of two subgroups of Landau levels (LLs) near the Fermi level according to their distinguishable localization centers. The strong competition between the two subgroups induces unusual quantization behaviors, such as multiple anticrossings for the Bz- and Ez-dependent energy spectra. These results are clearly explained by the spatial distributions of subenvelope functions from which two types of LLs are characterized by being either the usual or the perturbed distribution modes. The detailed analysis of the diverse magnetic quantizations is quite important in understanding other physical properties, such as the dispersion relations of magnetoplasmons, magneto-optical selection rules, as well as electron transport properties. The unusual energy spectra are directly revealed by the special features of the density of states, which could be further validated by measurements employing scanning tunneling spectroscopy.
Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field
Das, Praloy Pramanik, Souvik Ghosh, Subir
2016-11-15
Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.
Streda, Pavel; Jonckheere, Thibaut; Martin, Thierry
2008-04-11
A theory of the static electron polarizability of crystals whose energy spectrum is modified by quantizing magnetic fields is presented. The polarizability is strongly affected by nondissipative Hall currents induced by the presence of crossed electric and magnetic fields: these can even change its sign. Results are illustrated in detail for a two-dimensional square lattice. The polarizability and the Hall conductivity are, respectively, linked to the two topological quantum numbers entering the so-called Diophantine equation. These numbers could in principle be detected in actual experiments.
Quantized massive spin 1/2 fields on static spherically symmetric wormhole spacetimes
NASA Astrophysics Data System (ADS)
Shen, Zhiyong
Traversable wormholes have become a subject of intensive studies since 1988 when Morris and Thorne published their paper which put forward the energy conditions for traversable wormholes. A number of researchers have calculated the stress-energy tensors of different fields but failed to find one that meets the requirement of the wormhole geometry. Some others find different schemes to sustain traversable wormholes but either on the Planck scale or hypothetically on a macroscopic scale. Groves has developed a method to compute the renormalized stress-energy tensor for a quantized massive spin 1/2 field in a general static spherically symmetric spacetime. Using this method, I have computed the renormalized stress-energy tensors of two quantized massive spin 1/2 fields in four static spherically symmetric wormhole spacetimes. The results of my calculation suggest that these two fields can be considered exotic. However, due to the technical difficulties in implementing this method, a series of approximations are used in the computation in order to make the problem mathematically tractable; but it is not clear under what physical circumstances these approximations could hold. Besides, the cases that I investigated turned out to involve unphysically large energy densities. Because of these reasons, no firm physical conclusions can be drawn.
Covariant quantization of "massive" spin-3/2 fields in the de sitter space
NASA Astrophysics Data System (ADS)
Takook, M. V.; Azizi, A.; Babaian, E.
2012-06-01
We present a covariant quantization of the free "massive" spin-3/2 fields in four-dimensional de Sitter space-time based on analyticity in the complexified pseudo-Riemannian manifold. The field equation is obtained as an eigenvalue equation of the Casimir operator of the de Sitter group. The solutions are calculated in terms of coordinate-independent de Sitter plane-waves in tube domains and the null curvature limit is discussed. We give the group theoretical content of the field equation. The Wightman two-point function S^{i bar{j}}_{αα'}(x,x') is calculated. We introduce the spinor-vector field operator Ψ α ( f) and the Hilbert space structure. A coordinate-independent formula for the field operator Ψ α ( x) is also presented.
Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field
Piazza, L; Lummen, T.T.A.; Quiñonez, E; Murooka, Y; Reed, B.W.; Barwick, B; Carbone, F
2015-01-01
Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinduced near-field is imaged synchronously with its spatial interference pattern. This methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits. PMID:25728197
Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field
Piazza, L.; Lummen, T. T. A.; Quiñonez, E.; ...
2015-03-02
Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinducedmore » near-field is imaged synchronously with its spatial interference pattern. In conclusion, this methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits.« less
Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field
Piazza, L.; Lummen, T. T. A.; Quiñonez, E.; Murooka, Y.; Reed, B. W.; Barwick, B.; Carbone, F.
2015-03-02
Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinduced near-field is imaged synchronously with its spatial interference pattern. In conclusion, this methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits.
Group field theory as the second quantization of loop quantum gravity
NASA Astrophysics Data System (ADS)
Oriti, Daniele
2016-04-01
We construct a second quantized reformulation of canonical loop quantum gravity (LQG) at both kinematical and dynamical level, in terms of a Fock space of spin networks, and show in full generality that it leads directly to the group field theory (GFT) formalism. In particular, we show the correspondence between canonical LQG dynamics and GFT dynamics leading to a specific GFT model from any definition of quantum canonical dynamics of spin networks. We exemplify the correspondence of dynamics in the specific example of 3d quantum gravity. The correspondence between canonical LQG and covariant spin foam models is obtained via the GFT definition of the latter.
Baym, Gordon; Ozawa, Tomoki
2009-01-01
We analyze Niels Bohr's proposed two-slit interference experiment with highly charged particles which argues that the consistency of elementary quantum mechanics requires that the electromagnetic field must be quantized. In the experiment a particle's path through the slits is determined by measuring the Coulomb field that it produces at large distances; under these conditions the interference pattern must be suppressed. The key is that, as the particle's trajectory is bent in diffraction by the slits, it must radiate and the radiation must carry away phase information. Thus, the radiation field must be a quantized dynamical degree of freedom. However, if one similarly tries to determine the path of a massive particle through an inferometer by measuring the Newtonian gravitational potential the particle produces, the interference pattern would have to be finer than the Planck length and thus indiscernible. Unlike for the electromagnetic field, Bohr's argument does not imply that the gravitational field must be quantized. PMID:19218440
Non-quantized penetration of magnetic field in the vortex state of superconductors
Geim; Dubonos; Grigorieva; Novoselov; Peeters; Schweigert
2000-09-07
As first pointed out by Bardeen and Ginzburg in the early sixties, the amount of magnetic flux carried by vortices in superconducting materials depends on their distance from the sample edge, and can be smaller than one flux quantum, phi0 = h/2e (where h is Planck's constant and e is the electronic charge). In bulk superconductors, this reduction of flux becomes negligible at submicrometre distances from the edge, but in thin films the effect may survive much farther into the material. But the effect has not been observed experimentally, and it is often assumed that magnetic field enters type II superconductors in units of phi0. Here we measure the amount of flux introduced by individual vortices in a superconducting film, finding that the flux always differs substantially from phi0. We have observed vortices that carry as little as 0.001phi0, as well as 'negative vortices', whose penetration leads to the expulsion of magnetic field. We distinguish two phenomena responsible for non-quantized flux penetration: the finite-size effect and a nonlinear screening of the magnetic field due to the presence of a surface barrier. The latter effect has not been considered previously, but is likely to cause non-quantized penetration in most cases.
NASA Astrophysics Data System (ADS)
Falinejad, Hossein
2017-06-01
The three dimensional formalism of the Green function method of the electro-magnetic field quantization is extended to quantize the electromagnetic field, at the presence of two dispersive and dissipative dielectric slabs. It is shown that the system decomposes into a singlet and a doublet parts. The singlet system corresponds to the normal polarization state of the electric field and the doublet system corresponds to the sum of parallel and longitudinal polarization states. Each part is quantized separately and vector potential operator of the each part is derived in terms of rightward and leftwards annihilation and creation operators. By using the assuming commutation properties of the noise current density, the equal time canonical commutation relations between the vector potential operator and its conjugate generalized momentum are verified for each part. Finally as an application, the explicit form of field operators are used to obtain an expression for the Casimir force between the two slabs via Maxwell stress tensor.
Diffusion of electrons scattered by short-range impurities in a quantizing magnetic field
Andreev, S. P. Pavlova, T. V.
2008-04-15
Formulas for transverse diffusion and conductivity in a semiconductor are obtained for electrons scattered by neutral impurities in a quantizing magnetic field. The formulas are valid for an impurity potential of arbitrary depth. Based on Kubo's theory, calculations are performed using electron wavefunctions of the problem of single-impurity scattering in a magnetic field. The poles of the scattering amplitude correctly determine electron eigenstates and magnetic impurity states. As a result, an exact expression is found for the dependence of transverse diffusion coefficient D{sub perpendicular} on longitudinal electron energy {epsilon} due to scattering by short-range (neutral) impurities. The behavior of D{sub perpendicular} ({epsilon}) is examined over an interval of magnetic field strength for several values of impurity potential depth. The experimental observability of diffusion and conductivity using IR lasers is discussed.
Field-induced gap and quantized charge pumping in a nanoscale helical wire
NASA Astrophysics Data System (ADS)
Qi, Xiao-Liang; Zhang, Shou-Cheng
2009-06-01
We propose several physical phenomena based on nanoscale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. A similar idea can be applied to “geometrically” construct one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a standard for the high-precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nanoscale electromechanical motors. Finally, our methodology also enables ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.
Second quantized scalar QED in homogeneous time-dependent electromagnetic fields
Kim, Sang Pyo
2014-12-15
We formulate the second quantization of a charged scalar field in homogeneous, time-dependent electromagnetic fields, in which the Hamiltonian is an infinite system of decoupled, time-dependent oscillators for electric fields, but it is another infinite system of coupled, time-dependent oscillators for magnetic fields. We then employ the quantum invariant method to find various quantum states for the charged field. For time-dependent electric fields, a pair of quantum invariant operators for each oscillator with the given momentum plays the role of the time-dependent annihilation and the creation operators, constructs the exact quantum states, and gives the vacuum persistence amplitude as well as the pair-production rate. We also find the quantum invariants for the coupled oscillators for the charged field in time-dependent magnetic fields and advance a perturbation method when the magnetic fields change adiabatically. Finally, the quantum state and the pair production are discussed when a time-dependent electric field is present in parallel to the magnetic field.
Masood, W.; Shaukat, Muzzamal I.; Shah, H. A.; Mirza, Arshad M.
2015-03-15
In the present investigation, linear and nonlinear propagation of low frequency (ω≪Ω{sub ci}) electrostatic waves have been studied in a spatially inhomogeneous degenerate plasma with one dimensional electron trapping in the presence of a quantizing magnetic field and finite temperature effects. Using the drift approximation, formation of 1 and 2D drift ion solitary structures have been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs for illustrative purpose. It is observed that the inclusion of Landau quantization significantly changes the expression of the electron number density of a dense degenerate plasma which affects the linear and nonlinear propagation of drift acoustic solitary waves in such a system. The present work may be beneficial to understand the propagation of drift solitary structures with weak transverse perturbation in a variety of physical situations, such as white dwarfs and laser-induced plasmas, where the quantum effects are expected to dominate.
NASA Astrophysics Data System (ADS)
Lowney, Joseph Daniel
Methods to generate, manipulate, and measure optical and atomic fields with global or local angular momentum have a wide range of applications in both fundamental physics research and technology development. In optics, the engineering of angular momentum states of light can aid studies of orbital angular momentum (OAM) exchange between light and matter. The engineering of optical angular momentum states can also be used to increase the bandwidth of optical communications or serve as a means to distribute quantum keys, for example. Similar capabilities in Bose-Einstein condensates are being investigated to improve our understanding of superfluid dynamics, superconductivity, and turbulence, the last of which is widely considered to be one of most ubiquitous yet poorly understood subjects in physics. The first part of this two-part dissertation presents an analysis of techniques for measuring and manipulating quantized vortices in BECs. The second part of this dissertation presents theoretical and numerical analyses of new methods to engineer the OAM spectra of optical beams. The superfluid dynamics of a BEC are often well described by a nonlinear Schrodinger equation. The nonlinearity arises from interatomic scattering and enables BECs to support quantized vortices, which have quantized circulation and are fundamental structural elements of quantum turbulence. With the experimental tools to dynamically manipulate and measure quantized vortices, BECs are proving to be a useful medium for testing the theoretical predictions of quantum turbulence. In this dissertation we analyze a method for making minimally destructive in situ observations of quantized vortices in a BEC. Secondly, we numerically study a mechanism to imprint vortex dipoles in a BEC. With these advancements, more robust experiments of vortex dynamics and quantum turbulence will be within reach. A more complete understanding of quantum turbulence will enable principles of microscopic fluid flow to be
Master equation with quantized atomic motion including dipole-dipole interactions
NASA Astrophysics Data System (ADS)
Damanet, François; Braun, Daniel; Martin, John
2016-05-01
We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and is relevant for experiments with ultracold trapped atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find analytical formulas for a number of relevant states (Gaussian states, Fock states and thermal states). In particular, we show that the dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. The effects predicted should be experimentally observable with Rydberg atoms. FD would like to thank the F.R.S.-FNRS for financial support. FD is a FRIA Grant holder of the Fonds de la Recherche Scientifique-FNRS.
A comparison between the quasi-species evolution and stochastic quantization of fields
NASA Astrophysics Data System (ADS)
Bianconi, G.; Rahmede, C.
2012-06-01
The quasi-species equation describes the evolution of the probability that a random individual in a population carries a given genome. Here we map the quasi-species equation for individuals of a self-reproducing population to an ensemble of scalar field elementary units undergoing a creation and annihilation process. In this mapping, the individuals of the population are mapped to field units and their genome to the field value. The selective pressure is mapped to an inverse temperature β of the system regulating the evolutionary dynamics of the fields. We show that the quasi-species equation if applied to an ensemble of field units gives in the small β limit can be put in relation with existing stochastic quantization approaches. The ensemble of field units described by the quasi-species equation relaxes to the fundamental state, describing an intrinsically dissipative dynamics. For a quadratic dispersion relation the mean energy ⟨U⟩ of the system changes as a function of the inverse temperature β. For small values of β the average energy ⟨U⟩ takes a relativistic form, for large values of β, the average energy ⟨U⟩ takes a classical form.
Uniqueness of the Fock quantization of scalar fields in a Bianchi I cosmology with unitary dynamics
NASA Astrophysics Data System (ADS)
Cortez, Jerónimo; Navascués, Beatriz Elizaga; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.
2016-11-01
The Fock quantization of free scalar fields is subject to an infinite ambiguity when it comes to choosing a set of annihilation and creation operators, a choice that is equivalent to the determination of a vacuum state. In highly symmetric situations, this ambiguity can be removed by asking vacuum invariance under the symmetries of the system. Similarly, in stationary backgrounds, one can demand time-translation invariance plus positivity of the energy. However, in more general situations, additional criteria are needed. For the case of free (test) fields minimally coupled to a homogeneous and isotropic cosmology, it has been proven that the ambiguity is resolved by introducing the criterion of unitary implementability of the quantum dynamics, as an endomorphism in Fock space. This condition determines a specific separation of the time dependence of the field, so that this splits into a very precise background dependence and a genuine quantum evolution. Furthermore, together with the condition of vacuum invariance under the spatial Killing symmetries, unitarity of the dynamics selects a unique Fock representation for the canonical commutation relations, up to unitary equivalence. In this work, we generalize these results to anisotropic spacetimes with shear, which are therefore not conformally symmetric, by considering the case of a free scalar field in a Bianchi I cosmology.
NASA Astrophysics Data System (ADS)
Luu, Martin T.
2016-12-01
The quantization of a pair of commuting differential operators is a pair of non-commuting differential operators. Both at the classical and quantum levels, the flows of the Kadomtsev-Petviashvili (KP) hierarchy are defined and further one can consider switching, up to a sign, the ordering of the operators. We discuss the interaction of these operations with the quantization.
Uniqueness of the Fock quantization of Dirac fields in 2 +1 dimensions
NASA Astrophysics Data System (ADS)
Cortez, Jerónimo; Navascués, Beatriz Elizaga; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Velhinho, José M.
2017-07-01
We study the Fock quantization of a free Dirac field in 2 +1 -dimensional backgrounds which are conformally ultrastatic, with a time-dependent conformal factor. As it is typical for field theories, there is an infinite ambiguity in the Fock representation of the canonical anticommutation relations. Different choices may lead to unitarily inequivalent theories that describe different physics. To remove this ambiguity one usually requires that the vacuum be invariant under the unitary transformations that implement the symmetries of the equations of motion. However, in nonstationary backgrounds, where time translation is not a symmetry transformation, the requirement of vacuum invariance is in general not enough to fix completely the Fock representation. We show that this problem is overcome in the considered scenario by demanding, in addition, a unitarily implementable nontrivial quantum dynamics. The combined imposition of these conditions selects a unique family of equivalent Fock representations. Moreover, one also obtains an essentially unique splitting of the time variation of the Dirac field into an explicit dependence on the background scale factor and a quantum evolution of the corresponding creation and annihilation operators.
Field-induced Gap and Quantized Charge Pumping in Nano-helix
Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-02-15
We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to 'geometrically' constructing one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a new standard for the high precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nano-scale electro-mechanical motors. Finally, our methodology also enables new ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.
NASA Astrophysics Data System (ADS)
Hertfelder, C.; Kümmerer, B.
2001-03-01
The mathematical model describing a light beam prepared in an arbitrary quantum optical state is a quasifree quantum stochastic process on the C* algebra of the canonical commutatation relations. For such quantum stochastic processes the concept of stochastic states is introduced. Stochastic quantum states have a classical analog in the following sense: If the light beam is prepared in a stochastic state, one can construct a generalized classical stochastic process, such that the distributions of the quantum observables and the classical random variables coincide. A sufficient algebraic condition for the stochasticity of a quantum state is formulated. The introduced formalism generalizes the Wigner representation from a single field mode to a continuum of modes. For the special case of a single field mode the stochasticity condition provides a new criterion for the positivity of the Wigner function related to the given state. As an example the quantized eletromagnetic field in empty space at temperature T=0 is discussed. It turns out that the corresponding classical stochastic process is not a white noise but a colored noise with a linearly increasing spectrum.
Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization
NASA Astrophysics Data System (ADS)
Cortez, Jerónimo; Elizaga Navascués, Beatriz; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Velhinho, José M.
2017-01-01
We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.
Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid (4)He.
Mateo, David; Eloranta, Jussi; Williams, Gary A
2015-02-14
The interaction of a number of impurities (H2, Ag, Cu, Ag2, Cu2, Li, He3 (+), He(*) ((3)S), He2 (∗) ((3)Σu), and e(-)) with quantized rectilinear vortex lines in superfluid (4)He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He(*).
Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid {sup 4}He
Mateo, David; Eloranta, Jussi; Williams, Gary A.
2015-02-14
The interaction of a number of impurities (H{sub 2}, Ag, Cu, Ag{sub 2}, Cu{sub 2}, Li, He{sub 3}{sup +}, He{sup *} ({sup 3}S), He{sub 2}{sup ∗} ({sup 3}Σ{sub u}), and e{sup −}) with quantized rectilinear vortex lines in superfluid {sup 4}He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He{sup *}.
NASA Astrophysics Data System (ADS)
DeWitt, Bryce S.
2017-06-01
During the period June-July 1957 six physicists met at the Institute for Theoretical Physics of the University of Copenhagen in Denmark to work together on problems connected with the quantization of the gravitational field. A large part of the discussion was devoted to exposition of the individual work of the various participants, but a number of new results were also obtained. The topics investigated by these physicists are outlined in this report and may be grouped under the following main headings: The theory of measurement. Topographical problems in general relativity. Feynman quantization. Canonical quantization. Approximation methods. Special problems.
Crispino, Lui {prime}s C. B.; Higuchi, Atsushi; Matsas, George E. A.
2001-06-15
We discuss the Gupta-Bleuler quantization of the free electromagnetic field outside static black holes in the Boulware vacuum. We use a gauge which reduces to the Feynman gauge in Minkowski spacetime. We also discuss its relation with gauges used previously. Then we apply the low-energy sector of this field theory to investigate some low-energy phenomena. First, we discuss the response rate of a static charge outside the Schwarzschild black hole in four dimensions. Next, motivated by string physics, we compute the absorption cross sections of low-energy plane waves for the Schwarzschild and extreme Reissner-Nordstro''m black holes in arbitrary dimensions higher than three.
Quantization of emergent gravity
NASA Astrophysics Data System (ADS)
Yang, Hyun Seok
2015-02-01
Emergent gravity is based on a novel form of the equivalence principle known as the Darboux theorem or the Moser lemma in symplectic geometry stating that the electromagnetic force can always be eliminated by a local coordinate transformation as far as space-time admits a symplectic structure, in other words, a microscopic space-time becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC space-time, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing space-time itself, leading to a dynamical NC space-time. Therefore the quantization of emergent gravity is radically different from the conventional approach trying to quantize a phase space of metric fields. This approach for quantum gravity allows a background-independent formulation where space-time and matter fields are equally emergent from a universal vacuum of quantum gravity.
BRST quantization of cosmological perturbations
Armendariz-Picon, Cristian; Şengör, Gizem
2016-11-08
BRST quantization is an elegant and powerful method to quantize theories with local symmetries. In this article we study the Hamiltonian BRST quantization of cosmological perturbations in a universe dominated by a scalar field, along with the closely related quantization method of Dirac. We describe how both formalisms apply to perturbations in a time-dependent background, and how expectation values of gauge-invariant operators can be calculated in the in-in formalism. Our analysis focuses mostly on the free theory. By appropriate canonical transformations we simplify and diagonalize the free Hamiltonian. BRST quantization in derivative gauges allows us to dramatically simplify the structure of the propagators, whereas Dirac quantization, which amounts to quantization in synchronous gauge, dispenses with the need to introduce ghosts and preserves the locality of the gauge-fixed action.
BRST quantization of cosmological perturbations
NASA Astrophysics Data System (ADS)
Armendariz-Picon, Cristian; Şengör, Gizem
2016-11-01
BRST quantization is an elegant and powerful method to quantize theories with local symmetries. In this article we study the Hamiltonian BRST quantization of cosmological perturbations in a universe dominated by a scalar field, along with the closely related quantization method of Dirac. We describe how both formalisms apply to perturbations in a time-dependent background, and how expectation values of gauge-invariant operators can be calculated in the in-in formalism. Our analysis focuses mostly on the free theory. By appropriate canonical transformations we simplify and diagonalize the free Hamiltonian. BRST quantization in derivative gauges allows us to dramatically simplify the structure of the propagators, whereas Dirac quantization, which amounts to quantization in synchronous gauge, dispenses with the need to introduce ghosts and preserves the locality of the gauge-fixed action.
NASA Astrophysics Data System (ADS)
Didiş Körhasan, Nilüfer; Eryılmaz, Ali; Erkoç, Şakir
2016-01-01
Mental models are coherently organized knowledge structures used to explain phenomena. They interact with social environments and evolve with the interaction. Lacking daily experience with phenomena, the social interaction gains much more importance. In this part of our multiphase study, we investigate how instructional interactions influenced students’ mental models about the quantization of physical observables. Class observations and interviews were analysed by studying students’ mental models constructed in a modern physics course during an academic semester. The research revealed that students’ mental models were influenced by (1) the manner of teaching, including instructional methodologies and content specific techniques used by the instructor, (2) order of the topics and familiarity with concepts, and (3) peers.
NASA Astrophysics Data System (ADS)
Linzner, Dominik; Koster, Malte; Grusdt, Fabian; Fleischhauer, Michael
2016-05-01
Since the discovery of the quantum Hall effect, topological states of matter have attracted the attention of scientists in many fields of physics. By now there is a rather good understanding of topological order in closed, non-interacting systems. In contrast the extension to open systems in particular with interactions is entirely in its infancy. Recently there have been advances in characterizing topology in reservoir driven systems without interactions, but the topological invariants introduced lack a clear physical interpretation and are restricted to non-interacting systems. We consider a one-dimensional interacting topological system whose dynamics is entirely driven by reservoir couplings. By slowly tuning these couplings periodically in time we realize an open-system analogue of the Thouless charge pump that proves to be robust against unitary and non-unitary perturbations. Making use of this Thouless pump we introduce a topological invariant, which is applicable to interacting systems. Finally we propose a conceptual detection scheme that translates the open-system topological invariant into the context of a well understood closed system.
NASA Technical Reports Server (NTRS)
Gray, Robert M.
1989-01-01
During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.
NASA Astrophysics Data System (ADS)
Jacobs, Verne
2016-05-01
Semi-classical and quantum-field descriptions for the interaction of light with matter are systematically discussed. Applications of interest include resonant pump-probe optical phenomena, such as electromagnetically induced transparency. In the quantum-mechanical description of matter systems, we introduce a general reduced-density-matrix framework. Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified and self-consistent manner, using a Liouville-space operator representation. In the semi-classical description, the electromagnetic field is described as a classical field satisfying the Maxwell equations. Compact Liouville-space operator expressions are derived for the linear and the general (n'th order) non-linear electromagnetic-response tensors describing moving many-electron systems. The tetradic matrix elements of the Liouville-space self-energy operators are evaluated for environmental collisional and radiative interactions. The quantized-field approach is essential for a fully self-consistent quantum-mechanical description. Work supported by the Office of Naval Research through the Basic Research Program at The Naval Research Laboratory.
Coherent state quantization of quaternions
Muraleetharan, B. E-mail: santhar@gmail.com; Thirulogasanthar, K. E-mail: santhar@gmail.com
2015-08-15
Parallel to the quantization of the complex plane, using the canonical coherent states of a right quaternionic Hilbert space, quaternion field of quaternionic quantum mechanics is quantized. Associated upper symbols, lower symbols, and related quantities are analyzed. Quaternionic version of the harmonic oscillator and Weyl-Heisenberg algebra are also obtained.
NASA Astrophysics Data System (ADS)
Bowes, J. P.; Foot, R.; Volkas, R. R.
1996-12-01
In gauge theories such as the standard model, the electric charges of the fermions can be heavily constrained from the classical structure of the theory and from the cancellation of anomalies. There is, however, mounting evidence suggesting that these anomaly constraints are not as well motivated as the classical constraints. In light of this we discuss possible modifications of the minimal standard model that will give us complete electric charge quantization from classical constraints alone. Because these modifications to the standard model involve the consideration of baryon-number-violating scalar interactions, we present a complete catalogue of the simplest ways to modify the standard model so as to introduce explicit baryon number violation. This has implications for proton decay searches and baryogenesis.
Song, Kok Wee; Koshelev, Alexei E.
2017-05-04
We investigate the onset of superconductivity in a magnetic field for a clean two-dimensional multiple-band superconductor in the vicinity of the Lifshitz transition when one of the bands is very shallow. Due to the small number of carriers in this band, the quasiclassical Werthamer-Helfand approximation breaks down and Landau quantization has to be taken into account. We found that the transition temperature TC2(H) has giant oscillations and is resonantly enhanced at the magnetic fields corresponding to the matching of the chemical potential with the Landau levels in the shallow band. This enhancement is especially pronounced for the lowest Landau level.more » As a consequence, the reentrant superconducting regions in the temperature-field phase diagram emerge at low temperatures near the magnetic fields at which the shallow-band Landau levels cross the chemical potential. The specific behavior depends on the relative strength of the intraband and interband pairing interactions and the reentrance is most pronounced in the purely interband coupling scenario. The reentrant behavior is suppressed by the Zeeman spin splitting in the shallow band; the separated regions disappear already for very small spin-splitting factors. On the other hand, the reentrance is restored in the resonance cases when the spin-splitting energy exactly matches the separation between the Landau levels. As a result, the predicted behavior may be realized in the gate-tuned FeSe monolayer.« less
NASA Astrophysics Data System (ADS)
Song, Kok Wee; Koshelev, Alexei E.
2017-05-01
We investigate the onset of superconductivity in a magnetic field for a clean two-dimensional multiple-band superconductor in the vicinity of the Lifshitz transition when one of the bands is very shallow. Due to the small number of carriers in this band, the quasiclassical Werthamer-Helfand approximation breaks down and Landau quantization has to be taken into account. We found that the transition temperature TC 2(H ) has giant oscillations and is resonantly enhanced at the magnetic fields corresponding to the matching of the chemical potential with the Landau levels in the shallow band. This enhancement is especially pronounced for the lowest Landau level. As a consequence, the reentrant superconducting regions in the temperature-field phase diagram emerge at low temperatures near the magnetic fields at which the shallow-band Landau levels cross the chemical potential. The specific behavior depends on the relative strength of the intraband and interband pairing interactions and the reentrance is most pronounced in the purely interband coupling scenario. The reentrant behavior is suppressed by the Zeeman spin splitting in the shallow band; the separated regions disappear already for very small spin-splitting factors. On the other hand, the reentrance is restored in the resonance cases when the spin-splitting energy exactly matches the separation between the Landau levels. The predicted behavior may be realized in the gate-tuned FeSe monolayer.
Interactions between electromagnetic fields
NASA Astrophysics Data System (ADS)
Schwan, H. P.
1985-02-01
We applied for this grant to support a workshop at Erice, Italy. This workshop has been commonly called Erice School and the main subject of this workshop is the interaction of electromagnetic fields with biological cells and molecules. The grant from ONR enabled us to invite American scientists to participants in this workshop and deliver scientific papers. The duration of the Erice School was ten days. Therefore, we had sufficient time to discuss the problems of electromagnetic radiations. Vigorous discussions took place during official sessions and during private conversations. The participants of this workshop are mostly those who have been active in the research on bioelectromagnetics, but there are some numbers of speakers who discussed the basic electrical and magnetic properties of polyelectrolytes, biological membranes and tissue. The workshop was unique in that there were participants with a variety of training backgrounds. This enabled us to exchange the information between applied scientists and basic scientists. Also, active exchanges of opinions took place between biological scientists and physical scientists.
Quantized beam shifts in graphene
de Melo Kort-Kamp, Wilton Junior; Sinitsyn, Nikolai; Dalvit, Diego Alejandro Roberto
2015-10-08
We predict the existence of quantized Imbert-Fedorov, Goos-Hanchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant α, while the Goos-Hanchen ones in multiples of α^{2}. We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.
Consistent quantization of massive chiral electrodynamics in four dimensions
Andrianov, A. ); Bassetto, A.; Soldati, R.
1989-10-09
We discuss the quantization of a four-dimensional model in which a massive Abelian vector field interacts with chiral massless fermions. We show that, by introducing extra scalar fields, a renormalizable unitary {ital S} matrix can be obtained in a suitably defined Hilbert space of physical states.
Vacuum polarization of a quantized scalar field in the thermal state in a long throat
NASA Astrophysics Data System (ADS)
Popov, Arkady A.
2016-12-01
Vacuum polarization of scalar fields in the background of a long throat is investigated. The field is assumed to be both massive or massless, with arbitrary coupling to the scalar curvature, and in a thermal state at an arbitrary temperature. Analytical approximation for ⟨φ2⟩ren is obtained.
NASA Astrophysics Data System (ADS)
Liu, Jian
2017-01-01
We introduce the isomorphism between an multi-state Hamiltonian and the second-quantized many-electron Hamiltonian (with only 1-electron interactions). This suggests that all methods developed for the former can be employed for the latter, and vice versa. The resonant level (Landauer) model for nonequilibrium quantum transport is used as a proof-of-concept example. Such as the classical mapping models for the multi-state Hamiltonian proposed in our previous work [J. Liu, J. Chem. Phys. 145, 204105 (2016)] lead to exact results for this model problem. We further demonstrate how these methods can also be applied to the second-quantized many-electron Hamiltonian even when 2-electron interactions are included.
Nicolau, A.
1988-10-01
Loop unwinding is a known technique for reducing loop overhead, exposing parallelism, and increasing the efficiency of pipelining. Traditional loop unwinding is limited to the innermost loop in a group of nested loops and the amount of unwinding either is fixed or must be specified by the user, on a case by case basis. In this paper the authors present a general technique for automatically unwinding multiply nested loops, explain its advantages over other transformation techniques, and illustrate its practical effectiveness. Lopp Quantization could be beneficial by itself or coupled with other loop transformations.
NASA Astrophysics Data System (ADS)
Coman, Ioana; Gabella, Maxime; Teschner, Jörg
2015-10-01
Non-perturbative aspects of N=2 supersymmetric gauge theories of class S are deeply encoded in the algebra of functions on the moduli space {M}_{flat} of flat SL( N )- connections on Riemann surfaces. Expectation values of Wilson and 't Hooft line operators are related to holonomies of flat connections, and expectation values of line operators in the low-energy effective theory are related to Fock-Goncharov coordinates on {M}_{flat} . Via the decomposition of UV line operators into IR line operators, we determine their noncommutative algebra from the quantization of Fock-Goncharov Laurent polynomials, and find that it coincides with the skein algebra studied in the context of Chern-Simons theory. Another realization of the skein algebra is generated by Verlinde network operators in Toda field theory. Comparing the spectra of these two realizations provides non-trivial support for their equivalence. Our results can be viewed as evidence for the generalization of the AGT correspondence to higher-rank class S theories.
Field quantization in 5D space-time with Z{sub 2} parity and position/momentum propagator
Ichinose, S.; Murayama, A.
2007-09-15
Field quantization in 5D flat and warped space-times with Z{sub 2} parity is comparatively examined. We carefully and closely derive 5D position/momentum propagators. Their characteristic behaviors depend on the 4D (real world) momentum in relation to the boundary parameter (l) and the bulk curvature ({omega}). They also depend on whether the 4D momentum is spacelike or timelike. Their behaviors are graphically presented, and the Z{sub 2} symmetry, the brane formation, and the singularities are examined. It is shown that the use of absolute functions is important for properly treating the singular behavior. The extra coordinate appears as a directed one like the temperature. The {delta}(0) problem, which is an important consistency check of the bulk-boundary system, is solved without the use of Kaluza-Klein (KK) expansion. The relation between the position/momentum propagator (a closed expression which takes into account all KK modes) and the KK-expansion-series propagator is clarified. In this process of comparison, two views on the extra space naturally come up: the orbifold picture and the interval (boundary) picture. Sturm-Liouville expansion (a generalized Fourier expansion) is essential there. Both 5D flat and warped quantum systems are formulated by Dirac's bra and ket vector formalism, which shows that the warped model can be regarded as a deformation of the flat one with the deformation parameter {omega}. We examine the meaning of the position-dependent cutoff proposed by Randall and Schwartz.
NASA Astrophysics Data System (ADS)
Kasamatsu, Kenichi; Eto, Minoru; Nitta, Muneto
2016-01-01
We study the interaction and dynamics of two half-quantized vortices in two-component Bose-Einstein condensates. Using the Padé approximation for the vortex core profile, we calculate the intervortex potential, whose asymptotic form for a large distance has been derived by Eto et al. [Phys. Rev. A 83, 063603 (2011), 10.1103/PhysRevA.83.063603]. Through numerical simulations of the two-dimensional Gross-Pitaevskii equations, we reveal different kinds of dynamical trajectories of the vortices depending on the combinations of signs of circulations and the intercomponent density coupling. Under the adiabatic limit, we derive the equations of motion for the vortex coordinates, in which the motion is caused by the balance between Magnus force and the intervortex forces. The initial velocity of the vortex motion can be explained quantitatively by this point vortex approximation, but understanding the long-time behavior of the dynamics needs more consideration beyond our model.
Weinstein, M
2003-11-19
This paper discusses the problem of inflation in the context of Friedmann-Robertson-Walker Cosmology. We show how, after a simple change of variables, one can quantize the problem in a way which parallels the classical discussion. The result is that two of the Einstein equations arise as exact equations of motion; one of the usual Einstein equations (suitably quantized) survives as a constraint equation to be imposed on the space of physical states. However, the Friedmann equation, which is also a constraint equation and which is the basis of the Wheeler-DeWitt equation, acquires a welcome quantum correction that becomes significant for small scale factors. We then discuss the extension of this result to a full quantum mechanical derivation of the anisotropy ({delta}{rho}/{rho}) in the cosmic microwave background radiation and the possibility that the extra term in the Friedmann equation could have observable consequences. Finally, we suggest interesting ways in which these techniques can be generalized to cast light on the question of chaotic or eternal inflation. In particular, we suggest that one can put an experimental bound on how far away a universe with a scale factor very different from our own must be, by looking at its effects on our CMB radiation.
Faddeev-Jackiw quantization and the path integral
NASA Astrophysics Data System (ADS)
Toms, David J.
2015-11-01
The method for quantization of constrained theories that was suggested originally by Faddeev and Jackiw along with later modifications is discussed. The particular emphasis of this paper is to show how it is simple to implement their method within the path integral framework using the natural geometric structure that their method utilizes. The procedure is exemplified with the analysis of two models: a quantum mechanical particle constrained to a surface (of which the hypersphere is a special case), and a quantized Schrödinger field interacting with a quantized vector field for both the massive and the massless cases. The results are shown to agree with what is found using the Dirac method for constrained path integrals. We comment on a previous path integral analysis of the Faddeev-Jackiw method. We also discuss why a previous criticism of the Faddeev-Jackiw method is unfounded and why suggested modifications of their method are unnecessary.
Lattice Approximation in the Stochastic Quantization of (04)2 Fields
1988-08-01
for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...results .aere extended in [2], which also proves a finite to infinite volume imi_ theorem. The aim of tis note - is to prove a related limit theorem...viz., that of the finite dimensi- onal processes obtained by stochastic cuantization of the lattice (c&) 2 fields to their continuum limit , i.e., the
A quantization of twistor Yang-Mills theory through the background field method
NASA Astrophysics Data System (ADS)
Boels, Rutger
2007-11-01
Four-dimensional Yang-Mills theory formulated through an action on twistor space has a larger gauge symmetry than the usual formulation, which in previous work was shown to allow a simple gauge transformation between textbook perturbation theory and the Cachazo-Svrček-Witten rules. In this paper we study nonsupersymmetric twistor Yang-Mills theory at loop level using the background field method. For an appropriate partial quantum field gauge choice it is shown that the calculation of the effective action is equivalent to (the twistor lift of) the calculation in ordinary Yang-Mills theory in the Chalmers and Siegel formulation to all orders in perturbation theory. A direct consequence is that the twistor version of Yang-Mills theory is just as renormalizable in this particular gauge. As applications an explicit calculation of the Yang-Mills beta function and some preliminary investigations into using the formalism to calculate S-matrix elements at loop level are presented. In principle the technique described in this paper generates consistent quantum completions of the Cachazo-Svrček-Witten rules. However, by inherent limitations of the partial gauge choice employed here, this offers in its current form mainly simplifications for tree-level forestry. The method is expected to be applicable to a wide class of four-dimensional gauge theories.
Seligman, Thomas H.; Prosen, Tomaz
2010-12-23
The basic ideas of second quantization and Fock space are extended to density operator states, used in treatments of open many-body systems. This can be done for fermions and bosons. While the former only requires the use of a non-orthogonal basis, the latter requires the introduction of a dual set of spaces. In both cases an operator algebra closely resembling the canonical one is developed and used to define the dual sets of bases. We here concentrated on the bosonic case where the unboundedness of the operators requires the definitions of dual spaces to support the pair of bases. Some applications, mainly to non-equilibrium steady states, will be mentioned.
Quarter-Filled Honeycomb Lattice with a Quantized Hall Conductance
NASA Astrophysics Data System (ADS)
Shimshoni, Efrat; Murthy, Ganpathy; Shankar, Ramamurti; Fertig, Herbert
2012-02-01
We study a generic two-dimensional hopping model on a honeycomb lattice with strong spin-orbit coupling, without the requirement that the half-filled lattice be a Topological Insulator. For quarter-(or three-quarter) filling, we show that a state with a quantized Hall conductance generically arises in the presence of a Zeeman field of sufficient strength. We discuss the influence of Hubbard interactions and argue that spontaneous ferromagnetism (which breaks time-reversal) will occur, leading to a quantized anomalous Hall effect. G. Murthy, E. Shimshoni, R. Shankar, and H. A. Fertig, arxiv:1108.2010[cond-mat.mes-hall
NASA Astrophysics Data System (ADS)
Haro, Jaume; Amoros, Jaume
2011-08-01
There are two nonequivalent ways to check if quantum effects in the context of semiclassical gravity can moderate or even cancel the final singularity appearing in a universe filled with dark energy: The method followed in [J. D. Bates and P. R. Anderson, Phys. Rev. DPRVDAQ1550-7998 82, 024018 (2010).10.1103/PhysRevD.82.024018] is to introduce the classical Friedmann solution in the energy density of the quantum field, and to compare the result with the density of dark energy determined by the Friedmann equation. The method followed in this comment is to solve directly the semiclassical equations. The results obtained by either method are very different, leading to opposed conclusions. The authors of [J. D. Bates and P. R. Anderson, Phys. Rev. DPRVDAQ1550-7998 82, 024018 (2010)10.1103/PhysRevD.82.024018] find that for a perfect fluid with state equation p=ωρ and ω<-1 (phantom fluid), considering realistic values of ω leads to a quantum field energy density that remains small compared to the dark energy density until the curvature reaches the Planck scale or higher, at which point the semiclassical approach stops being valid. The conclusion is that quantum effects do not affect significantly the expansion of the universe until the scalar curvature reaches the Planck scale. In this comment we will show by numerical integration of the semiclassical equations that quantum effects modify drastically the expansion of the universe from an early point. We also present an analytic argument explaining why the method of [J. D. Bates and P. R. Anderson, Phys. Rev. DPRVDAQ1550-7998 82, 024018 (2010)10.1103/PhysRevD.82.024018] fails to detect this. The units employed are the same as in [J. D. Bates and P. R. Anderson, Phys. Rev. DPRVDAQ1550-7998 82, 024018 (2010)10.1103/PhysRevD.82.024018] (c=ℏ=G=1).
Graphene p n junction in a quantizing magnetic field: Conductance at intermediate disorder strength
NASA Astrophysics Data System (ADS)
Fräßdorf, Christian; Trifunovic, Luka; Bogdanoff, Nils; Brouwer, Piet W.
2016-11-01
In a graphene p n junction at high magnetic field, unidirectional "snake states" are formed at the p n interface. In a clean p n junction, each snake state exists in one of the valleys of the graphene band structure, and the conductance of the junction as a whole is determined by microscopic details of the coupling between the snake states at the p n interface and quantum Hall edge states at the sample boundaries [Tworzydło et al., Phys. Rev. B 76, 035411 (2007), 10.1103/PhysRevB.76.035411]. Disorder mixes and couples the snake states. We here report a calculation of the full conductance distribution in the crossover between the clean limit and the strong-disorder limit, in which the conductance distribution is given by random matrix theory [Abanin and Levitov, Science 317, 641 (2007), 10.1126/science.1144672]. Our calculation involves an exact solution of the relevant scaling equation for the scattering matrix, and the results are formulated in terms of parameters describing the microscopic disorder potential in bulk graphene.
NASA Astrophysics Data System (ADS)
Xin, Jun-Li; Liang, Jiu-Qing
2012-04-01
We study quantum—classical correspondence in terms of the coherent wave functions of a charged particle in two-dimensional central-scalar potentials as well as the gauge field of a magnetic flux in the sense that the probability clouds of wave functions are well localized on classical orbits. For both closed and open classical orbits, the non-integer angular-momentum quantization with the level space of angular momentum being greater or less than ħ is determined uniquely by the same rotational symmetry of classical orbits and probability clouds of coherent wave functions, which is not necessarily 2π-periodic. The gauge potential of a magnetic flux impenetrable to the particle cannot change the quantization rule but is able to shift the spectrum of canonical angular momentum by a flux-dependent value, which results in a common topological phase for all wave functions in the given model. The well-known quantum mechanical anyon model becomes a special case of the arbitrary quantization, where the classical orbits are 2π-periodic.
Cebula, D.P.
1992-12-31
The Skyrmion is a localized, persistent excitation of the Skyrme model, a field theory of three independent meson fields in three spatial dimensions that has proven to be useful for modeling the baryons (e.g. neutron, proton, delta, . . .). The standard approach to predicting values for physical observables within the Skyrme model consists of solving the classical field equations, quantizing the zero modes (such as rotation and translation) and fluctuations about the classical configuration, and projecting out states having the correct symmetries. With only three input parameters, this method has led to predictions for roughly three dozen quantities which differ from their corresponding experimental measurements by approximately 30%. In this thesis, the Herman-Klein method of quantization, an approach based on Heisenberg matrix mechanics, is applied to the Skyrme model. In this intrinsically quantum mechanical approach, the operator equations of motion are evaluated within an appropriately chosen Hilbert space, and the resulting set of c-number equations are solved to determine the values of matrix elements of the field operators. These values permit predictions for physical observables. In contrast with the usual approach of projecting symmetry-preserving states from configurations built around a symmetry-breaking mean-field solution, the Herman-Klein method allows symmetries to be maintained throughout the computation, a property shared with methods based on variation after projection techniques. This research focuses on quantization of the translational and rotational zero modes of a Skyrmion. The results indicate that (i) a symmetry-preserving treatment of the translational modes leads to a larger value for the mass of the hedgehog Skyrmion compared to that found in the previous treatments, and that (ii) the rotational modes cause a swelling of the delta states with respect to the nucleon states, and modify the predictions for physical observables.
