Renormalisation of Nonequilibrium Phonons Under Strong Perturbative Influences.
NASA Astrophysics Data System (ADS)
Mehta, Sushrut Madhukar
Effects of strong perturbative influences, namely the presence of a narrow distribution of acoustic phonons, and the presence of an electron plasma, on the dynamics of nonequilibrium, near zone center, longitudinal optical phonons in GaP have been investigated in two separate experiments. The study of the effects of the interaction between the LO phonons and a heavily populated, narrow distribution of acoustic phonons lead to the observation of a new optically driven nonequilibrium phonon state. Time Resolved Coherent Antistokes Raman Scattering (TR-CARS), with picosecond resolution, was used to investigate the new mode. In order to achieve high occupation numbers in the acoustic branch, the picosecond laser pulses used were amplified up to 1.0 GW/cm^2 peak power per laser beam. An important characteristic property of the new state which differentiates it from the well known LO phonon state is the fact that rather than having the single decay rate observed under thermal equilibrium, the new state has two decay rates. Moreover, these two decay rates depend strongly on the distribution of the acoustic phonon occupation number. The coupling of the LO phonons with an electron plasma, on the other hand, was investigated by measurements of the shape of the Raman scattered line associated with the phonon-plasmon coupled mode. The plasma was generated by thermal excitation of carriers in doped samples. It was possible to study a large variety of plasma excitations by controlling the concentration of the dopant and the ambient temperature. A complete, self consistant model based on standard dielectric response theory is presented, and applied to the measurements of the phonon-plasmon coupled mode. It is possible to recover, via this model, the effective coupled mode damping rate, the plasma damping rate, and the plasma frequency as functions of ambient temperature, or the carrier concentration.
Non-equilibrium magnetic interactions in strongly correlated systems
Secchi, A.; Brener, S.; Lichtenstein, A.I.; Katsnelson, M.I.
2013-06-15
We formulate a low-energy theory for the magnetic interactions between electrons in the multi-band Hubbard model under non-equilibrium conditions determined by an external time-dependent electric field which simulates laser-induced spin dynamics. We derive expressions for dynamical exchange parameters in terms of non-equilibrium electronic Green functions and self-energies, which can be computed, e.g., with the methods of time-dependent dynamical mean-field theory. Moreover, we find that a correct description of the system requires, in addition to exchange, a new kind of magnetic interaction, that we name twist exchange, which formally resembles Dzyaloshinskii–Moriya coupling, but is not due to spin–orbit, and is actually due to an effective three-spin interaction. Our theory allows the evaluation of the related time-dependent parameters as well. -- Highlights: •We develop a theory for magnetism of strongly correlated systems out of equilibrium. •Our theory is suitable for laser-induced ultrafast magnetization dynamics. •We write time-dependent exchange parameters in terms of electronic Green functions. •We find a new magnetic interaction, a “twist exchange”. •We give general expressions for magnetic noise in itinerant-electron systems.
NASA Astrophysics Data System (ADS)
Lempert, Walter R.; Adamovich, Igor V.
2014-10-01
The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed.
Strong electronic correlation effects in coherent multidimensional nonlinear optical spectroscopy.
Karadimitriou, M E; Kavousanaki, E G; Dani, K M; Fromer, N A; Perakis, I E
2011-05-12
We discuss a many-body theory of the coherent ultrafast nonlinear optical response of systems with a strongly correlated electronic ground state that responds unadiabatically to photoexcitation. We introduce a truncation of quantum kinetic density matrix equations of motion that does not rely on an expansion in terms of the interactions and thus applies to strongly correlated systems. For this we expand in terms of the optical field, separate out contributions to the time-evolved many-body state due to correlated and uncorrelated multiple optical transitions, and use "Hubbard operator" density matrices to describe the exact dynamics of the individual contributions within a subspace of strongly coupled states, including "pure dephasing". Our purpose is to develop a quantum mechanical tool capable of exploring how, by coherently photoexciting selected modes, one can trigger nonlinear dynamics of strongly coupled degrees of freedom. Such dynamics could lead to photoinduced phase transitions. We apply our theory to the nonlinear response of a two-dimensional electron gas (2DEG) in a magnetic field. We coherently photoexcite the two lowest Landau level (LL) excitations using three time-delayed optical pulses. We identify some striking temporal and spectral features due to dynamical coupling of the two LLs facilitated by inter-Landau-level magnetoplasmon and magnetoroton excitations and compare to three-pulse four-wave-mixing (FWM) experiments. We show that these features depend sensitively on the dynamics of four-particle correlations between an electron-hole pair and a magnetoplasmon/magnetoroton, reminiscent of exciton-exciton correlations in undoped semiconductors. Our results shed light into unexplored coherent dynamics and relaxation of the quantum Hall system (QHS) and can provide new insight into non-equilibrium co-operative phenomena in strongly correlated systems.