NASA Technical Reports Server (NTRS)
Hsu, J. P.
1983-01-01
The foundation of the quantum field theory is changed by introducing a new universal probability principle into field operators: one single inherent and invariant probability distribution P(/k/) is postulated for boson and fermion field oscillators. This can be accomplished only when one treats the four-dimensional symmetry from a broad viewpoint. Special relativity is too restrictive to allow such a universal probability principle. A radical length, R, appears in physics through the probability distribution P(/k/). The force between two point particles vanishes when their relative distance tends to zero. This appears to be a general property for all forces and resembles the property of asymptotic freedom. The usual infinities in vacuum fluctuations and in local interactions, however complicated they may be, are all removed from quantum field theories. In appendix A a simple finite and unitary theory of unified electroweak interactions is discussed without assuming Higgs scalar bosons.
NASA Technical Reports Server (NTRS)
Hsu, J. P.
1983-01-01
The foundation of the quantum field theory is changed by introducing a new universal probability principle into field operators: one single inherent and invariant probability distribution P(/k/) is postulated for boson and fermion field oscillators. This can be accomplished only when one treats the four-dimensional symmetry from a broad viewpoint. Special relativity is too restrictive to allow such a universal probability principle. A radical length, R, appears in physics through the probability distribution P(/k/). The force between two point particles vanishes when their relative distance tends to zero. This appears to be a general property for all forces and resembles the property of asymptotic freedom. The usual infinities in vacuum fluctuations and in local interactions, however complicated they may be, are all removed from quantum field theories. In appendix A a simple finite and unitary theory of unified electroweak interactions is discussed without assuming Higgs scalar bosons.
Generalized noise terms for the quantized fluctuational electrodynamics
NASA Astrophysics Data System (ADS)
Partanen, Mikko; Häyrynen, Teppo; Tulkki, Jukka; Oksanen, Jani
2017-03-01
The quantization of optical fields in vacuum has been known for decades, but extending the field quantization to lossy and dispersive media in nonequilibrium conditions has proven to be complicated due to the position-dependent electric and magnetic responses of the media. In fact, consistent position-dependent quantum models for the photon number in resonant structures have only been formulated very recently and only for dielectric media. Here we present a general position-dependent quantized fluctuational electrodynamics (QFED) formalism that extends the consistent field quantization to describe the photon number also in the presence of magnetic field-matter interactions. It is shown that the magnetic fluctuations provide an additional degree of freedom in media where the magnetic coupling to the field is prominent. Therefore, the field quantization requires an additional independent noise operator that is commuting with the conventional bosonic noise operator describing the polarization current fluctuations in dielectric media. In addition to allowing the detailed description of field fluctuations, our methods provide practical tools for modeling optical energy transfer and the formation of thermal balance in general dielectric and magnetic nanodevices. We use QFED to investigate the magnetic properties of microcavity systems to demonstrate an example geometry in which it is possible to probe fields arising from the electric and magnetic source terms. We show that, as a consequence of the magnetic Purcell effect, the tuning of the position of an emitter layer placed inside a vacuum cavity can make the emissivity of a magnetic emitter to exceed the emissivity of a corresponding electric emitter.
Field Theory of Fundamental Interactions
NASA Astrophysics Data System (ADS)
Wang, Shouhong; Ma, Tian
2017-01-01
First, we present two basic principles, the principle of interaction dynamics (PID) and the principle of representation invariance (PRI). Intuitively, PID takes the variation of the action under energy-momentum conservation constraint. We show that the PID is the requirement of the presence of dark matter and dark energy, the Higgs field and the quark confinement. PRI requires that the SU(N) gauge theory be independent of representations of SU(N). It is clear that PRI is the logic requirement of any gauge theory. With PRI, we demonstrate that the coupling constants for the strong and the weak interactions are the main sources of these two interactions, reminiscent of the electric charge. Second, we emphasize that symmetry principles-the principle of general relativity and the principle of Lorentz invariance and gauge invariance-together with the simplicity of laws of nature, dictate the actions for the four fundamental interactions. Finally, we show that the PID and the PRI, together with the symmetry principles give rise to a unified field model for the fundamental interactions, which is consistent with current experimental observations and offers some new physical predictions. The research is supported in part by the National Science Foundation (NSF) grant DMS-1515024, and by the Office of Naval Research (ONR) grant N00014-15-1-2662.
Light-Front Quantization of Gauge Theories
Brodskey, Stanley
2002-12-01
Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.
Quantization of gravitation with Weyl fermions
Schaposnik, F.A.; Vucetich, H.
1987-12-01
It is shown that quantization of gravitation consistent with the presence of Weyl fermions is possible, in spite of the existence of Lorentz anomalies; the group of local Lorentz transformations is quantized becoming a physical field and the anomaly is absorbed.
Magnetic quantization over Riemannian manifolds
NASA Astrophysics Data System (ADS)
Karasev, M. V.; Osborn, T. A.
2006-06-01
We demonstrate that Weyl's pioneering idea (1918) to intertwine metric and magnetic fields into a single joint connection can be naturally realized, on the phase space level, by the gauge-invariant quantization of the cotangent bundle with magnetic symplectic form. Quantization, for systems over a noncompact Riemannian configuration manifold, may be achieved by the introduction of a magneto-metric analog of the Stratonovich quantizer - a family of invertible, selfadjoint operators representing quantum delta functions. Based on the quantizer, we construct a generalized Wigner transform that maps Hilbert-Schmidt operators into L-2 phase-space functions. The algebraic properties of the quantizer allow one to extract a family of symplectic reflections, which are then used to (i) derive a simple, explicit, and geometrically invariant formula for the noncommutative product of functions on phase space, and (ii) construct a magneto-metric connection on phase space. The classical limit of this product is given by the usual multiplication of functions (zeroth-order term), the magnetic Poisson bracket (first-order term), and by the magneto-metric connection (second-order term).
Geometry of physical systems on quantized spaces
NASA Astrophysics Data System (ADS)
Milani, Vida; Mansourbeigi, Seyed M. H.; Clyde, Stephen W.
We present a mathematical model for physical systems. A large class of functions is built through the functional quantization method and applied to the geometric study of the model. Quantized equations of motion along the Hamiltonian vector field are built up. It is seen that the procedure in higher dimension carries more physical information. The metric tensor appears to induce an electromagnetic field into the system and the dynamical nature of the electromagnetic field in curved space arises naturally. In the end, an explicit formula for the curvature tensor in the quantized space is given.
Song, Peng; Zhou, Qiao; Li, Yuanzuo; Ma, Fengcai; Sun, Mengtao
2017-06-21
In this work, vibration-resolved photoinduced electron transfer of an organic conjugated DA system subjected to an external electric field was theoretically investigated. The ground and excited state vibrational relaxation energies were quantitatively characterized. The effective high frequency, ω(eff), could be estimated from the variation in energy of the excited-state equilibrium geometries of acceptor and donor sites as well as the analysis of the vibrational modes upon electron transfer. For a PCDTBT:PC70BM blend in an external electric field, the vibronic modes affected the charge separation process differently from the charge recombination process. The simulated results indicated that the vibrational quantum tunneling effect facilitated the charge recombination process to a large extent. Thus, for electron transfer reactions, considering the vibrational excitation influence and perturbed nucleus-electron interactions is essential. These results provide a feasible way to enhance the efficiency in yielding the electron transfer process products.
Escobar, M.; Meyerovich, A. E.
2014-12-15
We discuss transport of particles along random rough surfaces in quantum size effect conditions. As an intriguing application, we analyze gravitationally quantized ultracold neutrons in rough waveguides in conjunction with GRANIT experiments (ILL, Grenoble). We present a theoretical description of these experiments in the biased diffusion approximation for neutron mirrors with both one- and two-dimensional (1D and 2D) roughness. All system parameters collapse into a single constant which determines the depletion times for the gravitational quantum states and the exit neutron count. This constant is determined by a complicated integral of the correlation function (CF) of surface roughness. The reliable identification of this CF is always hindered by the presence of long fluctuation-driven correlation tails in finite-size samples. We report numerical experiments relevant for the identification of roughness of a new GRANIT waveguide and make predictions for ongoing experiments. We also propose a radically new design for the rough waveguide.
String fields and their interactions
NASA Astrophysics Data System (ADS)
Erler, Theodore George, IV
2005-07-01
In this thesis is devoted to illuminating the underlying structure of Witten's star product, which defines the interactions of open strings in cubic bosonic string field theory [3]. We give an in depth analysis of the product from the perspective of noncommutative geometry, specifically using the split string [19] and Moyal formalisms [20, 22]. We identify some fundamental algebraic features of the star product originating from the singular structure of the overlap conditions at the string midpoint. Finally, we use some of these insights to construct a consistent and nonsingular initial value formulation of the theory in lightcone time. Such a general formalism seems prerequisite to address questions of time, causality, and cosmology in string theory.
Quantization and Quantum-Like Phenomena: A Number Amplitude Approach
NASA Astrophysics Data System (ADS)
Robinson, T. R.; Haven, E.
2015-12-01
Historically, quantization has meant turning the dynamical variables of classical mechanics that are represented by numbers into their corresponding operators. Thus the relationships between classical variables determine the relationships between the corresponding quantum mechanical operators. Here, we take a radically different approach to this conventional quantization procedure. Our approach does not rely on any relations based on classical Hamiltonian or Lagrangian mechanics nor on any canonical quantization relations, nor even on any preconceptions of particle trajectories in space and time. Instead we examine the symmetry properties of certain Hermitian operators with respect to phase changes. This introduces harmonic operators that can be identified with a variety of cyclic systems, from clocks to quantum fields. These operators are shown to have the characteristics of creation and annihilation operators that constitute the primitive fields of quantum field theory. Such an approach not only allows us to recover the Hamiltonian equations of classical mechanics and the Schrödinger wave equation from the fundamental quantization relations, but also, by freeing the quantum formalism from any physical connotation, makes it more directly applicable to non-physical, so-called quantum-like systems. Over the past decade or so, there has been a rapid growth of interest in such applications. These include, the use of the Schrödinger equation in finance, second quantization and the number operator in social interactions, population dynamics and financial trading, and quantum probability models in cognitive processes and decision-making. In this paper we try to look beyond physical analogies to provide a foundational underpinning of such applications.
First quantized electrodynamics
Bennett, A.F.
2014-06-15
The parametrized Dirac wave equation represents position and time as operators, and can be formulated for many particles. It thus provides, unlike field-theoretic Quantum Electrodynamics (QED), an elementary and unrestricted representation of electrons entangled in space or time. The parametrized formalism leads directly and without further conjecture to the Bethe–Salpeter equation for bound states. The formalism also yields the Uehling shift of the hydrogenic spectrum, the anomalous magnetic moment of the electron to leading order in the fine structure constant, the Lamb shift and the axial anomaly of QED. -- Highlights: •First-quantized electrodynamics of the parametrized Dirac equation is developed. •Unrestricted entanglement in time is made explicit. •Bethe and Salpeter’s equation for relativistic bound states is derived without further conjecture. •One-loop scattering corrections and the axial anomaly are derived using a partial summation. •Wide utility of semi-classical Quantum Electrodynamics is argued.
Tse, Wang-Kong; MacDonald, A H
2012-12-07
We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large-separation (d) limit where retardation effects are essential, we find (i) that the Casimir force is quantized in units of 3ħcα(2)/8π(2)d(4) and (ii) that the force is repulsive for mirrors with the same type of carrier and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore electrically tunable in ambipolar materials such as graphene. The Casimir force is suppressed when one mirror is a charge-neutral graphene system in a filling factor ν=0 quantum Hall state.
Geothermal field's interaction with geophysical fields of another nature
Novik, Oleg B.; Mikhailovskaya, Irina B.; Repin, Dmitry G.; Yershov, Sergey V.
1996-01-24
The energy balance of active lithosphere zones is to a large extent determined by nonstationary interaction of mechanical (elastic and hydrodynamic), thermal, electromagnetic, and gravitational geophysical fields. Seismic disturbances of electromagnetic and temperature fields, repeatedly observed before earthquakes are a striking manifestation of this interaction (Sec. 1). Technological processes of exploitation of hydrothermal deposits are determined by the interaction of hydrodynamical and temperature field (Sec. 2). These “fast” interactions (with the characteristic time scale from seconds to years) take place against the background of “slow” thermomechanical interactions (time scale of Myears), the latter determining the formation of regional geothermal fields (Sec. 3).
An, Ji-Yong; Meng, Fan-Rong; You, Zhu-Hong; Fang, Yu-Hong; Zhao, Yu-Jun; Zhang, Ming
2016-01-01
We propose a novel computational method known as RVM-LPQ that combines the Relevance Vector Machine (RVM) model and Local Phase Quantization (LPQ) to predict PPIs from protein sequences. The main improvements are the results of representing protein sequences using the LPQ feature representation on a Position Specific Scoring Matrix (PSSM), reducing the influence of noise using a Principal Component Analysis (PCA), and using a Relevance Vector Machine (RVM) based classifier. We perform 5-fold cross-validation experiments on Yeast and Human datasets, and we achieve very high accuracies of 92.65% and 97.62%, respectively, which is significantly better than previous works. To further evaluate the proposed method, we compare it with the state-of-the-art support vector machine (SVM) classifier on the Yeast dataset. The experimental results demonstrate that our RVM-LPQ method is obviously better than the SVM-based method. The promising experimental results show the efficiency and simplicity of the proposed method, which can be an automatic decision support tool for future proteomics research. PMID:27314023
NASA Astrophysics Data System (ADS)
Rustaee, N.; Tavassoly, M. K.; Daneshmand, R.
2017-01-01
In this paper we study the interaction between two two-level atoms with a two-mode quantized field in the presence of damping. Dipole-dipole interaction between the two atoms and the correlation between the two modes of field are also taken into account. To solve the model, using appropriate transformations, we reduce the considered model to a well-known Jaynes-Cummings model. After finding the analytical solution for the atom-field system, the effects of damping, field-field correlation and atomic dipole-dipole interaction on the entanglement between atoms and population inversion are investigated, numerically. It is observed that the dynamical behavior of the degree of entanglement for damped systems, in relatively large domains of time, takes a low but constant value adequately far from the beginning of the interaction. In addition, it is found that the value of population inversion after the initial oscillations takes negative values for damped systems and eventually vanishes by increasing time. Also, it is seen that simultaneous presence of both dipole-dipole interaction and field-field correlation provides typical collapse-revival phenomenon in the time-behavior of atomic inversion.
Geometric Quantization and Foliation Reduction
NASA Astrophysics Data System (ADS)
Skerritt, Paul
A standard question in the study of geometric quantization is whether symplectic reduction interacts nicely with the quantized theory, and in particular whether "quantization commutes with reduction." Guillemin and Sternberg first proposed this question, and answered it in the affirmative for the case of a free action of a compact Lie group on a compact Kahler manifold. Subsequent work has focused mainly on extending their proof to non-free actions and non-Kahler manifolds. For realistic physical examples, however, it is desirable to have a proof which also applies to non-compact symplectic manifolds. In this thesis we give a proof of the quantization-reduction problem for general symplectic manifolds. This is accomplished by working in a particular wavefunction representation, associated with a polarization that is in some sense compatible with reduction. While the polarized sections described by Guillemin and Sternberg are nonzero on a dense subset of the Kahler manifold, the ones considered here are distributional, having support only on regions of the phase space associated with certain quantized, or "admissible", values of momentum. We first propose a reduction procedure for the prequantum geometric structures that "covers" symplectic reduction, and demonstrate how both symplectic and prequantum reduction can be viewed as examples of foliation reduction. Consistency of prequantum reduction imposes the above-mentioned admissibility conditions on the quantized momenta, which can be seen as analogues of the Bohr-Wilson-Sommerfeld conditions for completely integrable systems. We then describe our reduction-compatible polarization, and demonstrate a one-to-one correspondence between polarized sections on the unreduced and reduced spaces. Finally, we describe a factorization of the reduced prequantum bundle, suggested by the structure of the underlying reduced symplectic manifold. This in turn induces a factorization of the space of polarized sections that agrees
Laiho, R.; Nemov, S. A. Lashkul, A. V.; Laehderanta, E.; Svechnikova, T. E.; Dvornik, D. S.
2007-05-15
The magnetic-field dependences of the Hall coefficient and transverse magnetoresistance are studied experimentally and theoretically in p-Bi{sub 2}Te{sub 3} crystals doped heavily with Sn and grown by the Czochralski method in the case of both classical and quantizing magnetic fields as high as 12 T with the magnetic-field orientation along the C{sub 3} trigonal axis. The Shubnikov-de Haas effect and quantum oscillations of the Hall coefficient were measured at temperatures of 4.2 and 11 K. The six-ellipsoid Drabble-Wolfe model of the energy spectrum and the magnetic-field dependence of the Hall coefficient are used as the basis for the method for determining the Hall factor and Hall mobility. New evidence is obtained in support of the existence of the narrow band of impurity Sn states occupied partially with electrons against the background of the light-hole band spectrum. The parameters of impurity states are estimated including their energy (E{sub Sn} {approx} 15 meV), the broadening ({gamma} < kT), and the radius of localization of the impurity state (R {approx} 30 A)
Spacetime rotation-induced Landau quantization
NASA Astrophysics Data System (ADS)
Konno, Kohkichi; Takahashi, Rohta
2012-03-01
We investigate noninertial and gravitational effects on quantum states in electromagnetic fields and present the analytic solution for energy eigenstates for the Schrödinger equation including noninertial, gravitational, and electromagnetic effects. We find that in addition to the Landau quantization the rotation of spacetime itself leads to the additional quantization, and that the energy levels for an electron are different from those for a proton at the level of gravitational corrections.
Third Quantization and Quantum Cosmology.
NASA Astrophysics Data System (ADS)
McGuigan, Michael Deturck
My thesis consists of three separate parts. Part one consists of a study of CP violation in the Kaon decay: K to pi pi gamma . To study the short distance contribution to the matrix element we developed an operator expansion for the effective Hamiltonian. An effective s to dgamma vertex arises through operator mixing. We evaluated several two-loop graphs in order to obtain the coefficient of this operator. We studied the long distance contributions to the matrix element and demonstrated that this was the dominant contribution. This explained why the polarization of the emitted photon is primarily of the magnetic type. Part two of my thesis involves the treatment of string theory at finite temperature. We introduced finite temperature into string theory by compactifying time on a twisted torus of radius beta = 1/kT, the reciprical of the temperature. The twisted torus takes into account the different thermal properties of bosons and fermions. We computed the one-loop vacuum amplitude Lambda(beta) on a twisted torus which is manifestly modular invariant. We found that lnZ(beta) = -betaVLambda (beta) where Z(beta) is the partition function and V the volume of the system. We computed the function sigma(E) which counts the number of multi-string states of total energy E by taking the inverse Laplace transform of Z( beta). We also studied the effect of finite temperature on the effective potentials which determine a string theory's compactification. The third part of my thesis involved the Wheeler DeWitt equation and a new interpretation of quantum cosmology. We examined a proposal by DeWitt for the normalization of solutions to the Wheeler-DeWitt equation. We avoided negative probability problems with this proposal by reinterpreting the Wheeler-DeWitt wave function as a second quantized field. As the arguments of the Wheeler-DeWitt wave functional are second quantized fields this represented a third quantization. We developed a mode decomposition for the third quantized
NASA Astrophysics Data System (ADS)
Pejhan, Hamed; Rahbardehghan, Surena
2016-09-01
In a previous work [S. Rahbardehghan and H. Pejhan, Phys. Lett. B 750, 627 (2015)], we considered a simple brane-world model: a single four-dimensional brane embedded in a five-dimensional de Sitter (dS) space-time. Then, by including a conformally coupled scalar field in the bulk, we studied the induced Casimir energy-momentum tensor. Technically, the Krein-Gupta-Bleuler quantization scheme as a covariant and renormalizable quantum field theory in dS space was used to perform the calculations. In the present paper, we generalize this study to a less idealized, but physically motivated, scenario; namely, we consider Friedmann-Robertson-Walker (FRW) space-time which behaves asymptotically as a dS space-time. More precisely, we evaluate a Casimir energy-momentum tensor for a system with two D -dimensional curved branes on background of D +1 -dimensional FRW space-time with negative spatial curvature and a conformally coupled bulk scalar field that satisfied the Dirichlet boundary condition on the branes.
Generalized gravitational entropy of interacting scalar field and Maxwell field
NASA Astrophysics Data System (ADS)
Huang, Wung-Hong
2014-12-01
The generalized gravitational entropy proposed recently by Lewkowycz and Maldacena is extended to the interacting real scalar field and Maxwell field system. Using the BTZ geometry we first investigate the case of free real scalar field and then show a possible way to calculate the entropy of the interacting scalar field. Next, we investigate the Maxwell field system. We exactly solve the wave equation and calculate the analytic value of the generalized gravitational entropy. We also use the Einstein equation to find the effect of backreaction of the Maxwell field on the area of horizon. The associated modified area law is consistent with the generalized gravitational entropy.
Is there Unruh effect in polymer quantization?
NASA Astrophysics Data System (ADS)
Mortuza Hossain, Golam; Sardar, Gopal
2016-12-01
Unruh effect is a landmark prediction of standard quantum field theory in which Fock vacuum state appears as a thermal state with respect to a uniformly accelerating observer. Given its dependence on trans-Planckian modes, Unruh effect is often considered as an arena for exploring a candidate theory of quantum gravity. Here we show that Unruh effect disappears if, instead of using Fock quantization, one uses polymer quantization or loop quantization, the quantization method used in loop quantum gravity. Secondly, the polymer vacuum state remains a vacuum state even for the accelerating observer in the sense that expectation value of number density operator in it remains zero. Finally, if experimental measurement of Unruh effect is ever possible then it may be used either to verify or rule out a theory of quantum gravity.
Magnetic field evolution in interacting galaxies
NASA Astrophysics Data System (ADS)
Drzazga, R. T.; Chyży, K. T.; Jurusik, W.; Wiórkiewicz, K.
2011-09-01
Aims: Violent gravitational interactions can change the morphologies of galaxies and, by means of merging, transform them into elliptical galaxies. We aim to investigate how they affect the evolution of galactic magnetic fields. Methods: We selected 16 systems of interacting galaxies with available VLA archive radio data at 4.86 and 1.4 GHz and compared their radio emission and estimated magnetic field strengths with their star-forming activity, far-infrared emission, and the stage of tidal interaction. Results: The estimated mean of total magnetic field strength for our sample of interacting galaxies is 14 ± 5 μG, which is larger than for the non-interacting objects. The field regularity (of 0.27 ± 0.09) is lower than in typical spirals and indicates enhanced production of random magnetic fields in the interacting objects. We find a general evolution of magnetic fields: for weak interactions the strength of magnetic field is almost constant (10-15 μG) as interaction advances, then it increases up to 2× , peaks at the nuclear coalescence (25 μG), and decreases again, down to 5-6 μG, for the post-merger remnants. The main production of magnetic fields in colliding galaxies thus terminates somewhere close to the nuclear coalescence, after which magnetic field diffuses. The magnetic field strength for whole galaxies is weakly affected by the star formation rate (SFR), while the dependence is higher for galactic centres. We show that the morphological distortions visible in the radio total and polarized emission do not depend statistically on the global or local SFRs, while they do increase (especially in the polarization) with the advance of interaction. The constructed radio-far-infrared relations for interacting and non-interacting galaxies display a similar balance between the generation of cosmic rays, magnetic fields, and the production of the thermal energy and dust radiation. Conclusions: The regular magnetic fields are much more sensitive to
Polymer quantization, stability and higher-order time derivative terms
NASA Astrophysics Data System (ADS)
Cumsille, Patricio; Reyes, Carlos M.; Ossandon, Sebastian; Reyes, Camilo
2016-03-01
The possibility that fundamental discreteness implicit in a quantum gravity theory may act as a natural regulator for ultraviolet singularities arising in quantum field theory has been intensively studied. Here, along the same expectations, we investigate whether a nonstandard representation called polymer representation can smooth away the large amount of negative energy that afflicts the Hamiltonians of higher-order time derivative theories, rendering the theory unstable when interactions come into play. We focus on the fourth-order Pais-Uhlenbeck model which can be reexpressed as the sum of two decoupled harmonic oscillators one producing positive energy and the other negative energy. As expected, the Schrödinger quantization of such model leads to the stability problem or to negative norm states called ghosts. Within the framework of polymer quantization we show the existence of new regions where the Hamiltonian can be defined well bounded from below.
Basis light-front quantization approach to positronium
NASA Astrophysics Data System (ADS)
Wiecki, Paul; Li, Yang; Zhao, Xingbo; Maris, Pieter; Vary, James P.
2015-05-01
We present the first application of the recently developed basis light-front quantization (BLFQ) method to self-bound systems in quantum field theory, using the positronium system as a test case. Within the BLFQ framework, we develop a two-body effective interaction, operating only in the lowest Fock sector, that implements photon exchange, neglecting fermion self-energy effects. We then solve for the mass spectrum of this interaction at the unphysical coupling α =0.3 . The resulting spectrum is in good agreement with the expected Bohr spectrum of nonrelativistic quantum mechanics. We examine in detail the dependence of the results on the regulators of the theory.
Stochastic Quantization of Instantons
NASA Astrophysics Data System (ADS)
Grandati, Y.; Bérard, A.; Grangé, P.
1996-03-01
The method of Parisi and Wu to quantize classical fields is applied to instanton solutionsϕIof euclidian non-linear theory in one dimension. The solutionϕεof the corresponding Langevin equation is built through a singular perturbative expansion inε=ℏ1/2in the frame of the center of mass of the instanton, where the differenceϕε-ϕIcarries only fluctuations of the instanton form. The relevance of the method is shown for the stochasticK dVequation with uniform noise in space: the exact solution usually obtained by the inverse scattering method is retrieved easily by the singular expansion. A general diagrammatic representation of the solution is then established which makes a thorough use of regrouping properties of stochastic diagrams derived in scalar field theory. Averaging over the noise and in the limit of infinite stochastic time, we obtain explicit expressions for the first two orders inεof the perturbed instanton and of its Green function. Specializing to the Sine-Gordon andϕ4models, the first anharmonic correction is obtained analytically. The calculation is carried to second order for theϕ4model, showing good convergence.
Symmetry breaking induced by charge density and the entropy of interacting fields
NASA Astrophysics Data System (ADS)
Bekenstein, Jacob D.; Guendelman, E. I.
1987-01-01
We study interacting complex scalar field theories with global U(1) symmetry and concave potentials. It is usually assumed that spontaneous symmetry breaking is excluded for such interaction. However, we show that degenerate ground states appear when the system is considered as a charged medium, which we take to be so large that it makes sense to speak of a uniform, finite, charge density. This of course implies that we are considering as ground states solutions that select a particular Lorentz frame. The consequent symmetry breaking is accompanied by the usual Goldstone modes. It makes topological solitons possible in 1+1 dimensions. Further, a new kind of nontopological solitons appears, again in 1+1 dimensions. These are embedded in a uniformly charged background. Unlike the Friedberg-Lee-Sirlin solitons, those studied here do not require a complicatedly shaped potential to exist. Although Derrick's theorem, which forbids higher-dimensional solitons, cannot be proved in the present context, it appears that such solitons are still forbidden in the presence of finite charge density. When the field is confined to a box, the frequency spectrum is, classically, a continuum. This is in sharp contrast to the situation for linear fields. However, semiclassical quantization, or the requirement that charge be quantized, both make the spectrum discrete. We show by general arguments that the energy spectrum (distinct from the frequency spectrum for nonlinear fields) for the interacting field in a box must have widely spaced levels. For the case of a quartic potential we compute the energy levels exactly in 1+1 dimensions, and verify this conclusion directly. The interacting scalar field thus complies in detail with the bound on specific entropy proposed by one of us earlier as applicable to all finite physical systems.
On the quantum field theory of the gravitational interactions
NASA Astrophysics Data System (ADS)
Anselmi, Damiano
2017-06-01
We study the main options for a unitary and renormalizable, local quantum field theory of the gravitational interactions. The first model is a Lee-Wick superrenormalizable higher-derivative gravity, formulated as a nonanalytically Wick rotated Euclidean theory. We show that, under certain conditions, the S matrix is unitary when the cosmological constant vanishes. The model is the simplest of its class. However, infinitely many similar options are allowed, which raises the issue of uniqueness. To deal with this problem, we propose a new quantization prescription, by doubling the unphysical poles of the higher-derivative propagators and turning them into Lee-Wick poles. The Lagrangian of the simplest theory of quantum gravity based on this idea is the linear combination of R, R μν R μν , R 2 and the cosmological term. Only the graviton propagates in the cutting equations and, when the cosmological constant vanishes, the S matrix is unitary. The theory satisfies the locality of counterterms and is renormalizable by power counting. It is unique in the sense that it is the only one with a dimensionless gauge coupling.
Riemann surface and quantization
NASA Astrophysics Data System (ADS)
Perepelkin, E. E.; Sadovnikov, B. I.; Inozemtseva, N. G.
2017-01-01
This paper proposes an approach of the unified consideration of classical and quantum mechanics from the standpoint of the complex analysis effects. It turns out that quantization can be interpreted in terms of the Riemann surface corresponding to the multivalent LnΨ function. A visual interpretation of "trajectories" of the quantum system and of the Feynman's path integral is presented. A magnetic dipole having a magnetic charge that satisfies the Dirac quantization rule was obtained.
Perturbative quantization of two-dimensional space-time noncommutative QED
Ghasemkhani, M.; Sadooghi, N.
2010-02-15
Using the method of perturbative quantization in the first order approximation, we quantize a nonlocal QED-like theory including fermions and bosons whose interactions are described by terms containing higher order space-time derivatives. As an example, the two-dimensional space-time noncommutative QED (NC-QED) is quantized perturbatively up to O(e{sup 2},{theta}{sup 3}), where e is the NC-QED coupling constant and {theta} is the noncommutativity parameter. The resulting modified Lagrangian density is shown to include terms consisting of first order time-derivative and higher order space-derivatives of the modified field variables that satisfy the ordinary equal-time commutation relations up to O(e{sup 2},{theta}{sup 3}). Using these commutation relations, the canonical current algebra of the modified theory is also derived.
Action Quantization, Energy Quantization, and Time Parametrization
NASA Astrophysics Data System (ADS)
Floyd, Edward R.
2017-03-01
The additional information within a Hamilton-Jacobi representation of quantum mechanics is extra, in general, to the Schrödinger representation. This additional information specifies the microstate of ψ that is incorporated into the quantum reduced action, W. Non-physical solutions of the quantum stationary Hamilton-Jacobi equation for energies that are not Hamiltonian eigenvalues are examined to establish Lipschitz continuity of the quantum reduced action and conjugate momentum. Milne quantization renders the eigenvalue J. Eigenvalues J and E mutually imply each other. Jacobi's theorem generates a microstate-dependent time parametrization t-τ =partial _E W even where energy, E, and action variable, J, are quantized eigenvalues. Substantiating examples are examined in a Hamilton-Jacobi representation including the linear harmonic oscillator numerically and the square well in closed form. Two byproducts are developed. First, the monotonic behavior of W is shown to ease numerical and analytic computations. Second, a Hamilton-Jacobi representation, quantum trajectories, is shown to develop the standard energy quantization formulas of wave mechanics.
NASA Astrophysics Data System (ADS)
Menouar, Salah; Choi, Jeong Ryeol
2015-02-01
Quantum characteristics of a charged particle subjected to a singular oscillator potential under an external magnetic field is investigated via SU(1,1) Lie algebraic approach together with the invariant operator and the unitary transformation methods. The system we managed is somewhat complicated since we considered not only the time-variation of the effective mass of the system but also the dependence of the external magnetic field on time in an arbitrary fashion. In this case, the system is a kind of time-dependent Hamiltonian systems which require more delicate treatment when we study it. The complete wave functions are obtained without relying on the methods of perturbation and/or approximation, and the global phases of the system are identified. To promote the understanding of our development, we applied it to a particular case, assuming that the effective mass slowly varies with time under a time-dependent magnetic field.
Menouar, Salah; Choi, Jeong Ryeol
2015-02-15
Quantum characteristics of a charged particle subjected to a singular oscillator potential under an external magnetic field is investigated via SU(1,1) Lie algebraic approach together with the invariant operator and the unitary transformation methods. The system we managed is somewhat complicated since we considered not only the time-variation of the effective mass of the system but also the dependence of the external magnetic field on time in an arbitrary fashion. In this case, the system is a kind of time-dependent Hamiltonian systems which require more delicate treatment when we study it. The complete wave functions are obtained without relying on the methods of perturbation and/or approximation, and the global phases of the system are identified. To promote the understanding of our development, we applied it to a particular case, assuming that the effective mass slowly varies with time under a time-dependent magnetic field.
Deterministic Quantization by Dynamical Boundary Conditions
Dolce, Donatello
2010-06-15
We propose an unexplored quantization method. It is based on the assumption of dynamical space-time intrinsic periodicities for relativistic fields, which in turn can be regarded as dual to extra-dimensional fields. As a consequence we obtain a unified and consistent interpretation of Special Relativity and Quantum Mechanics in terms of Deterministic Geometrodynamics.
NASA Astrophysics Data System (ADS)
Biswas, S. N.; Ghatak, K. P.
1987-04-01
It is well-known that the gate capacitance of MOS strut tures of n-channel inversion layers on small ptap semiconductors is a very important one since the MOS capacitance can be very easily controlled by varying the gate voltage and also since it explores various other fundamental aspects of semiconductor surfaces in MOS structures. However, the gate capacitance of MOS structures on ternary semiconductors has relatively been less investigated in the literature and an attempt is made for the first time to investigate theoretically the above capacitance on ternary compounds by using the three-band Kane model. We have derived an expression of the surface electron statistics without any approximations of low or high electric field limits and taking into account the influence of the Dingle temperature respectively. We have then formulated a model expression of the magneto gate capacitance with the proper use of the electron concentration. We shall also formulate the same capacitance for both the limits excluding he broadening of Landau levels for the purpose of comparison. It is observed, taking n-channel inversion layers on Hg1-x Cdx Te as an example that the gate capacitance exhibits spiky oscillations with " changinp, magnetic field and the oscillatory behaviour is in qualitative agreement with the experimental observation reported in the recent literature for MOS structure of Hg1-x Cdx Te. The corresponding results for n-channel inversion layers on relatively large band-gap semi-conductors both in the presence and absence of magnetic quantization can also obtained from the expressions derived.
NASA Astrophysics Data System (ADS)
Melkikh, Alexey V.
2017-08-01
The result of Wheeler's delayed choice experiment is a natural consequence of the entanglement of moving photons and particles (atoms, molecules) of the slit through which they move. The inclusion of quantum fields (taking into account that speed of virtual particles is not limited) self-consistently explains why interaction’s propagation velocity after closing one slit is larger than the speed of light.
Quantization Effects on Complex Networks
Wang, Ying; Wang, Lin; Yang, Wen; Wang, Xiaofan
2016-01-01
Weights of edges in many complex networks we constructed are quantized values of the real weights. To what extent does the quantization affect the properties of a network? In this work, quantization effects on network properties are investigated based on the spectrum of the corresponding Laplacian. In contrast to the intuition that larger quantization level always implies a better approximation of the quantized network to the original one, we find a ubiquitous periodic jumping phenomenon with peak-value decreasing in a power-law relationship in all the real-world weighted networks that we investigated. We supply theoretical analysis on the critical quantization level and the power laws. PMID:27226049
An Exact Solution to the Quantized Electromagnetic Field in D-Dimensional de Sitter Space-Times
NASA Astrophysics Data System (ADS)
Alencar, G.; Guedes, I.; Landim, R. R.; Filho, R. N. Costa
2012-12-01
In this work, we investigate the quantum theory of light propagating in D-dimensional de Sitter space-times. To do so, we use the method of dynamic invariants to obtain the solution of the time-dependent Schrödinger equation. The quantum behavior of the electromagnetic field in this background is analyzed. As the electromagnetism loses its conformality in D≠4, we point out that there will be particle production and comoving objects will feel a Bunch-Davies thermal bath. This may become important in extra dimension physics and raises the intriguing possibility that precise measurements of the Cosmic Microwave Background could verify the existence of extra dimensions.
Quantization of general linear electrodynamics
Rivera, Sergio; Schuller, Frederic P.
2011-03-15
General linear electrodynamics allow for an arbitrary linear constitutive relation between the field strength 2-form and induction 2-form density if crucial hyperbolicity and energy conditions are satisfied, which render the theory predictive and physically interpretable. Taking into account the higher-order polynomial dispersion relation and associated causal structure of general linear electrodynamics, we carefully develop its Hamiltonian formulation from first principles. Canonical quantization of the resulting constrained system then results in a quantum vacuum which is sensitive to the constitutive tensor of the classical theory. As an application we calculate the Casimir effect in a birefringent linear optical medium.
Electronic quantization in dielectric nanolaminates
NASA Astrophysics Data System (ADS)
Willemsen, T.; Geerke, P.; Jupé, M.; Gallais, L.; Ristau, D.
2016-12-01
The scientific background in the field of the laser induced damage processes in optical coatings has been significantly extended during the last decades. Especially for the ultra-short pulse regime a clear correlation between the electronic material parameters and the laser damage threshold could be demonstrated. In the present study, the quantization in nanolaminates is investigated to gain a deeper insight into the behavior of the blue shift of the bandgap in specific coating materials as well as to find approximations for the effective mass of the electrons. The theoretical predictions are correlated to the measurements.
The lattice and quantized Yang–Mills theory
Creutz, Michael
2015-11-30
Quantized Yang–Mills fields lie at the heart of our understanding of the strong nuclear force. To understand the theory at low energies, we must work in the strong coupling regime. The primary technique for this is the lattice. While basically an ultraviolet regulator, the lattice avoids the use of a perturbative expansion. In this paper, I discuss the historical circumstances that drove us to this approach, which has had immense success, convincingly demonstrating quark confinement and obtaining crucial properties of the strong interactions from first principles.
Popov, V. G. Dubrovskii, Yu. V.; Portal, J.-C.
2006-04-15
The results of experimental investigation of the vertical electron transport in a GaAs/Al{sub 0.3}Ga{sub 0.7}As/GaAs single-barrier tunneling heterostructure with a doped barrier are presented. Two-dimensional accumulation layers appear on different sides of the barrier as a result of the ionization of Si donors in the barrier layer. The nonmonotonic shift of the current peak is found in the I-V curve of the tunneling diode in a magnetic field perpendicular to the planes of two-dimensional layers. Such a behavior is shown to be successfully explained in the model of appearing the Coulomb pseudogap and the pinning of the spin-split Landau levels at the Fermi levels of the contacts. In this explanation, it is necessary to assume that the Lande factor is independent of the filling factors of the Landau levels and is g* = 7.5 for both layers.
Black hole entropy quantization.
Corichi, Alejandro; Díaz-Polo, Jacobo; Fernández-Borja, Enrique
2007-05-04
Ever since the pioneering works of Bekenstein and Hawking, black hole entropy has been known to have a quantum origin. Furthermore, it has long been argued by Bekenstein that entropy should be quantized in discrete (equidistant) steps given its identification with horizon area in (semi-)classical general relativity and the properties of area as an adiabatic invariant. This lead to the suggestion that the black hole area should also be quantized in equidistant steps to account for the discrete black hole entropy. Here we shall show that loop quantum gravity, in which area is not quantized in equidistant steps, can nevertheless be consistent with Bekenstein's equidistant entropy proposal in a subtle way. For that we perform a detailed analysis of the number of microstates compatible with a given area and show consistency with the Bekenstein framework when an oscillatory behavior in the entropy-area relation is properly interpreted.
Skalozub, A.S.; Tsaune, A.Ya.
1994-12-01
A new approach for analyzing the highly excited vibration-rotation (VR) states of nonrigid molecules is suggested. It is based on the separation of the vibrational and rotational terms in the molecular VR Hamiltonian by introducing periodic auxiliary fields. These fields transfer different interactions within a molecule and are treated in terms of the mean-field approximation. As a result, the solution of the stationary Schroedinger equation with the VR Hamiltonian amounts to a quantization of the Berry phase in a problem of the molecular angular-momentum motion in a certain periodic VR field (rotational problem). The quantization procedure takes into account the motion of the collective vibrational variables in the appropriate VR potentials (vibrational problem). The quantization rules, the mean-field configurations of auxiliary interactions, and the solutions to the Schrodinger equations for the vibrational and rotational problems are self-consistently connected with one another. The potentialities of the theory are demonstrated by the bending-rotation interaction modeled by the Bunker-Landsberg potential function in the H{sub 2} molecule. The calculations are compared with both the results of the exact computations and those of other approximate methods. 32 refs., 4 tabs.
Interaction of the geomagnetic field with northward interplanetary magnetic field
NASA Astrophysics Data System (ADS)
Bhattarai, Shree Krishna
The interaction of the solar wind with Earth's magnetic field causes the transfer of momentum and energy from the solar wind to geospace. The study of this interaction is gaining significance as our society is becoming more and more space based, due to which, predicting space weather has become more important. The solar wind interacts with the geomagnetic field primarily via two processes: viscous interaction and the magnetic reconnection. Both of these interactions result in the generation of an electric field in Earth's ionosphere. The overall topology and dynamics of the magnetosphere, as well as the electric field imposed on the ionosphere, vary with speed, density, and magnetic field orientation of the solar wind as well as the conductivity of the ionosphere. In this dissertation, I will examine the role of northward interplanetary magnetic field (IMF) and discuss the global topology of the magnetosphere and the interaction with the ionosphere using results obtained from the Lyon-Fedder-Mobarry (LFM) simulation. The electric potentials imposed on the ionosphere due to viscous interaction and magnetic reconnection are called the viscous and the reconnection potentials, respectively. A proxy to measure the overall effect of these potentials is to measure the cross polar potential (CPP). The CPP is defined as the difference between the maximum and the minimum of the potential in a given polar ionosphere. I will show results from the LFM simulation showing saturation of the CPP during periods with purely northward IMF of sufficiently large magnitude. I will further show that the viscous potential, which was assumed to be independent of IMF orientation until this work, is reduced during periods of northward IMF. Furthermore, I will also discuss the implications of these results for a simulation of an entire solar rotation.
Effective colloidal interactions in rotating magnetic fields
NASA Astrophysics Data System (ADS)
Coughlan, Anna C. H.; Bevan, Michael A.
2017-08-01
Non-equilibrium, steady-state effective pair potentials of micron-sized superparamagnetic particles in rotating magnetic fields are obtained vs. field frequency and amplitude. Trajectories of center-to-center distance between particle pairs from Brownian dynamic simulations, which were previously matched to experimental measurements, are analyzed to obtain local drift and diffusion coefficients. These coefficients are used to obtain effective interaction potentials from solving a one-dimensional Fokker-Planck equation. Biased sampling of the effective energy landscape was implemented by intermittent switching between the field of interest and a repulsive field. Our findings show how the shape and attractive well-depth of pair interactions can be tuned by changing field frequency and amplitude.
Fractional quantization of charge and spin in topological quantum pumps
NASA Astrophysics Data System (ADS)
Marra, Pasquale; Citro, Roberta
2017-07-01
Topological quantum pumps are topologically equivalent to the quantum Hall state: In these systems, the charge pumped during each pumping cycle is quantized and coincides with the Chern invariant. However, differently from quantum Hall insulators, quantum pumps can exhibit novel phenomena such as the fractional quantization of the charge transport, as a consequence of their distinctive symmetries in parameter space. Here, we report the analogous fractional quantization of the spin transport in a topological spin pump realized in a one-dimensional lattice via a periodically modulated Zeeman field. In the proposed model, which is a spinfull generalization of the Harper-Hofstadter model, the amount of spin current pumped during well-defined fractions of the pumping cycle is quantized as fractions of the spin Chern number. This fractional quantization of spin is topological, and is a direct consequence of the additional symmetries ensuing from the commensuration of the periodic field with the underlying lattice.
On Quantizable Odd Lie Bialgebras
NASA Astrophysics Data System (ADS)
Khoroshkin, Anton; Merkulov, Sergei; Willwacher, Thomas
2016-09-01
Motivated by the obstruction to the deformation quantization of Poisson structures in infinite dimensions, we introduce the notion of a quantizable odd Lie bialgebra. The main result of the paper is a construction of the highly non-trivial minimal resolution of the properad governing such Lie bialgebras, and its link with the theory of so-called quantizable Poisson structures.
Canonical quantization of theories with higher derivatives. Quantization of R/sup 2/ gravitation
Bukhbinder, I.L.; Lyakhovich, S.L.
1988-02-01
Ostrogradskii's method for reducing theories with higher derivatives to Hamiltonian form is generalized to make it suitable for application to gauge field theories. A Hamiltonian formalism is constructed for the theory with the Lagrangian L-g(anti ..lambda.. - (1/x/sup 2/)R+aR/sub ..mu..v/R/sup ..mu..v/+bR/sup 2/). The structure of the constraints of this theory is investigated, and it is shown that, depending on the relationship between the parameters anti ..lambda.., x, a, b, five different variants of the theory are possible. In each of them, canonical quantization is performed and a local measure in the functional integral is found. The general form of local measure for an arbitrary boson theory interacting with gravity is established.
NASA Astrophysics Data System (ADS)
Bogolubov, Nikolai N.; Prykarpatsky, Anatoliy K.
2010-05-01
The Lagrangian and Hamiltonian properties of classical electrodynamics models and their associated Dirac quantizations are studied. Using the vacuum field theory approach developed in (Prykarpatsky et al. Theor. Math. Phys. 160(2): 1079-1095, 2009 and The field structure of a vacuum, Maxwell equations and relativity theory aspects. Preprint ICTP) consistent canonical Hamiltonian reformulations of some alternative classical electrodynamics models are devised, and these formulations include the Lorentz condition in a natural way. The Dirac quantization procedure corresponding to the Hamiltonian formulations is developed. The crucial importance of the rest reference systems, with respect to which the dynamics of charged point particles is framed, is explained and emphasized. A concise expression for the Lorentz force is derived by suitably taking into account the duality of electromagnetic field and charged particle interactions. Finally, a physical explanation of the vacuum field medium and its relativistic properties fitting the mathematical framework developed is formulated and discussed.
Hybrid quantization of an inflationary universe
NASA Astrophysics Data System (ADS)
Fernández-Méndez, Mikel; Mena Marugán, Guillermo A.; Olmedo, Javier
2012-07-01
We quantize to completion an inflationary universe with small inhomogeneities in the framework of loop quantum cosmology. The homogeneous setting consists of a massive scalar field propagating in a closed, homogeneous scenario. We provide a complete quantum description of the system employing loop quantization techniques. After introducing small inhomogeneities as scalar perturbations, we identify the true physical degrees of freedom by means of a partial gauge fixing, removing all the local degrees of freedom except the matter perturbations. We finally combine a Fock description for the inhomogeneities with the polymeric quantization of the homogeneous background, providing the quantum Hamiltonian constraint of the composed system. Its solutions are then completely characterized, owing to the suitable choice of quantum constraint, and the physical Hilbert space is constructed. Finally, we consider the analog description for an alternate gauge and, moreover, in terms of gauge-invariant quantities. In the deparametrized model, all these descriptions are unitarily equivalent at the quantum level.
ERIC Educational Resources Information Center
DeBuvitz, William
2014-01-01
I am a volunteer reader at the Princeton unit of "Learning Ally" (formerly "Recording for the Blind & Dyslexic") and I recently discovered that high school students are introduced to the concept of quantization well before they take chemistry and physics. For the past few months I have been reading onto computer files a…
ERIC Educational Resources Information Center
DeBuvitz, William
2014-01-01
I am a volunteer reader at the Princeton unit of "Learning Ally" (formerly "Recording for the Blind & Dyslexic") and I recently discovered that high school students are introduced to the concept of quantization well before they take chemistry and physics. For the past few months I have been reading onto computer files a…
Dual field theory of strong interactions
Akers, D.
1987-07-01
A dual field theory of strong interactions is derived from a Lagrangian of the Yang-Mills and Higgs fields. The existence of a magnetic monopole of mass 2397 MeV and Dirac charge g = (137/2)e is incorporated into the theory. Unification of the strong, weak, and electromagnetic forces is shown to converge at the mass of the intermediate vector boson W/sup +/-/. The coupling constants of the strong and weak interactions are derived in terms of the fine-structure constant ..cap alpha.. = 1/137.
Quantization of anomalous gauge theories
Wotzasek, C.J.
1990-01-01
The author discusses the quantization of Anomalous Gauge Theories (AGT) both in the context of functional integration and canonical Hamiltonian approach. The Wess-Zumino term (WZT), which repairs gauge symmetry in the AGT is discussed and its derivation is presented in the canonical approach as a consequence of the restoration of the first-class nature of the gauge constraints. He applied this technique in a few quantum field theories like the chiral Schwinger model, chiral bosons and massive electrodynamics. This construction of the WZT is intended to contrast with the one derived by functional methods with the use of the Faddeev-Popov trick. To shed some light into the physical significance of the WZ field he discusses a simple quantum mechanical model, the amputated planar rotor.' In the context the WZ field presents itself as a topological charge for the model. Possible generalizations are discussed.
Inconsistency of the ‘spin-3/2 gauge invariant’ interaction of Rarita-Schwinger fields
NASA Astrophysics Data System (ADS)
Badagnani, D.; Mariano, A.; Barbero, C.
2017-02-01
We perform the Dirac quantization of Rarita-Schwinger fields interacting with a spinor and the first derivative of a pseudoscalar field. We achieve the calculations for two forms of this interaction: first we review the conventional coupling of lowest derivative order, reproducing the well known inconsistencies in its anticommutator algebra. Then, we perform the analysis on the next order term popularly known as ‘spin-3/2 gauge invariant interaction’, which is claimed to be free of these inconsistencies. Nevertheless we find that the direct application of the Dirac formalism leads to inconsistencies in complete analogy to the previous case. This is of high relevance in the particle phenomenology field, where these interactions are used to interpret experimental data involving {{Δ }}(1232) resonances.
First Astronaut- Rover Interaction Field Test
NASA Technical Reports Server (NTRS)
Kosmo, Joseph J.; Ross, Amy; Cabrol, Nathalie A.
2000-01-01
The first Astronaut - Rover (ASRO) Interaction field test was conducted successfully on February 22-27, 1999, in Silver Lake, Mojave Desert, California in a representative planetary surface terrain. This test was a joint effort between the NASA Ames Research Center , Moffett Field, California and the NASA Johnson Space Center, Houston, Texas. As prototype advanced planetary surface space suit and rover technologies are being developed for human planetary surface exploration , it has been determined that it is important to better understand the potential interaction and benefits of an EVA astronaut interacting with a robotic rover . This interaction between an EVA astronaut and a robotic rover is seen as complementary and can greatly enhance the productivity and safety of surface excursions . This test also identified design requirements and options in an advanced space suit and robotic rover. The test objectives were: 1. To identify the operational domains where the EVA astronauts and rover are complementary and can interact and thus collaborate in a safe , productive and cost- effective way, 2. To identify preliminary requirements and recommendations for advanced space suits and rovers that facilitate their cooperative and complementary interaction, 3. To develop operational procedures for the astronaut-rover teams in the identified domains, 4. To test these procedures during representative mission scenarios during field tests by simulating the exploration of a planetary surface by an EVA crew interacting with a robotic rover, 5. To train a space suited test subject, simulated Earth-based and l or lander-based science teams, and robotic vehicle operators in mission configurations, and 6. To evaluate and understand socio-technical aspects of the astronaut - rover interaction experiment in order to guide future technologies and designs. Test results and areas for future research in the design of planetary space suits will be discussed .
Light-Front-Quantized QCD in Light-Cone Gauge
Brodsky, Stanley J.
2000-11-30
The light-front (LF) quantization of QCD in light-cone gauge has a number of remarkable advantages, including explicit unitarity, a physical Fock expansion, the absence of ghost degrees of freedom, and the decoupling properties needed to prove factorization theorems in high momentum transfer inclusive and exclusive reactions. We present a systematic study of LF-quantized gauge theory following the Dirac method and construct the Dyson-Wick S-matrix expansion based on LF-time-ordered products. The gauge field is shown to satisfy the Lorentz condition as an operator equation as well as the light-cone gauge condition. Its propagator is found to be transverse with respect to both its four-momentum and the gauge direction. The propagator of the dynamical + part of the free fermionic field is shown to be causal and to not contain instantaneous terms. The interaction Hamiltonian of QCD can be expressed in a form resembling that of covariant theory, except for additional instantaneous interactions which can be treated systematically. The renormalization factors are shown to be scalars and we find Z1 = Z3 at one loop order. The running coupling constant and QCD {beta} function are also computed in the noncovariant light-cone gauge. Some comments on the relationship of our LF framework to the analytic effective charge and renormalization scheme defined by the pinch technique are made. LF quantization thus provides a consistent formulation of gauge theory, despite the fact that the hyperplanes x{sup {+-}} = 0 used to impose boundary conditions constitute characteristic surfaces of a hyperbolic partial differential equation.
Interacting scale invariant but nonconformal field theories
NASA Astrophysics Data System (ADS)
Nakayama, Yu
2017-03-01
There is a dilemma in constructing interacting scale invariant Euclidean field theories that are not conformal invariant. On one hand, scale invariance without conformal invariance seems more generic by requiring only a smaller symmetry. On the other hand, the existence of a nonconserved current with exact scaling dimension d -1 in d dimensions seems to require extra fine-tuning. To understand the competition better, we explore some examples without the reflection positivity. We show that a theory of elasticity (also known as Riva-Cardy theory) coupled with massless fermions in d =4 -ɛ dimensions does not possess an interacting scale invariant fixed point except for an unstable (and unphysical) one with an infinite coefficient of compression. We do, however, find interacting scale invariant but nonconformal field theories in gauge fixed versions of the Banks-Zaks fixed points in d =4 dimensions.
Breathers on quantized superfluid vortices.
Salman, Hayder
2013-10-18
We consider the propagation of breathers along a quantized superfluid vortex. Using the correspondence between the local induction approximation (LIA) and the nonlinear Schrödinger equation, we identify a set of initial conditions corresponding to breather solutions of vortex motion governed by the LIA. These initial conditions, which give rise to a long-wavelength modulational instability, result in the emergence of large amplitude perturbations that are localized in both space and time. The emergent structures on the vortex filament are analogous to loop solitons but arise from the dual action of bending and twisting of the vortex. Although the breather solutions we study are exact solutions of the LIA equations, we demonstrate through full numerical simulations that their key emergent attributes carry over to vortex dynamics governed by the Biot-Savart law and to quantized vortices described by the Gross-Pitaevskii equation. The breather excitations can lead to self-reconnections, a mechanism that can play an important role within the crossover range of scales in superfluid turbulence. Moreover, the observation of breather solutions on vortices in a field model suggests that these solutions are expected to arise in a wide range of other physical contexts from classical vortices to cosmological strings.
Breathers on Quantized Superfluid Vortices
NASA Astrophysics Data System (ADS)
Salman, Hayder
2013-10-01
We consider the propagation of breathers along a quantized superfluid vortex. Using the correspondence between the local induction approximation (LIA) and the nonlinear Schrödinger equation, we identify a set of initial conditions corresponding to breather solutions of vortex motion governed by the LIA. These initial conditions, which give rise to a long-wavelength modulational instability, result in the emergence of large amplitude perturbations that are localized in both space and time. The emergent structures on the vortex filament are analogous to loop solitons but arise from the dual action of bending and twisting of the vortex. Although the breather solutions we study are exact solutions of the LIA equations, we demonstrate through full numerical simulations that their key emergent attributes carry over to vortex dynamics governed by the Biot-Savart law and to quantized vortices described by the Gross-Pitaevskii equation. The breather excitations can lead to self-reconnections, a mechanism that can play an important role within the crossover range of scales in superfluid turbulence. Moreover, the observation of breather solutions on vortices in a field model suggests that these solutions are expected to arise in a wide range of other physical contexts from classical vortices to cosmological strings.
Path-memory induced quantization of classical orbits
Fort, Emmanuel; Eddi, Antonin; Boudaoud, Arezki; Moukhtar, Julien; Couder, Yves
2010-01-01
A droplet bouncing on a liquid bath can self-propel due to its interaction with the waves it generates. The resulting “walker” is a dynamical association where, at a macroscopic scale, a particle (the droplet) is driven by a pilot-wave field. A specificity of this system is that the wave field itself results from the superposition of the waves generated at the points of space recently visited by the particle. It thus contains a memory of the past trajectory of the particle. Here, we investigate the response of this object to forces orthogonal to its motion. We find that the resulting closed orbits present a spontaneous quantization. This is observed only when the memory of the system is long enough for the particle to interact with the wave sources distributed along the whole orbit. An additional force then limits the possible orbits to a discrete set. The wave-sustained path memory is thus demonstrated to generate a quantization of angular momentum. Because a quantum-like uncertainty was also observed recently in these systems, the nonlocality generated by path memory opens new perspectives.
NASA Astrophysics Data System (ADS)
Calogero, Francesco
An estimate is presented of the angular momentum associated with the stochastic cosmic tremor, which has been hypothesized to be caused by universal gravitation and by the granularity of matter, and to be itself the cause of quantization ("cosmic origin of quantization"). If that universal tremor has the spatial coherence which is instrumental in order that the estimated action associated with it have the order of magnitude of Planck's constant h, then the estimated order of magnitude of the angular momentum associated with it also has the same value. We moreover indicate how these findings (originally based on a simplified model of the Universe, as being made up only of particles having the nucleon mass) are affected (in fact, essentially unaffected) by the possible presence in the mass of the Universe of a large component made up of particles much lighter than nucleons ("dark", or "missing", mass).
Uniform quantized electron gas
NASA Astrophysics Data System (ADS)
Høye, Johan S.; Lomba, Enrique
2016-10-01
In this work we study the correlation energy of the quantized electron gas of uniform density at temperature T = 0. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpreted as, and is equivalent to, a classical polymer problem in four dimensions where the fourth dimension is imaginary time. Thus methods, results, and properties obtained in the statistical mechanics of classical fluids can be utilized. From this viewpoint we recover the well known RPA (random phase approximation). Then to improve it we modify the RPA by requiring the corresponding correlation function to be such that electrons with equal spins can not be on the same position. Numerical evaluations are compared with well known results of a standard parameterization of Monte Carlo correlation energies.
Resurgence matches quantization
NASA Astrophysics Data System (ADS)
Couso-Santamaría, Ricardo; Mariño, Marcos; Schiappa, Ricardo
2017-04-01
The quest to find a nonperturbative formulation of topological string theory has recently seen two unrelated developments. On the one hand, via quantization of the mirror curve associated to a toric Calabi–Yau background, it has been possible to give a nonperturbative definition of the topological-string partition function. On the other hand, using techniques of resurgence and transseries, it has been possible to extend the string (asymptotic) perturbative expansion into a transseries involving nonperturbative instanton sectors. Within the specific example of the local {{{P}}2} toric Calabi–Yau threefold, the present work shows how the Borel–Padé–Écalle resummation of this resurgent transseries, alongside occurrence of Stokes phenomenon, matches the string-theoretic partition function obtained via quantization of the mirror curve. This match is highly non-trivial, given the unrelated nature of both nonperturbative frameworks, signaling at the existence of a consistent underlying structure.
Nonlinear Bubble Interactions in Acoustic Pressure Fields
NASA Technical Reports Server (NTRS)
Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi
1996-01-01
The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).
Interaction Between Flames and Electric Fields Studied
NASA Technical Reports Server (NTRS)
Yuan, Zeng-Guang; Hegde, Uday
2003-01-01
The interaction between flames and electric fields has long been an interesting research subject that has theoretical importance as well as practical significance. Many of the reactions in a flame follow an ionic pathway: that is, positive and negative ions are formed during the intermediate steps of the reaction. When an external electric field is applied, the ions move according to the electric force (the Coulomb force) exerted on them. The motion of the ions modifies the chemistry because the reacting species are altered, it changes the velocity field of the flame, and it alters the electric field distribution. As a result, the flame will change its shape and location to meet all thermal, chemical, and electrical constraints. In normal gravity, the strong buoyant effect often makes the flame multidimensional and, thus, hinders the detailed study of the problem.
Inelastic scattering of xenon atoms by quantized vortices in superfluids
NASA Astrophysics Data System (ADS)
Pshenichnyuk, I. A.; Berloff, N. G.
2016-11-01
We study inelastic interactions of particles with quantized vortices in superfluids by using a semiclassical matter wave theory that is analogous to the Landau two-fluid equations, but allows for the vortex dynamics. The research is motivated by recent experiments on xenon-doped helium nanodroplets that show clustering of the impurities along the vortex cores. We numerically simulate the dynamics of trapping and interactions of xenon atoms by quantized vortices in superfluid helium and the obtained results can be extended to scattering of other impurities by quantized vortices. Different energies and impact parameters of incident particles are considered. We show that inelastic scattering is closely linked to the generation of Kelvin waves along a quantized vortex during the interaction even if there is no capture. The capture criterion of an impurity is formulated in terms of the binding energy.
Electromagnetic field interactions with biological systems
Frey, A.H. )
1993-02-01
This is a report on Symposia organized by the International Society for Bioelectricity and presented at the 1992 FASEB Meeting. The presentations summarized here were intended to provide a sampling of new and fruitful lines of research. The theme topics for the Symposia were cancer, neural function, cell signaling, pineal gland function, and immune system interactions. Living organisms are complex electrochemical systems that evolved over billions of years in a world with a relatively simple weak magnetic field and with few electromagnetic energy emitters. As is characteristic of living organisms, they interacted with and adapted to this environment of electric and magnetic fields. In recent years there has been a massive introduction of equipment that emits electromagnetic fields in an enormous range of new frequencies, modulations, and intensities. As living organisms have only recently found themselves immersed in this new and virtually ubiquitous environment, they have not had the opportunity to adapt to it. This gives biologists the opportunity to use these electromagnetic fields as probes to study the functioning of living systems. This is a significant opportunity, as new approaches to studying living systems so often provide the means to make great leaps in science. In recent years, a diversity of biologists have carried out experiments using electromagnetic fields to study the function of living cells and systems. This approach is now becoming quite fruitful and is yielding data that are advancing our knowledge in diverse areas of biology. 25 refs., 6 figs., 3 tabs.
Interaction of electromagnetic fields and biological tissues
NASA Astrophysics Data System (ADS)
Darshan Shrivastava, Bhakt; Barde, Ravindra; Mishra, Ashutosh; Phadke, S.
2014-09-01
This paper deals with the electromagnetic field interact in biological tissues. It is actually one of the important challenges for the electromagnetic field for the recent years. The experimental techniques are use in Broad-band Dielectric Measurement (BDM) with LCR meters. The authors used Bones and scales of Fish taken from Narmada River (Rajghat Dist. Barwani) as biological tissues. Experimental work carried out done in inter-university consortium (IUC) Indore. The major difficulties that appear are related to the material properties, to the effect of the electromagnetic problem and to the thermal model of the biological tissues.
Quantum Computing and Second Quantization
Makaruk, Hanna Ewa
2017-02-10
Quantum computers are by their nature many particle quantum systems. Both the many-particle arrangement and being quantum are necessary for the existence of the entangled states, which are responsible for the parallelism of the quantum computers. Second quantization is a very important approximate method of describing such systems. This lecture will present the general idea of the second quantization, and discuss shortly some of the most important formulations of second quantization.
BRST Quantization of Unimodular Gravity
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker; Oksanen, Markku; Bufalo, Rodrigo
2017-06-01
We study the quantization of two versions of unimodular gravity, namely fully diffeomorphism-invariant unimodular gravity and unimodular gravity with fixed metric determinant, utilizing standard path integral approach. We derive the BRST symmetry of effective actions corresponding to several relevant gauge conditions. We observe that for some gauge conditions, the restricted gauge structure may complicate the formulation and effective actions, in particular, if the chosen gauge conditions involve the canonical momentum conjugate to the induced metric on the spatial hypersurface. The BRST symmetry is extended further to the finite field-dependent BRST transformation, in order to establish the mapping between different gauge conditions in each of the two versions of unimodular gravity.
An adaptive vector quantization scheme
NASA Technical Reports Server (NTRS)
Cheung, K.-M.
1990-01-01
Vector quantization is known to be an effective compression scheme to achieve a low bit rate so as to minimize communication channel bandwidth and also to reduce digital memory storage while maintaining the necessary fidelity of the data. However, the large number of computations required in vector quantizers has been a handicap in using vector quantization for low-rate source coding. An adaptive vector quantization algorithm is introduced that is inherently suitable for simple hardware implementation because it has a simple architecture. It allows fast encoding and decoding because it requires only addition and subtraction operations.
Effects of quantization on detrended fluctuation analysis
NASA Astrophysics Data System (ADS)
Zhu, Song-Sheng; Xu, Ze-Xi; Yin, Kui-Xi; Xu, Yin-Lin
2011-05-01
Detrended fluctuation analysis (DFA) is a method foro estimating the long-range power-law correlation exponent in noisy signals. It has been used successfully in many different fields, especially in the research of physiological signals. As an inherent part of these studies, quantization of continuous signals is inevitable. In addition, coarse-graining, to transfer original signals into symbol series in symbolic dynamic analysis, can also be considered as a quantization-like operation. Therefore, it is worth considering whether the quantization of signal has any effect on the result of DFA and if so, how large the effect will be. In this paper we study how the quantized degrees for three types of noise series (anti-correlated, uncorrelated and long-range power-law correlated signals) affect the results of DFA and find that their effects are completely different. The conclusion has an essential value in choosing the resolution of data acquisition instrument and in the processing of coarse-graining of signals.
Hysteresis in a quantized superfluid 'atomtronic' circuit.
Eckel, Stephen; Lee, Jeffrey G; Jendrzejewski, Fred; Murray, Noel; Clark, Charles W; Lobb, Christopher J; Phillips, William D; Edwards, Mark; Campbell, Gretchen K
2014-02-13
Atomtronics is an emerging interdisciplinary field that seeks to develop new functional methods by creating devices and circuits where ultracold atoms, often superfluids, have a role analogous to that of electrons in electronics. Hysteresis is widely used in electronic circuits-it is routinely observed in superconducting circuits and is essential in radio-frequency superconducting quantum interference devices. Furthermore, it is as fundamental to superfluidity (and superconductivity) as quantized persistent currents, critical velocity and Josephson effects. Nevertheless, despite multiple theoretical predictions, hysteresis has not been previously observed in any superfluid, atomic-gas Bose-Einstein condensate. Here we directly detect hysteresis between quantized circulation states in an atomtronic circuit formed from a ring of superfluid Bose-Einstein condensate obstructed by a rotating weak link (a region of low atomic density). This contrasts with previous experiments on superfluid liquid helium where hysteresis was observed directly in systems in which the quantization of flow could not be observed, and indirectly in systems that showed quantized flow. Our techniques allow us to tune the size of the hysteresis loop and to consider the fundamental excitations that accompany hysteresis. The results suggest that the relevant excitations involved in hysteresis are vortices, and indicate that dissipation has an important role in the dynamics. Controlled hysteresis in atomtronic circuits may prove to be a crucial feature for the development of practical devices, just as it has in electronic circuits such as memories, digital noise filters (for example Schmitt triggers) and magnetometers (for example superconducting quantum interference devices).
Hysteresis in a quantized superfluid `atomtronic' circuit
NASA Astrophysics Data System (ADS)
Eckel, Stephen; Lee, Jeffrey G.; Jendrzejewski, Fred; Murray, Noel; Clark, Charles W.; Lobb, Christopher J.; Phillips, William D.; Edwards, Mark; Campbell, Gretchen K.
2014-02-01
Atomtronics is an emerging interdisciplinary field that seeks to develop new functional methods by creating devices and circuits where ultracold atoms, often superfluids, have a role analogous to that of electrons in electronics. Hysteresis is widely used in electronic circuits--it is routinely observed in superconducting circuits and is essential in radio-frequency superconducting quantum interference devices. Furthermore, it is as fundamental to superfluidity (and superconductivity) as quantized persistent currents, critical velocity and Josephson effects. Nevertheless, despite multiple theoretical predictions, hysteresis has not been previously observed in any superfluid, atomic-gas Bose-Einstein condensate. Here we directly detect hysteresis between quantized circulation states in an atomtronic circuit formed from a ring of superfluid Bose-Einstein condensate obstructed by a rotating weak link (a region of low atomic density). This contrasts with previous experiments on superfluid liquid helium where hysteresis was observed directly in systems in which the quantization of flow could not be observed, and indirectly in systems that showed quantized flow. Our techniques allow us to tune the size of the hysteresis loop and to consider the fundamental excitations that accompany hysteresis. The results suggest that the relevant excitations involved in hysteresis are vortices, and indicate that dissipation has an important role in the dynamics. Controlled hysteresis in atomtronic circuits may prove to be a crucial feature for the development of practical devices, just as it has in electronic circuits such as memories, digital noise filters (for example Schmitt triggers) and magnetometers (for example superconducting quantum interference devices).
NASA Astrophysics Data System (ADS)
Shaukat, Muzzamal Iqbal
2017-06-01
In the present work, we have investigated the effect of trapping as a microscopic phenomenon on the propagation of 1 and 2D linear and nonlinear quantum drift ion acoustic waves in a spatially inhomogeneous degenerate electron-positron-ion plasma in the presence of quantizing magnetic field having degenerate electrons and positrons. We derive the linear dispersion relation and nonlinear Korteweg-deVries and Kadomtsev Petviashvili equation for drift ion acoustic waves. It is observed that the characteristics of the dispersion relation and nonlinear drift ion solitary structures have been modified significantly by the positron concentration and quantizing magnetic field. The work presented here may be beneficial to understand the propagation of drift solitary structures in dense astrophysical environments and in intense-laser plasma interactions.
Quantizing dilatonic black holes. Towards nonperturbative canonical quantization of the CGHS model.
NASA Astrophysics Data System (ADS)
Varadarajan, M.
Motivated by the search for a nonperturbative quantization, the author casts the Callan-Giddings-Harvey-Strominger (CGHS) model of dilatonic black holes into a Hamiltonian framework. By making transformations to new "embedding" variables, he maps the model into that of a parametrized scalar field propagating on a fixed flat 1+1 background spacetime. The description in terms of the new variables is thus more amenable to quantization. Issues of asymptotics and boundary terms are dealt with systematically. This work has been done in collaboration with K. Kuchař (Univ of Utah) and J. Romano (Univ of Wisconsin-Milwaukee).
Intense-field-stimulated multiphoton transitions in a two-level system
Milman, Perola; Zagury, Nicim
2011-11-15
We study the interaction of an intense classical field with a two-level system coupled to a bosonic quantized field. We focus on the regime where the classical field and the two-level system characteristic frequencies are the same, while the quantized mode is set off resonance with both. We show that a parameter governing the dynamics of the system is the ratio between the classical field's intensity and the quantized mode detuning. Depending on this parameter, multiple excitations can be created in the quantized mode in a single cycle of the two-level system. Examples of physical setups allowing for the application of the presented ideas are superconducting circuits in strip-line resonators, laser cooled trapped ions, and neutral atoms coupled to the quantized field of a cavity. We focus on the latter in order to show that, with realistic experimental parameters, it is possible to generate up to four photons in a single Rabi cycle.
Quantization of interface currents
Kotani, Motoko; Schulz-Baldes, Hermann; Villegas-Blas, Carlos
2014-12-15
At the interface of two two-dimensional quantum systems, there may exist interface currents similar to edge currents in quantum Hall systems. It is proved that these interface currents are macroscopically quantized by an integer that is given by the difference of the Chern numbers of the two systems. It is also argued that at the interface between two time-reversal invariant systems with half-integer spin, one of which is trivial and the other non-trivial, there are dissipationless spin-polarized interface currents.
Spin wave quantization in continuous film with stripe domains
NASA Astrophysics Data System (ADS)
Ha, Seung-Seok; Yoon, Jungbum; Lee, Sukmock; You, Chun-Yeol; Jung, Myung-Hwa; Kim, Young Keun
2009-04-01
We investigated the spin wave dynamics of CoFeSiB film, which has a stripe domain structure at a low magnetic field region (<1 kOe). We measured the spin wave excitation spectra by employing Brillouin light scattering. Abnormal field dependence and dispersion relations were observed, and they are similar to spin wave quantization in laterally confined magnetic structures such as arrays of magnetic nanowires. The observed spin wave excitation spectra must be interpreted with spin wave quantization such as Damon-Eshbach mode separation. It was found that the spin wave quantization is related to the stripe magnetic domain structure in continuous film. The physical origin of the quantization is the partial reflection of the propagating spin wave at the periodic stripe domain boundaries.
Light-cone quantization and hadron structure
Brodsky, S.J.
1996-04-01
Quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. In this talk, the author will discuss light-cone quantization and the light-cone Fock expansion as a tractable and consistent representation of relativistic many-body systems and bound states in quantum field theory. The Fock state representation in QCD includes all quantum fluctuations of the hadron wavefunction, including fax off-shell configurations such as intrinsic strangeness and charm and, in the case of nuclei, hidden color. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer. In other applications, such as the calculation of the axial, magnetic, and quadrupole moments of light nuclei, the QCD relativistic Fock state description provides new insights which go well beyond the usual assumptions of traditional hadronic and nuclear physics.
Interacting quantum fields around a black hole
NASA Astrophysics Data System (ADS)
Hawking, S. W.
1981-09-01
If one studies interacting fields on a black hole background using ordinary Feynman diagrams, one is faced with a problem of what to do with lines that cross the horizon. To avoid this difficulty a formulation is developed which can be expressed graphically in terms of a new class of diagram with external lines only at infinity. This formalism is applied to study the question of whether spontaneously broken symmetry would be restored near the black hole. It is also used to show that a black hole can emit more particles than antiparticles even in theories where the particle number is locally conserved by a global U(1) symmetry.
Quaternionic quantization principle in general relativity and supergravity
NASA Astrophysics Data System (ADS)
Kober, Martin
2016-01-01
A generalized quantization principle is considered, which incorporates nontrivial commutation relations of the components of the variables of the quantized theory with the components of the corresponding canonical conjugated momenta referring to other space-time directions. The corresponding commutation relations are formulated by using quaternions. At the beginning, this extended quantization concept is applied to the variables of quantum mechanics. The resulting Dirac equation and the corresponding generalized expression for plane waves are formulated and some consequences for quantum field theory are considered. Later, the quaternionic quantization principle is transferred to canonical quantum gravity. Within quantum geometrodynamics as well as the Ashtekar formalism, the generalized algebraic properties of the operators describing the gravitational observables and the corresponding quantum constraints implied by the generalized representations of these operators are determined. The generalized algebra also induces commutation relations of the several components of the quantized variables with each other. Finally, the quaternionic quantization procedure is also transferred to 𝒩 = 1 supergravity. Accordingly, the quantization principle has to be generalized to be compatible with Dirac brackets, which appear in canonical quantum supergravity.
Exercises in exact quantization
NASA Astrophysics Data System (ADS)
Voros, André
2000-10-01
The formalism of exact 1D quantization is reviewed in detail and applied to the spectral study of three concrete Schrödinger Hamiltonians [-d2/dq2 + V(q)]± on the half-line {q>0}, with a Dirichlet (-) or Neumann (+) condition at q = 0. Emphasis is put on the analytical investigation of the spectral determinants and spectral zeta-functions with respect to singular perturbation parameters. We first discuss the homogeneous potential V(q) = qN as N→ + ∞ versus its (solvable) N = ∞ limit (an infinite square well): useful distinctions are established between regular and singular behaviours of spectral quantities; various identities among the square-well spectral functions are unravelled as limits of finite-N properties. The second model is the quartic anharmonic oscillator: the zero-energy spectral determinants det (-d2/dq2 + q4 + vq2)± are explicitly analysed in detail, revealing many special values, algebraic identities between Taylor coefficients and functional equations of a quartic type coupled to asymptotic v→∞ properties of Airy type. The third study addresses the potentials V(q) = qN + vqN/2-1 of even degree: their zero-energy spectral determinants prove computable in closed form, and the generalized eigenvalue problems with v as spectral variable admit exact quantization formulae which are perfect extensions of the harmonic oscillator case (corresponding to N = 2); these results partly reflect the presence of quasi-exactly solvable potentials in the family above.
NASA Astrophysics Data System (ADS)
O'Brien, Paul
2017-01-01
Max Plank did not quantize temperature. I will show that the Plank temperature violates the Plank scale. Plank stated that the Plank scale was Natures scale and independent of human construct. Also stating that even aliens would derive the same values. He made a huge mistake, because temperature is based on the Kelvin scale, which is man-made just like the meter and kilogram. He did not discover natures scale for the quantization of temperature. His formula is flawed, and his value is incorrect. Plank's calculation is Tp = c2Mp/Kb. The general form of this equation is T = E/Kb Why is this wrong? The temperature for a fixed amount of energy is dependent upon the volume it occupies. Using the correct formula involves specifying the radius of the volume in the form of (RE). This leads to an inequality and a limit that is equivalent to the Bekenstein Bound, but using temperature instead of entropy. Rewriting this equation as a limit defines both the maximum temperature and Boltzmann's constant. This will saturate any space-time boundary with maximum temperature and information density, also the minimum radius and entropy. The general form of the equation then becomes a limit in BH thermodynamics T <= (RE)/(λKb) .
NASA Astrophysics Data System (ADS)
Frønsdal, Christian; Kontsevich, Maxim
2007-02-01
Deformation quantization on varieties with singularities offers perspectives that are not found on manifolds. The Harrison component of Hochschild cohomology, vanishing on smooth manifolds, reflects information about singularities. The Harrison 2-cochains are symmetric and are interpreted in terms of abelian *-products. This paper begins a study of abelian quantization on plane curves over mathbb{C}, being algebraic varieties of the form {mathbb{C}}^2/R, where R is a polynomial in two variables; that is, abelian deformations of the coordinate algebra mathbb{C}[x,y]/(R). To understand the connection between the singularities of a variety and cohomology we determine the algebraic Hochschild (co)homology and its Barr Gerstenhaber Schack decomposition. Homology is the same for all plane curves mathbb{C}[x,y]/R, but the cohomology depends on the local algebra of the singularity of R at the origin. The Appendix, by Maxim Kontsevich, explains in modern mathematical language a way to calculate Hochschild and Harrison cohomology groups for algebras of functions on singular planar curves etc. based on Koszul resolutions.
Covariant quantization of the CBS superparticle
NASA Astrophysics Data System (ADS)
Grassi, P. A.; Policastro, G.; Porrati, M.
2001-07-01
The quantization of the Casalbuoni-Brink-Schwarz superparticle is performed in an explicitly covariant way using the antibracket formalism. Since an infinite number of ghost fields are required, within a suitable off-shell twistor-like formalism, we are able to fix the gauge of each ghost sector without modifying the physical content of the theory. The computation reveals that the antibracket cohomology contains only the physical degrees of freedom.
Divergence-based vector quantization.
Villmann, Thomas; Haase, Sven
2011-05-01
Supervised and unsupervised vector quantization methods for classification and clustering traditionally use dissimilarities, frequently taken as Euclidean distances. In this article, we investigate the applicability of divergences instead, focusing on online learning. We deduce the mathematical fundamentals for its utilization in gradient-based online vector quantization algorithms. It bears on the generalized derivatives of the divergences known as Fréchet derivatives in functional analysis, which reduces in finite-dimensional problems to partial derivatives in a natural way. We demonstrate the application of this methodology for widely applied supervised and unsupervised online vector quantization schemes, including self-organizing maps, neural gas, and learning vector quantization. Additionally, principles for hyperparameter optimization and relevance learning for parameterized divergences in the case of supervised vector quantization are given to achieve improved classification accuracy.
Analysis of the quantum bouncer using polymer quantization
NASA Astrophysics Data System (ADS)
Martín-Ruiz, A.; Frank, A.; Urrutia, L. F.
2015-08-01
Polymer quantization (PQ) is a background independent quantization scheme that arises in loop quantum gravity. This framework leads to a new short-distance (discretized) structure characterized by a fundamental length. In this paper we use PQ to analyze the problem of a particle bouncing on a perfectly reflecting surface under the influence of Earth's gravitational field. In this scenario, deviations from the usual quantum effects are induced by the spatial discreteness, but not by a new short-range gravitational interaction. We solve the polymer Schrödinger equation in an analytical fashion, and we evaluate numerically the corresponding energy levels. We find that the polymer energy spectrum exhibits a negative shift compared to the one obtained for the quantum bouncer. The comparison of our results with those obtained in the GRANIT experiment leads to an upper bound for the fundamental length scale, namely λ ≪0.6 Å . We find polymer corrections to the transition probability between levels, induced by small vibrations, together with the probability of spontaneous emission in the quadrupole approximation.
Second quantization in bit-string physics
NASA Technical Reports Server (NTRS)
Noyes, H. Pierre
1993-01-01
Using a new fundamental theory based on bit-strings, a finite and discrete version of the solutions of the free one particle Dirac equation as segmented trajectories with steps of length h/mc along the forward and backward light cones executed at velocity +/- c are derived. Interpreting the statistical fluctuations which cause the bends in these segmented trajectories as emission and absorption of radiation, these solutions are analogous to a fermion propagator in a second quantized theory. This allows us to interpret the mass parameter in the step length as the physical mass of the free particle. The radiation in interaction with it has the usual harmonic oscillator structure of a second quantized theory. How these free particle masses can be generated gravitationally using the combinatorial hierarchy sequence (3,10,137,2(sup 127) + 136), and some of the predictive consequences are sketched.
Relational symplectic groupoid quantization for constant poisson structures
NASA Astrophysics Data System (ADS)
Cattaneo, Alberto S.; Moshayedi, Nima; Wernli, Konstantin
2017-09-01
As a detailed application of the BV-BFV formalism for the quantization of field theories on manifolds with boundary, this note describes a quantization of the relational symplectic groupoid for a constant Poisson structure. The presence of mixed boundary conditions and the globalization of results are also addressed. In particular, the paper includes an extension to space-times with boundary of some formal geometry considerations in the BV-BFV formalism, and specifically introduces into the BV-BFV framework a "differential" version of the classical and quantum master equations. The quantization constructed in this paper induces Kontsevich's deformation quantization on the underlying Poisson manifold, i.e., the Moyal product, which is known in full details. This allows focussing on the BV-BFV technology and testing it. For the inexperienced reader, this is also a practical and reasonably simple way to learn it.
Relational symplectic groupoid quantization for constant poisson structures
NASA Astrophysics Data System (ADS)
Cattaneo, Alberto S.; Moshayedi, Nima; Wernli, Konstantin
2017-04-01
As a detailed application of the BV-BFV formalism for the quantization of field theories on manifolds with boundary, this note describes a quantization of the relational symplectic groupoid for a constant Poisson structure. The presence of mixed boundary conditions and the globalization of results are also addressed. In particular, the paper includes an extension to space-times with boundary of some formal geometry considerations in the BV-BFV formalism, and specifically introduces into the BV-BFV framework a "differential" version of the classical and quantum master equations. The quantization constructed in this paper induces Kontsevich's deformation quantization on the underlying Poisson manifold, i.e., the Moyal product, which is known in full details. This allows focussing on the BV-BFV technology and testing it. For the inexperienced reader, this is also a practical and reasonably simple way to learn it.
Remarks on the geometric quantization of Landau levels
NASA Astrophysics Data System (ADS)
Galasso, Andrea; Spera, Mauro
2016-08-01
In this note, we resume the geometric quantization approach to the motion of a charged particle on a plane, subject to a constant magnetic field perpendicular to the latter, by showing directly that it gives rise to a completely integrable system to which we may apply holomorphic geometric quantization. In addition, we present a variant employing a suitable vertical polarization and we also make contact with Bott’s quantization, enforcing the property “quantization commutes with reduction”, which is known to hold under quite general conditions. We also provide an interpretation of translational symmetry breaking in terms of coherent states and index theory. Finally, we give a representation theoretic description of the lowest Landau level via the use of an S1-equivariant Dirac operator.
Quantized electric multipole insulators
NASA Astrophysics Data System (ADS)
Benalcazar, Wladimir A.; Bernevig, B. Andrei; Hughes, Taylor L.
2017-07-01
The Berry phase provides a modern formulation of electric polarization in crystals. We extend this concept to higher electric multipole moments and determine the necessary conditions and minimal models for which the quadrupole and octupole moments are topologically quantized electromagnetic observables. Such systems exhibit gapped boundaries that are themselves lower-dimensional topological phases. Furthermore, they host topologically protected corner states carrying fractional charge, exhibiting fractionalization at the boundary of the boundary. To characterize these insulating phases of matter, we introduce a paradigm in which “nested” Wilson loops give rise to topological invariants that have been overlooked. We propose three realistic experimental implementations of this topological behavior that can be immediately tested. Our work opens a venue for the expansion of the classification of topological phases of matter.
Spin foam model from canonical quantization
Alexandrov, Sergei
2008-01-15
We suggest a modification of the Barrett-Crane spin foam model of four-dimensional Lorentzian general relativity motivated by the canonical quantization. The starting point is Lorentz covariant loop quantum gravity. Its kinematical Hilbert space is found as a space of the so-called projected spin networks. These spin networks are identified with the boundary states of a spin foam model and provide a generalization of the unique Barrett-Crane intertwiner. We propose a way to modify the Barrett-Crane quantization procedure to arrive at this generalization: the B field (bivectors) should be promoted not to generators of the gauge algebra, but to their certain projection. The modification is also justified by the canonical analysis of the Plebanski formulation. Finally, we compare our construction with other proposals to modify the Barrett-Crane model.
Flow field interactions between two tandem cyclists
NASA Astrophysics Data System (ADS)
Barry, Nathan; Burton, David; Sheridan, John; Thompson, Mark; Brown, Nicholas A. T.
2016-12-01
Aerodynamic drag is the primary resistive force acting on cyclists at racing speeds. Many events involve cyclists travelling in very close proximity. Previous studies have shown that interactions result in significant drag reductions for inline cyclists. However, the interaction between cyclist leg position (pedalling) and the vortical flow structures that contribute significantly to the drag on an isolated cyclist has not previously been quantified or described for tandem cyclists of varying separation. To this end, scale model cyclists were constructed for testing in a water channel for inline tandem configurations. Particle image velocimetry was used to capture time-averaged velocity fields around two tandem cyclists. Perhaps surprisingly, the wake of a trailing cyclist maintains strong similarity to the characteristic wake of a single cyclist despite a significant disturbance to the upstream flow. Together with streamwise velocity measurements through the wake and upstream of the trailing cyclist, this work supports previous findings, which showed that the trailing cyclist drag reduction is primarily due to upstream sheltering effects reducing the stagnation pressure on forward-facing surfaces.
Immersion versus interactivity and analytic field.
Civitarese, Giuseppe
2008-04-01
Losing oneself in a story, a film or a picture is nothing but another step in the suspension of disbelief that permits one to become immersed in the 'novel' of reality. It is not by chance that the text-world metaphor informs classical aesthetics that, more than anything else, emphasizes emotional involvement. On the contrary, as in much of modern art, self-reflexivity and metafictional attention to the rhetoric of the real, to the framework, to the conventions and to the processes of meaning production, all involve a disenchanted, detached and sceptic vision--in short, an aesthetics of the text as game. By analogy, any analytic style or model that aims to produce a transformative experience must satisfactorily resolve the conflict between immersion (the analyst's emotional participation and sticking to the dreamlike or fictional climate of the session, dreaming knowing it's a dream) and interactivity (for the most part, interpretation as an anti-immersive device that 'wakes' one from fiction and demystifies consciousness). In analytic field theory the setting can be defined--because of the weight given to performativity of language, to the sensory matrix of the transference and the transparency of the medium--the place where an ideal balance is sought between immersion and interaction.
Generalized Bergman kernels and geometric quantization
NASA Astrophysics Data System (ADS)
Tuynman, G. M.
1987-03-01
In geometric quantization it is well known that, if f is an observable and F a polarization on a symplectic manifold (M,ω), then the condition ``Xf leaves F invariant'' (where Xf denotes the Hamiltonian vector field associated to f ) is sufficient to guarantee that one does not have to compute the BKS kernel explicitly in order to know the corresponding quantum operator. It is shown in this paper that this condition on f can be weakened to ``Xf leaves F+F° invariant''and the corresponding quantum operator is then given implicitly by formula (4.8); in particular when F is a (positive) Kähler polarization, all observables can be quantized ``directly'' and moreover, an ``explicit'' formula for the corresponding quantum operator is derived (Theorem 5.8). Applying this to the phase space R2n one obtains a quantization prescription which ressembles the normal ordering of operators in quantum field theory. When we translate this prescription to the usual position representation of quantum mechanics, the result is (a.o) that the operator associated to a classical potential is multiplication by a function which is essentially the convolution of the potential function with a Gaussian function of width ℏ, instead of multiplication by the potential itself.