Nonequilibrium Energy Transfer at Nanoscale: A Unified Theory from Weak to Strong Coupling.
Wang, Chen; Ren, Jie; Cao, Jianshu
2015-07-08
Unraveling the microscopic mechanism of quantum energy transfer across two-level systems provides crucial insights to the optimal design and potential applications of low-dimensional nanodevices. Here, we study the non-equilibrium spin-boson model as a minimal prototype and develop a fluctuation-decoupled quantum master equation approach that is valid ranging from the weak to the strong system-bath coupling regime. The exact expression of energy flux is analytically established, which dissects the energy transfer as multiple boson processes with even and odd parity. Our analysis provides a unified interpretation of several observations, including coherence-enhanced heat flux and negative differential thermal conductance. The results will have broad implications for the fine control of energy transfer in nano-structural devices.
Nonequilibrium Energy Transfer at Nanoscale: A Unified Theory from Weak to Strong Coupling
NASA Astrophysics Data System (ADS)
Wang, Chen; Ren, Jie; Cao, Jianshu
2015-07-01
Unraveling the microscopic mechanism of quantum energy transfer across two-level systems provides crucial insights to the optimal design and potential applications of low-dimensional nanodevices. Here, we study the non-equilibrium spin-boson model as a minimal prototype and develop a fluctuation-decoupled quantum master equation approach that is valid ranging from the weak to the strong system-bath coupling regime. The exact expression of energy flux is analytically established, which dissects the energy transfer as multiple boson processes with even and odd parity. Our analysis provides a unified interpretation of several observations, including coherence-enhanced heat flux and negative differential thermal conductance. The results will have broad implications for the fine control of energy transfer in nano-structural devices.
Nonequilibrium Energy Transfer at Nanoscale: A Unified Theory from Weak to Strong Coupling
Wang, Chen; Ren, Jie; Cao, Jianshu
2015-01-01
Unraveling the microscopic mechanism of quantum energy transfer across two-level systems provides crucial insights to the optimal design and potential applications of low-dimensional nanodevices. Here, we study the non-equilibrium spin-boson model as a minimal prototype and develop a fluctuation-decoupled quantum master equation approach that is valid ranging from the weak to the strong system-bath coupling regime. The exact expression of energy flux is analytically established, which dissects the energy transfer as multiple boson processes with even and odd parity. Our analysis provides a unified interpretation of several observations, including coherence-enhanced heat flux and negative differential thermal conductance. The results will have broad implications for the fine control of energy transfer in nano-structural devices. PMID:26152705
Strongly Non-equilibrium Dynamics of Nanochannel Confined DNA
NASA Astrophysics Data System (ADS)
Reisner, Walter
Nanoconfined DNA exhibits a wide-range of fascinating transient and steady-state non-equilibrium phenomena. Yet, while experiment, simulation and scaling analytics are converging on a comprehensive picture regarding the equilibrium behavior of nanochannel confined DNA, non-equilibrium behavior remains largely unexplored. In particular, while the DNA extension along the nanochannel is the key observable in equilibrium experiments, in the non-equilibrium case it is necessary to measure and model not just the extension but the molecule's full time-dependent one-dimensional concentration profile. Here, we apply controlled compressive forces to a nanochannel confined molecule via a nanodozer assay, whereby an optically trapped bead is slid down the channel at a constant speed. Upon contact with the molecule, a propagating concentration ``shockwave'' develops near the bead and the molecule is dynamically compressed. This experiment, a single-molecule implementation of a macroscopic cylinder-piston apparatus, can be used to observe the molecule response over a range of forcings and benchmark theoretical description of non-equilibrium behavior. We show that the dynamic concentration profiles, including both transient and steady-state response, can be modelled via a partial differential evolution equation combining nonlinear diffusion and convection. Lastly, we present preliminary results for dynamic compression of multiple confined molecules to explore regimes of segregation and mixing for multiple chains in confinement.