Theory of the Knight Shift and Flux Quantization in Superconductors
DOE R&D Accomplishments Database
Cooper, L. N.; Lee, H. J.; Schwartz, B. B.; Silvert, W.
1962-05-01
Consequences of a generalization of the theory of superconductivity that yields a finite Knight shift are presented. In this theory, by introducing an electron-electron interaction that is not spatially invariant, the pairing of electrons with varying total momentum is made possible. An expression for Xs (the spin susceptibility in the superconducting state) is derived. In general Xs is smaller than Xn, but is not necessarily zero. The precise magnitude of Xs will vary from sample to sample and will depend on the nonuniformity of the samples. There should be no marked size dependence and no marked dependence on the strength of the magnetic field; this is in accord with observation. The basic superconducting properties are retained, but there are modifications in the various electromagnetic and thermal properties since the electrons paired are not time sequences of this generalized theory on flux quantization arguments are presented.(auth)
The Hamiltonian structure of Dirac's equation in tensor form and its Fermi quantization
NASA Technical Reports Server (NTRS)
Reifler, Frank; Morris, Randall
1992-01-01
Currently, there is some interest in studying the tensor forms of the Dirac equation to elucidate the possibility of the constrained tensor fields admitting Fermi quantization. We demonstrate that the bispinor and tensor Hamiltonian systems have equivalent Fermi quantizations. Although the tensor Hamiltonian system is noncanonical, representing the tensor Poisson brackets as commutators for the Heisenberg operators directly leads to Fermi quantization without the use of bispinors.
Minimum distortion quantizers. [determined by max algorithm
NASA Technical Reports Server (NTRS)
Jones, H. W., Jr.
1977-01-01
The well-known algorithm of Max is used to determine the minimum distortion quantizers for normal, two-sided exponential, and specialized two-sided gamma input distributions and for mean-square, magnitude, and relative magnitude error distortion criteria. The optimum equally-spaced and unequally-spaced quantizers are found, with the resulting quantizer distortion and entropy. The quantizers, and the quantizers with entropy coding, are compared to the rate distortion bounds for mean-square and magnitude error.
Immersive, interactive virtual field trips promote learning
NASA Astrophysics Data System (ADS)
Bruce, G.; Mead, C.; Buxner, S.; Taylor, W.; Semken, S. C.; Anbar, A. D.; Sundstrom, J.
2016-12-01
We are assessing the educational effectiveness of a new type of immersive virtual field trip (iVFT) that we are developing, grounded in active, inquiry-based learning, and accessible via web browsers. To this end, we collected data from five high school AP biology classes (n = 153) that were assigned an iVFT lesson focused on life and environment during the Ediacaran time period, 550 million years ago. Students explore a series of fossil beds using high resolution imagery and video acquired during a field expedition to the Nilpena site in the Flinders Ranges, South Australia. They first encounter an immersive spherical image, which orients them to the area. Then, they identify fossils in the iVFT, using a dichotomous key. Finally, they explore an interactive simulation of this ancient ecosystem. The average time spent on the experience was approximately two hours. The learning objective is for students to be able to describe the Ediacaran ecosystem preserved in the rocks at Nilpena. To assess this outcome, we administered identical pre- and post-lesson quizzes to students. Results showed a statistically significant improvement on the six-item quiz with a normalized gain of 0.96 (pre-lesson mean: 2.4, post-lesson mean: 5.9, p < .001). All but three students demonstrated an increase in score or maintained a perfect score. The pre-lesson scores are close to what would be expected from guessing, so these results represent a substantial growth in understanding. These findings encourage the use of iVFT-based learning experiences in education (an evolving suite is publicly available at http://vft.asu.edu). In the future, we will explore in more detail which aspects of the experience provide greatest educational benefit, and the effectiveness in teaching scientific reasoning skills in addition to content knowledge. To answer these questions, we will supplement content-based questions with mixed-methods data including interviews.
NASA Astrophysics Data System (ADS)
Daneshmand, R.; Tavassoly, M. K.
2016-04-01
Based on the Jaynes-Cummings interaction model of a Ξ-type three-level atom with a single-mode quantized field, the effect of damping on teleportation is studied. To achieve this purpose, we have taken into account the decay rates of the two upper atomic levels. The influences of such atomic damping on the teleportation of atomic as well as field states are evaluated. It is shown that, by increasing the damping parameter the fidelity and success probability is decreased. Finally, beside our main motivation of the paper, we end it with some marginal, however, of interest purposes like the analyzing the dynamics of a few interesting physical properties such as entanglement, Mandel parameter and quadrature squeezing in the presence of damping.
Integrability, Quantization and Moduli Spaces of Curves
NASA Astrophysics Data System (ADS)
Rossi, Paolo
2017-07-01
This paper has the purpose of presenting in an organic way a new approach to integrable (1+1)-dimensional field systems and their systematic quantization emerging from intersection theory of the moduli space of stable algebraic curves and, in particular, cohomological field theories, Hodge classes and double ramification cycles. This methods are alternative to the traditional Witten-Kontsevich framework and its generalizations by Dubrovin and Zhang and, among other advantages, have the merit of encompassing quantum integrable systems. Most of this material originates from an ongoing collaboration with A. Buryak, B. Dubrovin and J. Guéré.
Visibility of wavelet quantization noise
NASA Technical Reports Server (NTRS)
Watson, A. B.; Yang, G. Y.; Solomon, J. A.; Villasenor, J.
1997-01-01
The discrete wavelet transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that we call DWT uniform quantization noise; it is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2-lambda, where r is display visual resolution in pixels/degree, and lambda is the wavelet level. Thresholds increase rapidly with wavelet spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from lowpass to horizontal/vertical to diagonal. We construct a mathematical model for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution. This allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.
Visibility of Wavelet Quantization Noise
NASA Technical Reports Server (NTRS)
Watson, Andrew B.; Yang, Gloria Y.; Solomon, Joshua A.; Villasenor, John; Null, Cynthia H. (Technical Monitor)
1995-01-01
The Discrete Wavelet Transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter, which we call DWT uniform quantization noise. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2(exp)-L , where r is display visual resolution in pixels/degree, and L is the wavelet level. Amplitude thresholds increase rapidly with spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from low-pass to horizontal/vertical to diagonal. We describe a mathematical model to predict DWT noise detection thresholds as a function of level, orientation, and display visual resolution. This allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.
Visibility of Wavelet Quantization Noise
NASA Technical Reports Server (NTRS)
Watson, Andrew B.; Yang, Gloria Y.; Solomon, Joshua A.; Villasenor, John; Null, Cynthia H. (Technical Monitor)
1995-01-01
The Discrete Wavelet Transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter, which we call DWT uniform quantization noise. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2(exp)-L , where r is display visual resolution in pixels/degree, and L is the wavelet level. Amplitude thresholds increase rapidly with spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from low-pass to horizontal/vertical to diagonal. We describe a mathematical model to predict DWT noise detection thresholds as a function of level, orientation, and display visual resolution. This allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.
Cosmology with three interacting spin-2 fields
NASA Astrophysics Data System (ADS)
Lüben, Marvin; Akrami, Yashar; Amendola, Luca; Solomon, Adam R.
2016-08-01
Theories of massive gravity with one or two dynamical metrics generically lack stable and observationally viable cosmological solutions that are distinguishable from Λ cold dark matter (CDM). We consider an extension to trimetric gravity, with three interacting spin-2 fields which are not plagued by the Boulware-Deser ghost. We systematically explore every combination with two free parameters in search of background cosmologies that are competitive with Λ CDM . For each case we determine whether the expansion history satisfies viability criteria, and whether or not it contains beyond-Λ CDM phenomenology. Among the many models we consider, there are only three cases that seem to be both viable and distinguishable from standard cosmology. One of the models has only one free parameter and displays a crossing from above to below the phantom divide. The other two provide scaling behavior, although they contain future singularities that need to be studied in more detail. These models possess interesting features that make them compelling targets for a full comparison to observations of both cosmological expansion history and structure formation.
Escobar, W. A.
2013-01-01
The proposed model holds that, at its most fundamental level, visual awareness is quantized. That is to say that visual awareness arises as individual bits of awareness through the action of neural circuits with hundreds to thousands of neurons in at least the human striate cortex. Circuits with specific topologies will reproducibly result in visual awareness that correspond to basic aspects of vision like color, motion, and depth. These quanta of awareness (qualia) are produced by the feedforward sweep that occurs through the geniculocortical pathway but are not integrated into a conscious experience until recurrent processing from centers like V4 or V5 select the appropriate qualia being produced in V1 to create a percept. The model proposed here has the potential to shift the focus of the search for visual awareness to the level of microcircuits and these likely exist across the kingdom Animalia. Thus establishing qualia as the fundamental nature of visual awareness will not only provide a deeper understanding of awareness, but also allow for a more quantitative understanding of the evolution of visual awareness throughout the animal kingdom. PMID:24319436
Topological states and quantized current in helical organic molecules
NASA Astrophysics Data System (ADS)
Guo, Ai-Min; Sun, Qing-Feng
2017-04-01
We report a theoretical study of electron transport along helical organic molecules subject to an external electric field which is perpendicular to molecular helix axis. Our results reveal that topological states can appear in single-helical molecules as well as double-stranded DNA under the perpendicular electric field. In particular, a topological charge pumping can be realized by rotating the electric field in the transverse plane, where during each pumping cycle, an integer number of electrons can transport across the helical molecules at zero bias voltage, with pumped current being quantized. The quantized current constitutes multiple plateaus by scanning the Fermi energy as well as the bias voltage, and holds for various model parameters, since the edge states are topologically protected. These results could pave the way to explore topological states and quantized current in the biological systems and the helical molecules, and help in designing stable molecular devices.
Phase control of optical bistability and multistability in closed-type Landau-quantized graphene
NASA Astrophysics Data System (ADS)
Zhang, Duo; Yu, Rong; Ding, Chunling; Huang, Hailin; Sun, Zhaoyu; Yang, Xiaoxue
2016-12-01
We investigate the dynamic characteristics of a Landau-quantized graphene monolayer system interacting with three infrared laser probe fields in a monodirectional ring cavity, and analyse the input-output properties of the infrared laser probe field under a steady-state condition. The results show that we can effectively control the appearance or disappearance of optical bistability (OB) or optical multistability (OM) by adjusting the relative phase of three coherent fields, the coupling field intensity, as well as the frequency detunings of the probe field and the control field. In addition, we discuss in detail the influences of the left-hand and right-hand circularly polarized component intensity of the control field on the behaviors of OB and OM. Our investigation may be used to build more efficient logic-gate devices to realize an all-optic switching process.
Semiclassical Quantization of the Electron-Dipole System.
ERIC Educational Resources Information Center
Turner, J. E.
1979-01-01
This paper presents a derivation of the number given by Fermi in 1925, in his semiclassical treatment of the motion of an electron in the field of two stationary positive charges, for Bohr quantization of the electron orbits when the stationary charges are positive, and applies it to an electron moving in the field of a stationary dipole.…
Study made of interaction between sound fields and structural vibrations
NASA Technical Reports Server (NTRS)
Lyon, R. H.; Smith, P. W., Jr.
1967-01-01
Study analyzes structural vibrations and the interactions between them and sound fields. It outlines a conceptual framework to analyze the vibrations of systems and their interactions, incorporating the results of earlier studies and establishing a unified basis for continuing research.
Divergent Integrals of QED in Krein Space Quantization
Payandeh, F.
2010-06-15
The usual quantum field theory leads to an ultraviolet divergence in the vacuum energies and an infrared divergence in the two-point functions. It has been shown that the presence of unphysical negative-frequency states (Krein space quantization) plays the role of an automatic renormalization tool for the theory of quantized fields. In the standard QED, the divergent quantities are found in the self-energy, vacuum polarization, and vertex graphs. It seems as if evaluating divergent integrals of QED in Krein space leads to convergent values.
NASA Astrophysics Data System (ADS)
Kope, T. K.; Usadel, K. D.
2006-02-01
We consider the short-range interaction disordered quantum Ising model with symmetric binary +/-J bond distribution on the Bethe lattice (with coordination number z). The system exhibits quantum phase transition separating the spin glass and disordered phases where the quantum effect are regulated by a param- eter describing the transverse field. By introducing a mapping of the quantum Hamiltonian of the model onto a soft-spin action we consider it truncated version in a form of the solvable quantized spherical model. Quantum dynamics is examined via various correlation functions on the infinite tree which are evaluated in a closed form.
Vector quantization and learning vector quantization for radar target classification
NASA Astrophysics Data System (ADS)
Stewart, Clayton V.; Lu, Yi-Chuan; Larson, Victor J.
1993-10-01
Radar target classification performance is greatly dependent on how the classifier represents the strongly angle dependent radar target signatures. This paper compares the performance of classifiers that represent radar target signatures using vector quantization (VQ) and learning vector quantization (LVQ). The classifier performance is evaluated with a set of high resolution millimeter-wave radar data from four ground vehicles (Camaro, van, pickup, and bulldozer). LVQ explicitly includes classification performance in its data representation criterion, whereas VQ only makes use of a distortion measure such as mean square distance. The classifier that uses LVQ to represent the radar data has a much higher probability of correct classification than VQ.
A Second Quantized Approach to the Rabi Problem
NASA Astrophysics Data System (ADS)
Baldiotti, M. C.; Molina, C.
2017-10-01
In the present work, the Rabi Problem, involving the response of a spin 1/2 particle subjected to a magnetic field, is considered in a second quantized approach. In this concrete physical scenario, we show that the second quantization procedure can be applied directly in a non-covariant theory. The proposed development explicits not only the relation between the full quantum treatment of the problem and the semiclassical Rabi model, but also the connection of these approaches with the Jaynes-Cummings model. The consistency of the method is checked in the semiclassical limit. The treatment is then extended to the matter component of the Rabi problem so that the Schrödinger equation is directly quantized. Considering the spinorial field, the appearance of a negative energy sector implies a specific identification between Schrödinger's and Maxwell's theories. The generalized theory is consistent, strictly quantum and non-relativistic.
Quantization of compact Riemannian symmetric spaces
NASA Astrophysics Data System (ADS)
Szőke, Róbert
2017-09-01
The phase space of a compact, irreducible, simply connected, Riemannian symmetric space admits a natural family of Kähler polarizations parametrized by the upper half plane S. Using this family, geometric quantization, including the half-form correction, produces the field Hcorr → S of quantum Hilbert spaces. We show that projective flatness of Hcorr implies, that the symmetric space must be isometric to a compact Lie group equipped with a biinvariant metric. In the latter case the flatness of Hcorr was previously established.
Electron Anomalous Magnetic Moment in Basis Light-Front Quantization Approach
Zhao, Xingbo; Honkanen, Heli; Maris, Pieter; Vary, James P.; Brodsky, Stanley J.; /SLAC
2012-02-17
We apply the Basis Light-Front Quantization (BLFQ) approach to the Hamiltonian field theory of Quantum Electrodynamics (QED) in free space. We solve for the mass eigenstates corresponding to an electron interacting with a single photon in light-front gauge. Based on the resulting non-perturbative ground state light-front amplitude we evaluate the electron anomalous magnetic moment. The numerical results from extrapolating to the infinite basis limit reproduce the perturbative Schwinger result with relative deviation less than 1.2%. We report significant improvements over previous works including the development of analytic methods for evaluating the vertex matrix elements of QED.
Observed quantization of anyonic heat flow
NASA Astrophysics Data System (ADS)
Banerjee, Mitali; Heiblum, Moty; Rosenblatt, Amir; Oreg, Yuval; Feldman, Dima E.; Stern, Ady; Umansky, Vladimir
2017-04-01
The quantum of thermal conductance of ballistic (collisionless) one-dimensional channels is a unique fundamental constant. Although the quantization of the electrical conductance of one-dimensional ballistic conductors has long been experimentally established, demonstrating the quantization of thermal conductance has been challenging as it necessitated an accurate measurement of very small temperature increase. It has been accomplished for weakly interacting systems of phonons, photons and electronic Fermi liquids; however, it should theoretically also hold in strongly interacting systems, such as those in which the fractional quantum Hall effect is observed. This effect describes the fractionalization of electrons into anyons and chargeless quasiparticles, which in some cases can be Majorana fermions. Because the bulk is incompressible in the fractional quantum Hall regime, it is not expected to contribute substantially to the thermal conductance, which is instead determined by chiral, one-dimensional edge modes. The thermal conductance thus reflects the topological properties of the fractional quantum Hall electronic system, to which measurements of the electrical conductance give no access. Here we report measurements of thermal conductance in particle-like (Laughlin-Jain series) states and the more complex (and less studied) hole-like states in a high-mobility two-dimensional electron gas in GaAs-AlGaAs heterostructures. Hole-like states, which have fractional Landau-level fillings of 1/2 to 1, support downstream charged modes as well as upstream neutral modes, and are expected to have a thermal conductance that is determined by the net chirality of all of their downstream and upstream edge modes. Our results establish the universality of the quantization of thermal conductance for fractionally charged and neutral modes. Measurements of anyonic heat flow provide access to information that is not easily accessible from measurements of conductance.
Is Planck's quantization constant unique?
NASA Astrophysics Data System (ADS)
Livadiotis, George
2016-07-01
A cornerstone of Quantum Mechanics is the existence of a non-zero least action, the Planck constant. However, the basic concepts and theoretical developments of Quantum Mechanics are independent of its specific numerical value. A different constant h _{*}, similar to the Planck constant h, but ˜12 orders of magnitude larger, characterizes plasmas. The study of >50 different geophysical, space, and laboratory plasmas, provided the first evidence for the universality and the quantum nature of h _{*}, revealing that it is a new quantization constant. The recent results show the diagnostics for determining whether plasmas are characterized by the Planck or the new quantization constant, compounding the challenge to reconcile both quantization constants in quantum mechanics.
Dancing in the thresholds: Exploring the interactive field
NASA Astrophysics Data System (ADS)
Rodriguez, Constance S.
This dissertation is an attempt to investigate the nature of the interactive field to deepen as well as broaden its scope as it applies to depth psychology and its praxis. With a phenomenological eye toward field dynamics from other paradigms, this exploration demonstrates an additional theoretical framework within the interactive field. It opens other possibilities creating a neither/nor position from which to contain our work with an alchemical/metaphorical position and allows for the liberation of the imaginal realm through which ``the Other'' may be of service, and in fact, may ask us to be in service to it. The literature review not only surveys the three primary schools in psychology-the psychoanalytical, the classical, and archetypal as the genesis of the interactive field, but also investigates shamanic realms as a backdrop from which to see field theory. Field theory is also explored in the world of quantum physics where the universal field is examined from paradigms situated in varied consciousness models. The somatic unconscious, an intrinsic part of the interactive field in mutual engagement with two or more persons, is also woven into the fabric of this study as an intersection between the universal field and the psychodynamic field. This study, as a psychological gnosis, initiates subtle body awareness from Eastern cosmologies from a depth perspective in the psychodynamics of the interactive field. Synchronistic encounters are integrated into field theory as a threshold where universal fields engage the somatic unconscious, initiating numinous and sometimes transformative change into one's life.
EZW coding using nonuniform quantization
NASA Astrophysics Data System (ADS)
Yin, Che-Yi; Derin, Haluk
1999-10-01
This paper presents an image coder that modifies the EZW coder and provides an improvement in its performance. The subband EZW image coder uses a uniform quantizer with a threshold (deadzone). Whereas, we know that the distribution/histogram of the wavelet tree subband coefficients, all except the lowest subband, tend to be Laplacian. To accommodate for this, we modify the refining procedure in EZW and use a non-uniform quantizer on the coefficients that better fits their distribution. The experimental results show that the new image coder performs better than EZW.
Color Quantization by Multiresolution Analysis
NASA Astrophysics Data System (ADS)
Ramella, Giuliana; di Baja, Gabriella Sanniti
A color quantization method is presented, which is based on the analysis of the histogram at different resolutions computed on a Gaussian pyramid of the input image. Criteria based on persistence and dominance of peaks and pits of the histograms are introduced to detect the modes in the histogram of the input image and to define the reduced colormap. Important features of the method are, besides its limited computational cost, the possibility to obtain quantized images with a variable number of colors, depending on the user’s need, and that the number of colors in the resulting image does not need to be a priori fixed.
On supersymmetric Lifshitz field theories
NASA Astrophysics Data System (ADS)
Chapman, Shira; Oz, Yaron; Raviv-Moshe, Avia
2015-10-01
We consider field theories that exhibit a supersymmetric Lifshitz scaling with two real supercharges. The theories can be formulated in the language of stochastic quan-tization. We construct the free field supersymmetry algebra with rotation singlet fermions for an even dynamical exponent z = 2 k in an arbitrary dimension. We analyze the classical and quantum z = 2 supersymmetric interactions in 2 + 1 and 3 + 1 spacetime dimensions and reveal a supersymmetry preserving quantum diagrammatic cancellation. Stochastic quantization indicates that Lifshitz scale invariance is broken in the (3 + 1)-dimensional quantum theory.
Resonant Strong Field Nonlinear Optical Interactions
NASA Astrophysics Data System (ADS)
Coppeta, David Anthony
This work considers the steady state nonlinear response of a medium subjected to electromagnetic fields which are resonant and/or strong. In this regime, pertubation expansions in the field amplitude(s) diverge and non-pertubative techniques are required. Two general cases are considered. In the first case, radiative renormalization is applied to Four Wave Mixing (FWM) in a four level system with three resonant driving fields. The absorption and generation of a weak FWM signal are considered. Several variants including coherent anti-Stokes Raman scattering are considered. The second case is a two level atom subject to excitation by an arbitrarily amplitude modulated field. The domain of solution is extended to non-equal damping rates with zero detuning from resonance. As an example, the steady state response to step function amplitude modulation is treated.
Probabilistic distance-based quantizer design for distributed estimation
NASA Astrophysics Data System (ADS)
Kim, Yoon Hak
2016-12-01
We consider an iterative design of independently operating local quantizers at nodes that should cooperate without interaction to achieve application objectives for distributed estimation systems. We suggest as a new cost function a probabilistic distance between the posterior distribution and its quantized one expressed as the Kullback Leibler (KL) divergence. We first present the analysis that minimizing the KL divergence in the cyclic generalized Lloyd design framework is equivalent to maximizing the logarithmic quantized posterior distribution on the average which can be further computationally reduced in our iterative design. We propose an iterative design algorithm that seeks to maximize the simplified version of the posterior quantized distribution and discuss that our algorithm converges to a global optimum due to the convexity of the cost function and generates the most informative quantized measurements. We also provide an independent encoding technique that enables minimization of the cost function and can be efficiently simplified for a practical use of power-constrained nodes. We finally demonstrate through extensive experiments an obvious advantage of improved estimation performance as compared with the typical designs and the novel design techniques previously published.
Motion vector quantization for video coding.
Lee, Y Y; Woods, J W
1995-01-01
A new algorithm is developed for the vector quantization of motion vectors. This algorithm, called motion vector quantization (MVQ), simultaneously estimates and vector quantizes the motion vectors by reinterpreting the block matching algorithm as a type of vector quantization. An iterative design algorithm, based on this concept, is developed. In addition to reducing rate for fixed length encoding, the algorithm also reduces the computation considerably. We include coding simulation results on the Flower Garden sequence.
Self-interacting complex scalar field as dark matter
Briscese, F.
2011-10-14
We study the viability of a a complex scalar field {chi} with self-interacting potential V = m{sub 0}{sup {chi}/}2|{chi}|{sup 2}+h|{chi}|{sup 4} as dark matter. Due to the self interaction, the scalar field forms a Bose-Einstein condensate at early times that represents dark matter. The self interaction is also responsible of quantum corrections to the scalar field mass that naturally give the dark matter domination at late times without any fine tuning on the energy density of the scalar field at early times. Finally the properties of the spherically symmetric dark matter halos are also discussed.
The cosmology of interacting spin-2 fields
Tamanini, Nicola; Saridakis, Emmanuel N.; Koivisto, Tomi S. E-mail: Emmanuel_Saridakis@baylor.edu
2014-02-01
We investigate the cosmology of interacting spin-2 particles, formulating the multi-gravitational theory in terms of vierbeins and without imposing any Deser-van Nieuwen-huizen-like constraint. The resulting multi-vierbein theory represents a wider class of gravitational theories if compared to the corresponding multi-metric models. Moreover, as opposed to its metric counterpart which in general seems to contain ghosts, it has already been proved to be ghost-free. We outline a discussion about the possible matter couplings and we focus on the study of cosmological scenarios in the case of three and four interacting vierbeins. We find rich behavior, including de Sitter solutions with an effective cosmological constant arising from the multi-vierbein interaction, dark-energy solutions and nonsingular bouncing behavior.
Second quantization techniques in the scattering of nonidentical composite bodies
NASA Technical Reports Server (NTRS)
Norbury, J. W.; Townsend, L. W.; Deutchman, P. A.
1986-01-01
Second quantization techniques for describing elastic and inelastic interactions between nonidentical composite bodies are presented and are applied to nucleus-nucleus collisions involving ground-state and one-particle-one-hole excitations. Evaluations of the resultant collision matrix elements are made through use of Wick's theorem.
Canonical quantization of four- and five-dimensional U(1) gauge theories
NASA Astrophysics Data System (ADS)
Shnerb, N.; Horwitz, L. P.
1993-12-01
We discuss the canonical quantization of an interacting massless U(1) gauge field using a bosonic gauge-fixing method. We present a way to make the transformation between the Lorentz and the Coulomb gauge of such theories, without using an explicit representation of the fields in terms of creation-annihilation operators. We demonstrate this method in the case of Maxwell photons interacting with Schrödinger electrons and then we treat, with the same methods, a system of higher-dimensional equations appearing in the framework of a manifestly covariant relativistic quantum theory. The nonrelativistic limit of the Coulomb term for such a theory is discussed and compared to the Fokker action appearing in the Wheeler-Feynman action-at-a-distance theory for electromagnetic interactions.
Deformation Quantization and the Baum-Connes Conjecture
NASA Astrophysics Data System (ADS)
Landsman, N. P.
Alternative titles of this paper would have been `Index theory without index' or `The Baum-Connes conjecture without Baum.' In 1989, Rieffel introduced an analytic version of deformation quantization based on the use of continuous fields of C*-algebras. We review how a wide variety of examples of such quantizations can be understood on the basis of a single lemma involving amenable groupoids. These include Weyl-Moyal quantization on manifolds, C*-algebras of Lie groups and Lie groupoids, and the E-theoretic version of the Baum-Connes conjecture for smooth groupoids as described by Connes in his book Noncommutative Geometry. Concerning the latter, we use a different semidirect product construction from Connes. This enables one to formulate the Baum-Connes conjecture in terms of twisted Weyl-Moyal quantization. The underlying mechanical system is a noncommutative desingularization of a stratified Poisson space, and the Baum-Connes conjecture actually suggests a strategy for quantizing such singular spaces.
Laughlin's argument for the quantized thermal Hall effect
NASA Astrophysics Data System (ADS)
Nakai, Ryota; Ryu, Shinsei; Nomura, Kentaro
2017-04-01
We extend Laughlin's magnetic-flux-threading argument to the quantized thermal Hall effect. A proper analog of Laughlin's adiabatic magnetic-flux threading process for the case of the thermal Hall effect is given in terms of an external gravitational field. From the perspective of the edge theories of quantum Hall systems, the quantized thermal Hall effect is closely tied to the breakdown of large diffeomorphism invariance, that is, a global gravitational anomaly. In addition, we also give an argument from the bulk perspective in which a free energy, decomposed into its Fourier modes, is adiabatically transferred under an adiabatic process involving external gravitational perturbations.
Topology, Magnetic Field, and Strongly Interacting Matter
Kharzeev, Dmitri E.
2015-06-05
Gauge theories with compact symmetry groups possess topologically nontrivial configurations of gauge field. This characteristic has dramatic implications for the vacuum structure of quantum chromodynamics (QCD) and for the behavior of QCD plasma, as well as for condensed matter systems with chiral quasi-particles. Here, I review the current status of this problem with an emphasis both on the interplay between chirality and a background magnetic field and on the observable manifestations of topology in heavy-ion collisions, Dirac semimetals, neutron stars, and the early Universe.
Landau quantization of Dirac fermions in graphene and its multilayers
NASA Astrophysics Data System (ADS)
Yin, Long-Jing; Bai, Ke-Ke; Wang, Wen-Xiao; Li, Si-Yu; Zhang, Yu; He, Lin
2017-08-01
When electrons are confined in a two-dimensional (2D) system, typical quantum-mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and few-layer stacked crystals, are ideal 2D materials for studying a variety of quantum-mechanical problems. In this article, we review the experimental progress in the unusual Landau quantized behaviors of Dirac fermions in monolayer and multilayer graphene by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Through STS measurement of the strong magnetic fields, distinct Landau-level spectra and rich level-splitting phenomena are observed in different graphene layers. These unique properties provide an effective method for identifying the number of layers, as well as the stacking orders, and investigating the fundamentally physical phenomena of graphene. Moreover, in the presence of a strain and charged defects, the Landau quantization of graphene can be significantly modified, leading to unusual spectroscopic and electronic properties.
Duality symmetric quantization of superstrings
Kallosh, R.
1995-11-15
A general covariant quantization of a superparticle, Green-Schwarz superstring, and a supermembrane with manifest supersymmetry and duality symmetry is proposed. This quantization provides a natural quantum-mechanical description of curved BPS-type backgrounds related to the ultrashort supersymmetry multiplets. Half-size commuting and anticommuting Killing spinors admitted by such backgrounds in quantum theory become truncated {kappa}-symmetry ghosts. The symmetry of Killing spinors under dualities transfers to the symmetry of the spectrum of states. A GS superstring in the generalized semi-light-cone gauge can be quantized consistently in the background of ten-dimensional supersymmetric gravitational waves. Upon compactification they become supersymmetric electrically charged black holes, either massive or massless. However, the generalized light-cone gauge breaks {ital S} duality. We propose a new family of gauges, which we call black hole gauges. These gauges are suitable for quantization both in flat Minkowski space and in the black hole background, and they are duality symmetric. As an example, a manifestly {ital S}-duality symmetric black hole gauge is constructed in terms of the axion-dilaton-electric-magnetic black hole hair. We also suggest the {ital U}-duality covariant class of gauges for type II superstrings.
Light-cone quantization of quantum chromodynamics
Brodsky, S.J. ); Pauli, H.C. )
1991-06-01
We discuss the light-cone quantization of gauge theories from two perspectives: as a calculational tool for representing hadrons as QCD bound-states of relativistic quarks and gluons, and also as a novel method for simulating quantum field theory on a computer. The light-cone Fock state expansion of wavefunctions at fixed light cone time provides a precise definition of the parton model and a general calculus for hadronic matrix elements. We present several new applications of light-cone Fock methods, including calculations of exclusive weak decays of heavy hadrons, and intrinsic heavy-quark contributions to structure functions. A general nonperturbative method for numerically solving quantum field theories, discretized light-cone quantization,'' is outlined and applied to several gauge theories, including QCD in one space and one time dimension, and quantum electrodynamics in physical space-time at large coupling strength. The DLCQ method is invariant under the large class of light-cone Lorentz transformations, and it can be formulated such at ultraviolet regularization is independent of the momentum space discretization. Both the bound-state spectrum and the corresponding relativistic light-cone wavefunctions can be obtained by matrix diagonalization and related techniques. We also discuss the construction of the light-cone Fock basis, the structure of the light-cone vacuum, and outline the renormalization techniques required for solving gauge theories within the light-cone Hamiltonian formalism.
Interaction mechanisms and biological effects of static magnetic fields
Tenforde, T.S.
1994-06-01
Mechanisms through which static magnetic fields interact with living systems are described and illustrated by selected experimental observations. These mechanisms include electrodynamic interactions with moving, ionic charges (blood flow and nerve impulse conduction), magnetomechanical interactions (orientation and translation of molecules structures and magnetic particles), and interactions with electronic spin states in charge transfer reactions (photo-induced electron transfer in photosynthesis). A general summary is also presented of the biological effects of static magnetic fields. There is convincing experimental evidence for magnetoreception mechanisms in several classes of lower organisms, including bacteria and marine organisms. However, in more highly evolved species of animals, there is no evidence that the interactions of static magnetic fields with flux densities up to 2 Tesla (1 Tesla [T] = 10{sup 4} Gauss) produce either behavioral or physiolocical alterations. These results, based on controlled studies with laboratory animals, are consistent with the outcome of recent epidemiological surveys on human populations exposed occupationally to static magnetic fields.
Deformation of second and third quantization
NASA Astrophysics Data System (ADS)
Faizal, Mir
2015-03-01
In this paper, we will deform the second and third quantized theories by deforming the canonical commutation relations in such a way that they become consistent with the generalized uncertainty principle. Thus, we will first deform the second quantized commutator and obtain a deformed version of the Wheeler-DeWitt equation. Then we will further deform the third quantized theory by deforming the third quantized canonical commutation relation. This way we will obtain a deformed version of the third quantized theory for the multiverse.
Applications of Basis Light-Front Quantization to QED
NASA Astrophysics Data System (ADS)
Vary, James P.; Zhao, Xingbo; Ilderton, Anton; Honkanen, Heli; Maris, Pieter; Brodsky, Stanley J.
2014-06-01
Hamiltonian light-front quantum field theory provides a framework for calculating both static and dynamic properties of strongly interacting relativistic systems. Invariant masses, correlated parton amplitudes and time-dependent scattering amplitudes, possibly with strong external time-dependent fields, represent a few of the important applications. By choosing the light-front gauge and adopting an orthonormal basis function representation, we obtain a large, sparse, Hamiltonian matrix eigenvalue problem for mass eigenstates that we solve by adapting ab initio no-core methods of nuclear many-body theory. In the continuum limit, the infinite matrix limit, we recover full covariance. Guided by the symmetries of light-front quantized theory, we adopt a two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall anti-de Sitter/quantum chromodynamics (AdS/QCD) model obtained from light-front holography. We outline our approach and present results for non-linear Compton scattering, evaluated non-perturbatively, where a strong and time-dependent laser field accelerates the electron and produces states of higher invariant mass i.e. final states with photon emission.
Cold atom simulation of interacting relativistic quantum field theories.
Cirac, J Ignacio; Maraner, Paolo; Pachos, Jiannis K
2010-11-05
We demonstrate that Dirac fermions self-interacting or coupled to dynamic scalar fields can emerge in the low energy sector of designed bosonic and fermionic cold atom systems. We illustrate this with two examples defined in two spacetime dimensions. The first one is the self-interacting Thirring model. The second one is a model of Dirac fermions coupled to a dynamic scalar field that gives rise to the Gross-Neveu model. The proposed cold atom experiments can be used to probe spectral or correlation properties of interacting quantum field theories thereby presenting an alternative to lattice gauge theory simulations.
On the macroscopic quantization in mesoscopic rings and single-electron devices
NASA Astrophysics Data System (ADS)
Semenov, Andrew G.
2016-05-01
In this letter we investigate the phenomenon of macroscopic quantization and consider particle on the ring interacting with the dissipative bath as an example. We demonstrate that even in presence of environment, there is macroscopically quantized observable which can take only integer values in the zero temperature limit. This fact follows from the total angular momentum conservation combined with momentum quantization for bare particle on the ring. The nontrivial thing is that the model under consideration, including the notion of quantized observable, can be mapped onto the Ambegaokar-Eckern-Schon model of the single-electron box (SEB). We evaluate SEB observable, originating after mapping, and reveal new physics, which follows from the macroscopic quantization phenomenon and the existence of additional conservation law. Some generalizations of the obtained results are also presented.
Decoherence in an interacting quantum field theory: The vacuum case
Koksma, Jurjen F.; Prokopec, Tomislav; Schmidt, Michael G.
2010-03-15
We apply the decoherence formalism to an interacting scalar field theory. In the spirit of the decoherence literature, we consider a 'system field' and an 'environment field' that interact via a cubic coupling. We solve for the propagator of the system field, where we include the self-energy corrections due to the interaction with the environment field. In this paper, we consider an environment in the vacuum state (T=0). We show that neglecting inaccessible non-Gaussian correlators increases the entropy of the system as perceived by the observer. Moreover, we consider the effect of a changing mass of the system field in the adiabatic regime, and we find that at late times no additional entropy has been generated.
Wake Fields in the Super B Factory Interaction Region
Weathersby, Stephen; Novokhatski, Alexander; /SLAC
2011-06-02
The geometry of storage ring collider interaction regions present an impedance to beam fields resulting in the generation of additional electromagnetic fields (higher order modes or wake fields) which affect the beam energy and trajectory. These affects are computed for the Super B interaction region by evaluating longitudinal loss factors and averaged transverse kicks for short range wake fields. Results indicate at least a factor of 2 lower wake field power generation in comparison with the interaction region geometry of the PEP-II B-factory collider. Wake field reduction is a consderation in the Super B design. Transverse kicks are consistent with an attractive potential from the crotch nearest the beam trajectory. The longitudinal loss factor scales as the -2.5 power of the bunch length. A factor of 60 loss factor reduction is possible with crotch geometry based on an intersecting tubes model.
Compact and extended objects from self-interacting phantom fields
NASA Astrophysics Data System (ADS)
Dzhunushaliev, Vladimir; Folomeev, Vladimir; Makhmudov, Arislan; Urazalina, Ainur; Singleton, Douglas; Scott, John
2016-07-01
In this work, we investigate localized and extended objects for gravitating, self-interacting phantom fields. The phantom fields come from two scalar fields with a "wrong-sign" (negative) kinetic energy term in the Lagrangian. This study covers several solutions supported by these phantom fields: phantom balls, traversable wormholes, phantom cosmic strings, and "phantom" domain walls. These four systems are solved numerically, and we try to draw out general, interesting features in each case.
Context quantization by kernel Fisher discriminant.
Xu, Mantao; Wu, Xiaolin; Fränti, Pasi
2006-01-01
Optimal context quantizers for minimum conditional entropy can be constructed by dynamic programming in the probability simplex space. The main difficulty, operationally, is the resulting complex quantizer mapping function in the context space, in which the conditional entropy coding is conducted. To overcome this difficulty, we propose new algorithms for designing context quantizers in the context space based on the multiclass Fisher discriminant and the kernel Fisher discriminant (KFD). In particular, the KFD can describe linearly nonseparable quantizer cells by projecting input context vectors onto a high-dimensional curve, in which these cells become better separable. The new algorithms outperform the previous linear Fisher discriminant method for context quantization. They approach the minimum empirical conditional entropy context quantizer designed in the probability simplex space, but with a practical implementation that employs a simple scalar quantizer mapping function rather than a large lookup table.
Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings
Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan; Rousseau, Olivier; Otani, YoshiChika
2014-10-28
We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.
Magnetic quantization of s p3 bonding in monolayer gray tin
NASA Astrophysics Data System (ADS)
Chen, Szu-Chao; Wu, Chung-Lin; Wu, Jhao-Ying; Lin, Ming-Fa
2016-07-01
A generalized tight-binding model, which is based on the subenvelope functions of the different sublattices, is developed to explore the novel magnetic quantization in monolayer gray tin (tinene). The effects due to the s p3 bonding, the spin-orbital coupling, the magnetic field, and the electric field are simultaneously taken into consideration. The unique magnetoelectronic properties lie in two groups of low-lying Landau levels, with different orbital components, localization centers, state degeneracy, spin configurations, and magnetic- and electric-field dependencies. The first and second groups mainly come from the 5 pz and (5 px,5 py ) orbitals, respectively. Their Landau-level splittings are, respectively, induced by the electric field and spin-orbital interactions. The intragroup anticrossings are only revealed in the former. The unique tinene Landau levels are absent in graphene, silicene, and germanene.
NASA Astrophysics Data System (ADS)
Merad, M.
2006-05-01
We present, via the path-integral approach, the quantum study of a particle without spin constrained to move on a circle and subjected to the action of an external field (V, A). In the first stage, we follow the Faddeev-Senjanovic constraints technique that is essentially based on the Dirac algorithm; and in the second stage, we use the path-integral coherent state relative to the circle, compatible with the topological properties. In the two cases, the free particle and the problem of the magnetic field are shown as an illustrative calculation.
Thermal balance and photon-number quantization in layered structures
NASA Astrophysics Data System (ADS)
Partanen, Mikko; Häyrynen, Teppo; Oksanen, Jani; Tulkki, Jukka
2014-03-01
The quantization of the electromagnetic field in lossy and dispersive dielectric media has been widely studied during the last few decades. However, several aspects of energy transfer and its relation to consistently defining position-dependent ladder operators for the electromagnetic field in nonequilibrium conditions have partly escaped the attention. In this work we define the position-dependent ladder operators and an effective local photon-number operator that are consistent with the canonical commutation relations and use these concepts to describe the energy transfer and thermal balance in layered geometries. This approach results in a position-dependent photon-number concept that is simple and consistent with classical energy conservation arguments. The operators are formed by first calculating the vector potential operator using Green's function formalism and Langevin noise source operators related to the medium and its temperature, and then defining the corresponding position-dependent annihilation operator that is required to satisfy the canonical commutation relations in arbitrary geometry. Our results suggest that the effective photon number associated with the electric field is generally position dependent and enables a straightforward method to calculate the energy transfer rate between the field and the local medium. In particular, our results predict that the effective photon number in a vacuum cavity formed between two lossy material layers can oscillate as a function of the position suggesting that also the local field temperature oscillates. These oscillations are expected to be directly observable using relatively straightforward experimental setups in which the field-matter interaction is dominated by the coupling to the electric field. The approach also gives further insight on separating the photon ladder operators into the conventional right and left propagating parts and on the anomalies reported for the commutation relations of the
Analysis of magnetic field plasma interactions using microparticles as probes
NASA Astrophysics Data System (ADS)
Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin S.; Hyde, Truell W.
2015-08-01
The interaction between a magnetic field and plasma close to a nonconductive surface is of interest for both science and technology. In space, crustal magnetic fields on celestial bodies without atmosphere can interact with the solar wind. In advanced technologies such as those used in fusion or spaceflight, magnetic fields can be used to either control a plasma or protect surfaces exposed to the high heat loads produced by plasma. In this paper, a method will be discussed for investigating magnetic field plasma interactions close to a nonconductive surface inside a Gaseous Electronics Conference reference cell employing dust particles as probes. To accomplish this, a magnet covered by a glass plate was exposed to a low power argon plasma. The magnetic field was strong enough to magnetize the electrons, while not directly impacting the dynamics of the ions or the dust particles used for diagnostics. In order to investigate the interaction of the plasma with the magnetic field and the nonconductive surface, micron-sized dust particles were introduced into the plasma and their trajectories were recorded with a high-speed camera. Based on the resulting particle trajectories, the accelerations of the dust particles were determined and acceleration maps over the field of view were generated which are representative of the forces acting on the particles. The results show that the magnetic field is responsible for the development of strong electric fields in the plasma, in both horizontal and vertical directions, leading to complex motion of the dust particles.
Effective Field Theory of Interactions on the Lattice
NASA Astrophysics Data System (ADS)
Valiente, Manuel; Zinner, Nikolaj Thomas
2015-12-01
We consider renormalization of effective field theory interactions by discretizing the continuum on a tight-binding lattice. After studying the one-dimensional problem, we address s-wave collisions in three dimensions and relate the bare lattice coupling constants to the continuum coupling constants. Our method constitutes a very simple avenue for the systematic renormalization in effective field theory, and is especially useful as the number of interaction parameters increases.
Dimitriadis, Stavros; Sun, Yu; Laskaris, Nikolaos; Thakor, Nitish; Bezerianos, Anastasios
2016-10-01
Working memory (WM) is a distributed cognitive process that employs communication between prefrontal cortex and posterior brain regions in the form of cross-frequency coupling between theta ( θ) and high-alpha ( α2) brain waves. A novel method for deriving causal interactions between brain waves of different frequencies is essential for a better understanding of the neural dynamics of such complex cognitive process. Here, we proposed a novel method to estimate transfer entropy ( TE) through a symbolization scheme, which is based on neural-gas algorithm (NG) and encodes a bivariate time series in the form of two symbolic sequences. Given the symbolic sequences, the delay symbolic transfer entropy ( dSTE(NG)) is defined. Our approach is akin to standard symbolic transfer entropy ( STE) that incorporates the ordinal pattern (OP) symbolization technique. We assessed the proposed method in a WM-invoked paradigm that included a mental arithmetic task at various levels of difficulty. Effective interactions between Frontal(θ) ( F(θ) ) and [Formula: see text] ( PO(α2)) brain waves were detected in multichannel EEG recordings from 16 subjects. Compared with conventional methods, our technique was less sensitive to noise and demonstrated improved computational efficiency in quantifying the dominating direction of effective connectivity between brain waves of different spectral content. Moreover, we discovered an efferent F(θ) connectivity pattern and an afferent PO(α2) one, in all the levels of the task. Further statistical analysis revealed an increasing dSTE(NG) strength following the task's difficulty.
Strong-Field THz Interactions with Wavepackets
NASA Astrophysics Data System (ADS)
Bucksbaum, Philip H.
1998-03-01
Intense THz radiation from photoconducting antennas are particularly useful for manipulating the structure and dynamics of atomic and molecular Rydberg states. We have used sub-picosecond ``half-cycle'' field pulses to follow both the radial(C. Raman, C.W.S. Conover, C.I. Sukenik, and P. H. Bucksbaum, Physical Review Letters 76), 2436 (1996). and angular motion(C.S. Raman, T.C. Weinacht, and P.H. Bucksbaum, Physical Review A 55), R3995-8 (1997). of wavepackets. The impulse imparted to an atomic electron by these pulses can also be used to produce or alter wavepacket motion. The THz radiation can be shaped by modulating optical radiation which photo-excites the antenna.(A. S. Weling et al., Appl. Phys. Lett. 64), 137, 1994. In this way we have produced intense tunable narrow-band THz radiation, which was employed to study population transfer in strongly driven Rydberg systems.(C. Raman, M. F. DeCamp and P. H. Bucksbaum, Optics Express 1) 186 (1997). The same techniques is used to arbitrarily adjust the intensity envelope of the THz pulse, alter its central frequency over a wide range, and to produce and control dispersion. When combined with active pulse-shaping and adaptive feedback techniques, wavepacket shapes and dispersion properties can be controlled.
Quantization of Multiply Connected Manifolds
NASA Astrophysics Data System (ADS)
Hawkins, Eli
2005-04-01
The standard (Berezin-Toeplitz) geometric quantization of a compact Kähler manifold is restricted by integrality conditions. These restrictions can be circumvented by passing to the universal covering space, provided that the lift of the symplectic form is exact. I relate this construction to the Baum-Connes assembly map and prove that it gives a strict quantization of the original manifold. I also propose a further generalization, classify the required structure, and provide a means of computing the resulting algebras. These constructions involve twisted group C*-algebras of the fundamental group which are determined by a group cocycle constructed from the cohomology class of the symplectic form. This provides an algebraic counterpart to the Morita equivalence of a symplectic manifold with its fundamental group.
Seating Position and Interaction in Triads: A Field Study
ERIC Educational Resources Information Center
Silverstein, C. Harris; Stang, David J.
1976-01-01
Relationships between seating position, length of acquaintance between subjects, observer bias toward the experimental outcome, and interaction rates are examined in a field study. Subjects with greatest visual centrality spoke most often. Length of acquaintance between subjects was unrelated to interaction rates. (Author/DEP)
Quantum field theory on timelike hypersurfaces in Rindler space
NASA Astrophysics Data System (ADS)
Colosi, Daniele; Rätzel, Dennis
2013-06-01
The general boundary formulation of quantum field theory is applied to a massive scalar field in two-dimensional Rindler space. The field is quantized according to both the Schrödinger-Feynman quantization prescription and the holomorphic one in two different spacetime regions: a region bounded by two Cauchy surfaces and a region bounded by one timelike curve. An isomorphism is constructed between the Hilbert spaces associated with these two boundaries. This isomorphism preserves the probabilities that can be extracted from the free and the interacting quantum field theories, proving the equivalence of the S-matrices defined in the two settings, when both apply.
Derivative self-interactions for a massive vector field
NASA Astrophysics Data System (ADS)
Beltrán Jiménez, Jose; Heisenberg, Lavinia
2016-06-01
In this work we revisit the construction of theories for a massive vector field with derivative self-interactions such that only the 3 desired polarizations corresponding to a Proca field propagate. We start from the decoupling limit by constructing healthy interactions containing second derivatives of the Stueckelberg field with itself and also with the transverse modes. The resulting interactions can then be straightforwardly generalized beyond the decoupling limit. We then proceed to a systematic construction of the interactions by using the Levi-Civita tensors. Both approaches lead to a finite family of allowed derivative self-interactions for the Proca field. This construction allows us to show that some higher order terms recently introduced as new interactions trivialize in 4 dimensions by virtue of the Cayley-Hamilton theorem. Moreover, we discuss how the resulting derivative interactions can be written in a compact determinantal form, which can also be regarded as a generalization of the Born-Infeld lagrangian for electromagnetism. Finally, we generalize our results for a curved background and give the necessary non-minimal couplings guaranteeing that no additional polarizations propagate even in the presence of gravity.
Point-form quantum field theory
Biernat, E.P. Klink, W.H. Schweiger, W. Zelzer, S.
2008-06-15
We examine canonical quantization of relativistic field theories on the forward hyperboloid, a Lorentz-invariant surface of the form x{sub {mu}}x{sup {mu}} = {tau}{sup 2}. This choice of quantization surface implies that all components of the 4-momentum operator are affected by interactions (if present), whereas rotation and boost generators remain interaction free-a feature characteristic of Dirac's 'point-form' of relativistic dynamics. Unlike previous attempts to quantize fields on space-time hyperboloids, we keep the usual plane-wave expansion of the field operators and consider evolution of the system generated by the 4-momentum operator. We verify that the Fock-space representations of the Poincare generators for free scalar and spin-1/2 fields look the same as for equal-time quantization. Scattering is formulated for interacting fields in a covariant interaction picture and it is shown that the familiar perturbative expansion of the S-operator is recovered by our approach. An appendix analyzes special distributions, integrals over the forward hyperboloid, that are used repeatedly in the paper.
Effects of an electric field on interaction of aromatic systems.
Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S
2016-04-30
The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc.
Cellular studies and interaction mechanisms of extremely low frequency fields
NASA Astrophysics Data System (ADS)
Liburdy, Robert P.
1995-01-01
Worldwide interest in the biological effects of ELF (extremely low frequency, <1 kHz) electromagnetic fields has grown significantly. Health professionals and government administrators and regulators, scientists and engineers, and, importantly, an increasing number of individuals in the general public are interested in this health issue. The goal of research at the cellular level is to identify cellular responses to ELF fields, to develop a dose threshold for such interactions, and with such information to formulate and test appropriate interaction mechanisms. This review is selective and will discuss the most recent cellular studies directed at these goals which relate to power line, sinusoidal ELF fields. In these studies an interaction site at the cell membrane is by consensus a likely candidate, since changes in ion transport, ligand-receptor events such as antibody binding, and G protein activation have been reported. These changes strongly indicate that signal transduction (ST) can be influenced. Also, ELF fields are reported to influence enzyme activation, gene expression, protein synthesis, and cell proliferation, which are triggered by earlier ST events at the cell membrane. The concept of ELF fields altering early cell membrane events and thereby influencing intracellular cell function via the ST cascade is perhaps the most plausible biological framework currently being investigated for understanding ELF effects on cells. For example, the consequence of an increase due to ELF fields in mitogenesis, the final endpoint of the ST cascade, is an overall increase in the probability of mutagenesis and consequently cancer, according to the Ames epigenetic model of carcinogenesis. Consistent with this epigenetic mechanism and the ST pathway to carcinogenesis is recent evidence that ELF fields can alter breast cancer cell proliferation and can act as a copromoter in vitro. The most important dosimetric question being addressed currently is whether the electric (E
NASA Astrophysics Data System (ADS)
Faraji, Elham; Baghshahi, Hamid Reza; Tavassoly, Mohammad Kazem
2017-02-01
In this paper, the non-resonant interaction of two two-level atoms with two quantized cavity fields is studied by considering the dipole-dipole interaction between the two atoms. The correlation between the fields has been taken into account and the parametric down conversion is considered. Under certain initial conditions which is determined for the atoms and the fields, the analytical solution for the time-dependent Schrödinger equation is obtained. Employing this solution, we are able to discuss about some physical properties such as atomic population inversion and entanglement between various subsystems, i.e. “atoms-fields” and “atom-atom” by using respectively von Neumann entropy and negativity. It is deduced from the numerical results that, the mentioned quantities can be controlled by the atomic dipole-dipole interaction and detuning parameter, appropriately. The results show that the degree of entanglement between the two atoms is increased due to the presence of dipole-dipole coupling of the atoms at the beginning of atom-field interaction. Furthermore, it is found that, in the non-resonance condition, the so-called entanglement sudden death occurs in the presence of dipole-dipole interaction.
Vector Quantization With Emergent Codebook Structure
NASA Technical Reports Server (NTRS)
Ahalt, Stanley C.; Krishnamurthy, Ashok
1993-01-01
Proposed scheme under development for transmission of vector-quantized digital video images, vector quantizer codebook updated to adapt quantizer to changing signal statistics. Intended to be realized with electronic neural network. Codebook, which consists of patterns constituting video images, will undergo training during operation and scheme will develop codebooks ordered during training. System enables coding more compact, more immune to noise, and supports variable rate compression.
Exact quantization conditions for cluster integrable systems
NASA Astrophysics Data System (ADS)
Franco, Sebastián; Hatsuda, Yasuyuki; Mariño, Marcos
2016-06-01
We propose exact quantization conditions for the quantum integrable systems of Goncharov and Kenyon, based on the enumerative geometry of the corresponding toric Calabi-Yau manifolds. Our conjecture builds upon recent results on the quantization of mirror curves, and generalizes a previous proposal for the quantization of the relativistic Toda lattice. We present explicit tests of our conjecture for the integrable systems associated to the resolved {{{C}}3}/{{{Z}}5} and {{{C}}3}/{{{Z}}6} orbifolds.
Quantized-"Gray-Scale" Electronic Synapses
NASA Technical Reports Server (NTRS)
Lamb, James L.; Daud, Taher; Thakoor, Anilkumar P.
1990-01-01
Proposed array of programmable synaptic connections for electronic neural network applications offers multiple quantized levels of connection strength using only simple, two-terminal, binary microswitch devices. Subgrids in fine grid of programmable resistive connections connected externally in parallel to form coarser synaptic grid. By selection of pattern of connections in each subgrid, connection strength of synaptic node represented by that subgrid set at quantized "gray level". Device structures promise implementations of quantized-"gray-scale" synaptic arrays with very high density.
Quantized-"Gray-Scale" Electronic Synapses
NASA Technical Reports Server (NTRS)
Lamb, James L.; Daud, Taher; Thakoor, Anilkumar P.
1990-01-01
Proposed array of programmable synaptic connections for electronic neural network applications offers multiple quantized levels of connection strength using only simple, two-terminal, binary microswitch devices. Subgrids in fine grid of programmable resistive connections connected externally in parallel to form coarser synaptic grid. By selection of pattern of connections in each subgrid, connection strength of synaptic node represented by that subgrid set at quantized "gray level". Device structures promise implementations of quantized-"gray-scale" synaptic arrays with very high density.
Plasma-satellite interaction driven magnetic field perturbations
Saeed-ur-Rehman; Marchand, Richard
2014-09-15
We report the first fully kinetic quantitative estimate of magnetic field perturbations caused by the interaction of a spacecraft with space environment. Such perturbations could affect measurements of geophysical magnetic fields made with very sensitive magnetometers on-board satellites. Our approach is illustrated with a calculation of perturbed magnetic fields near the recently launched Swarm satellites. In this case, magnetic field perturbations do not exceed 20 pT, and they are below the sensitivity threshold of the on-board magnetometers. Anticipating future missions in which satellites and instruments would be subject to more intense solar UV radiation, however, it appears that magnetic field perturbations associated with satellite interaction with space environment, might approach or exceed instruments' sensitivity thresholds.
Lattice radial quantization: 3D Ising
NASA Astrophysics Data System (ADS)
Brower, R. C.; Fleming, G. T.; Neuberger, H.
2013-04-01
Lattice radial quantization is introduced as a nonperturbative method intended to numerically solve Euclidean conformal field theories that can be realized as fixed points of known Lagrangians. As an example, we employ a lattice shaped as a cylinder with a 2D Icosahedral cross-section to discretize dilatations in the 3D Ising model. Using the integer spacing of the anomalous dimensions of the first two descendants (l = 1, 2), we obtain an estimate for η = 0.034 (10). We also observed small deviations from integer spacing for the 3rd descendant, which suggests that a further improvement of our radial lattice action will be required to guarantee conformal symmetry at the Wilson-Fisher fixed point in the continuum limit.
Topics in the semiclassical quantization of gravitation
Ratra, B.V.
1986-01-01
Three problems are discussed in which general coordinate covariance and quantum mechanics play fundamental roles. A functional approach to scalar quantum field theory in n + 1 dimensional de Sitter spacetime is formulated, and the functional Schroedinger equation is solved for the conformally and minimally coupled scalar fields in both the k = 0 and k = 1 gauges. It is shown that there is a natural initial condition, the requirement that the field energy remain finite as the scale factor a becomes small, which specifies a unique, time-dependent, de Sitter vacuum state. It is argued that spontaneously broken continuous symmetries are always dynamically restored in de Sitter spacetime. Second, the author discusses the canonical quantization of gravitation in the vielbein formalism and derives the Harrison-Zeldovich spectrum by perturbatively solving the Wheeler-DeWitt equations for an inflating universe coupled to a scalar field in 2 + 1 and 3 + 1 dimensions. Finally, he presents a gauge invariant action that describes the propagation of the superstring in curves superspace in the presence of background super Yang-Mills fields. It is shown that this action possesses the local fermionic world sheet symmetry needed for a consistent coupling of the string to background fields. Some other aspects of the superspace nonlinear sigma-model described by this action are also discussed.
Berezin-Toeplitz Quantization and Berezin Transform
NASA Astrophysics Data System (ADS)
Schlichenmaier, Martin
2001-04-01
In this lecture results on the Berezin-Toeplitz quantization of arbitrary compact quantizable Kähler manifolds are presented. These results are obtained in joint work with M. Bordemann and E. Meinrenken. The existence of the Berezin-Toeplitz deformation quantization is also covered. Recent results obtained in joint work with A. Karabegov on the asymptotic expansion of the Berezin transform for arbitrary quantizable compact Kähler manifolds are explained. As an application the asymptotic expansion of the Fubini-Study fundamental form under the coherent state embedding is considered. Some comments on the dynamics of the quantum operators are given.
Adaptive scalar quantization without side information.
Ortega, A; Vetterli, M
1997-01-01
In this paper, we introduce a novel technique for adaptive scalar quantization. Adaptivity is useful in applications, including image compression, where the statistics of the source are either not known a priori or will change over time. Our algorithm uses previously quantized samples to estimate the distribution of the source, and does not require that side information be sent in order to adapt to changing source statistics. Our quantization scheme is thus backward adaptive. We propose that an adaptive quantizer can be separated into two building blocks, namely, model estimation and quantizer design. The model estimation produces an estimate of the changing source probability density function, which is then used to redesign the quantizer using standard techniques. We introduce nonparametric estimation techniques that only assume smoothness of the input distribution. We discuss the various sources of error in our estimation and argue that, for a wide class of sources with a smooth probability density function (pdf), we provide a good approximation to a "universal" quantizer, with the approximation becoming better as the rate increases. We study the performance of our scheme and show how the loss due to adaptivity is minimal in typical scenarios. In particular, we provide examples and show how our technique can achieve signal-to-noise ratios within 0.05 dB of the optimal Lloyd-Max quantizer for a memoryless source, while achieving over 1.5 dB gain over a fixed quantizer for a bimodal source.
Can one ADM quantize relativistic bosonicstrings and membranes?
NASA Astrophysics Data System (ADS)
Moncrief, Vincent
2006-04-01
The standard methods for quantizing relativistic strings diverge significantly from the Dirac-Wheeler-DeWitt program for quantization of generally covariant systems and one wonders whether the latter could be successfully implemented as an alternative to the former. As a first step in this direction, we consider the possibility of quantizing strings (and also relativistic membranes) via a partially gauge-fixed ADM (Arnowitt, Deser and Misner) formulation of the reduced field equations for these systems. By exploiting some (Euclidean signature) Hamilton-Jacobi techniques that Mike Ryan and I had developed previously for the quantization of Bianchi IX cosmological models, I show how to construct Diff( S 1)-invariant (or Diff(Σ)-invariant in the case of membranes) ground state wave functionals for the cases of co-dimension one strings and membranes embedded in Minkowski spacetime. I also show that the reduced Hamiltonian density operators for these systems weakly commute when applied to physical (i.e. Diff( S 1) or Diff(Σ)-invariant) states. While many open questions remain, these preliminary results seem to encourage further research along the same lines.
Light-Front Quantized Chiral Model and its Vacuum Structure
Srivastava, Prem P.
1998-11-30
The bosonized Chiral Schwinger model (CSM) is quantized on the light-front (LF). The physical Hilbert space of CSM is obtained directly once the constraints on the LF phase space are eliminated. The discussion of the degenerate vacua and the absence in the CSM of the theta-vacua, as found in the Schwinger model (SM), becomes straightforward. The differences in the structures of the mass excitations and the vacua in these gauge theories are displayed transparently. The procedure followed is the one used successfully in the previous works for describing the spontaneous symmetry breaking (SSB) and the SM on the LF. The physical contents following from the LF quantized theory agree with those known in the conventional treatment. The LF hyperplane is argued to be equally appropriate as the conventional equal-time one for the canonical quantization. Some comments on the irrelevance, in quantized field theory, of the fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of hyperbolic partial differential equation are also made.
Field theories and exact stochastic equations for interacting particle systems
Andreanov, Alexei; Lefevre, Alexandre; Biroli, Giulio; Bouchaud, Jean-Philippe
2006-09-15
We consider the dynamics of interacting particles with reaction and diffusion. Starting from the underlying discrete stochastic jump process we derive a general field theory describing the dynamics of the density field, which we relate to an exact stochastic equation on the density field. We show how our field theory maps onto the original Doi-Peliti formalism, allowing us to clarify further the issue of the 'imaginary' Langevin noise that appears in the context of reaction-diffusion processes. Our procedure applies to a wide class of problems and is related to large deviation functional techniques developed recently to describe fluctuations of nonequilibrium systems in the hydrodynamic limit.
Quantum Monte Carlo calculations with chiral effective field theory interactions.
Gezerlis, A; Tews, I; Epelbaum, E; Gandolfi, S; Hebeler, K; Nogga, A; Schwenk, A
2013-07-19
We present the first quantum Monte Carlo (QMC) calculations with chiral effective field theory (EFT) interactions. To achieve this, we remove all sources of nonlocality, which hamper the inclusion in QMC calculations, in nuclear forces to next-to-next-to-leading order. We perform auxiliary-field diffusion Monte Carlo (AFDMC) calculations for the neutron matter energy up to saturation density based on local leading-order, next-to-leading order, and next-to-next-to-leading order nucleon-nucleon interactions. Our results exhibit a systematic order-by-order convergence in chiral EFT and provide nonperturbative benchmarks with theoretical uncertainties. For the softer interactions, perturbative calculations are in excellent agreement with the AFDMC results. This work paves the way for QMC calculations with systematic chiral EFT interactions for nuclei and nuclear matter, for testing the perturbativeness of different orders, and allows for matching to lattice QCD results by varying the pion mass.
Vector quantization for volume rendering
NASA Technical Reports Server (NTRS)
Ning, Paul; Hesselink, Lambertus
1992-01-01
Volume rendering techniques typically process volumetric data in raw, uncompressed form. As algorithmic and architectural advances improve rendering speeds, however, larger data sets will be evaluated requiring consideration of data storage and transmission issues. In this paper, we analyze the data compression requirements for volume rendering applications and present a solution based on vector quantization. The proposed system compresses volumetric data and then renders images directly from the new data format. Tests on a fluid flow data set demonstrate that good image quality may be achieved at a compression ratio of 17:1 with only a 5 percent cost in additional rendering time.
Shape Invariance in Deformation Quantization
NASA Astrophysics Data System (ADS)
Rasinariu, Constantin
2013-03-01
Shape invariance is a powerful solvability condition, that allows for complete knowledge of the energy spectrum, and eigenfunctions of a system. After a short introduction into the deformation quantization formalism, this work explores the implications of the supersymmetric quantum mechanics and shape invariance techniques to the phase space formalism. We show that shape invariance induces a new set of relations between the Wigner functions of the system, that allows for their direct calculation, once we know one of them. The simple harmonic oscillator and the Morse potential are presented as examples. I would like to acknowledge a sabbatical leave and grant from Columbia College Chicago that made this work possible.
Weyl quantization of fractional derivatives
Tarasov, Vasily E.
2008-10-15
The quantum analogs of the derivatives with respect to coordinates q{sub k} and momenta p{sub k} are commutators with operators P{sub k} and Q{sub k}. We consider quantum analogs of fractional Riemann-Liouville and Liouville derivatives. To obtain the quantum analogs of fractional Riemann-Liouville derivatives, which are defined on a finite interval of the real axis, we use a representation of these derivatives for analytic functions. To define a quantum analog of the fractional Liouville derivative, which is defined on the real axis, we can use the representation of the Weyl quantization by the Fourier transformation.
`Third' Quantization of Vacuum Einstein Gravity and Free Yang-Mills Theories
NASA Astrophysics Data System (ADS)
Raptis, Ioannis
2007-05-01
Certain pivotal results from various applications of Abstract Differential Geometry (ADG) to gravity and gauge theories are presently collected and used to argue that we already possess a geometrically (pre)quantized, second quantized and manifestly background spacetime manifold independent vacuum Einstein gravitational field dynamics. The arguments carry also mutatis mutandis to the case of free Yang-Mills theories, since from the ADG-theoretic perspective gravity is regarded as another gauge field theory. The powerful algebraico-categorical, sheaf cohomological conceptual and technical machinery of ADG is then employed, based on the fundamental ADG-theoretic conception of a field as a pair ({mathcal{E}},{mathcal{D}}) consisting of a vector sheaf {mathcal{E}} and an algebraic connection {mathcal{D}} acting categorically as a sheaf morphism on {mathcal{E}}'s local sections, to introduce a ‘universal’, because expressly functorial, field quantization scenario coined third quantization. Although third quantization is fully covariant, on intuitive and heuristic grounds alone it formally appears to follow a canonical route; albeit, in a purely algebraic and, in contradistinction to geometric (pre)quantization and (canonical) second quantization, manifestly background geometrical spacetime manifold independent fashion, as befits ADG. All in all, from the ADG-theoretic vantage, vacuum Einstein gravity and free Yang-Mills theories are regarded as external spacetime manifold unconstrained, third quantized, pure gauge field theories. The paper abounds with philosophical smatterings and speculative remarks about the potential import and significance of our results to current and future Quantum Gravity research. A postscript gives a brief account of this author's personal encounters with Rafael Sorkin and his work.
Interaction of dynamical fractional branes with background fields: Superstring calculations
NASA Astrophysics Data System (ADS)
Saidy-Sarjoubi, Maryam; Kamani, Davoud
2017-05-01
We compute the boundary state corresponding to a fractional Dp-brane with transverse motion and internal background fields: Kalb-Ramond and a U(1) gauge field. The space-time has the orbifold structure ℝ1,5 × ℂ2/ℤ 2. The calculations are in the superstring theory. Using this boundary state we shall obtain the interaction amplitude between two parallel moving fractional Dp-branes. We shall extract behavior of the interaction amplitude for large distances of the branes.
Suppressing photochemical reactions with quantized light fields
Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes
2016-01-01
Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction. PMID:27941754
Suppressing photochemical reactions with quantized light fields
NASA Astrophysics Data System (ADS)
Galego, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes
2016-12-01
Photoisomerization, that is, a photochemical reaction leading to a change of molecular structure after absorption of a photon, can have detrimental effects such as leading to DNA damage under solar irradiation, or as a limiting factor for the efficiency of solar cells. Here, we show that strong coupling of organic molecules to a confined light mode can be used to strongly suppress photoisomerization, as well as other photochemical reactions, and thus convert molecules that normally show fast photodegradation into photostable forms. We find this to be especially efficient in the case of collective strong coupling, where the distribution of a single excitation over many molecules and the light mode leads to a collective protection effect that almost completely suppresses the photochemical reaction.
Finite- to zero-range relativistic mean-field interactions
Niksic, T.; Vretenar, D.; Lalazissis, G. A.; Ring, P.
2008-03-15
We study the relation between the finite-range (meson-exchange) and zero-range (point-coupling) representations of effective nuclear interactions in the relativistic mean-field framework. Starting from the phenomenological interaction DD-ME2 with density-dependent meson-nucleon couplings, we construct a family of point-coupling effective interactions for different values of the strength parameter of the isoscalar-scalar derivative term. In the meson-exchange picture this corresponds to different values of the {sigma}-meson mass. The parameters of the isoscalar-scalar and isovector-vector channels of the point-coupling interactions are adjusted to nuclear matter and ground-state properties of finite nuclei. By comparing results for infinite and semi-infinite nuclear matter, ground-state masses, charge radii, and collective excitations, we discuss constraints on the parameters of phenomenological point-coupling relativistic effective interaction.
Experimental evidence for a two-dimensional quantized Hall insulator
NASA Astrophysics Data System (ADS)
Hilke, M.; Shahar, D.; Song, S. H.; Tsui, D. C.; Xie, Y. H.; Monroe, Don
1998-10-01
The general theoretical definition of an insulator is a material in which the conductivity vanishes at the absolute zero of temperature. In classical insulators, such as materials with a band gap, vanishing conductivities lead to diverging resistivities. But other insulators can show more complex behaviour, particularly in the presence of a high magnetic field, where different components of the resistivity tensor can display different behaviours: the magnetoresistance diverges as the temperature approaches absolute zero, but the transverse (Hall) resistance remains finite. Such a system is known as a Hall insulator. Here we report experimental evidence for a quantized Hall insulator in a two-dimensional electron system-confined in a semiconductor quantum well. The Hall resistance is quantized in the quantum unit of resistance h/e2, where h is Planck's constant and e the electronic charge. At low fields, the sample reverts to being a normal Hall insulator.
The Quantization of the E ⊗ e Jahn-Teller Hamiltonian.
Arvanitidis, Athanasios G; Vandaele, Eva R J; Szopa, Marek; Ceulemans, Arnout
2017-09-18
The E ⊗ e Jahn-Teller Hamiltonian in the Bargmann-Fock representation gives rise to a system of two coupled first-order differential equations in the complex field, which may be rewritten in the Birkhoff standard form. General leapfrog recurrence relations are derived, from which the quantized solutions of these equations can be obtained. The results are compared to the analogous quantization scheme for the Rabi Hamiltonian.
The method of Ostrogradsky, quantization, and a move toward a ghost-free future
Nucci, M C; Leach, P G L
2009-11-15
The method of Ostrogradsky has been used to construct a first-order Lagrangian, hence Hamiltonian, for the fourth-order field-theoretical model of Pais-Uhlenbeck with unfortunate results when quantization is undertaken since states with negative norm, commonly called ''ghosts,'' appear. We propose an alternative route based on the preservation of symmetry and this leads to a ghost-free quantization.
Weak associativity and deformation quantization
NASA Astrophysics Data System (ADS)
Kupriyanov, V. G.
2016-09-01
Non-commutativity and non-associativity are quite natural in string theory. For open strings it appears due to the presence of non-vanishing background two-form in the world volume of Dirichlet brane, while in closed string theory the flux compactifications with non-vanishing three-form also lead to non-geometric backgrounds. In this paper, working in the framework of deformation quantization, we study the violation of associativity imposing the condition that the associator of three elements should vanish whenever each two of them are equal. The corresponding star products are called alternative and satisfy important for physical applications properties like the Moufang identities, alternative identities, Artin's theorem, etc. The condition of alternativity is invariant under the gauge transformations, just like it happens in the associative case. The price to pay is the restriction on the non-associative algebra which can be represented by the alternative star product, it should satisfy the Malcev identity. The example of nontrivial Malcev algebra is the algebra of imaginary octonions. For this case we construct an explicit expression of the non-associative and alternative star product. We also discuss the quantization of Malcev-Poisson algebras of general form, study its properties and provide the lower order expression for the alternative star product. To conclude we define the integration on the algebra of the alternative star products and show that the integrated associator vanishes.
Weighted Bergman Kernels and Quantization}
NASA Astrophysics Data System (ADS)
Engliš, Miroslav
Let Ω be a bounded pseudoconvex domain in CN, φ, ψ two positive functions on Ω such that - log ψ, - log φ are plurisubharmonic, and z∈Ω a point at which - log φ is smooth and strictly plurisubharmonic. We show that as k-->∞, the Bergman kernels with respect to the weights φkψ have an asymptotic expansion
Integral quantizations with two basic examples
Bergeron, H.; Gazeau, J.P.
2014-05-15
The paper concerns integral quantization, a procedure based on operator-valued measure and resolution of the identity. We insist on covariance properties in the important case where group representation theory is involved. We also insist on the inherent probabilistic aspects of this classical–quantum map. The approach includes and generalizes coherent state quantization. Two applications based on group representation are carried out. The first one concerns the Weyl–Heisenberg group and the euclidean plane viewed as the corresponding phase space. We show that a world of quantizations exist, which yield the canonical commutation rule and the usual quantum spectrum of the harmonic oscillator. The second one concerns the affine group of the real line and gives rise to an interesting regularization of the dilation origin in the half-plane viewed as the corresponding phase space. -- Highlights: •Original approach to quantization based on (positive) operator-valued measures. •Includes Berezin–Klauder–Toeplitz and Weyl–Wigner quantizations. •Infinitely many such quantizations produce canonical commutation rule. •Set of objects to be quantized is enlarged in order to include singular functions or distributions. •Are given illuminating examples like quantum angle and affine or wavelet quantization.
Causal Poisson bracket via deformation quantization
NASA Astrophysics Data System (ADS)
Berra-Montiel, Jasel; Molgado, Alberto; Palacios-García, César D.
2016-06-01
Starting with the well-defined product of quantum fields at two spacetime points, we explore an associated Poisson structure for classical field theories within the deformation quantization formalism. We realize that the induced star-product is naturally related to the standard Moyal product through an appropriate causal Green’s functions connecting points in the space of classical solutions to the equations of motion. Our results resemble the Peierls-DeWitt bracket that has been analyzed in the multisymplectic context. Once our star-product is defined, we are able to apply the Wigner-Weyl map in order to introduce a generalized version of Wick’s theorem. Finally, we include some examples to explicitly test our method: the real scalar field, the bosonic string and a physically motivated nonlinear particle model. For the field theoretic models, we have encountered causal generalizations of the creation/annihilation relations, and also a causal generalization of the Virasoro algebra for the bosonic string. For the nonlinear particle case, we use the approximate solution in terms of the Green’s function, in order to construct a well-behaved causal bracket.
Background independent noncommutative gravity from Fedosov quantization of endomorphism bundle
NASA Astrophysics Data System (ADS)
Dobrski, Michał
2017-04-01
A model of noncommutative gravity is constructed by means of Fedosov deformation quantization of an endomorphism bundle. The fields describing noncommutativity—symplectic form and symplectic connection—are dynamical, and the resulting theory is coordinate covariant and background independent. Its interpretation in terms of a Seiberg–Witten map is provided. Also, a new action for ordinary (commutative) general relativity is given, which in the present context appears as a commutative limit of noncommutative theory.
Energy released by the interaction of coronal magnetic fields
NASA Technical Reports Server (NTRS)
Sheeley, N. R., Jr.
1976-01-01
Comparisons between coronal spectroheliograms and photospheric magnetograms are presented to support the idea that as coronal magnetic fields interact, a process of field-line reconnection usually takes place as a natural way of preventing magnetic stresses from building up in the lower corona. This suggests that the energy which would have been stored in stressed fields is continuously released as kinetic energy of material being driven aside to make way for the reconnecting fields. However, this kinetic energy is negligible compared with the thermal energy of the coronal plasma. Therefore, it appears that these slow adjustments of coronal magnetic fields cannot account for even the normal heating of the corona, much less the energetic events associated with solar flares.
Plasma effects in electromagnetic field interaction with biological tissue
NASA Astrophysics Data System (ADS)
Sharma, R. P.; Batra, Karuna; Excell, Peter S.
2011-02-01
Theoretical analysis is presented of the nonlinear behavior of charge carriers in biological tissue under the influence of varying low-intensity electromagnetic (EM) field. The interaction occurs because of the nonlinear force arising due to the gradient of the EM field intensity acting on free electrons in the conduction band of proteins in metabolically active biological cell membrane receptors leading to a redistribution of charge carriers. Field dependence of the resulting dielectric constant is investigated by a suitable modification to include an additional electronic contribution term to the three-term Debye model. The exogenous EM field propagating in this nonlinear cellular medium satisfies the nonlinear Schrödinger equation and can be affected significantly. Resulting field effect can be substantially augmented and effective rectification/demodulation can occur. Possible implications of this modification on biological processes in white and grey matter are discussed.
Strongly interacting photons in a synthetic magnetic field
NASA Astrophysics Data System (ADS)
Roushan, Pedram; Neill, C.; Megrant, A.; Chen, Y.; Barends, R.; Cambell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Fowler, A.; Jeffrey, E.; Kelly, J.; Lucero, E.; Mutus, J.; O'Malley, P.; Neeley, M.; Quintana, C.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T.; Kapit, E.; Martinis, J.
Interacting electrons in the presence of magnetic fields exhibit some of the most fascinating phases in condensed matter systems. Realizing these phases in an engineered platform could provide deeper insight into their. Using three superconducting qubits, we synthesize artificial magnetic fields by modulating the inter-qubit coupling. In the closed loop formed by the qubits, we observe the directional circulation of a microwave photon as well as chiral groundstate currents, the signatures of broken time-reversal symmetry. The existence of strong interactions in our system is seen via the creation of photon vacancies, or ''holes'', which circulate in the opposite direction from the photons. Our work demonstrates an experimental approach for engineering quantum phases of strongly interacting bosons.
Kinetic Interactions Between the Solar Wind and Lunar Magnetic Fields
NASA Astrophysics Data System (ADS)
Halekas, J. S.; Poppe, A. R.; Fatemi, S.; Turner, D. L.; Holmstrom, M.
2016-12-01
Despite their relatively weak strength, small scale, and incoherence, lunar magnetic anomalies can affect the incoming solar wind flow. The plasma interaction with lunar magnetic fields drives significant compressions of the solar wind plasma and magnetic field, deflections of the incoming flow, and a host of plasma waves ranging from the ULF to the electrostatic range. Recent work suggests that the large-scale features of the solar wind-magnetic anomaly interactions may be driven by ion-ion instabilities excited by reflected ions, raising the possibility that they are analogous to ion foreshock phenomena. Indeed, despite their small scale, many of the phenomena observed near lunar magnetic anomalies appear to have analogues in the foreshock regions of terrestrial planets. We discuss the charged particle distributions, fields, and waves observed near lunar magnetic anomalies, and place them in a context with the foreshocks of the Earth, Mars, and other solar system objects.
Pomeron-Odderon interactions in a Reggeon field theory
NASA Astrophysics Data System (ADS)
Bartels, Jochen; Contreras, Carlos; Vacca, Gian Paolo
2017-01-01
In this paper we extend our recent nonperturbative functional renormalization group analysis of Reggeon field theory to the interactions of Pomeron and Odderon fields. We establish the existence of a fixed point and its universal properties, which exhibits a novel symmetry structure in the space of Odderon-Pomeron interactions. As in our previous analysis, this part of our program aims at the investigation of the IR limit of Reggeon field theory (the limit of high energies and large transverse distances). It should be seen in the broader context of trying to connect the nonperturbative infrared region (large transverse distances) with the UV region of small transverse distances where the high energy limit of perturbative QCD applies. We briefly discuss the implications of our findings for the existence of an Odderon in high energy scattering.
Adiabatically tuning quantized supercurrents in an annular Bose-Einstein condensate
NASA Astrophysics Data System (ADS)
Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, Chuanwei
2017-07-01
The ability to generate and tune quantized persistent supercurrents is crucial for building superconducting or atomtronic devices with novel functionalities. In ultracold atoms, previous methods for generating quantized supercurrents are generally based on dynamical processes to prepare atoms in metastable excited states. Here, we show that arbitrary quantized circulation states can be adiabatically prepared and tuned as the ground state of a ring-shaped Bose-Einstein condensate by utilizing spin-orbital-angular-momentum (SOAM) coupling and an external potential. There exists superfluid hysteresis for tuning supercurrents between different quantization values with nonlinear atomic interactions, which is explained by developing a nonlinear Landau-Zener theory. Our work will provide a powerful platform for studying SOAM-coupled ultracold atomic gases and building atomtronic circuits.
Near-threshold quantization for potentials with inverse-cube tails
Mueller, Tim-Oliver; Friedrich, Harald
2011-02-15
For potential wells with long-range attractive tails proportional to -1/r{sup 3}, as occur in the resonant dipole-dipole interaction in homonuclear alkali-metal dimers, we present a highly accurate analytical expression for the tail contribution to the quantization function F(E). This quantization function determines the near-threshold bound-state energies via the quantization rule n{sub th}-n=F(E{sub n}). The performance of the quantization function derived in this paper is demonstrated by applying it to a model Lennard-Jones potential and to vibrational bound-state spectra of sodium dimers (Na{sub 2}). These results are compared with those obtained via the semiclassical LeRoy-Bernstein formula which neglects quantum effects that are important in the near-threshold regime.
HBT Pion Interferometry with Phenomenological Mean Field Interaction
NASA Astrophysics Data System (ADS)
Hattori, K.
2010-11-01
To extract information on hadron production dynamics in the ultrarelativistic heavy ion collision, the space-time structure of the hadron source has been measured using Hanbury Brown and Twiss interferometry. We study the distortion of the source images due to the effect of a final state interaction. We describe the interaction, taking place during penetrating through a cloud formed by evaporating particles, in terms of a one-body mean field potential localized in the vicinity of the source region. By adopting the semiclassical method, the modification of the propagation of an emitted particle is examined. In analogy to the optical model applied to nuclear reactions, our phenomenological model has an imaginary part of the potential, which describes the absorption in the cloud. In this work, we focus on the pion interferometry and mean field interaction obtained using a phenomenological pipi forward scattering amplitude in the elastic channels. The p-wave scattering wit h rho meson resonance leads to an attractive mean field interaction, and the presence of the absorptive part is mainly attributed to the formation of this resonance. We also incorporate a simple time dependence of the potential reflecting the dynamics of the evaporating source. Using the obtained potential, we examine how and to what extent the so-called HBT Gaussian radius is varied by the modification of the propagation.
Microwave magnetoelectric fields and their role in the matter-field interaction.
Kamenetskii, E O; Joffe, R; Shavit, R
2013-02-01
We show that in a source-free subwavelength region of microwave fields, there can exist field structures with a local coupling between the time-varying electric and magnetic fields differing from the electric-magnetic coupling in regular-propagating free-space electromagnetic waves. To distinguish such field structures from regular electromagnetic (EM) field structures, we term them as magnetoelectric (ME) fields. We study a structure and conservation laws of microwave ME near fields. We show that there exist sources of microwave ME near fields-the ME particles. These particles are represented by small quasi-two-dimensional ferrite disks with magnetic-dipolar-oscillation spectra. The near fields originating from such particles are characterized by topologically distinctive power-flow vortices, nonzero helicity, and a torsion degree of freedom. The paper consists of two main parts. In the first one, we give a theoretical background of properties of the electric and magnetic fields inside and outside of a ferrite particle with magnetic-dipolar-oscillation spectra resulting in the appearance of microwave ME near fields. In the second main part, we represent numerical and experimental studies of the microwave ME near fields and their interactions with matter. Based on the obtained properties of the ME near fields, we discuss possibilities for effective microwave sensing of natural and artificial chiral structures.
Simulating electric field interactions with polar molecules using spectroscopic databases
Owens, Alec; Zak, Emil J.; Chubb, Katy L.; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey
2017-01-01
Ro-vibrational Stark-associated phenomena of small polyatomic molecules are modelled using extensive spectroscopic data generated as part of the ExoMol project. The external field Hamiltonian is built from the computed ro-vibrational line list of the molecule in question. The Hamiltonian we propose is general and suitable for any polar molecule in the presence of an electric field. By exploiting precomputed data, the often prohibitively expensive computations associated with high accuracy simulations of molecule-field interactions are avoided. Applications to strong terahertz field-induced ro-vibrational dynamics of PH3 and NH3, and spontaneous emission data for optoelectrical Sisyphus cooling of H2CO and CH3Cl are discussed. PMID:28338042
Simulating electric field interactions with polar molecules using spectroscopic databases
NASA Astrophysics Data System (ADS)
Owens, Alec; Zak, Emil J.; Chubb, Katy L.; Yurchenko, Sergei N.; Tennyson, Jonathan; Yachmenev, Andrey
2017-03-01
Ro-vibrational Stark-associated phenomena of small polyatomic molecules are modelled using extensive spectroscopic data generated as part of the ExoMol project. The external field Hamiltonian is built from the computed ro-vibrational line list of the molecule in question. The Hamiltonian we propose is general and suitable for any polar molecule in the presence of an electric field. By exploiting precomputed data, the often prohibitively expensive computations associated with high accuracy simulations of molecule-field interactions are avoided. Applications to strong terahertz field-induced ro-vibrational dynamics of PH3 and NH3, and spontaneous emission data for optoelectrical Sisyphus cooling of H2CO and CH3Cl are discussed.
Dynamic near-field optical interaction between oscillating nanomechanical structures
Ahn, Phillip; Chen, Xiang; Zhang, Zhen; ...
2015-05-27
Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequencymore » demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.« less
Dynamic near-field optical interaction between oscillating nanomechanical structures
Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi
2015-05-27
Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz^{1/2}, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.
Dynamic near-field optical interaction between oscillating nanomechanical structures
Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi
2015-01-01
Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45 pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20 nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129 MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures. PMID:26014599
Electrical field interactions in different cochlear implant systems
NASA Astrophysics Data System (ADS)
Boëx, Colette; de Balthasar, Chloé; Kós, Maria-Izabel; Pelizzone, Marco
2003-10-01
The goal of this study was to evaluate electrical field interactions produced by the stimulation of different types of intracochlear electrodes in 12 adult subjects (three Ineraid™, four Clarion™ S-Series, three S-Series with the electrode positioning system-EPS and two Clarion™ HiFocus-I with the EPS). Psychophysical measurements were conducted with biphasic stimuli (813 pulse per second, 153.8 μs/phase). ``Perturbation'' signals (300 ms) were applied to one electrode chosen at the middle of the array and their effects on detection thresholds of ``probe'' signals (30 ms) were measured on the neighbor basal electrode. Perturbation levels were set below the detection threshold of the perturbation electrode (-2 dB re threshold). Measurements were first conducted for simultaneous stimulation of the probe and of the perturbation electrodes, for monopolar for all subjects and for bipolar stimulus configurations for both Clarion™ HiFocus-I subjects. The tested Clarion™ electrodes did not present lower monopolar interactions than the Ineraid™ electrodes. Nevertheless, considering the shorter distance between electrodes for the Clarion™ than for the Ineraid™, the tested Clarion™ electrodes might be more selective than the Ineraid™. We did not find any significant monopolar electrical field-interaction differences between subjects who received the S-Series array with and without the EPS. We did not find lower interactions for both subjects who received the HiFocus-I array than for subjects who received the S-Series. Electrical field interactions were lower for bipolar than for monopolar configurations for both HiFocus-I subjects. A second set of measurements was conducted for nonsimultaneous stimulation similar to the one used in continuous interleaved sampling sound strategy. These measurements showed that interactions evaluated for simultaneous biphasic stimuli were larger than for nonsimultaneous stimulation.
The Necessity of Quantizing Gravity
NASA Astrophysics Data System (ADS)
Adelman, Jeremy
2016-03-01
The Eppley Hannah thought experiment is often cited as justification for attempts by theorists to develop a complete, consistent theory of quantum gravity. A modification of the earlier ``Heisenberg microscope'' argument for the necessity of quantized light, the Eppley-Hannah thought experiment purports to show that purely classical gravitational waves would either not conserve energy or else allow for violations of the uncertainty principle. However, several subsequent papers have cast doubt as to the validity of the Eppley-Hannah argument. In this talk, we will show how to resurrect the Eppley-Hannah thought experiment by modifying the original argument in a way that gets around the present criticisms levied against it. With support from the Department of Energy, Grant Number DE-FG02-91ER40674.