NASA Technical Reports Server (NTRS)
Yeh, Leehwa
1993-01-01
The phase-space-picture approach to quantum non-equilibrium statistical mechanics via the characteristic function of infinite-mode squeezed coherent states is introduced. We use quantum Brownian motion as an example to show how this approach provides an interesting geometrical interpretation of quantum non-equilibrium phenomena.
NASA Astrophysics Data System (ADS)
Yan, Jiawei; Ke, Youqi
2016-07-01
Electron transport properties of nanoelectronics can be significantly influenced by the inevitable and randomly distributed impurities/defects. For theoretical simulation of disordered nanoscale electronics, one is interested in both the configurationally averaged transport property and its statistical fluctuation that tells device-to-device variability induced by disorder. However, due to the lack of an effective method to do disorder averaging under the nonequilibrium condition, the important effects of disorders on electron transport remain largely unexplored or poorly understood. In this work, we report a general formalism of Green's function based nonequilibrium effective medium theory to calculate the disordered nanoelectronics. In this method, based on a generalized coherent potential approximation for the Keldysh nonequilibrium Green's function, we developed a generalized nonequilibrium vertex correction method to calculate the average of a two-Keldysh-Green's-function correlator. We obtain nine nonequilibrium vertex correction terms, as a complete family, to express the average of any two-Green's-function correlator and find they can be solved by a set of linear equations. As an important result, the averaged nonequilibrium density matrix, averaged current, disorder-induced current fluctuation, and averaged shot noise, which involve different two-Green's-function correlators, can all be derived and computed in an effective and unified way. To test the general applicability of this method, we applied it to compute the transmission coefficient and its fluctuation with a square-lattice tight-binding model and compared with the exact results and other previously proposed approximations. Our results show very good agreement with the exact results for a wide range of disorder concentrations and energies. In addition, to incorporate with density functional theory to realize first-principles quantum transport simulation, we have also derived a general form of
Strong and Coherent Coupling between Localized and Propagating Phonon Polaritons.
Gubbin, Christopher R; Martini, Francesco; Politi, Alberto; Maier, Stefan A; De Liberato, Simone
2016-06-17
Following the recent observation of localized phonon polaritons in user-defined silicon carbide nanoresonators, here we demonstrate strong and coherent coupling between those localized modes and propagating phonon polaritons bound to the surface of the nanoresonator's substrate. In order to obtain phase matching, the nanoresonators have been fabricated to serve the double function of hosting the localized modes, while also acting as a grating for the propagating ones. The coherent coupling between long lived, optically accessible localized modes, and low-loss propagative ones, opens the way to the design and realization of phonon-polariton based coherent circuits. PMID:27367398
Strong and Coherent Coupling between Localized and Propagating Phonon Polaritons
NASA Astrophysics Data System (ADS)
Gubbin, Christopher R.; Martini, Francesco; Politi, Alberto; Maier, Stefan A.; De Liberato, Simone
2016-06-01
Following the recent observation of localized phonon polaritons in user-defined silicon carbide nanoresonators, here we demonstrate strong and coherent coupling between those localized modes and propagating phonon polaritons bound to the surface of the nanoresonator's substrate. In order to obtain phase matching, the nanoresonators have been fabricated to serve the double function of hosting the localized modes, while also acting as a grating for the propagating ones. The coherent coupling between long lived, optically accessible localized modes, and low-loss propagative ones, opens the way to the design and realization of phonon-polariton based coherent circuits.
Strong Quantum Coherence between Fermi Liquid Mahan Excitons.
Paul, J; Stevens, C E; Liu, C; Dey, P; McIntyre, C; Turkowski, V; Reno, J L; Hilton, D J; Karaiskaj, D
2016-04-15
In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.
NASA Astrophysics Data System (ADS)
Tovbin, Yu. K.