Quantized ionic conductance in nanopores
Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimilliano
2009-01-01
Ionic transport in nanopores is a fundamentally and technologically important problem in view of its ubiquitous occurrence in biological processes and its impact on DNA sequencing applications. Using microscopic calculations, we show that ion transport may exhibit strong non-liDearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.
Deformation quantization: Twenty years after
NASA Astrophysics Data System (ADS)
Sternheimer, Daniel
1998-12-01
We first review the historical developments, both in physics and in mathematics, that preceded (and in some sense provided the background of) deformation quantization. Then we describe the birth of the latter theory and its evolution in the past twenty years, insisting on the main conceptual developments and keeping here as much as possible on the physical side. For the physical part the accent is put on its relations to, and relevance for, ``conventional'' physics. For the mathematical part we concentrate on the questions of existence and equivalence, including most recent developments for general Poisson manifolds; we touch also noncommutative geometry and index theorems, and relations with group theory, including quantum groups. An extensive (though very incomplete) bibliography is appended and includes background mathematical literature.
Cutoff quantization and the Skyrmion
Balakrishna, B.S.; Sanyuk, V.; Schechter, J.; Subbaraman, A. )
1992-01-01
The putative classical soliton in the minimal nonlinear {sigma} model (no Skyrme term) is known to be unstable to collapse. We note that the imposition of a short-distance cutoff (which is anyway physically reasonable for a nonrenormalizable model) yields a stable classical soliton. We further suggest that this cutoff, carrying as it does some implicit dynamical information, be treated as a quantized dynamical variable. The resulting one- (experimentally fixed) parameter model agrees with experiment roughly as well as the simple {sigma} model {ital with} the Skyrme term. We interpret this feature as an indication of the robustness of the description of the nucleon as being dominated by a hedgehog-type meson cloud. It is suggested that the same approach might be useful in some other situations where the long-distance description of the physics is more precisely known than is the short-distance description.
Cosmology Quantized in Cosmic Time
Weinstein, M
2004-06-03
This paper discusses the problem of inflation in the context of Friedmann-Robertson-Walker Cosmology. We show how, after a simple change of variables, to quantize the problem in a way which parallels the classical discussion. The result is that two of the Einstein equations arise as exact equations of motion and one of the usual Einstein equations (suitably quantized) survives as a constraint equation to be imposed on the space of physical states. However, the Friedmann equation, which is also a constraint equation and which is the basis of the Wheeler-deWitt equation, acquires a welcome quantum correction that becomes significant for small scale factors. We discuss the extension of this result to a full quantum mechanical derivation of the anisotropy ({delta} {rho}/{rho}) in the cosmic microwave background radiation, and the possibility that the extra term in the Friedmann equation could have observable consequences. To clarify the general formalism and explicitly show why we choose to weaken the statement of the Wheeler-deWitt equation, we apply the general formalism to de Sitter space. After exactly solving the relevant Heisenberg equations of motion we give a detailed discussion of the subtleties associated with defining physical states and the emergence of the classical theory. This computation provides the striking result that quantum corrections to this long wavelength limit of gravity eliminate the problem of the big crunch. We also show that the same corrections lead to possibly measurable effects on the CMB radiation. For the sake of completeness, we discuss the special case, {lambda} = 0, and its relation to Minkowski space. Finally, we suggest interesting ways in which these techniques can be generalized to cast light on the question of chaotic or eternal inflation. In particular, we suggest one can put an experimental lower bound on the distance to a universe with a scale factor very different from our own, by looking at its effects on our CMB
Differentiation of optical isomers through enhanced weak-field interactions
NASA Technical Reports Server (NTRS)
Aronowitz, S.
1980-01-01
The influence of weak field interaction terms due to the cooperative effects which arise from a macroscopic assemblage of interacting sites is studied. Differential adsorption of optical isomers onto an achiral surface is predicted to occur if the surface was continuous and sufficiently large. However, the quantity of discontinuous crystal surfaces did not enhance the percentage of differentiation and thus the procedure of using large quantities of small particles was not a viable technique for obtaining a detectable differentiation of optical isomers on an achiral surface.
Interaction of multiple supersonic jets with a transonic flow field
NASA Technical Reports Server (NTRS)
Seginer, A.; Manela, J.
1983-01-01
The influence of multiple high pressure, supersonic, radial or tangential jets, that are injected from the circumference of the base plane of an axisymmetric body, on its longitudinal aerodynamic coefficients in transonic flow is studied experimentally. The interaction of the jets with the body flow field increases the pressures on the forebody, thus altering its lift and static stability characteristics. It is shown that, within the range of parameters studied. This interaction has a stabilizing effect on the body. The contribution to lift and stability is significant at small angles of attack and decreases nonlinearly at higher angles when the crossflow mechanism becomes dominant.
Generalized Weyl quantization on the cylinder and the quantum phase
Przanowski, Maciej Brzykcy, Przemysław
2013-10-15
Generalized Weyl quantization formalism for the cylindrical phase space S{sup 1}×R{sup 1} is developed. It is shown that the quantum observables relevant to the phase of the linear harmonic oscillator or electromagnetic field can be represented within this formalism by the self-adjoint operators on the Hilbert space L{sup 2}(S{sup 1}). -- Highlights: •The generalized Weyl quantization on the cylindrical phase space is formulated. •A self-adjoint phase operator on the Hilbert space of the square integrable functions on the circle is given. •A new uncertainty relation between the quantum phase and the number operator is found.
Stream-Field Interactions in the Magnetic Accretor AO Piscium
NASA Astrophysics Data System (ADS)
Hellier, Coel; van Zyl, Liza
2005-06-01
UV spectra of the magnetic accretor AO Psc show absorption features for half the binary orbit. The absorption is unlike the wind-formed features often seen in similar stars. Instead, we attribute it to a fraction of the stream that overflows the impact with the accretion disk. Rapid velocity variations can be explained by changes in the trajectory of the stream depending on the orientation of the white dwarf's magnetic field. Hence, we are directly observing the interaction of an accretion stream with a rotating field. We compare this behavior to that seen in other intermediate polars and in SW Sex stars.
Percolation of optical excitation mediated by near-field interactions
NASA Astrophysics Data System (ADS)
Naruse, Makoto; Kim, Song-Ju; Takahashi, Taiki; Aono, Masashi; Akahane, Kouichi; D'Acunto, Mario; Hori, Hirokazu; Thylén, Lars; Katori, Makoto; Ohtsu, Motoichi
2017-04-01
Optical excitation transfer in nanostructured matter has been intensively studied in various material systems for versatile applications. Herein, we theoretically and numerically discuss the percolation of optical excitations in randomly organized nanostructures caused by optical near-field interactions governed by Yukawa potential in a two-dimensional stochastic model. The model results demonstrate the appearance of two phases of percolation of optical excitation as a function of the localization degree of near-field interaction. Moreover, it indicates sublinear scaling with percolation distances when the light localization is strong. Furthermore, such a character is maximized at a particular size of environments. The results provide fundamental insights into optical excitation transfer and will facilitate the design and analysis of nanoscale signal-transfer characteristics.
Interaction of extremely-low-frequency electromagnetic fields with humans
Tenforde, T.S.
1991-07-01
At a macroscopic level, the effects of extremely low frequency (ELF) electromagnetic fields on humans are well understood based on fundamental physical principles, but far less is known about the nature of the interactions at a cellular or molecular level. Current evidence suggests the effects of ELF on cellular biochemistry are due to interactions with the cell membrane. Elucidation of the mechanism that underlies this transmembrane signaling is critical for a molecular-level understanding of ELF field effects. Further research is also required to clarify a possible link between ELF exposure and increased cancer risk, since estimated ELF exposure in occupational or residential settings is much lower that the levels used in laboratory studies. There is a clear need for additional epidemiological research in which qualitative dosimetry is used to characterize ELF exposure and careful attention is given to possible effects of confounding variables. 24 refs.
Quantized vortices around wavefront nodes, 2
NASA Technical Reports Server (NTRS)
Hirschfelder, J. O.; Goebel, C. J.; Bruch, L. W.
1974-01-01
Quantized vortices can occur around nodal points in wavefunctions. The derivation depends only on the wavefunction being single valued, continuous, and having continuous first derivatives. Since the derivation does not depend upon the dynamical equations, the quantized vortices are expected to occur for many types of waves such as electromagnetic and acoustic. Such vortices have appeared in the calculations of the H + H2 molecular collisions and play a role in the chemical kinetics. In a companion paper, it is shown that quantized vortices occur when optical waves are internally reflected from the face of a prism or particle beams are reflected from potential energy barriers.
Robust vector quantization for noisy channels
NASA Technical Reports Server (NTRS)
Demarca, J. R. B.; Farvardin, N.; Jayant, N. S.; Shoham, Y.
1988-01-01
The paper briefly discusses techniques for making vector quantizers more tolerant to tranmsission errors. Two algorithms are presented for obtaining an efficient binary word assignment to the vector quantizer codewords without increasing the transmission rate. It is shown that about 4.5 dB gain over random assignment can be achieved with these algorithms. It is also proposed to reduce the effects of error propagation in vector-predictive quantizers by appropriately constraining the response of the predictive loop. The constrained system is shown to have about 4 dB of SNR gain over an unconstrained system in a noisy channel, with a small loss of clean-channel performance.
Magnetic Oscillations and Landau Quantization in Decoupled Epitaxial Graphene Multilayers*
NASA Astrophysics Data System (ADS)
Stroscio, Joseph A.
2009-03-01
A fundamental challenge to the development of a new electronics based on single atomic sheets of carbon, known as graphene, is to realize a large-area production platform that can produce a carbon system with the same intrinsic properties as a single sheet of graphene. Multi-layer epitaxial graphene (MEG) grown on SiC substrates has been proposed as a possible platform to this end [1]. The central question is, Can MEG behave as single layer graphene with the same intrinsic electrical characteristics? In this talk we show that MEG graphene on SiC exhibits single layer graphene properties through new tunneling magnetic measurements. The circular motion of electrons in a magnetic field has historically been a powerful probe of the Fermi surface properties of materials. Oscillations in many measureable properties, such as magnetization, thermal conductivity, and resistance, all reflect the Landau quantization of the electron energy levels. In this talk we show the ability to observe tunneling magneto-conductance oscillations (TMCOs) in the tunneling differential conductance as a function of both magnetic field and electron energy. The TMCO arise from intense Dirac quantization of the 2-dimensional Dirac electron and hole quasiparticles in MEG grown on SiC substrates. Spatial profiles of the Landau quantization demonstrate the high quality of MEG on SiC with carrier concentrations that vary less than 10% over hundreds of nm. The single layer quantization observed in these multi-layer samples is attributed to observed rotational stacking domains that effectively decouple the carbon layers in MEG on SiC, thereby yielding single layer graphene properties in a large area carbon production method. *In collaboration with Lee Miller, Kevin Kubista, Gregory M. Rutter, Ming Ruan, Mike Sprinkle, Claire Berger, Walt A. de Heer, and Phillip N. First, Georgia Institute of Technology [1] W.A. de Heer et. al., Solid State Comm. 143, 92 (2007).
qPIPSA: Relating enzymatic kinetic parameters and interaction fields
Gabdoulline, Razif R; Stein, Matthias; Wade, Rebecca C
2007-01-01
Background The simulation of metabolic networks in quantitative systems biology requires the assignment of enzymatic kinetic parameters. Experimentally determined values are often not available and therefore computational methods to estimate these parameters are needed. It is possible to use the three-dimensional structure of an enzyme to perform simulations of a reaction and derive kinetic parameters. However, this is computationally demanding and requires detailed knowledge of the enzyme mechanism. We have therefore sought to develop a general, simple and computationally efficient procedure to relate protein structural information to enzymatic kinetic parameters that allows consistency between the kinetic and structural information to be checked and estimation of kinetic constants for structurally and mechanistically similar enzymes. Results We describe qPIPSA: quantitative Protein Interaction Property Similarity Analysis. In this analysis, molecular interaction fields, for example, electrostatic potentials, are computed from the enzyme structures. Differences in molecular interaction fields between enzymes are then related to the ratios of their kinetic parameters. This procedure can be used to estimate unknown kinetic parameters when enzyme structural information is available and kinetic parameters have been measured for related enzymes or were obtained under different conditions. The detailed interaction of the enzyme with substrate or cofactors is not modeled and is assumed to be similar for all the proteins compared. The protein structure modeling protocol employed ensures that differences between models reflect genuine differences between the protein sequences, rather than random fluctuations in protein structure. Conclusion Provided that the experimental conditions and the protein structural models refer to the same protein state or conformation, correlations between interaction fields and kinetic parameters can be established for sets of related enzymes
Long-range interactions in lattice field theory
Rabin, J.M.
1981-06-01
Lattice quantum field theories containing fermions can be formulated in a chirally invariant way provided long-range interactions are introduced. It is established that in weak-coupling perturbation theory such a lattice theory is renormalizable when the corresponding continuum theory is, and that the continuum theory is indeed recovered in the perturbative continuum limit. In the strong-coupling limit of these theories one is led to study an effective Hamiltonian describing a Heisenberg antiferromagnet with long-range interactions. Block-spin renormalization group methods are used to find a critical rate of falloff of the interactions, approximately as inverse distance squared, which separates a nearest-neighbor-antiferromagnetic phase from a phase displaying identifiable long-range effects. A duality-type symmetry is present in some block-spin calculations.
Interaction field modeling of mini-UAV swarm
NASA Astrophysics Data System (ADS)
Liou, William W.; Ro, Kapseong; Szu, Harold
2006-05-01
A behavior-based, simple interaction model inspired by molecular interaction field depicted by the Lennard-Jones function is examined for the averaged interaction in swarming. The modeled kinematic equation of motion contains only one variable, instead of a multiple state variable dependence a more complete dynamics entails. The model assumes a spatial distribution of the potential associate with the swarm. The model has been applied to examine the formation of swarm and the results are reported. The modeling can be reflected in an equilibrium theory for the operation of a swarm of mini-UAVs pioneered by Szu, where every member serves the mission while exploiting other's loss, resulting in a zero-sum game among the team members.
Role of magnetic field tangency points in ICRF sheath interactions
Myra, J. R.; D'Ippolito, D. A.; Kohno, H.
2014-02-12
ICRF waves can sometimes interact with plasma-facing surfaces in tokamak fusion experiments causing degradation of core heating efficiency, impurity injection and even component damage. While presently available low dimensionality rf sheath models are useful in understanding many features of these interactions, more quantitative modeling will require attention to realistic geometrical details of the boundary plasma and surfaces. In this paper, we explore the situation in which there exists a tangency point of the background magnetic field with a surface. We find that the rf interactions are strongly influenced by the generation and propagation of sheath-plasma waves (SPW) along the surface. It is found that these waves preferentially propagate towards, and accumulate at, a convex tangency point. An analytical theory of SPW propagation is developed to understand these features.
Gigagauss magnetic field generation from high intensity laser solid interactions
Cowan, T; Moran, M; Hammer, J; Hatchett, S; Hunt, A; Key, M H; Langdon, A B; Lasinski, B F; Pennington, D; Perry, M D; Sefcik, J A; Snavely, R; Trebes, J; Wilks, S C
1998-10-15
Intense laser (>10^{21} W/cm2 ) sources using pulse compression techniques in the sub-picosecond time frame have been used to create dynamic electric field strenghs in excess of 100 Megavolts/micron with associated magnetic field strengths in the Gigagauss regime. We have begun a series of experiments using the Petawatt Laser system at LLNL to determine the potential of these sources for a variety of applications. Hot electron spectra from laser-target interactions in Au have been measured with energies up to 100 MeV. Hot x-ray production has been measured using filtered thermoluminescent dosimeters and threshold nuclear activation ({gamma},n) from giant resonance interactions. High resolution radiographs through a {rho}r > 165 gm/cm² have been obtained. Dose levels in the x-ray band from 2-8 MeV have been measured at the level of several Rads at one meter from the target for a single pulse. The physics of these sources and the scaling relationships and laser technology required to provide high magnetic fields will be discussed. Results of preliminary magnetic field calculations will be presented along with potential applications of this technology and estimates of the fundamental scaling limits for future development.
Shock-vortex interactions; computing approximate post-shock fields
NASA Astrophysics Data System (ADS)
O'Reilly, G. K.; Pullin, D. I.
2003-11-01
We apply Ribner's method to the interaction of a planar shock with a linear array of compressible Stuart vortices (CSV). The CSV is a family of steady, homentropic, two-dimensional solutions to the compressible Euler equations, parameterized by the free stream Mach number and the mass flux inside a single vortex core. To compute an approximate post-shock field, the CSV's velocity, density and pressure profiles are decomposed by Fourier transform into a sum of frozen sinusoidal modes. The vorticity, entropy and plane sound waves produced by the interaction of each frozen Fourier mode with the shock are computed analytically and combined through Fourier integrals to produce the approximate post-shock fields. The passage of the shock has been treated as an instantaneous event, an ansatz most suitable for weak shocks. Shock curvature effects are included in constructing the post-shock fields. These fields can then be evolved forward in time using a high order numerical method. Supported by the Caltech ASCI-Alliance Program.
Magnetic fields of Mars and Venus - Solar wind interactions
NASA Technical Reports Server (NTRS)
Ness, N. F.
1974-01-01
Recent USSR studies of the magnetic field and solar wind flow in the vicinity of Mars and Venus confirm earlier U.S. reports of a bow shock wave developed as the solar wind interacts with these planets. Mars 2 and 3 magnetometer experiments report the existence of an intrinsic planetary magnetic field, sufficiently strong to form a magnetopause, deflecting the solar wind around the planet and its ionosphere. This is in contrast to the case for Venus, where it is assumed to be the ionosphere and processes therein which are responsible for the solar wind deflection. An empirical relationship appears to exist between planetary dipole magnetic moments and their angular momentum for the Moon, Mars, Venus, Earth, and Jupiter. Implications for the magnetic fields of Mercury and Saturn are discussed.
Interaction Forces Between Multiple Bodies in a Magnetic Field
NASA Technical Reports Server (NTRS)
Joffe, Benjamin
1996-01-01
Some of the results from experiments to determine the interaction forces between multiple bodies in a magnetic field are presented in this paper. It is shown how the force values and the force directions depend on the configuration of the bodies, their relative positions to each other, and the vector of the primary magnetic field. A number of efficient new automatic loading and assembly machines, as well as manipulators and robots, have been created based on the relationship between bodies and magnetic fields. A few of these patented magnetic devices are presented. The concepts involved open a new way to design universal grippers for robot and other kinds of mechanisms for the manipulation of objects. Some of these concepts can be used for space applications.
Quantized Conductance and Large g-Factor Anisotropy in InSb Quantum Point Contacts.
Qu, Fanming; van Veen, Jasper; de Vries, Folkert K; Beukman, Arjan J A; Wimmer, Michael; Yi, Wei; Kiselev, Andrey A; Nguyen, Binh-Minh; Sokolich, Marko; Manfra, Michael J; Nichele, Fabrizio; Marcus, Charles M; Kouwenhoven, Leo P
2016-12-14
Because of a strong spin-orbit interaction and a large Landé g-factor, InSb plays an important role in research on Majorana fermions. To further explore novel properties of Majorana fermions, hybrid devices based on quantum wells are conceived as an alternative approach to nanowires. In this work, we report a pronounced conductance quantization of quantum point contact devices in InSb/InAlSb quantum wells. Using a rotating magnetic field, we observe a large in-plane (|g1| = 26) and out-of-plane (|g1| = 52) g-factor anisotropy. Additionally, we investigate crossings of subbands with opposite spins and extract the electron effective mass from magnetic depopulation of one-dimensional subbands.
Interaction of magnetic resonators studied by the magnetic field enhancement
Hou, Yumin
2013-12-15
It is the first time that the magnetic field enhancement (MFE) is used to study the interaction of magnetic resonators (MRs), which is more sensitive than previous parameters–shift and damping of resonance frequency. To avoid the coherence of lattice and the effect of Bloch wave, the interaction is simulated between two MRs with same primary phase when the distance is changed in the range of several resonance wavelengths, which is also compared with periodic structure. The calculated MFE oscillating and decaying with distance with the period equal to resonance wavelength directly shows the retardation effect. Simulation also shows that the interaction at normal incidence is sensitive to the phase correlation which is related with retardation effect and is ultra-long-distance interaction when the two MRs are strongly localized. When the distance is very short, the amplitude of magnetic resonance is oppressed by the strong interaction and thus the MFE can be much lower than that of single MR. This study provides the design rules of metamaterials for engineering resonant properties of MRs.
Topologies on quantum topoi induced by quantization
Nakayama, Kunji
2013-07-15
In the present paper, we consider effects of quantization in a topos approach of quantum theory. A quantum system is assumed to be coded in a quantum topos, by which we mean the topos of presheaves on the context category of commutative subalgebras of a von Neumann algebra of bounded operators on a Hilbert space. A classical system is modeled by a Lie algebra of classical observables. It is shown that a quantization map from the classical observables to self-adjoint operators on the Hilbert space naturally induces geometric morphisms from presheaf topoi related to the classical system to the quantum topos. By means of the geometric morphisms, we give Lawvere-Tierney topologies on the quantum topos (and their equivalent Grothendieck topologies on the context category). We show that, among them, there exists a canonical one which we call a quantization topology. We furthermore give an explicit expression of a sheafification functor associated with the quantization topology.
Loop quantization of Schwarzschild interior revisited
NASA Astrophysics Data System (ADS)
Singh, Parampreet; Corichi, Alejandro
2016-03-01
Several studies of different inequivalent loop quantizations have shown, that there exists no fully satisfactory quantum theory for the Schwarzschild interior. Existing quantizations fail either on dependence on the fiducial structure or on the lack of the classical limit. Here we put forward a novel viewpoint to construct the quantum theory that overcomes all of the known problems of the existing quantizations. It is shown that the quantum gravitational constraint is well defined past the singularity and that its effective dynamics possesses a bounce into an expanding regime. The classical singularity is avoided, and a semiclassical spacetime satisfying vacuum Einstein's equations is recovered on the ``other side'' of the bounce. We argue that such metric represents the interior region of a white-hole spacetime, but for which the corresponding ``white-hole mass'' differs from the original black hole mass. We compare the differences in physical implications with other quantizations.
Quantized hard-x-ray phase vortices nucleated by aberrated nanolenses
Pavlov, Konstantin M.; Paganin, David M.; Vine, David J.; Schmalz, Jelena A.; Suzuki, Yoshio; Uesugi, Kentaro; Takeuchi, Akihisa; Yagi, Naoto; Jakubek, Jan; Altissimo, Matteo; Clark, Jesse N.
2011-01-15
Quantized x-ray phase vortices, namely, screw-type topological defects in the wave fronts of a coherent monochromatic scalar x-ray wave field, may be spontaneously nucleated by x-ray lenses. Phase retrieval is used to reconstruct the phase and amplitude of the complex disturbance created by aberrated gold nanolenses illuminated with hard x rays. A nanoscale quantized x-ray vortex-antivortex dipole is observed, manifest both as a pair of opposite-helicity branch points in the Riemann sheets of the multivalued x-ray phase map of the complex x-ray field and in the vorticity of the associated Poynting vector field.
Color quantization and processing by Fibonacci lattices.
Mojsilovic, A; Soljanin, E
2001-01-01
Color quantization is sampling of three-dimensional (3-D) color spaces (such as RGB or Lab) which results in a discrete subset of colors known as a color codebook or palette. It is extensively used for display, transfer, and storage of natural images in Internet-based applications, computer graphics, and animation. We propose a sampling scheme which provides a uniform quantization of the Lab space. The idea is based on several results from number theory and phyllotaxy. The sampling algorithm is very much systematic and allows easy design of universal (image-independent) color codebooks for a given set of parameters. The codebook structure allows fast quantization and ordered dither of color images. The display quality of images quantized by the proposed color codebooks is comparable with that of image-dependent quantizers. Most importantly, the quantized images are more amenable to the type of processing used for grayscale ones. Methods for processing grayscale images cannot be simply extended to color images because they rely on the fact that each gray-level is described by a single number and the fact that a relation of full order can be easily established on the set of those numbers. Color spaces (such as RGB or Lab) are, on the other hand, 3-D. The proposed color quantization, i.e., color space sampling and numbering of sampled points, makes methods for processing grayscale images extendible to color images. We illustrate possible processing of color images by first introducing the basic average and difference operations and then implementing edge detection and compression of color quantized images.
NASA Astrophysics Data System (ADS)
Dvornikov, Maxim; Gitman, D. M.
2012-11-01
We study massive 1/2-spin particles in various external backgrounds keeping in mind applications to neutrino physics. We are mainly interested in massive Majorana (Weyl) fields. However, massive neutral Dirac particles are also considered. We formulate classical Lagrangian theory of the massive Weyl field in terms of Grassmann-odd two-component spinors. Then we construct the Hamiltonian formulation of such a theory, which turns out to be a theory with second-class constraints. Using this formulation we canonically quantize the massive free Weyl field. We derive propagators of the Weyl field and relate them to the propagator of a massive Dirac particle. We also study the massive Weyl particles propagating in the background mater. We find the path integral representation for the propagator of such a field, as well as the corresponding pseudoclassical particle action. The massless limit of the Weyl field interacting with the matter is considered and compared with results of other works. Finally, the path integral representation for the propagator of the neutral massive Dirac particle with an anomalous magnetic moment moving in the background matter and external electromagnetic field, as well as the corresponding pseudoclassical particle action are constructed.
Colloidal interactions in field-directed self-assembly
NASA Astrophysics Data System (ADS)
Lele, Pushkar P.
This thesis discusses: (1) the fabrication of an experimental tool, namely holographic optical tweezers for simultaneously manipulating spatial locations of multiple particles, (2) development of a framework for interpreting hydrodynamic interactions between multiple particles close to a no-slip surface and comparisons of experimental data with predictive modeling results (Stokesian dynamics simulations) (3) investigations of colloidal particle interactions under external AC fields and the intriguing spontaneous pattern formations in the suspension and, (4) the use of an unconventional assemble-stretch technique for creating novel 2D and 3D crystalline arrays of anisotropically shaped particles, from spherical particle templates. By blinking holographic optical traps, we investigate the hydrodynamic interactions in multi-particle ensembles, influenced by a no-slip surface. The measurements are carried out by screening out electrostatic interactions in the suspension. We observe that with increasing proximity with the surface, the effect of particle-particle hydrodynamic interactions on the short-time self-diffusivities is screened. We use the Stokeslet representation of particles and combine it with the method of images to understand the correlated motion of particles within the ensembles. Analysis of the resultant ensemble eigen-modes reveals that even in dilute suspensions, the effective diffusivities decay as the inverse of the separations, over the range of particle-particle separations we experimented with. The relative modes exhibit dominant contributions from close neighboring particles and the collective modes incorporate long-range contributions from all particles in the ensemble. Our analysis also confirms that for larger number of particles in the ensemble, the contributions from particle-particle interactions increase and in concentrated suspensions they over-ride the strong hydrodynamic screening by the wall. We investigate the microstructure of
Covariant quantization of C P T -violating photons
NASA Astrophysics Data System (ADS)
Colladay, D.; McDonald, P.; Noordmans, J. P.; Potting, R.
2017-01-01
We perform the covariant canonical quantization of the C P T - and Lorentz-symmetry-violating photon sector of the minimal Standard-Model Extension, which contains a general (timelike, lightlike, or spacelike) fixed background tensor kAF μ. Well-known stability issues, arising from complex-valued energy states, are solved by introducing a small photon mass, orders of magnitude below current experimental bounds. We explicitly construct a covariant basis of polarization vectors, in which the photon field can be expanded. We proceed to derive the Feynman propagator and show that the theory is microcausal. Despite the occurrence of negative energies and vacuum-Cherenkov radiation, we do not find any runaway stability issues, because the energy remains bounded from below. An important observation is that the ordering of the roots of the dispersion relations is the same in any observer frame, which allows for a frame-independent condition that selects the correct branch of the dispersion relation. This turns out to be critical for the consistency of the quantization. To our knowledge, this is the first system for which quantization has consistently been performed, in spite of the fact that the theory contains negative energies in some observer frames.
Light-front-quantized QCD in Covariant Gauge
Srivastava, Prem P.
1999-06-17
The light-front (LF) canonical quantization of quantum chromodynamics in covariant gauge is discussed. The Dirac procedure is used to eliminate the constraints in the gauge-fixed front form theory quantum action and to construct the LF Hamiltonian formulation. The physical degrees of freedom emerge naturally. The propagator of the dynamical {psi}{sub +} part of the free fermionic propagator in the LF quantized field theory is shown to be causal and not to contain instantaneous terms. Since the relevant propagators in the covariant gauge formulation are causal, rotational invariance--including the Coulomb potential in the static limit--can be recovered, avoiding the difficulties encountered in light-cone gauge. The Wick rotation may also be performed allowing the conversion of momentum space integrals into Euclidean space forms. Some explicit computations are done in quantum electrodynamics to illustrate the equivalence of front form theory with the conventional covariant formulation. LF quantization thus provides a consistent formulation of gauge theory, despite the fact that the hyperplanes x{sup {+-}} = 0 used to impose boundary conditions constitute characteristic surfaces of a hyperbolic partial differential equation.
Weibel magnetic field competes with Biermann fields in laser-solid interactions
NASA Astrophysics Data System (ADS)
Shukla, Nitin; Schoeffler, Kevin; Vieira, Jorge; Fonseca, Ricardo; Silva, Luis
2016-10-01
Biermann battery induced magnetic fields caused by non-parallel density and temperature gradients, first investigated experimentally, continue to be measured in many current experiments. A detailed study of Biermann generated magnetic fields in collisionless systems has been carried out, showing that for large system sizes (L /de >= 100) , where de is the electron inertial length, the Weibel instability dominates as the major source of magnetic field. In this work, we demonstrate the possibility of experimentally generating this strong Weibel magnetic field. We model, using ab initio PIC simulations, the interaction of a short (ps) high intensity (a0 >= 1) laser pulse, with a target of sufficiently large gradient scale length, L. The expanding hot energetic electron population generated by the laser produces an anisotropy in the velocity distribution. This anisotropy provides the free energy that drives the Weibel instability that appears on the surfaces of the target and dominates over the Biermann battery field.
Spin-resolved conductance quantization in InAs
NASA Astrophysics Data System (ADS)
Lehmann, H.; Benter, T.; von Ahnen, I.; Jacob, J.; Matsuyama, T.; Merkt, U.; Kunze, U.; Wieck, A. D.; Reuter, D.; Heyn, C.; Hansen, W.
2014-07-01
We report on the quantized conductance through side- and top-gated InAs quantum point contacts and discuss its dependence on the temperature and on a magnetic field applied perpendicular to the sample plane. Even in the absence of a magnetic field we observe besides the integer steps in units of 2e2/h spin-resolved steps in units of e2/h up to the highest occupied mode. A conductance anomaly at 0.7 × 2e2/h is found as well.
Observation of quantized conductance in neutral matter
NASA Astrophysics Data System (ADS)
Husmann, Dominik; Krinner, Sebastian; Lebrat, Martin; Grenier, Charles; Nakajima, Shuta; Häusler, Samuel; Brantut, Jean-Philippe; Esslinger, Tilman
2015-05-01
In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer's formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. We eventually explore the behavior of a strongly interacting Fermi gas in the same configuration, and the consequences of the emergence of superfluidity.
A recursive technique for adaptive vector quantization
NASA Technical Reports Server (NTRS)
Lindsay, Robert A.
1989-01-01
Vector Quantization (VQ) is fast becoming an accepted, if not preferred method for image compression. The VQ performs well when compressing all types of imagery including Video, Electro-Optical (EO), Infrared (IR), Synthetic Aperture Radar (SAR), Multi-Spectral (MS), and digital map data. The only requirement is to change the codebook to switch the compressor from one image sensor to another. There are several approaches for designing codebooks for a vector quantizer. Adaptive Vector Quantization is a procedure that simultaneously designs codebooks as the data is being encoded or quantized. This is done by computing the centroid as a recursive moving average where the centroids move after every vector is encoded. When computing the centroid of a fixed set of vectors the resultant centroid is identical to the previous centroid calculation. This method of centroid calculation can be easily combined with VQ encoding techniques. The defined quantizer changes after every encoded vector by recursively updating the centroid of minimum distance which is the selected by the encoder. Since the quantizer is changing definition or states after every encoded vector, the decoder must now receive updates to the codebook. This is done as side information by multiplexing bits into the compressed source data.
Quantization by cochain twists and nonassociative differentials
Beggs, E. J.; Majid, S.
2010-05-15
We show that several standard associative quantizations in mathematical physics can be expressed as cochain module-algebra twists in the spirit of Moyal products at least to O(({Dirac_h}/2{pi}){sup 3}), but to achieve this we twist not by a 2-cocycle but by a 2-cochain. This implies a hidden nonassociativity not visible in the algebra itself but present in its deeper noncommutative differential geometry, a phenomenon first seen in our previous work on semiclassicalization of differential structures. The quantizations are induced by a classical group covariance and include enveloping algebras U(g) as quantizations of g*, a Fedosov-type quantization of the sphere S{sup 2} under a Lorentz group covariance, the Mackey quantization of homogeneous spaces, and the standard quantum groups C{sub q}[G]. We also consider the differential quantization of R{sup n} for a given symplectic connection as part of our semiclassical analysis and we outline a proposal for the Dirac operator.
Controlling charge quantization with quantum fluctuations
NASA Astrophysics Data System (ADS)
Jezouin, S.; Iftikhar, Z.; Anthore, A.; Parmentier, F. D.; Gennser, U.; Cavanna, A.; Ouerghi, A.; Levkivskyi, I. P.; Idrisov, E.; Sukhorukov, E. V.; Glazman, L. I.; Pierre, F.
2016-08-01
In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.
Controlling charge quantization with quantum fluctuations.
Jezouin, S; Iftikhar, Z; Anthore, A; Parmentier, F D; Gennser, U; Cavanna, A; Ouerghi, A; Levkivskyi, I P; Idrisov, E; Sukhorukov, E V; Glazman, L I; Pierre, F
2016-08-04
In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.
Effective field theories for van der Waals interactions
NASA Astrophysics Data System (ADS)
Brambilla, Nora; Shtabovenko, Vladyslav; Tarrús Castellà, Jaume; Vairo, Antonio
2017-06-01
Van der Waals interactions between two neutral but polarizable systems at a separation R much larger than the typical size of the systems are at the core of a broad sweep of contemporary problems in settings ranging from atomic, molecular and condensed matter physics to strong interactions and gravity. In this paper, we reexamine the dispersive van der Waals interactions between two hydrogen atoms. The novelty of the analysis resides in the usage of nonrelativistic effective field theories of quantum electrodynamics. In this framework, the van der Waals potential acquires the meaning of a matching coefficient in an effective field theory, dubbed van der Waals effective field theory, suited to describe the low-energy dynamics of an atom pair. It may be computed systematically as a series in R times some typical atomic scale and in the fine-structure constant α . The van der Waals potential gets short-range contributions and radiative corrections, which we compute in dimensional regularization and renormalize here for the first time. Results are given in d space-time dimensions. One can distinguish among different regimes depending on the relative size between 1 /R and the typical atomic bound-state energy, which is of order m α2. Each regime is characterized by a specific hierarchy of scales and a corresponding tower of effective field theories. The short-distance regime is characterized by 1 /R ≫m α2 and the leading-order van der Waals potential is the London potential. We also compute next-to-next-to-next-to-leading-order corrections. In the long-distance regime we have 1 /R ≪m α2. In this regime, the van der Waals potential contains contact terms, which are parametrically larger than the Casimir-Polder potential that describes the potential at large distances. In the effective field theory, the Casimir-Polder potential counts as a next-to-next-to-next-to-leading-order effect. In the intermediate-distance regime, 1 /R ˜m α2, a significantly more complex
Coupling fluid-structure interaction with phase-field fracture
NASA Astrophysics Data System (ADS)
Wick, Thomas
2016-12-01
In this work, a concept for coupling fluid-structure interaction with brittle fracture in elasticity is proposed. The fluid-structure interaction problem is modeled in terms of the arbitrary Lagrangian-Eulerian technique and couples the isothermal, incompressible Navier-Stokes equations with nonlinear elastodynamics using the Saint-Venant Kirchhoff solid model. The brittle fracture model is based on a phase-field approach for cracks in elasticity and pressurized elastic solids. In order to derive a common framework, the phase-field approach is re-formulated in Lagrangian coordinates to combine it with fluid-structure interaction. A crack irreversibility condition, that is mathematically characterized as an inequality constraint in time, is enforced with the help of an augmented Lagrangian iteration. The resulting problem is highly nonlinear and solved with a modified Newton method (e.g., error-oriented) that specifically allows for a temporary increase of the residuals. The proposed framework is substantiated with several numerical tests. In these examples, computational stability in space and time is shown for several goal functionals, which demonstrates reliability of numerical modeling and algorithmic techniques. But also current limitations such as the necessity of using solid damping are addressed.
Detection of Binding Site Molecular Interaction Field Similarities.
Chartier, Matthieu; Najmanovich, Rafael
2015-08-24
Protein binding-site similarity detection methods can be used to predict protein function and understand molecular recognition, as a tool in drug design for drug repurposing and polypharmacology, and for the prediction of the molecular determinants of drug toxicity. Here, we present IsoMIF, a method able to identify binding site molecular interaction field similarities across protein families. IsoMIF utilizes six chemical probes and the detection of subgraph isomorphisms to identify geometrically and chemically equivalent sections of protein cavity pairs. The method is validated using six distinct data sets, four of those previously used in the validation of other methods. The mean area under the receiver operator curve (AUC) obtained across data sets for IsoMIF is higher than those of other methods. Furthermore, while IsoMIF obtains consistently high AUC values across data sets, other methods perform more erratically across data sets. IsoMIF can be used to predict function from structure, to detect potential cross-reactivity or polypharmacology targets, and to help suggest bioisosteric replacements to known binding molecules. Given that IsoMIF detects spatial patterns of molecular interaction field similarities, its predictions are directly related to pharmacophores and may be readily translated into modeling decisions in structure-based drug design. IsoMIF may in principle detect similar binding sites with distinct amino acid arrangements that lead to equivalent interactions within the cavity. The source code to calculate and visualize MIFs and MIF similarities are freely available.
Lunar Swirls: Plasma Magnetic Field Interaction and Dust Transport
NASA Astrophysics Data System (ADS)
Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin; Hyde, Truell
2013-10-01
In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma facilities have been established using the Inductively heated Plasma Generator 6 (IPG6), based on proven IRS designs. A wide range of applications is currently under consideration for both test and research facilities. Basic investigations in the area of plasma radiation and catalysis, simulation of certain parameters of fusion divertors and space applications are planned. In this paper, the facility at Baylor University (IPG6-B) will be used for simulation of mini-magnetospheres on the Moon. The interaction of the solar wind with magnetic fields leads to the formation of electric fields, which can influence the incoming solar wind ion flux and affect dust transport processes on the lunar surface. Both effects may be partially responsible for the occurrence of lunar swirls. Interactions of the solar wind with such mini-magnetospheres will be simulated in the IPG6-B by observing the interaction between a plasma jet and a permanent magnet. The resulting data should lead to better models of dust transport processes and solar wind deflection on the moon.
Matching Contact Interactions in QED-NRQED Effective Field Theory
NASA Astrophysics Data System (ADS)
Dye, Steven; Gonderinger, Matthew; Paz, Gil
2017-01-01
In 2010 the proton charge radius was first extracted from muonic hydrogen and was found to have a value five standard deviations away from the regular hydrogen value. An effective field theory analysis using Non-Relativistic Quantum Electrodynamics (NRQED) indicates that the muonic hydrogen result can be interpreted as a large, compared to some model estimates, muon-proton spin-independent contact interaction. One of the most promising avenues to resolve this puzzle is by muon-proton scattering. Such an experiment, called MUSE, is planned at the Paul Scherrer Institute in Switzerland. The typical momenta of the muons in this experiment are of the order of the muon mass. In this energy regime the muons are relativistic but the protons are still non-relativistic. The interaction between them can be described by a QED-NRQED effective field theory. Here we present elements of this effective field theory. In particular, we look at O (Zα) scattering up to power m2 /M2 , where m (M) is the muon (proton) mass, and O (Z2α2) scattering at leading power. We also take a brief look at O (Z2α2) at subleading power.
NASA Astrophysics Data System (ADS)
Dürr, W.; Oppelt, R.
1990-02-01
Electromagnetic field probes are described which use ultrasonic transmission lines for signal transmission from a small electric or magnetic measuring dipole to the data processing unit. These transmission lines are made of nonmetallic material with low permittivity and permeability so that its interaction with the field to be measured is minimum. In particular, there is no evidence of energy leakage via surface or sheath waves, which normally cause problems when usual metallic connecting cables are used. This is especially important when measuring near fields of antennas or fields in resonators with high Q factors. Wide-band operation was achieved by amplitude modulating the field to be measured at a low frequency. The purpose of this modulation is to create a low-frequency (kHz) signal which can be transmitted via an ultrasonic line, designed to resonate at this low frequency. The radio frequency (rf) itself can extend over a broad range since the ultrasonic line does not transmit this frequency directly. Since the ultrasonic line is operated at a low frequency, its design and manufacture including ultrasonic transducers are essentially simple, even for field probes working in the gigahertz range. The design of the transmission line and of the measuring dipoles with demodulation circuitry are described. The probe performance is discussed for a magnetic field probe used for field measurements in resonant antennas for magnetic resonance imaging in the frequency range up to about 200 MHz. A typical field measurement result is presented for this application.
Modeling of interactions of electromagnetic fields with human bodies
NASA Astrophysics Data System (ADS)
Caputa, Krzysztof
Interactions of electromagnetic fields with the human body have been a subject of scientific interest and public concern. In recent years, issues in power line field effects and those of wireless telephones have been in the forefront of research. Engineering research compliments biological investigations by quantifying the induced fields in biological bodies due to exposure to external fields. The research presented in this thesis aims at providing reliable tools, and addressing some of the unresolved issues related to interactions with the human body of power line fields and fields produced by handheld wireless telephones. The research comprises two areas, namely development of versatile models of the human body and their visualisation, and verification and application of numerical codes to solve selected problems of interest. The models of the human body, which are based on the magnetic resonance scans of the body, are unique and differ considerably from other models currently available. With the aid of computer software developed, the models can be arranged to different postures, and medical devices can be accurately placed inside them. A previously developed code for modeling interactions of power line fields with biological bodies has been verified by rigorous, quantitative inter-laboratory comparison for two human body models. This code has been employed to model electromagnetic interference (EMI) of the magnetic field with implanted cardiac pacemakers. In this case, the correct placement and representation of the pacemaker leads are critical, as simplified computations have been shown to result in significant errors. In modeling interactions of wireless communication devices, the finite difference time domain technique (FDTD) has become a de facto standard. The previously developed code has been verified by comparison with the analytical solution for a conductive sphere. While previously researchers limited their verifications to principal axes of the sphere
Effects of interaction between plasma-flow fields and electrostatic fields in dusty plasmas
NASA Astrophysics Data System (ADS)
Tsytovich, V. N.
2007-04-01
Interaction between plasma-flow fields and electrostatic fields is considered as the most appropriate method for describing the characteristic properties of a dusty plasma. This method makes it possible to treat the openness of the dusty plasma systems and to describe the processes of self-organization and change in interaction between dust particles that are caused by the presence of plasma flows, in particular, to describe attraction between the dust particles at large distances, as well as the pairing of identically charged particles and the formation of complicated dusty structures including dusty plasma crystals. Interaction between the plasma-flow fields and electrostatic fields was previously taken into account only when considering particular problems but was not considered as the general characteristic property of the dusty plasma. It is emphasized that the model taking into account the plasma-flow fields and their interaction with the electrostatic fields is the only model that allows simultaneous explanation of all basic parameters characterizing the condensation of the dusty plasma to plasma crystals (coupling constant Γ, interparticle distance r min, and melting temperature T d) obtained in observations. Attraction between the dust particles at large distances leads to instability similar to gravitational instability, which was erroneously disregarded in previous descriptions of the dust sound. The corresponding critical size is similar to the Jeans radius. As a result of such attraction, dusty systems are structured, and such structuring is similar to known gravitational structuring and can explain the observation of dusty structures in most laboratory experiments on the dusty plasma.
Interactions of massless higher spin fields from string theory
Polyakov, Dimitri
2010-09-15
We construct vertex operators for massless higher spin fields in Ramond-Neveu-Schwarz superstring theory and compute some of their three-point correlators, describing gauge-invariant cubic interactions of the massless higher spins. The Fierz-Pauli on-shell conditions for the higher spins (including tracelessness and vanishing divergence) follow from the Becchi-Rouet-Stora-Tyutin-invariance conditions for the vertex operators constructed in this paper. The gauge symmetries of the massless higher spins emerge as a result of the Becchi-Rouet-Stora-Tyutin-nontriviality conditions for these operators, being equivalent to transformations with the traceless gauge parameter in the Fronsdal's approach. The gauge invariance of the interaction terms of the higher spins is therefore ensured automatically by that of the vertex operators in string theory. We develop a general algorithm to compute the cubic interactions of the massless higher spins and use it to explicitly describe the gauge-invariant interaction of two s=3 and one s=4 massless particles.
Wavelength Dependent Strong Field Interactions with Atoms and Molecules
NASA Astrophysics Data System (ADS)
Szafruga, Urszula Bozena
In the regime of strong-field physics the electric field of a laser begins to strongly rival the binding potential of an atomic or molecular species. During these interactions an ionized electron can be driven away and then back towards its parent ion by the strong laser field and undergo rescattering before being detected. The amount of energy an electron can acquire during propagation is proportional to the laser intensity and the square of the wavelength. Recent improvements in laser technology have allowed us to push strong-field studies from visible/near-infrared wavelengths to the mid-infrared regime and thereby greatly increase the electron's maximum recollision energy. These high energy scattering events imprint target dependent structural information on the electron angular distribution from which we can extract atomic and molecular specific properties. Further, Keldysh invariance suggests that we can control the dominant ionization mechanism (multiphoton absorption versus tunneling through the field modified potential) by choosing an appropriate laser wavelength, laser intensity and target atom. Exploratory investigations in strong-field physics have produced many fascinating results which have led to production of attosecond duration laser pulses and atomic/molecular imaging techniques. As technological improvements continue we are able to gain further insights into these interesting physical phenomena. In this work we examine photoelectron spectra and ion yields in order to gain a deeper understanding of the fundamental processes that underlie atomic and molecular strong field interactions. Alkali metal atoms at mid-infrared wavelengths possess similar Keldysh parameter values as noble gas atoms at near-infrared wavelengths, which have received much more investigative attention. Therefore, by examining alkali metal atoms at longer wavelengths we hope to expand on our understanding of the global, Keldysh invariant, and atom specific ionization features
Intense Field-Matter Interactions: Multiple Ionization of Clusters
Snyder, E.M.; Buzza, S.A.; Castleman, A.W. Jr.
1996-10-01
We report the results for the production of highly charged atomic species (e.g., Xe{sup 20+}, Kr{sup 18+}, O{sup 5+}, and C{sup 4+}) resulting from the interaction of intense laser fields (up to {approximately}10{sup 15} W/cm{sup 2}) with atomic and multicenter molecular clusters. The processes are also investigated using ultrafast pump-probe techniques, showing distinct beating patterns for the ionization structure in the molecular system. A comparison of our results with predictions of several different theoretical models provides strong support for the ionization ignition mechanism. {copyright} {ital 1996 The American Physical Society.}
Mean Field Evolution of Fermions with Coulomb Interaction
NASA Astrophysics Data System (ADS)
Porta, Marcello; Rademacher, Simone; Saffirio, Chiara; Schlein, Benjamin
2017-03-01
We study the many body Schrödinger evolution of weakly coupled fermions interacting through a Coulomb potential. We are interested in a joint mean field and semiclassical scaling, that emerges naturally for initially confined particles. For initial data describing approximate Slater determinants, we prove convergence of the many-body evolution towards Hartree-Fock dynamics. Our result holds under a condition on the solution of the Hartree-Fock equation, that we can only show in a very special situation (translation invariant data, whose Hartree-Fock evolution is trivial), but that we expect to hold more generally.
NASA Astrophysics Data System (ADS)
Shaukat, Muzzamal I.; Masood, W.; Shah, H. A.; Iqbal, M. J.; Mirza, Arshad M.
2016-10-01
In the present investigation, linear and nonlinear electrostatic drift waves in the presence of trapped electrons with quantizing magnetic field and finite electron temperature effects in dense plasmas have been studied. The linear dispersion relation of the ion drift wave has been derived and it has been found that the Landau quantization and finite temperature effects significantly alter the linear propagation characteristics of the wave under consideration. Employing the Sagdeev potential approach, the formation of finite amplitude drift solitary structures has been investigated in the presence of a quantizing magnetic field for both fully and partially degenerate plasmas. Both compressive and rarefactive drift solitary structures have been obtained for different values of quantizing magnetic field and finite electron temperature effects. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs.
Imaging of quantized magnetostatic modes using spatially resolved ferromagnetic resonance
NASA Astrophysics Data System (ADS)
Tamaru, S.; Bain, J. A.; van de Veerdonk, R. J. M.; Crawford, T. M.; Covington, M.; Kryder, M. H.
2002-05-01
We present a measurement technique for performing spatially resolved ferromagnetic resonance and directly imaging quantized magnetostatic modes in magnetic samples that undergo high frequency magnetic drive fields (up to 8 GHz). The dynamic response of a 50×50 μm2 permalloy structure (100 nm thick) under a 7.04 GHz highly nonuniform drive field was measured as a function of the dc bias field using this technique. The magnetization variation observed indicates that quantized magnetostatic mode waves appear at certain bias fields, with the number of nodes decreasing with an increase in the bias field. We tentatively assign the indices of each mode using the Damon-Eshbach (DE) model. Similar modes have been observed for a similar sample geometry using an inductive measurement and they showed good agreement with the DE model. However, the result measured using this technique showed some discrepancy with the DE model and the spatial patterns observed are more complicated than simple one-dimensional standing waves. This complexity suggests that analysis beyond that of the DE model is required to explain the observations.
Field Guide for Designing Human Interaction with Intelligent Systems
NASA Technical Reports Server (NTRS)
Malin, Jane T.; Thronesbery, Carroll G.
1998-01-01
The characteristics of this Field Guide approach address the problems of designing innovative software to support user tasks. The requirements for novel software are difficult to specify a priori, because there is not sufficient understanding of how the users' tasks should be supported, and there are not obvious pre-existing design solutions. When the design team is in unfamiliar territory, care must be taken to avoid rushing into detailed design, requirements specification, or implementation of the wrong product. The challenge is to get the right design and requirements in an efficient, cost-effective manner. This document's purpose is to describe the methods we are using to design human interactions with intelligent systems which support Space Shuttle flight controllers in the Mission Control Center at NASA/Johnson Space Center. Although these software systems usually have some intelligent features, the design challenges arise primarily from the innovation needed in the software design. While these methods are tailored to our specific context, they should be extensible, and helpful to designers of human interaction with other types of automated systems. We review the unique features of this context so that you can determine how to apply these methods to your project Throughout this Field Guide, goals of the design methods are discussed. This should help designers understand how a specific method might need to be adapted to the project at hand.
Predicting drug pharmacokinetic properties using molecular interaction fields and SIMCA
NASA Astrophysics Data System (ADS)
Wolohan, Philippa R. N.; Clark, Robert D.
2003-01-01
We have developed a method that combines molecular interaction fields with soft independent modeling of class analogy (SIMCA) Wold:1977 to predict pharmacokinetic drug properties. Several additional considerations to those made in traditional QSAR are required in order to develop a successful QSPR strategy that is capable of accommodating the many complex factors that contribute to key pharmacokinetic properties such as ADME (absorption, distribution, metabolism, and excretion) and toxicology. An accurate prediction of oral bioavailability, for example, requires that absorption and first-pass hepatic elimination both be taken into consideration. To accomplish this, general properties of molecules must be related to their solubility and ability to penetrate biological membranes, and specific features must be related to their particular metabolic and toxicological profiles. Here we describe a method, which is applicable to structurally diverse data sets while utilizing as much detailed structural information as possible. We address the issue of the molecular alignment of a structurally diverse set of compounds using idiotropic field orientation (IFO), a generalization of inertial field orientation Clark:1998. We have developed a second flavor of this method, which directly incorporates electrostatics into the molecular alignment. Both variations of IFO produce a characteristic orientation for each structure and the corresponding molecular fields can then be analyzed using SIMCA. Models are presented for human intestinal absorption, blood-brain barrier penetration and bioavailability to demonstrate ways in which this tool can be used early in the drug development process to identify leads likely to exhibit poor pharmacokinetic behavior in pre-clinical studies, and we have explored the influence of conformation and molecular field type on the statistical properties of the models obtained.
Exact Quantization of Einstein-Rosen Waves Coupled to Massless Scalar Matter
NASA Astrophysics Data System (ADS)
Barbero G., J. Fernando; Garay, Iñaki; Villaseñor, Eduardo J.
2005-07-01
We show in this Letter that gravity coupled to a massless scalar field with full cylindrical symmetry can be exactly quantized by an extension of the techniques used in the quantization of Einstein-Rosen waves. This system provides a useful test bed to discuss a number of issues in quantum general relativity, such as the emergence of the classical metric, microcausality, and large quantum gravity effects. It may also provide an appropriate framework to study gravitational critical phenomena from a quantum point of view, issues related to black hole evaporation, and the consistent definition of test fields and particles in quantum gravity.
Tsintsadze, N. L.; Tagviashvili, M. N.; Shah, H. A.; Qureshi, M. N. S.
2015-02-15
We have undertaken the investigation of ion acoustic solitary waves in both weakly and strongly quantized degenerate magnetoplasmas. It is seen that a singular point clearly demarcates the regions of weak and strong quantization due to the ambient magnetic field. The effect of the magnetic field is taken into account via the parameter η{sub 0}=ℏω{sub ce}/ε{sub Fe} and the Mach number, and their effect on the formation of solitary structures is investigated in both cases and some results are presented graphically.
Strongly interacting phases of metallic wires in strong magnetic field
NASA Astrophysics Data System (ADS)
Bulmash, Daniel; Jian, Chao-Ming; Qi, Xiao-Liang
2017-07-01
We investigate theoretically an interacting metallic wire with a strong magnetic field directed along its length and show that it is a highly tunable one-dimensional system. By considering a suitable change in spatial geometry, we build an analogy between the problem in the zeroth Landau level with Landau level degeneracy N to one-dimensional fermions with an N -component pseudospin degree of freedom and S U (2 ) -symmetric interactions. This analogy allows us to establish the phase diagram as a function of the interactions for small N (and make conjectures for large N ) using renormalization group and bosonization techniques. We find pseudospin-charge separation with a gapless U (1 ) charge sector and several possible strong-coupling phases in the pseudospin sector. For odd N , we find a fluctuating pseudospin-singlet charge density wave phase and a fluctuating pseudospin-singlet superconducting phase which are topologically distinct. For even N >2 , similar phases exist, although they are not topologically distinct, and an additional novel pseudospin-gapless phase appears. We discuss experimental conditions for observing our proposals.
Perturbation theory in light-cone quantization
Langnau, A.
1992-01-01
A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the perturbative level, i.e., to gain control over the perturbative treatment first. A clear understanding of divergences in perturbation theory, as well as their numerical treatment, is a necessary first step towards formulating such a program. The first objective of this dissertation is to clarify this issue, at least in second and fourth-order in perturbation theory. The work in this dissertation can provide guidance for the choice of counterterms in Discrete Light-Cone Quantization or the Tamm-Dancoff approach. A second objective of this work is the study of light-cone perturbation theory as a competitive tool for conducting perturbative Feynman diagram calculations. Feynman perturbation theory has become the most practical tool for computing cross sections in high energy physics and other physical properties of field theory. Although this standard covariant method has been applied to a great range of problems, computations beyond one-loop corrections are very difficult. Because of the algebraic complexity of the Feynman calculations in higher-order perturbation theory, it is desirable to automatize Feynman diagram calculations so that algebraic manipulation programs can carry out almost the entire calculation. This thesis presents a step in this direction. The technique we are elaborating on here is known as light-cone perturbation theory.
Perturbation theory in light-cone quantization
Langnau, A.
1992-01-01
A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the perturbative level, i.e., to gain control over the perturbative treatment first. A clear understanding of divergences in perturbation theory, as well as their numerical treatment, is a necessary first step towards formulating such a program. The first objective of this dissertation is to clarify this issue, at least in second and fourth-order in perturbation theory. The work in this dissertation can provide guidance for the choice of counterterms in Discrete Light-Cone Quantization or the Tamm-Dancoff approach. A second objective of this work is the study of light-cone perturbation theory as a competitive tool for conducting perturbative Feynman diagram calculations. Feynman perturbation theory has become the most practical tool for computing cross sections in high energy physics and other physical properties of field theory. Although this standard covariant method has been applied to a great range of problems, computations beyond one-loop corrections are very difficult. Because of the algebraic complexity of the Feynman calculations in higher-order perturbation theory, it is desirable to automatize Feynman diagram calculations so that algebraic manipulation programs can carry out almost the entire calculation. This thesis presents a step in this direction. The technique we are elaborating on here is known as light-cone perturbation theory.
An Interactive Web System for Field Data Sharing and Collaboration
NASA Astrophysics Data System (ADS)
Weng, Y.; Sun, F.; Grigsby, J. D.
2010-12-01
A Web 2.0 system is designed and developed to facilitate data collection for the field studies in the Geological Sciences department at Ball State University. The system provides a student-centered learning platform that enables the users to first upload their collected data in various formats, interact and collaborate dynamically online, and ultimately create a shared digital repository of field experiences. The data types considered for the system and their corresponding format and requirements are listed in the table below. The system has six main functionalities as follows. (1) Only the registered users can access the system with confidential identification and password. (2) Each user can upload/revise/delete data in various formats such as image, audio, video, and text files to the system. (3) Interested users are allowed to co-edit the contents and join the collaboration whiteboard for further discussion. (4) The system integrates with Google, Yahoo, or Flickr to search for similar photos with same tags. (5) Users can search the web system according to the specific key words. (6) Photos with recorded GPS readings can be mashed and mapped to Google Maps/Earth for visualization. Application of the system to geology field trips at Ball State University will be demonstrated to assess the usability of the system.Data Requirements
Tribology of the lubricant quantized sliding state.
Castelli, Ivano Eligio; Capozza, Rosario; Vanossi, Andrea; Santoro, Giuseppe E; Manini, Nicola; Tosatti, Erio
2009-11-07
In the framework of Langevin dynamics, we demonstrate clear evidence of the peculiar quantized sliding state, previously found in a simple one-dimensional boundary lubricated model [A. Vanossi et al., Phys. Rev. Lett. 97, 056101 (2006)], for a substantially less idealized two-dimensional description of a confined multilayer solid lubricant under shear. This dynamical state, marked by a nontrivial "quantized" ratio of the averaged lubricant center-of-mass velocity to the externally imposed sliding speed, is recovered, and shown to be robust against the effects of thermal fluctuations, quenched disorder in the confining substrates, and over a wide range of loading forces. The lubricant softness, setting the width of the propagating solitonic structures, is found to play a major role in promoting in-registry commensurate regions beneficial to this quantized sliding. By evaluating the force instantaneously exerted on the top plate, we find that this quantized sliding represents a dynamical "pinned" state, characterized by significantly low values of the kinetic friction. While the quantized sliding occurs due to solitons being driven gently, the transition to ordinary unpinned sliding regimes can involve lubricant melting due to large shear-induced Joule heating, for example at large speed.
Effect of intensity quantization level in parallel phase-shifting digital holography
NASA Astrophysics Data System (ADS)
Miao, Lin; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro
2013-11-01
Parallel phase-shifting digital holography (PPSDH) enables the instantaneous recording of three-dimensional fields. The three-dimensional field can be reconstructed using a computer by numerical scalar wave propagation. In PPSDH, we record a space-division multiplexed hologram that includes the required phase retardation in the spatial distribution of the reference wave and then interpolate the data at blanked pixels for each phase retardation to obtain the complex amplitude distribution of an object wave. The recorded quality of the multiplexed hologram influences the reconstruction quality. In this study, we investigate the effect of the intensity quantization of a multiplexed hologram on the reconstruction quality. We compare the influence of intensity quantization in PPSDH with that in the conventional phase-shifting method. Random noise is also added to the multiplexed hologram. The required intensity quantization level is helpful for selecting a digital image sensor.
Comparison of different quantization strategies for subband coding of medical images
NASA Astrophysics Data System (ADS)
Castagno, Roberto; Lancini, Rosa C.; Egger, Olivier
1996-04-01
In this paper different methods for the quantization of wavelet transform coefficients are compared in view of medical imaging applications. The goal is to provide users with a comprehensive and application-oriented review of these techniques. The performance of four quantization methods (namely standard scalar quantization, embedded zerotree, variable dimension vector quantization and pyramid vector quantization) are compared with regard to their application in the field of medical imaging. In addition to the standard rate-distortion criterion, we took into account the possibility of bitrate control, the feasibility of real-time implementation, the genericity (for use in non-dedicated multimedia environments) of each approach. In addition, the diagnostical reliability of the decompressed images has been assessed during a viewing session and with the help of a specialist. Classical scalar quantization methods are briefly reviewed. As a result, it is shown that despite the relatively simple design of the optimum quantizers, their performance in terms of rate-distortion tradeoff are quite poor. For high quality subband coding, it is of major importance to exploit the existing zero-correlation across subbands as proposed with the embedded zerotree wavelet (EZW) algorithm. In this paper an improved EZW-algorithm is used which is termed embedded zerotree lossless (EZL) algorithm -- due to the importance of lossless compression in medical imaging applications -- having the additional possibility of producing an embedded lossless bitstream. VQ based methods take advantage of statistical properties of a block or a vector of data values, yielding good quality results of reconstructed images at the same bitrates. In this paper, we take in account two classes of VQ methods, random quantizers (VQ) and geometric quantizers (PVQ). Algorithms belonging to the first group (the most widely known being that developed by Linde-Buzo-Gray) suffer from the common drawback of requiring a
Electron g-2 in Light-front Quantization
Zhao, Xingbo; Honkanen, Heli; Maris, Pieter; ...
2014-08-13
In this study, basis Light-front Quantization has been proposed as a nonperturbative framework for solving quantum field theory. We apply this approach to Quantum Electrodynamics and explicitly solve for the light-front wave function of a physical electron. Based on the resulting light-front wave function, we evaluate the electron anomalous magnetic moment. Nonperturbative mass renormalization is performed. Upon extrapolation to the infinite basis limit our numerical results agree with the Schwinger result obtained in perturbation theory to an accuracy of 0.06%.
Nucleation of Quantized Vortices from Rotating Superfluid Drops
NASA Technical Reports Server (NTRS)
Donnelly, Russell J.
2001-01-01
The long-term goal of this project is to study the nucleation of quantized vortices in helium II by investigating the behavior of rotating droplets of helium II in a reduced gravity environment. The objective of this ground-based research grant was to develop new experimental techniques to aid in accomplishing that goal. The development of an electrostatic levitator for superfluid helium, described below, and the successful suspension of charged superfluid drops in modest electric fields was the primary focus of this work. Other key technologies of general low temperature use were developed and are also discussed.
Canonical Functional Quantization of Pseudo-Photons in Planar Systems
Ferreira, P. Castelo
2008-06-25
Extended U{sub e}(1)xU{sub g}(1) electromagnetism containing both a photon and a pseudo-photon is introduced at the variational level and is justified by the violation of the Bianchi identities in conceptual systems, either in the presence of magnetic monopoles or non-regular external fields, not being accounted for by the standard Maxwell Lagrangian. A dimensional reduction is carried out that yields a U{sub e}(1)xU{sub g}(1) Maxwell-BF type theory and a canonical functional quantization in planar systems is considered which may be relevant in Hall systems.
Quantization of spin waves in oval-shaped nanorings
NASA Astrophysics Data System (ADS)
Tan, C. G.; Lim, H. S.; Wang, Z. K.; Ng, S. C.; Kuok, M. H.; Goolaup, S.; Adeyeye, A. O.; Singh, N.
Regular arrays of oval-shaped permalloy nanorings have been fabricated using deep ultraviolet lithography and their spin dynamics measured by Brillouin light scattering with the magnetic field applied along long (easy) axes of the rings. The dispersionless behavior of the spin wave modes observed reveals their standing wave nature. Two-dimensional simulations and analytical calculations have been performed for a single isolated nanoring. Results reveal that the observed modes can be interpreted in terms of quantized Damon-Eshbach modes due to lateral confinement in the finite size rings.
Temporal evolutional absorption behaviors of graphene under Landau quantization
NASA Astrophysics Data System (ADS)
Hamedi, H. R.; Sahrai, M.
2017-02-01
We investigate the evolutional absorption behaviors of Landau-quantized graphene structure based on the transient solution to the density matrix equations of the motion. The impact of various system parameters on temporal evolution of probe absorption is studied. In addition, the required times for switching the high-absorption case to the zero-absorption (transparency) of a probe field is discussed. Due to unusual optical and electronic characteristics of graphene resulting from linear, massless dispersion of electrons near the Dirac point and the chiral character of electron states, our study may have potential applications in telecommunication, biomedicine, and optical information processing and may cause significant impact on technological applications.
Canonical quantization of general relativity in discrete space-times.
Gambini, Rodolfo; Pullin, Jorge
2003-01-17
It has long been recognized that lattice gauge theory formulations, when applied to general relativity, conflict with the invariance of the theory under diffeomorphisms. We analyze discrete lattice general relativity and develop a canonical formalism that allows one to treat constrained theories in Lorentzian signature space-times. The presence of the lattice introduces a "dynamical gauge" fixing that makes the quantization of the theories conceptually clear, albeit computationally involved. The problem of a consistent algebra of constraints is automatically solved in our approach. The approach works successfully in other field theories as well, including topological theories. A simple cosmological application exhibits quantum elimination of the singularity at the big bang.
Quantization of a theory of 2D dilaton gravity
NASA Astrophysics Data System (ADS)
de Alwis, S. P.
1992-09-01
We discuss the quantization of the 2D gravity theory of Callan, Giddings, Harvey, and Strominger (CGHS), following the procedure of David, and of Distler and Kawai. We find that the physics depends crucially on whether the number of matter fields is greater than or less than 24. In the latter case the singularity pointed out by several authors is absent but the physical interpretation is unclear. In the former case (the one studied by CGHS) the quantum theory which gives CGHS in the linear dilaton semi-classical limit, is different from that which gives CGHS in the extreme Liouville regime.
Theoretical analysis of magnetic field interactions with aortic blood flow
Kinouchi, Y.; Yamaguchi, H.; Tenforde, T.S.
1996-04-01
The flow of blood in the presence of a magnetic field gives rise to induced voltages in the major arteries of the central circulatory system. Under certain simplifying conditions, such as the assumption that the length of major arteries (e.g., the aorta) is infinite and that the vessel walls are not electrically conductive, the distribution of induced voltages and currents within these blood vessels can be calculated with reasonable precision. However, the propagation of magnetically induced voltages and currents from the aorta into neighboring tissue structures such as the sinuatrial node of the heart has not been previously determined by any experimental or theoretical technique. In the analysis presented in this paper, a solution of the complete Navier-Stokes equation was obtained by the finite element technique for blood flow through the ascending and descending aortic vessels in the presence of a uniform static magnetic field. Spatial distributions of the magnetically induced voltage and current were obtained for the aortic vessel and surrounding tissues under the assumption that the wall of the aorta is electrically conductive. Results are presented for the calculated values of magnetically induced voltages and current densities in the aorta and surrounding tissue structures, including the sinuatrial node, and for their field-strength dependence. In addition, an analysis is presented of magnetohydrodynamic interactions that lead to a small reduction of blood volume flow at high field levels above approximately 10 tesla (T). Quantitative results are presented on the offsetting effects of oppositely directed blood flows in the ascending and descending aortic segments, and a quantitative estimate is made of the effects of assuming an infinite vs. a finite length of the aortic vessel in calculating the magnetically induced voltage and current density distribution in tissue.
Single Abrikosov vortices as quantized information bits.
Golod, T; Iovan, A; Krasnov, V M
2015-10-12
Superconducting digital devices can be advantageously used in future supercomputers because they can greatly reduce the dissipation power and increase the speed of operation. Non-volatile quantized states are ideal for the realization of classical Boolean logics. A quantized Abrikosov vortex represents the most compact magnetic object in superconductors, which can be utilized for creation of high-density digital cryoelectronics. In this work we provide a proof of concept for Abrikosov-vortex-based random access memory cell, in which a single vortex is used as an information bit. We demonstrate high-endurance write operation and two different ways of read-out using a spin valve or a Josephson junction. These memory cells are characterized by an infinite magnetoresistance between 0 and 1 states, a short access time, a scalability to nm sizes and an extremely low write energy. Non-volatility and perfect reproducibility are inherent for such a device due to the quantized nature of the vortex.
Gravitational surface Hamiltonian and entropy quantization
NASA Astrophysics Data System (ADS)
Bakshi, Ashish; Majhi, Bibhas Ranjan; Samanta, Saurav
2017-02-01
The surface Hamiltonian corresponding to the surface part of a gravitational action has xp structure where p is conjugate momentum of x. Moreover, it leads to TS on the horizon of a black hole. Here T and S are temperature and entropy of the horizon. Imposing the hermiticity condition we quantize this Hamiltonian. This leads to an equidistant spectrum of its eigenvalues. Using this we show that the entropy of the horizon is quantized. This analysis holds for any order of Lanczos-Lovelock gravity. For general relativity, the area spectrum is consistent with Bekenstein's observation. This provides a more robust confirmation of this earlier result as the calculation is based on the direct quantization of the Hamiltonian in the sense of usual quantum mechanics.
Virtual topological insulators with real quantized physics
NASA Astrophysics Data System (ADS)
Prodan, Emil
2015-06-01
A concrete strategy is presented for generating strong topological insulators in d +d' dimensions which have quantized physics in d dimensions. Here, d counts the physical and d' the virtual dimensions. It consists of seeking d -dimensional representations of operator algebras which are usually defined in d +d' dimensions where topological elements display strong topological invariants. The invariants are shown, however, to be fully determined by the physical dimensions, in the sense that their measurement can be done at fixed virtual coordinates. We solve the bulk-boundary correspondence and show that the boundary invariants are also fully determined by the physical coordinates. We analyze the virtual Chern insulator in 1 +1 dimensions realized in Y. E. Kraus et al., Phys. Rev. Lett. 109, 106402 (2012), 10.1103/PhysRevLett.109.106402 and predict quantized forces at the edges. We generate a topological system in (3 +1 ) dimensions, which is predicted to have quantized magnetoelectric response.
The totally constrained model: three quantization approaches
NASA Astrophysics Data System (ADS)
Gambini, Rodolfo; Olmedo, Javier
2014-08-01
We provide a detailed comparison of the different approaches available for the quantization of a totally constrained system with a constraint algebra generating the non-compact group. In particular, we consider three schemes: the Refined Algebraic Quantization, the Master Constraint Programme and the Uniform Discretizations approach. For the latter, we provide a quantum description where we identify semiclassical sectors of the kinematical Hilbert space. We study the quantum dynamics of the system in order to show that it is compatible with the classical continuum evolution. Among these quantization approaches, the Uniform Discretizations provides the simpler description in agreement with the classical theory of this particular model, and it is expected to give new insights about the quantum dynamics of more realistic totally constrained models such as canonical general relativity.
A quantum mechanical polarizable force field for biomolecular interactions
Donchev, A. G.; Ozrin, V. D.; Subbotin, M. V.; Tarasov, O. V.; Tarasov, V. I.
2005-01-01
We introduce a quantum mechanical polarizable force field (QMPFF) fitted solely to QM data at the MP2/aTZ(-hp) level. Atomic charge density is modeled by point-charge nuclei and floating exponentially shaped electron clouds. The functional form of interaction energy parallels quantum mechanics by including electrostatic, exchange, induction, and dispersion terms. Separate fitting of each term to the counterpart calculated from high-quality QM data ensures high transferability of QMPFF parameters to different molecular environments, as well as accurate fit to a broad range of experimental data in both gas and liquid phases. QMPFF, which is much more efficient than ab initio QM, is optimized for the accurate simulation of biomolecular systems and the design of drugs. PMID:15911753
Atoms and Ions Interacting with Particles and Fields: Final Report
Robicheaux, Francis
2014-09-18
This grant supported research in basic atomic, molecular and optical physics related to the interactions of atoms with particles and fields. The duration of the grant was the 10 year period from 8/2003 to 8/2013. All of the support from the grant was used to pay salaries of the PI, postdocs, graduate students, and undergraduates and travel to conferences and meetings. The results were in the form of publications in peer reviewed journals. There were 65 peer reviewed publications over these 10 years with 8 of the publications in Physical Review Letters; all of the other articles were in respected peer reviewed journals (Physical Review A, New Journal of Physics, Journal of Physics B, ...). I will disuss the results for the periods of time relevant for each grant period.
NASA Astrophysics Data System (ADS)
Abdel Wahab, N. H.; Salah, Ahmed
2015-05-01
In this paper, the interaction of a three-level -configration atom and a one-mode quantized electromagnetic cavity field has been studied. The detuning parameters, the Kerr nonlinearity and the arbitrary form of both the field and intensity-dependent atom-field coupling have been taken into account. The wave function when the atom and the field are initially prepared in the excited state and coherent state, respectively, by using the Schrödinger equation has been given. The analytical approximation solution of this model has been obtained by using the modified homotopy analysis method (MHAM). The homotopy analysis method is mentioned summarily. MHAM can be obtained from the homotopy analysis method (HAM) applied to Laplace, inverse Laplace transform and Pade approximate. MHAM is used to increase the accuracy and accelerate the convergence rate of truncated series solution obtained by the HAM. The time-dependent parameters of the anti-bunching of photons, the amplitude-squared squeezing and the coherent properties have been calculated. The influence of the detuning parameters, Kerr nonlinearity and photon number operator on the temporal behavior of these phenomena have been analyzed. We noticed that the considered system is sensitive to variations in the presence of these parameters.
Field evaluation of an acid rain-drought stress interaction.
Banwart, W L
1988-01-01
Various methods have been proposed to simulate natural field conditions for growing agricultural crops while controlling conditions to study specific environmental effects. This report briefly describes the use of moveable rain exclusion shelters (10.4 x 40.9 m) to study the results of the interaction of acid rain and drought stress on corn and soybean yields. The rain exclusion shelters are constructed of galvanized pipe framing and covered with polyethylene film. Movement is automated by a rain switch to protect crops from ambient rainfall and to treat them with simulated acid rain The facility simulates a real environment with respect to variables such as solar exposure, wind movement, dew formation, and insect exposure, while allowing careful control of moisture regimes. Soybeans and corn were treated with average rainfall amounts, and with one-half and one-quarter of these rainfall amounts (drought stress) at two levels of rainfall acidity, pH 5.6 and 3.0. While drought stress resulted in considerable yield reduction for Amsoy and Williams soybeans, no additional reduction in yield was observed with rainfall of pH 3.0, as compared to rainfall of approximately pH 5.6. Similar results were observed for one corn cultivar, Pioneer 3377. For one year of the study however, yield of B73 x Mo17 (corn) was reduced 3139 kg ha(-1) by the most severe drought, and an additional 1883 kg ha(-1) by acid rain of pH 3.0, as compared to the control (pH 5.6). Yield reduction from acidic rain was considerably less at full water rates, resulting in a significant pH by drought stress interaction. However, during the second year of the experiment, no pH effect or drought by pH interaction was observed for this cultivar. The reason for the difference in the two years was not identified.
Field Observations of Coastal Air-Sea Interaction
NASA Astrophysics Data System (ADS)
Ortiz-Suslow, D. G.; Haus, B. K.; Williams, N. J.; Graber, H. C.
2016-12-01
In the nearshore zone wind, waves, and currents generated from different forcing mechanisms converge in shallow water. This can profoundly affect the physical nature of the ocean surface, which can significantly modulate the exchange of momentum, heat, and mass across the air-sea interface. For decades, the focus of air-sea interaction research has been on the open ocean while the shallow water regime has been relatively under-explored. This bears implications for efforts to understand and model various coastal processes, such as mixing, surface transport, and air-sea gas flux. The results from a recent study conducted at the New River Inlet in North Carolina showed that directly measured air-sea flux parameters, such as the atmospheric drag coefficient, are strong functions of space as well as the ambient conditions (i.e. wind speed and direction). The drag is typically used to parameterize the wind stress magnitude. It is generally assumed that the wind direction is the direction of the atmospheric forcing (i.e. wind stress), however significant wind stress steering off of the azimuthal wind direction was observed and was found to be related to the horizontal surface current shear. The authors have just returned from a field campaign carried out within Monterey Bay in California. Surface observations made from two research vessels were complimented by an array of beach and inland flux stations, high-resolution wind forecasts, and satellite image acquisitions. This is a rich data set and several case studies will be analyzed to highlight the importance of various processes for understanding the air-sea fluxes. Preliminary findings show that interactions between the local wind-sea and the shoaling, incident swell can have a profound effect on the wind stress magnitude. The Monterey Bay coastline contains a variety of topographical features and the importance of land-air-sea interactions will also be investigated.
Minimal representations, geometric quantization, and unitarity.
Brylinski, R; Kostant, B
1994-01-01
In the framework of geometric quantization we explicitly construct, in a uniform fashion, a unitary minimal representation pio of every simply-connected real Lie group Go such that the maximal compact subgroup of Go has finite center and Go admits some minimal representation. We obtain algebraic and analytic results about pio. We give several results on the algebraic and symplectic geometry of the minimal nilpotent orbits and then "quantize" these results to obtain the corresponding representations. We assume (Lie Go)C is simple. PMID:11607478
Subband Image Coding with Jointly Optimized Quantizers
NASA Technical Reports Server (NTRS)
Kossentini, Faouzi; Chung, Wilson C.; Smith Mark J. T.
1995-01-01
An iterative design algorithm for the joint design of complexity- and entropy-constrained subband quantizers and associated entropy coders is proposed. Unlike conventional subband design algorithms, the proposed algorithm does not require the use of various bit allocation algorithms. Multistage residual quantizers are employed here because they provide greater control of the complexity-performance tradeoffs, and also because they allow efficient and effective high-order statistical modeling. The resulting subband coder exploits statistical dependencies within subbands, across subbands, and across stages, mainly through complexity-constrained high-order entropy coding. Experimental results demonstrate that the complexity-rate-distortion performance of the new subband coder is exceptional.
Image Coding Based on Address Vector Quantization.
NASA Astrophysics Data System (ADS)
Feng, Yushu
Image coding is finding increased application in teleconferencing, archiving, and remote sensing. This thesis investigates the potential of Vector Quantization (VQ), a relatively new source coding technique, for compression of monochromatic and color images. Extensions of the Vector Quantization technique to the Address Vector Quantization method have been investigated. In Vector Quantization, the image data to be encoded are first processed to yield a set of vectors. A codeword from the codebook which best matches the input image vector is then selected. Compression is achieved by replacing the image vector with the index of the code-word which produced the best match, the index is sent to the channel. Reconstruction of the image is done by using a table lookup technique, where the label is simply used as an address for a table containing the representative vectors. A code-book of representative vectors (codewords) is generated using an iterative clustering algorithm such as K-means, or the generalized Lloyd algorithm. A review of different Vector Quantization techniques are given in chapter 1. Chapter 2 gives an overview of codebook design methods including the Kohonen neural network to design codebook. During the encoding process, the correlation of the address is considered and Address Vector Quantization is developed for color image and monochrome image coding. Address VQ which includes static and dynamic processes is introduced in chapter 3. In order to overcome the problems in Hierarchical VQ, Multi-layer Address Vector Quantization is proposed in chapter 4. This approach gives the same performance as that of the normal VQ scheme but the bit rate is about 1/2 to 1/3 as that of the normal VQ method. In chapter 5, a Dynamic Finite State VQ based on a probability transition matrix to select the best subcodebook to encode the image is developed. In chapter 6, a new adaptive vector quantization scheme, suitable for color video coding, called "A Self -Organizing
Minimal representations, geometric quantization, and unitarity.
Brylinski, R; Kostant, B
1994-06-21
In the framework of geometric quantization we explicitly construct, in a uniform fashion, a unitary minimal representation pio of every simply-connected real Lie group Go such that the maximal compact subgroup of Go has finite center and Go admits some minimal representation. We obtain algebraic and analytic results about pio. We give several results on the algebraic and symplectic geometry of the minimal nilpotent orbits and then "quantize" these results to obtain the corresponding representations. We assume (Lie Go)C is simple.
Constraints on operator ordering from third quantization
Ohkuwa, Yoshiaki; Faizal, Mir; Ezawa, Yasuo
2016-02-15
In this paper, we analyse the Wheeler–DeWitt equation in the third quantized formalism. We will demonstrate that for certain operator ordering, the early stages of the universe are dominated by quantum fluctuations, and the universe becomes classical at later stages during the cosmic expansion. This is physically expected, if the universe is formed from quantum fluctuations in the third quantized formalism. So, we will argue that this physical requirement can be used to constrain the form of the operator ordering chosen. We will explicitly demonstrate this to be the case for two different cosmological models.
Optical field enhancement by strong plasmon interaction in graphene nanostructures.
Thongrattanasiri, Sukosin; García de Abajo, F Javier
2013-05-03
The ability of plasmons to enhance the electromagnetic field intensity in the gap between metallic nanoparticles derives from their strong optical confinement relative to the light wavelength. The spatial extension of plasmons in doped graphene has recently been shown to be boldly reduced with respect to conventional plasmonic metals. Here, we show that graphene nanostructures are capable of capitalizing such strong confinement to yield unprecedented levels of field enhancement, well beyond what is found in noble metals of similar dimensions (~ tens of nanometers). We perform realistic, quantum-mechanical calculations of the optical response of graphene dimers formed by nanodisks and nanotriangles, showing a strong sensitivity of the level of enhancement to the type of carbon edges near the gap region, with armchair edges favoring stronger interactions than zigzag edges. Our quantum-mechanical description automatically incorporates nonlocal effects that are absent in classical electromagnetic theory, leading to over an order of magnitude higher enhancement in armchair structures. The classical limit is recovered for large structures. We predict giant levels of light concentration for dimers ~200 nm, leading to infrared-absorption enhancement factors ~10(8). This extreme light enhancement and confinement in nanostructured graphene has great potential for optical sensing and nonlinear devices.
Quantized impedance dealing with the damping behavior of the one-dimensional oscillator
Zhu, Jinghao; Zhang, Jing; Li, Yuan; Zhang, Yong; Fang, Zhengji; Zhao, Peide E-mail: pdzhao@hebut.edu.cn; Li, Erping
2015-11-15
A quantized impedance is proposed to theoretically establish the relationship between the atomic eigenfrequency and the intrinsic frequency of the one-dimensional oscillator in this paper. The classical oscillator is modified by the idea that the electron transition is treated as a charge-discharge process of a suggested capacitor with the capacitive energy equal to the energy level difference of the jumping electron. The quantized capacitance of the impedance interacting with the jumping electron can lead the resonant frequency of the oscillator to the same as the atomic eigenfrequency. The quantized resistance reflects that the damping coefficient of the oscillator is the mean collision frequency of the transition electron. In addition, the first and third order electric susceptibilities based on the oscillator are accordingly quantized. Our simulation of the hydrogen atom emission spectrum based on the proposed method agrees well with the experimental one. Our results exhibits that the one-dimensional oscillator with the quantized impedance may become useful in the estimations of the refractive index and one- or multi-photon absorption coefficients of some nonmagnetic media composed of hydrogen-like atoms.
Interaction of the Barbero-Immirzi field with matter and pseudoscalar perturbations
NASA Astrophysics Data System (ADS)
Mercuri, Simone; Taveras, Victor
2009-11-01
In loop quantum gravity the classical point of departure is the Einstein-Hilbert action modified by the addition of the so-called Holst term. Classically, this term does not affect the equations of motion, but it induces a well-known quantization ambiguity in the quantum theory, parametrized by the Barbero-Immirzi parameter. Recently, it has been suggested to promote the Barbero-Immirzi parameter to a field. The resulting theory, obtainable starting from the usual Holst action, is general relativity coupled to a pseudoscalar field. However, this theory turns out to have an unconventional kinetic term for the Barbero-Immirzi field and a rather unnatural coupling with fermions. The main goal of this work is twofold: First, to propose a further generalization of the Holst action, which yields a theory of gravity and matter with a more natural coupling to the Barbero-Immirzi field; second, to study the possible implications for cosmology correlated to the existence of this new pseudoscalar field.
Stability of the quantized circulation of an attractive Bose-Einstein condensate in a rotating torus
Kanamoto, Rina; Saito, Hiroki; Ueda, Masahito
2003-10-01
We investigate rotational properties of a system of attractive bosons confined in a one-dimensional torus. Two kinds of ground states, uniform-density and bright soliton, are obtained analytically as functions of the strength of interaction and of the rotational frequency of the torus. The quantization of circulation appears in the uniform-density state, but disappears upon formation of the soliton. By comparing the results of exact diagonalization with those predicted by the Bogoliubov theory, we show that the Bogoliubov theory is valid at absolute zero over a wide range of parameters. At finite temperatures we employ the exact diagonalization method to examine how thermal fluctuations smear the plateaus of the quantized circulation. Finally, by rotating the system with an axisymmetry-breaking potential, we clarify the process by which the quantized circulation becomes thermodynamically stabilized.
Integrable structures and the quantization of free null initial data for gravity
NASA Astrophysics Data System (ADS)
Fuchs, Andreas; Reisenberger, Michael P.
2017-09-01
Variables for constraint free null canonical vacuum general relativity are presented which have simple Poisson brackets that facilitate quantization. Free initial data for vacuum general relativity on a pair of intersecting null hypersurfaces has been known since the 1960s. These consist of the ‘main’ data which are set on the bulk of the two null hypersurfaces, and additional ‘surface’ data set only on their intersection 2-surface. More recently the complete set of Poisson brackets of such data has been obtained. However the complexity of these brackets is an obstacle to their quantization. Part of this difficulty may be overcome using methods from the treatment of cylindrically symmetric gravity. Specializing from general to cylindrically symmetric solutions changes the Poisson algebra of the null initial data surprisingly little, but cylindrically symmetric vacuum general relativity is an integrable system, making powerful tools available. Here a transformation is constructed at the cylindrically symmetric level which maps the main initial data to new data forming a Poisson algebra for which an exact deformation quantization is known. (Although an auxiliary condition on the data has been quantized only in the asymptotically flat case, and a suitable representation of the algebra of quantum data by operators on a Hilbert space has not yet been found.) The definition of the new main data generalizes naturally to arbitrary, symmetryless gravitational fields, with the Poisson brackets retaining their simplicity. The corresponding generalization of the quantization is however ambiguous and requires further analysis.
Observation and suppression of quantized spin waves in microfabricated permalloy elements
NASA Astrophysics Data System (ADS)
Yamamoto, Tatsuya; Seki, Takeshi; Ono, Shimpei; Takanashi, Koki
2014-01-01
We report the observation and suppression of quantized spin wave modes in a microfabricated rectangular permalloy (Py) element. The Py element was located on a coplanar waveguide and was connected to a Cu wire. The quantized Damon-Eshbach spin wave and the perpendicular standing spin wave modes appeared in the resonance spectra for the Py elements. Those non-uniform magnetization dynamics were suppressed when the non-uniformity of the radio frequency magnetic field for the excitation was reduced by changing the design of the device structure.
NASA Astrophysics Data System (ADS)
Chu, Hao; Wu, Chengdong
2016-10-01
The source localization base on wireless sensor network has attracted considerable attention in recent years. However, most of the previous works focus on the accurate measurement or single source localization. The multiple-source localization has extensive application prospect in many fields. The quantized measurement is a low-cost and low energy consumption solution for wireless sensor network. In this paper, we present a novel multiple-source consecutive localization algorithm using the quantized measurement. We first introduce the multiple acoustic sources model and quantized measurement method. Then the maximum likelihood method is used to establish the localization function and the particle swarm optimization is employed to estimate the initial position of the source. Finally the Kalman filter is used to mitigate the random processing noise. Simulation results show that the proposed method owns high localization accuracy.
Multiverse in the Third Quantized Formalism
NASA Astrophysics Data System (ADS)
Mir, Faizal
2014-11-01
In this paper we will analyze the third quantization of gravity in path integral formalism. We will use the time-dependent version of Wheeler—DeWitt equation to analyze the multiverse in this formalism. We will propose a mechanism for baryogenesis to occur in the multiverse, without violating the baryon number conservation.
Bolometric Device Based on Fluxoid Quantization
NASA Technical Reports Server (NTRS)
Bonetti, Joseph A.; Kenyon, Matthew E.; Leduc, Henry G.; Day, Peter K.
2010-01-01
The temperature dependence of fluxoid quantization in a superconducting loop. The sensitivity of the device is expected to surpass that of other superconducting- based bolometric devices, such as superconducting transition-edge sensors and superconducting nanowire devices. Just as important, the proposed device has advantages in sample fabrication.
Visual data mining for quantized spatial data
NASA Technical Reports Server (NTRS)
Braverman, Amy; Kahn, Brian
2004-01-01
In previous papers we've shown how a well known data compression algorithm called Entropy-constrained Vector Quantization ( can be modified to reduce the size and complexity of very large, satellite data sets. In this paper, we descuss how to visualize and understand the content of such reduced data sets.
Visual data mining for quantized spatial data
NASA Technical Reports Server (NTRS)
Braverman, Amy; Kahn, Brian
2004-01-01
In previous papers we've shown how a well known data compression algorithm called Entropy-constrained Vector Quantization ( can be modified to reduce the size and complexity of very large, satellite data sets. In this paper, we descuss how to visualize and understand the content of such reduced data sets.
Deformation quantization and boundary value problems
NASA Astrophysics Data System (ADS)
Tarkhanov, Nikolai
2016-11-01
We describe a natural construction of deformation quantization on a compact symplectic manifold with boundary. On the algebra of quantum observables a trace functional is defined which as usual annihilates the commutators. This gives rise to an index as the trace of the unity element. We formulate the index theorem as a conjecture and examine it by the classical harmonic oscillator.
On Quantization of Quadratic Poisson Structures
NASA Astrophysics Data System (ADS)
Manchon, D.; Masmoudi, M.; Roux, A.
Any classical r-matrix on the Lie algebra of linear operators on a real vector space V gives rise to a quadratic Poisson structure on V which admits a deformation quantization stemming from the construction of V. Drinfel'd [Dr], [Gr]. We exhibit in this article an example of quadratic Poisson structure which does not arise this way.
Combining Vector Quantization and Histogram Equalization.
ERIC Educational Resources Information Center
Cosman, Pamela C.; And Others
1992-01-01
Discussion of contrast enhancement techniques focuses on the use of histogram equalization with a data compression technique, i.e., tree-structured vector quantization. The enhancement technique of intensity windowing is described, and the use of enhancement techniques for medical images is explained, including adaptive histogram equalization.…
Image compression using address-vector quantization
NASA Astrophysics Data System (ADS)
Nasrabadi, Nasser M.; Feng, Yushu
1990-12-01
A novel vector quantization scheme, the address-vector quantizer (A-VQ), is proposed which exploits the interblock correlation by encoding a group of blocks together using an address-codebook (AC). The AC is a set of address-codevectors (ACVs), each representing a combination of addresses or indices. Each element of the ACV is an address of an entry in the LBG-codebook, representing a vector-quantized block. The AC consists of an active (addressable) region and an inactive (nonaddressable) region. During encoding the ACVs in the AC are reordered adaptively to bring the most probable ACVs into the active region. When encoding an ACV, the active region is checked, and if such an address combination exists, its index is transmitted to the receiver. Otherwise, the address of each block is transmitted individually. The SNR of the images encoded by the A-VQ method is the same as that of a memoryless vector quantizer, but the bit rate is by a factor of approximately two.
Vacuum Energy in Two Dimensional Box Through the Krein Quantization
NASA Astrophysics Data System (ADS)
Ghaffari, Ali; Karimaghaee, Sanaz; Tanhayi, M. R.
2017-03-01
In this work we reexamine the Casimir effect in which the vacuum expectation value of quantum fields is calculated over a so-called Krein space. This method has already been successfully applied to study Casimir effect on non-trivial topologies and also the covariance problem in the massless minimally coupled scalar field in de Sitter space-time. It is shown that within this method, no infinite term appears in the computation of the vacuum expectation value of energy-momentum tensor. We investigate the behavior of the Krein quantization for a scalar field in a box satisfying the Dirichlet boundary condition. We show that one can recover the usual theory with the exception that the vacuum energy of the free theory is zero.
Vacuum Energy in Two Dimensional Box Through the Krein Quantization
NASA Astrophysics Data System (ADS)
Ghaffari, Ali; Karimaghaee, Sanaz; Tanhayi, M. R.
2016-12-01
In this work we reexamine the Casimir effect in which the vacuum expectation value of quantum fields is calculated over a so-called Krein space. This method has already been successfully applied to study Casimir effect on non-trivial topologies and also the covariance problem in the massless minimally coupled scalar field in de Sitter space-time. It is shown that within this method, no infinite term appears in the computation of the vacuum expectation value of energy-momentum tensor. We investigate the behavior of the Krein quantization for a scalar field in a box satisfying the Dirichlet boundary condition. We show that one can recover the usual theory with the exception that the vacuum energy of the free theory is zero.
Four-Wave Mixing in Landau-Quantized Graphene.
König-Otto, Jacob C; Wang, Yongrui; Belyanin, Alexey; Berger, Claire; de Heer, Walter A; Orlita, Milan; Pashkin, Alexej; Schneider, Harald; Helm, Manfred; Winnerl, Stephan
2017-04-12
For Landau-quantized graphene, featuring an energy spectrum consisting of nonequidistant Landau levels, theory predicts a giant resonantly enhanced optical nonlinearity. We verify the nonlinearity in a time-integrated degenerate four-wave mixing (FWM) experiment in the mid-infrared spectral range, involving the Landau levels LL-1, LL0 and LL1. A rapid dephasing of the optically induced microscopic polarization on a time scale shorter than the pulse duration (∼4 ps) is observed, while a complementary pump-probe experiment under the same experimental conditions reveals a much longer lifetime of the induced population. The FWM signal shows the expected field dependence with respect to lowest order perturbation theory for low fields. Saturation sets in for fields above ∼6 kV/cm. Furthermore, the resonant behavior and the order of magnitude of the third-order susceptibility are in agreement with our theoretical calculations.
Creation of quantized particles, gravitons, and scalar perturbations by the expanding universe
NASA Astrophysics Data System (ADS)
Parker, Leonard
2015-04-01
Quantum creation processes during the very rapid early expansion of the universe are believed to give rise to temperature anisotropies and polarization patterns in the CMB radiation. These have been observed by satellites such as COBE, WMAP, and PLANCK, and by bolometric instruments placed near the South Pole by the BICEP collaborations. The expected temperature anisotropies are well-confirmed. The B-mode polarization patterns in the CMB are currently under measurement jointly by the PLANCK and BICEP groups to determine the extent to which the B-modes can be attributed to gravitational waves from the creation of gravitons in the earliest universe. As the original discoverer of the quantum phenomenon of particle creation from vacuum by the expansion of the universe, I will explain how the discovery came about and how it relates to the current observations. The first system that I considered when I started my Ph.D. thesis in 1962 was the quantized minimally-coupled scalar field in an expanding FLRW (Friedmann, Lemaitré, Robertson, Walker) universe having a general continuous scale factor a(t) with continuous time derivatives. I also considered quantized fermion fields of spin-1/2 and the spin-1 massless photon field, as well as the quantized conformally-invariant field equations of arbitrary integer and half-integer spins that had been written down in the classical context for general gravitational metrics by Penrose. It was during 1962 that I proved that quanta of the minimally-coupled scalar field were created by the general expanding FLRW universe. This was relevant also to the creation of quantized perturbations of the gravitational field, since these perturbations satisfied linear field equations that could be quantized in the same way as the minimally-coupled scalar field equation. In fact, in 1946, E.M. Lifshitz had considered the classical Einstein gravitational field in FLRW expanding universes and had shown that the classical linearized Einstein field
Universal behavior after a quantum quench in interacting field theories
NASA Astrophysics Data System (ADS)
Mitra, Aditi
The dynamics of an isolated quantum system represented by a field theory with O(N) symmetry, and in d>2 spatial dimensions, is investigated after a quantum quench from a disordered initial state to the critical point. A perturbative renormalization-group approach involving an expansion around d=4 is employed to study the time-evolution, and is supplemented by an exact solution of the Hartree-Fock equations in the large-N limit. The results show that the dynamics is characterized by a prethermal regime controlled by elastic dephasing where excitations propagate ballistically, and a light cone emerges in correlation functions in real space. The memory of the initial state, together with the absence of time-scales at the critical point, gives rise to universal power-law aging which is characterized by a new non-equilibrium short-time exponent. The dynamics of the entanglement following a quench is also explored, and reveals that while the time evolution of the entanglement entropy itself is not much different between a free bosonic theory and an interacting bosonic theory, the low-energy entanglement spectrum on the other hand shows clear signature of the non-equilibrium short-time exponent related to aging. This work was done in collaboration with Y. Lemonik (NYU), M. Tavora (NYU), A. Chiocchetta (SISSA), A. Maraga (SISSA), and A. Gambassi (SISSA). Supported by NSF-DMR 1303177.
Conditional random field modelling of interactions between findings in mammography
NASA Astrophysics Data System (ADS)
Kooi, Thijs; Mordang, Jan-Jurre; Karssemeijer, Nico
2017-03-01
Recent breakthroughs in training deep neural network architectures, in particular deep Convolutional Neural Networks (CNNs), made a big impact on vision research and are increasingly responsible for advances in Computer Aided Diagnosis (CAD). Since many natural scenes and medical images vary in size and are too large to feed to the networks as a whole, two stage systems are typically employed, where in the first stage, small regions of interest in the image are located and presented to the network as training and test data. These systems allow us to harness accurate region based annotations, making the problem easier to learn. However, information is processed purely locally and context is not taken into account. In this paper, we present preliminary work on the employment of a Conditional Random Field (CRF) that is trained on top the CNN to model contextual interactions such as the presence of other suspicious regions, for mammography CAD. The model can easily be extended to incorporate other sources of information, such as symmetry, temporal change and various patient covariates and is general in the sense that it can have application in other CAD problems.
Quantization of non-Hamiltonian and dissipative systems
NASA Astrophysics Data System (ADS)
Tarasov, Vasily E.
2001-09-01
A generalization of canonical quantization which maps a dynamical operator to a dynamical superoperator is suggested. Weyl quantization of dynamical operator, which cannot be represented as Poisson bracket with some function, is considered. The usual Weyl quantization of observables is a specific case of suggested quantization. This approach allows to define consistent quantization procedure for non-Hamiltonian and dissipative systems. Examples of the harmonic oscillator with friction (generalized Lorenz-Rossler-Leipnik-Newton equation), the Fokker-Planck-type system and Lorenz-type system are considered.
Video data compression using artificial neural network differential vector quantization
NASA Technical Reports Server (NTRS)
Krishnamurthy, Ashok K.; Bibyk, Steven B.; Ahalt, Stanley C.
1991-01-01
An artificial neural network vector quantizer is developed for use in data compression applications such as Digital Video. Differential Vector Quantization is used to preserve edge features, and a new adaptive algorithm, known as Frequency-Sensitive Competitive Learning, is used to develop the vector quantizer codebook. To develop real time performance, a custom Very Large Scale Integration Application Specific Integrated Circuit (VLSI ASIC) is being developed to realize the associative memory functions needed in the vector quantization algorithm. By using vector quantization, the need for Huffman coding can be eliminated, resulting in superior performance against channel bit errors than methods that use variable length codes.
The Angular Momentum Dilemma and Born-Jordan Quantization
NASA Astrophysics Data System (ADS)
de Gosson, Maurice A.
2017-01-01
The rigorous equivalence of the Schrödinger and Heisenberg pictures requires that one uses Born-Jordan quantization in place of Weyl quantization. We confirm this by showing that the much discussed " angular momentum dilemma" disappears if one uses Born-Jordan quantization. We argue that the latter is the only physically correct quantization procedure. We also briefly discuss a possible redefinition of phase space quantum mechanics, where the usual Wigner distribution has to be replaced with a new quasi-distribution associated with Born-Jordan quantization, and which has proven to be successful in time-frequency analysis.
Canonical quantization of constrained systems and coadjoint orbits of Diff(S sup 1 )
Scherer, W.M.
1988-01-01
It is shown that Dirac's treatment of constrained Hamiltonian systems and Schwinger's action principle quantization lead to identical commutations relations. An explicit relation between the Lagrange multipliers in the action principle approach and the additional terms in the Dirac bracket is derived. The equivalence of the two methods is demonstrated in the case of the non-linear sigma model. Dirac's method is extended to superspace and this extension is applied to the chiral superfield. The Dirac brackets of the massive interacting chiral superfluid are derived and shown to give the correct commutation relations for the component fields. The Hamiltonian of the theory is given and the Hamiltonian equations of motion are computed. They agree with the component field results. An infinite sequence of differential operators which are covariant under the coadjoint action of Diff(S{sup 1}) and analogues to Hill's operator is constructed. They map conformal fields of negative integer and half-integer weight to their dual space. Some properties of these operators are derived and possible applications are discussed. The Korteweg-de Vries equation is formulated as a coadjoint orbit of Diff(S{sup 1}).
Education and Education Research: Moribund Fields or Dynamic Interacting Systems?
ERIC Educational Resources Information Center
Reddy, C.
2011-01-01
The complex field of education is often depicted as a static field governed by technocratic approaches to activities that characterise the field. Education change is equally viewed in such limited and positivistic ways and linear means-end processes (Hoban 2002). In such orientations to the field, educational research therefore, is about finding…
The Multiphoton Interaction of Lambda Model Atom and Two-Mode Fields
NASA Technical Reports Server (NTRS)
Liu, Tang-Kun
1996-01-01
The system of two-mode fields interacting with atom by means of multiphotons is addressed, and the non-classical statistic quality of two-mode fields with interaction is discussed. Through mathematical calculation, some new rules of non-classical effects of two-mode fields which evolue with time, are established.
Near-field optics: The nightmare of the photon
NASA Astrophysics Data System (ADS)
Keller, Ole
2000-05-01
A first-quantized theory describing the birth process of a single photon in the near-field zone of a pointlike particle (atom, molecule, etc.) is established. The space-time description of the photon energy wave function embryo is shown to be useful for the understanding of the role played by (unborn) photons in near-field interactions where the spatial confinement of light plays a crucial role.
Size quantization of Dirac fermions in graphene constrictions.
Terrés, B; Chizhova, L A; Libisch, F; Peiro, J; Jörger, D; Engels, S; Girschik, A; Watanabe, K; Taniguchi, T; Rotkin, S V; Burgdörfer, J; Stampfer, C
2016-05-20
Quantum point contacts are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wavelength in high-quality bulk graphene can be tuned up to hundreds of nanometres, the observation of quantum confinement of Dirac electrons in nanostructured graphene has proven surprisingly challenging. Here we show ballistic transport and quantized conductance of size-confined Dirac fermions in lithographically defined graphene constrictions. At high carrier densities, the observed conductance agrees excellently with the Landauer theory of ballistic transport without any adjustable parameter. Experimental data and simulations for the evolution of the conductance with magnetic field unambiguously confirm the identification of size quantization in the constriction. Close to the charge neutrality point, bias voltage spectroscopy reveals a renormalized Fermi velocity of ∼1.5 × 10(6) m s(-1) in our constrictions. Moreover, at low carrier density transport measurements allow probing the density of localized states at edges, thus offering a unique handle on edge physics in graphene devices.
Deformation Quantization and Superconformal Symmetry in Three Dimensions
NASA Astrophysics Data System (ADS)
Beem, Christopher; Peelaers, Wolfger; Rastelli, Leonardo
2017-08-01
We investigate the structure of certain protected operator algebras that arise in three-dimensional {\\mathcal{N}=4} superconformal field theories. We find that these algebras can be understood as a quantization of (either of) the half-BPS chiral ring(s). An important feature of this quantization is that it has a preferred basis in which the structure constants of the quantum algebra are equal to the OPE coefficients of the underlying superconformal theory. We identify several nontrivial conditions that the quantum algebra must satisfy in this basis. We consider examples of theories for which the moduli space of vacua is either the minimal nilpotent orbit of a simple Lie algebra or a Kleinian singularity. For minimal nilpotent orbits, the quantum algebras (and their preferred bases) can be uniquely determined. These algebras are related to higher spin algebras. For Kleinian singularities the algebras can be characterized abstractly—they are spherical subalgebras of symplectic reflection algebras—but the preferred basis is not easily determined. We find evidence in these examples that for a given choice of quantum algebra (defined up to a certain gauge equivalence), there is at most one choice of canonical basis. We conjecture that this is the case for general {\\mathcal{N}=4} SCFTs.
Deformation Quantization and Superconformal Symmetry in Three Dimensions
NASA Astrophysics Data System (ADS)
Beem, Christopher; Peelaers, Wolfger; Rastelli, Leonardo
2017-02-01
We investigate the structure of certain protected operator algebras that arise in three-dimensional N=4 superconformal field theories. We find that these algebras can be understood as a quantization of (either of) the half-BPS chiral ring(s). An important feature of this quantization is that it has a preferred basis in which the structure constants of the quantum algebra are equal to the OPE coefficients of the underlying superconformal theory. We identify several nontrivial conditions that the quantum algebra must satisfy in this basis. We consider examples of theories for which the moduli space of vacua is either the minimal nilpotent orbit of a simple Lie algebra or a Kleinian singularity. For minimal nilpotent orbits, the quantum algebras (and their preferred bases) can be uniquely determined. These algebras are related to higher spin algebras. For Kleinian singularities the algebras can be characterized abstractly—they are spherical subalgebras of symplectic reflection algebras—but the preferred basis is not easily determined. We find evidence in these examples that for a given choice of quantum algebra (defined up to a certain gauge equivalence), there is at most one choice of canonical basis. We conjecture that this is the case for general N=4 SCFTs.
A short course on quantum mechanics and methods of quantization
NASA Astrophysics Data System (ADS)
Ercolessi, Elisa
2015-07-01
These notes collect the lectures given by the author to the "XXIII International Workshop on Geometry and Physics" held in Granada (Spain) in September 2014. The first part of this paper aims at introducing a mathematical oriented reader to the realm of Quantum Mechanics (QM) and then to present the geometric structures that underline the mathematical formalism of QM which, contrary to what is usually done in Classical Mechanics (CM), are usually not taught in introductory courses. The mathematics related to Hilbert spaces and Differential Geometry are assumed to be known by the reader. In the second part, we concentrate on some quantization procedures, that are founded on the geometric structures of QM — as we have described them in the first part — and represent the ones that are more operatively used in modern theoretical physics. We will discuss first the so-called Coherent State Approach which, mainly complemented by "Feynman Path Integral Technique", is the method which is most widely used in quantum field theory. Finally, we will describe the "Weyl Quantization Approach" which is at the origin of modern tomographic techniques, originally used in optics and now in quantum information theory.
Charge quantization in the CP(1) nonlinear σ-model
NASA Astrophysics Data System (ADS)
Hellerman, Simeon; Kehayias, John; Yanagida, Tsutomu T.
2014-01-01
We investigate the consistency conditions for matter fields coupled to the four-dimensional (N=1 supersymmetric) CP(1) nonlinear sigma model (the coset space SU(2/U(1). We find that consistency requires that the U(1 charge of the matter be quantized, in units of half of the U(1 charge of the Nambu-Goldstone (NG) boson, if the matter has a nonsingular kinetic term and the dynamics respect the full group SU(2. We can then take the linearly realized group U(1 to comprise the weak hypercharge group U(1 of the Standard Model. Thus we have charge quantization without a Grand Unified Theory (GUT), completely avoiding problems like proton decay, doublet-triplet splitting, and magnetic monopoles. We briefly investigate the phenomenological implications of this model-building framework. The NG boson is fractionally charged and completely stable. It can be naturally light, avoiding constraints while being a component of dark matter or having applications in nuclear physics. We also comment on the extension to other NLSMs on coset spaces, which will be explored more fully in a followup paper.
Size quantization of Dirac fermions in graphene constrictions
Terrés, B.; Chizhova, L. A.; Libisch, F.; Peiro, J.; Jörger, D.; Engels, S.; Girschik, A.; Watanabe, K.; Taniguchi, T.; Rotkin, S. V.; Burgdörfer, J.; Stampfer, C.
2016-01-01
Quantum point contacts are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wavelength in high-quality bulk graphene can be tuned up to hundreds of nanometres, the observation of quantum confinement of Dirac electrons in nanostructured graphene has proven surprisingly challenging. Here we show ballistic transport and quantized conductance of size-confined Dirac fermions in lithographically defined graphene constrictions. At high carrier densities, the observed conductance agrees excellently with the Landauer theory of ballistic transport without any adjustable parameter. Experimental data and simulations for the evolution of the conductance with magnetic field unambiguously confirm the identification of size quantization in the constriction. Close to the charge neutrality point, bias voltage spectroscopy reveals a renormalized Fermi velocity of ∼1.5 × 106 m s−1 in our constrictions. Moreover, at low carrier density transport measurements allow probing the density of localized states at edges, thus offering a unique handle on edge physics in graphene devices. PMID:27198961
Point-particle effective field theory III: relativistic fermions and the Dirac equation
NASA Astrophysics Data System (ADS)
Burgess, C. P.; Hayman, Peter; Rummel, Markus; Zalavári, László
2017-09-01
We formulate point-particle effective field theory (PPEFT) for relativistic spin-half fermions interacting with a massive, charged finite-sized source using a first-quantized effective field theory for the heavy compact object and a second-quantized language for the lighter fermion with which it interacts. This description shows how to determine the near-source boundary condition for the Dirac field in terms of the relevant physical properties of the source, and reduces to the standard choices in the limit of a point source. Using a first-quantized effective description is appropriate when the compact object is sufficiently heavy, and is simpler than (though equivalent to) the effective theory that treats the compact source in a second-quantized way. As an application we use the PPEFT to parameterize the leading energy shift for the bound energy levels due to finite-sized source effects in a model-independent way, allowing these effects to be fit in precision measurements. Besides capturing finite-source-size effects, the PPEFT treatment also efficiently captures how other short-distance source interactions can shift bound-state energy levels, such as due to vacuum polarization (through the Uehling potential) or strong interactions for Coulomb bound states of hadrons, or any hypothetical new short-range forces sourced by nuclei.
Magnetic anisotropy and quantized spin waves in hematite nanoparticles
Klausen, S.N.; Lefmann, K.; Lindgaard, P.-A.; Kuhn, L. Theil; Bahl, C.R.H.; Frandsen, C.; Moerup, S.; Roessli, B.; Cavadini, N.; Niedermayer, C.
2004-12-01
We report on the observation of high-frequency collective magnetic excitations ({Dirac_h}/2{pi}){omega}{approx_equal}1.1 meV, in hematite ({alpha}-Fe{sub 2}O{sub 3}) nanoparticles. The neutron scattering experiments include measurements at temperatures in the range 6-300 K and applied fields up to 7.5 T as well as polarization analysis. We give an explanation for the field- and temperature dependence of the excitations, which are found to have strongly elliptical out-of-plane precession. The frequency of the excitations gives information on the magnetic anisotropy constants in the system. We have in this way determined the temperature dependence of the magnetic anisotropy, which is strongly related to the suppression of the Morin transition in nanoparticles of hematite. Further, the localization of the signal in both energy and momentum transfer brings evidence for finite-size quantization of spin waves in the system.
Oscillating magnetocaloric effect in size-quantized diamagnetic film
Alisultanov, Z. Z.
2014-03-21
We investigate the oscillating magnetocaloric effect on a size-quantized diamagnetic film in a transverse magnetic field. We obtain the analytical expression for the thermodynamic potential in case of the arbitrary spectrum of carriers. The entropy change is shown to be the oscillating function of the magnetic field and the film thickness. The nature of this effect is the same as for the de Haas–van Alphen effect. The magnetic part of entropy has a maximal value at some temperature. Such behavior of the entropy is not observed in magneto-ordered materials. We discuss the nature of unusual behavior of the magnetic entropy. We compare our results with the data obtained for 2D and 3D cases.
Paul Weiss and the genesis of canonical quantization
NASA Astrophysics Data System (ADS)
Rickles, Dean; Blum, Alexander
2015-12-01
This paper describes the life and work of a figure who, we argue, was of primary importance during the early years of field quantisation and (albeit more indirectly) quantum gravity. A student of Dirac and Born, he was interned in Canada during the second world war as an enemy alien and after his release never seemed to regain a good foothold in physics, identifying thereafter as a mathematician. He developed a general method of quantizing (linear and non-linear) field theories based on the parameters labelling an arbitrary hypersurface. This method (the `parameter formalism' often attributed to Dirac), though later discarded, was employed (and viewed at the time as an extremely important tool) by the leading figures associated with canonical quantum gravity: Dirac, Pirani and Schild, Bergmann, DeWitt, and others. We argue that he deserves wider recognition for this and other innovations.
Quantized fluctuational electrodynamics for three-dimensional plasmonic structures
NASA Astrophysics Data System (ADS)
Partanen, Mikko; Häyrynen, Teppo; Tulkki, Jukka; Oksanen, Jani
2017-01-01
We recently introduced a quantized fluctuational electrodynamics (QFED) formalism that provides a physically insightful definition of an effective position-dependent photon-number operator and the associated ladder operators. However, this far the formalism has been applicable only for the normal incidence of the electromagnetic field in planar structures. In this work, we overcome the main limitation of the one-dimensional QFED formalism by extending the model to three dimensions, allowing us to use the QFED method to study, e.g., plasmonic structures. To demonstrate the benefits of the developed formalism, we apply it to study the local steady-state photon numbers and field temperatures in a light-emitting near-surface InGaN quantum-well structure with a metallic coating supporting surface plasmons.
Solar Wind Interaction with Lunar Crustal Magnetic Fields: Relation to Albedo Swirls
NASA Technical Reports Server (NTRS)
Mitchell, D. L.; Lin, R. P.; Harrison, L.; Halekas, J. S.; Hood, L. L.; Acuna, M. H.; Binder, A. B.
2000-01-01
The Magnetometer/Electron Reflectometer onboard Lunar Prospector has observed the solar wind interaction with remanent crustal magnetic fields at altitudes from 20 to 120 km. This interaction may be responsible for the formation of albedo swirls.
NASA Technical Reports Server (NTRS)
Parasarathy, R.; Karamcheti, K.
1972-01-01
The Lighthill method was the basic procedure used to analyze the sound field associated with a vortex of modified strength interacting with an airfoil. A free vortex interacting with an airfoil in uniform motion was modeled in order to determine the sound field due to all the acoustic sources, not only on the airfoil surfaces (dipoles), but also the ones distributed on the perturbed flow field (quadrupoles) due to the vortex-airfoil interaction. Because inviscid flow is assumed in the study of the interaction, the quadrupoles considered in the perturbed flow field are entirely due to an unsteady flow field. The effects of airfoil thickness on the second radiation are examined by using a symmetric Joukowski airfoil for the vortex-airfoil interaction. Sound radiation in a plane, far field simplification, and computation of the sound field are discussed.
Flux quantization on quasicrystalline networks
Behrooz, A.; Burns, M.J.; Deckman, H.; Levine, D.; Whitehead, B.; Chaikin, P.M.
1986-07-21
We have measured the superconducting transition temperature T-italic/sub c-italic/(H) as a function of magnetic field for a network of thin aluminum wires arranged in two quasicrystalline arrays, a Fibonacci sequence and the eightfold-symmetric version of a Penrose tiling. The quasicrystals have two periods whose ratio sigma is irrational and are constructed of two tiles with irrationally related areas. We find a series of dips in deltaT-italic/sub c-italic/(H) corresponding to favorable arrangements of the flux lattice on the quasicrystalline substrate. The largest dips are found at sigma/sup n-italic/ and the dips approach the zero-field transition temperature as n-italic increases.
Bianchi type I Universe and interacting ghost scalar fields models of dark energy
NASA Astrophysics Data System (ADS)
Hossienkhani, H.
2016-04-01
We suggest a correspondence between interacting ghost dark energy model with the quintessence, tachyon and K-essence scalar field in a non-isotropic universe. This correspondence allows to reconstruct the potential and the dynamics for the scalar field of the interacting ghost dark energy model, which describe accelerated expansion of the universe. Our numerical result show the effects of the interaction and anisotropic on the evolutionary behavior the ghost scalar field models.
Nonlinear interactions between black holes and Proca fields
NASA Astrophysics Data System (ADS)
Zilhão, Miguel; Witek, Helvi; Cardoso, Vitor
2015-12-01
Physics beyond the standard model is an important candidate for dark matter, and an interesting testing ground for strong-field gravity: the equivalence principle ‘forces’ all forms of matter to fall in the same way, and it is therefore natural to look for imprints of these fields in regions with strong gravitational fields, such as compact stars or black holes (BHs). Here we study general relativity minimally coupled to a massive vector field, and how BHs in this theory lose ‘hair’. Our results indicate that BHs can sustain Proca field condensates for extremely long time-scales.
Quantized circular photogalvanic effect in Weyl semimetals.
de Juan, Fernando; Grushin, Adolfo G; Morimoto, Takahiro; Moore, Joel E
2017-07-06
The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. Here we find that in a class of Weyl semimetals (for example, SrSi2) and three-dimensional Rashba materials (for example, doped Te) without inversion and mirror symmetries, the injection contribution to the CPGE trace is effectively quantized in terms of the fundamental constants e, h, c and with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.
Quantized circular photogalvanic effect in Weyl semimetals
de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E
2017-01-01
The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. Here we find that in a class of Weyl semimetals (for example, SrSi2) and three-dimensional Rashba materials (for example, doped Te) without inversion and mirror symmetries, the injection contribution to the CPGE trace is effectively quantized in terms of the fundamental constants e, h, c and with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques. PMID:28681840
Quantized Vortices in Superfluids and Superconductors
NASA Astrophysics Data System (ADS)
Thouless, D. J.; Ao, Ping; Niu, Qian; Geller, M. R.; Wexler, C.
We give a general review of recent developments in the theory of vortices in superfluids and superconductors, discussing why the dynamics of vortices is important, and why some key results are still controversial. We discuss work that we have done on the dynamics of quantized vortices in a superfluid. Despite the fact that this problem has been recognized as important for forty years, there is still a lot of controversy about the forces on and masses of quantized vortices. We think that one can get unambiguous answers by considering a broken symmetry state that consists of one vortex in an infinite ideal system. We argue for a Magnus force that is proportional to the superfluid density, and we find that the effective mass density of a vortex in a neutral superfluid is divergent at low frequencies. We have generalized some of the results for a neutral superfluid to a charged system.
Quantized charge pump of massive Dirac electrons
NASA Astrophysics Data System (ADS)
Wang, Jun; Liu, Jun-Feng
2017-05-01
We study a new scheme to realize a quantized two-parameter charge pump based on massive Dirac electrons. It is shown that the two time-dependent and out-of-phase staggered potentials introduced in graphene can pump out an integer number of electrons in a pumping cycle as long as the Fermi energy resides in the effective energy gap opened by pumping potentials. The dependence of the pumped charge per mode on the pumping phase or the dynamic phase exhibits a binary alternation from +e to -e . This quantization has a topological origin and can be accounted for by adiabatic evolution of the topologically protected interfacial state forming between the two pumping sources.
Precise Quantization of Anomalous Hall Effect
NASA Astrophysics Data System (ADS)
Bestwick, Andrew
In the quantum anomalous Hall effect, electron transport in a magnetically-doped topological insulator takes place through chiral, dissipationless edge channels. In this talk, we discuss the behavior of a nearly ideal implementations of the effect in which the Hall resistance is within a part per 10,000 of its quantized value and the longitudinal resistivity can reach below 1 Ω per square. Nearly all Cr-doped topological insulator samples demonstrate extreme temperature dependence that is well-modeled by a small effective gap, allowing control over quantization with an unexpected magnetocaloric effect. We also discuss measurements of new device geometries and non-local resistances that identify the sources of dissipation that limit the effect. (Now at Rigetti Computing).
Block adaptive quantization of Magellan SAR data
NASA Technical Reports Server (NTRS)
Kwok, Ronald; Johnson, William T. K.
1989-01-01
A report is presented on a data compression scheme that will be used to reduce the SAR data rate on the NASA Magellan mission to Venus. The spacecraft has only one scientific instrument, a radar system for imaging the surface, for altimetric profiling of the planet topography, and for measuring radiation from the planet surface. A straightforward implementation of the scientific requirements of the mission results in a data rate higher than can be accommodated by the available system bandwidth. A data-rate-reduction scheme which includes operation of the radar in burst mode and block-adaptive quantization of the SAR data is selected to satisfy the scientific requirements. Descriptions of the quantization scheme and its hardware implementation are given. Burst-mode SAR operation is also briefly discussed.
Neural net approach to predictive vector quantization
NASA Astrophysics Data System (ADS)
Mohsenian, Nader; Nasrabadi, Nasser M.
1992-11-01
A new predictive vector quantization (PVQ) technique, capable of exploring the nonlinear dependencies in addition to the linear dependencies that exist between adjacent blocks of pixels, is introduced. Two different classes of neural nets form the components of the PVQ scheme. A multi-layer perceptron is embedded in the predictive component of the compression system. This neural network, using the non-linearity condition associated with its processing units, can perform as a non-linear vector predictor. The second component of the PVQ scheme vector quantizes (VQ) the residual vector that is formed by subtracting the output of the perceptron from the original wave-pattern. Kohonen Self-Organizing Feature Map (KSOFM) was utilized as a neural network clustering algorithm to design the codebook for the VQ technique. Coding results are presented for monochrome 'still' images.
Quantized circular photogalvanic effect in Weyl semimetals
NASA Astrophysics Data System (ADS)
de Juan, Fernando; Grushin, Adolfo G.; Morimoto, Takahiro; Moore, Joel E.
2017-07-01
The circular photogalvanic effect (CPGE) is the part of a photocurrent that switches depending on the sense of circular polarization of the incident light. It has been consistently observed in systems without inversion symmetry and depends on non-universal material details. Here we find that in a class of Weyl semimetals (for example, SrSi2) and three-dimensional Rashba materials (for example, doped Te) without inversion and mirror symmetries, the injection contribution to the CPGE trace is effectively quantized in terms of the fundamental constants e, h, c and with no material-dependent parameters. This is so because the CPGE directly measures the topological charge of Weyl points, and non-quantized corrections from disorder and additional bands can be small over a significant range of incident frequencies. Moreover, the magnitude of the CPGE induced by a Weyl node is relatively large, which enables the direct detection of the monopole charge with current techniques.
Canonical quantization of gravitation with higher derivatives
Dukhbinder, I.L.; Lyakhovich, S.L.
1986-06-01
The authors construct a Hamiltonian formulation, canonically quantize it, and find the local measure for a theory of gravitation with Langrangian. The approach is based on the general method of ''Hamiltonianization'' of theories with higher derivatives containing coupling, in a form specially suited for work with gauge theories. An expression is obtained for the generating functional for Green's functions in the form of a continuum over the metric, with a nontrivial measure different from that of Einsteinian gravitation.
Quantization, group contraction and zero point energy
NASA Astrophysics Data System (ADS)
Blasone, M.; Celeghini, E.; Jizba, P.; Vitiello, G.
2003-04-01
We study algebraic structures underlying 't Hooft's construction relating classical systems with the quantum harmonic oscillator. The role of group contraction is discussed. We propose the use of SU(1,1) for two reasons: because of the isomorphism between its representation Hilbert space and that of the harmonic oscillator and because zero point energy is implied by the representation structure. Finally, we also comment on the relation between dissipation and quantization.
Field Dependence and Prior Reinforcement as Determinants of Social Interaction in Judgment
ERIC Educational Resources Information Center
Mausner, Bernard; Graham, Judith
1970-01-01
Explores the relationship of anxiety and field dependency in individuals to their tendency to conform to the judgments of others. A significant interaction occurred between field dependency and the prior reinforcement of a subject's judgment. Tables and bibliography. (RW)
Conductance Quantization in Resistive Random Access Memory
NASA Astrophysics Data System (ADS)
Li, Yang; Long, Shibing; Liu, Yang; Hu, Chen; Teng, Jiao; Liu, Qi; Lv, Hangbing; Suñé, Jordi; Liu, Ming
2015-10-01
The intrinsic scaling-down ability, simple metal-insulator-metal (MIM) sandwich structure, excellent performances, and complementary metal-oxide-semiconductor (CMOS) technology-compatible fabrication processes make resistive random access memory (RRAM) one of the most promising candidates for the next-generation memory. The RRAM device also exhibits rich electrical, thermal, magnetic, and optical effects, in close correlation with the abundant resistive switching (RS) materials, metal-oxide interface, and multiple RS mechanisms including the formation/rupture of nanoscale to atomic-sized conductive filament (CF) incorporated in RS layer. Conductance quantization effect has been observed in the atomic-sized CF in RRAM, which provides a good opportunity to deeply investigate the RS mechanism in mesoscopic dimension. In this review paper, the operating principles of RRAM are introduced first, followed by the summarization of the basic conductance quantization phenomenon in RRAM and the related RS mechanisms, device structures, and material system. Then, we discuss the theory and modeling of quantum transport in RRAM. Finally, we present the opportunities and challenges in quantized RRAM devices and our views on the future prospects.
Single Abrikosov vortices as quantized information bits
Golod, T.; Iovan, A.; Krasnov, V. M.
2015-01-01
Superconducting digital devices can be advantageously used in future supercomputers because they can greatly reduce the dissipation power and increase the speed of operation. Non-volatile quantized states are ideal for the realization of classical Boolean logics. A quantized Abrikosov vortex represents the most compact magnetic object in superconductors, which can be utilized for creation of high-density digital cryoelectronics. In this work we provide a proof of concept for Abrikosov-vortex-based random access memory cell, in which a single vortex is used as an information bit. We demonstrate high-endurance write operation and two different ways of read-out using a spin valve or a Josephson junction. These memory cells are characterized by an infinite magnetoresistance between 0 and 1 states, a short access time, a scalability to nm sizes and an extremely low write energy. Non-volatility and perfect reproducibility are inherent for such a device due to the quantized nature of the vortex. PMID:26456592
Influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction
Forsberg, M.; Brodin, G.; Papadopoulos, D.
2010-07-15
The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the QED effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered due to the QED effects. The consequences of our results are discussed.
A study of the flow field surrounding interacting line fires
Trevor Maynard; Marko Princevac; David R. Weise
2016-01-01
The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which...
NASA Astrophysics Data System (ADS)
Oh, Jae-Hyuk
2016-11-01
We explore the mathematical relation between stochastic quantization (SQ) and the holographic Wilsonian renormalization group (HWRG) of a massive scalar field defined in asymptotically anti-de Sitter space. We compute the stochastic two-point correlation function by quantizing the boundary on-shell action (it is identified with the Euclidean action in our stochastic frame) of the scalar field, requiring the initial value of the stochastic field Dirichlet boundary condition, and study its relationship with the double-trace deformation in HWRG computation. It turns out that the stochastic two-point function precisely corresponds to the double-trace deformation through the relation proposed in [J. High Energy Phys. 11 (2012) 144] even in the case that the scalar field mass is arbitrary. In our stochastic framework, the Euclidean action constituting the Langevin equation is not the same as that in the original stochastic theory; in fact, it contains the stochastic time "t -dependent" kernel in it. A justification for the exotic Euclidean action is provided by proving that it transforms to the usual form of the Euclidean action in a new stochastic frame by an appropriate rescaling of both the stochastic fields and time. We also apply the Neumann boundary condition to the stochastic fields to study the relation between SQ and the HWRG when alternative quantization is allowed. It turns out that the application of the Neumann boundary condition to the stochastic fields generates the radial evolution of the single-trace operator as well as the double-trace term.
Particle localization, spinor two-valuedness, and Fermi quantization of tensor systems
NASA Technical Reports Server (NTRS)
Reifler, Frank; Morris, Randall
1994-01-01
Recent studies of particle localization shows that square-integrable positive energy bispinor fields in a Minkowski space-time cannot be physically distinguished from constrained tensor fields. In this paper we generalize this result by characterizing all classical tensor systems, which admit Fermi quantization, as those having unitary Lie-Poisson brackets. Examples include Euler's tensor equation for a rigid body and Dirac's equation in tensor form.
Chiral baryon with quantized pions
McNeil, J.A.; Price, J.A.
1993-04-01
The authors consider a hybrid chiral baryon model starting from the Gell-Mann-Levy linear sigma model with the sigma and pion fields coupled to quarks. Instead of employing the standard hedgehog ansatz, the authors solve the model using a Fock-space configuration consisting of a component with three quarks plus a component with three quarks and an explicit pion. In each component, the quarks (and pion) are directly coupled to the spin and isospin appropriate to a nucleon and the coupling is preserved throughout the calculation. The authors minimizes the groundstate expectation value of the Gell-Mann-Levy Hamiltonian to obtain the equations of motion which are solved self-consistently. They calculatess the canonical set of nucleon observables and compare them with previous work.
NASA Astrophysics Data System (ADS)
Napsuciale, M.; Rodríguez, S.; Ferro-Hernández, Rodolfo; Gómez-Ávila, Selim
2016-04-01
Spin-one matter fields are relevant both for the description of hadronic states and as potential extensions of the Standard Model. In this work we present a formalism for the description of massive spin-one fields transforming in the (1 ,0 )⊕(0 ,1 ) representation of the Lorentz group, based on the covariant projection onto parity eigenspaces and Poincaré orbits. The formalism yields a constrained dynamics. We solve the constraints and perform the canonical quantization accordingly. This formulation uses the recent construction of a parity-based covariant basis for matrix operators acting on the (j ,0 )⊕(0 ,j ) representations. The algebraic properties of the covariant basis play an important role in solving the constraints and allowing the canonical quantization of the theory. We study the chiral structure of the theory and conclude that it is not chirally symmetric in the massless limit, hence it is not possible to have chiral gauge interactions. However, spin-one matter fields can have vector gauge interactions. Also, the dimension of the field makes self-interactions naively renormalizable. Using the covariant basis, we classify all possible self-interaction terms.
NASA Astrophysics Data System (ADS)
Belotsky, K. M.; Golikova, Yu. A.; Rubin, S. G.
2017-07-01
It is shown that the formation of primordialmassive black holes may be accompanied by a local heating of matter. The proposed heating mechanism is based on the interaction of the Higgs field with a scalar field that is responsible for the formation of black holes.
Master equation for collective spontaneous emission with quantized atomic motion
NASA Astrophysics Data System (ADS)
Damanet, François; Braun, Daniel; Martin, John
2016-02-01
We derive a Markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and applies equally well to distinguishable and indistinguishable atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find closed-form formulas for a number of relevant states (Gaussian states, Fock states, and thermal states). In particular, we show that dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion.
Quantized orbits in weakly coupled Belousov-Zhabotinsky reactors
NASA Astrophysics Data System (ADS)
Weiss, S.; Deegan, R. D.
2015-06-01
Using numerical and experimental tools, we study the motion of two coupled spiral cores in a light-sensitive variant of the Belousov-Zhabotinsky reaction. Each core resides on a separate two-dimensional domain, and is coupled to the other by light. When both spirals have the same sense of rotation, the cores are attracted to a circular trajectory with a diameter quantized in integer units of the spiral wavelength λ. When the spirals have opposite senses of rotation, the cores are attracted towards different but parallel straight trajectories, separated by an integer multiple of λ/2. We present a model that explains this behavior as the result of a spiral wavefront-core interaction that produces a deterministic displacement of the core and a retardation of its phase.
Quantizing and sampling considerations in digital phased-locked loops
NASA Technical Reports Server (NTRS)
Hurst, G. T.; Gupta, S. C.
1974-01-01
The quantizer problem is first considered. The conditions under which the uniform white sequence model for the quantizer error is valid are established independent of the sampling rate. An equivalent spectral density is defined for the quantizer error resulting in an effective SNR value. This effective SNR may be used to determine quantized performance from infinitely fine quantized results. Attention is given to sampling rate considerations. Sampling rate characteristics of the digital phase-locked loop (DPLL) structure are investigated for the infinitely fine quantized system. The predicted phase error variance equation is examined as a function of the sampling rate. Simulation results are presented and a method is described which enables the minimum required sampling rate to be determined from the predicted phase error variance equations.