2015-09-01
Consequences of the complete system of transfer equations of the properties (momentum, energy, and mass) of particles and their pairs are considered under local equilibrium conditions with regard to the Bogoliubov hierarchy of relaxation times between the first and second distribution functions (DFs) and distinctions in the characteristic relaxation times of particle momentum, energy, and mass. It is found that even under the local equilibrium condition in the Bogoliubov hierarchy of relaxation times between the first and second DFs, pair correlations are maintained between all dynamic variables (velocity, temperature, and density) whose values are proportional to the gradients of transferable properties. A criterion is introduced requiring there be no local equilibrium condition upon reaching the critical value at which the description of the transfer process becomes incorrect in classical nonequilibrium thermodynamics. External forces are considered in the equations for strongly nonequilibrium processes. Along with allowing for intermolecular potentials, it becomes possible to discuss the concept of passive forces (introduced in thermodynamics by Gibbs) from the standpoint of the kinetic theory. It is shown that use of this concept does not reflect modern representations of real processes.
Non-Equilibrium Dynamics of C-QED Arrays in Strong Correlation Regime
NASA Astrophysics Data System (ADS)
Zhang, Xin-Ding; Li, Zhi-Hang; Zhang, Xiao-Ming
2016-07-01
Recently increasing interests are attracted in the physics of controlled arrays of nonlinear cavity resonators because of the rapid experimental progress achieved in cavity and circuit quantum electrodynamics (QED). For a driven-dissipative two-dimentional planar C-QED array, standard Markov master equation is generally used to study the dynamics of this system. However, when in the case that the on-site photon-photon interaction enters strong correlation regime, standard Markov master equation may lead to incorrect results. In this paper we study the non-equilibrium dynamics of a two-dimentional C-QED array, which is homogeneously pumped by an external pulse, at the same time dissipation exits. We study the evolution of the average photon number of a single cavity by deriving a modified master equation to. In comparison with the standard master equation, the numerical result obtained by our newly derived master equation shows significant difference for the non-equilibrium dynamics of the system.
Strong quantum coherence between Fermi liquid Mahan excitons
Paul, J.; Stevens, C. E.; Liu, C.; Dey, P.; McIntyre, C.; Turkowski, V.; Reno, J. L.; Hilton, D. J.; Karaiskaj, D.
2016-04-14
In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called “Mahan excitons.” The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the opticalmore » Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Furthermore, time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.« less
Strong Quantum Coherence between Fermi Liquid Mahan Excitons.
Paul, J; Stevens, C E; Liu, C; Dey, P; McIntyre, C; Turkowski, V; Reno, J L; Hilton, D J; Karaiskaj, D
2016-04-15
In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system. PMID:27127985
Role of trap-induced scales in non-equilibrium dynamics of strongly interacting trapped bosons
NASA Astrophysics Data System (ADS)
Dutta, Anirban; Sensarma, Rajdeep; Sengupta, K.
2016-08-01
We use a time-dependent hopping expansion technique to study the non-equilibrium dynamics of strongly interacting bosons in an optical lattice in the presence of a harmonic trap characterized by a force constant K. We show that after a sudden quench of the hopping amplitude J across the superfluid (SF)-Mott insulator (MI) transition, the SF order parameter |{{Δ }\\mathbf{r}}(t)| and the local density fluctuation δ {{n}\\mathbf{r}}(t) exhibit sudden decoherence beyond a trap-induced time scale {{T}0}∼ {{K}-1/2} . We also show that after a slow linear ramp down of J, |{{Δ }\\mathbf{r}}| and the boson defect density {{P}\\mathbf{r}} display a novel non-monotonic spatial profile. Both these phenomena can be explained as consequences of trap-induced time and length scales affecting the dynamics and can be tested by concrete experiments.
Zhang, Z. D.; Wang, J.
2014-06-28
We established a theoretical framework in terms of the curl flux, population landscape, and coherence for non-equilibrium quantum systems at steady state, through exploring the energy and charge transport in molecular processes. The curl quantum flux plays the key role in determining transport properties and the system reaches equilibrium when flux vanishes. The novel curl quantum flux reflects the degree of non-equilibriumness and the time-irreversibility. We found an analytical expression for the quantum flux and its relationship to the environmental pumping (non-equilibriumness quantified by the voltage away from the equilibrium) and the quantum tunneling. Furthermore, we investigated another quantum signature, the coherence, quantitatively measured by the non-zero off diagonal element of the density matrix. Populations of states give the probabilities of individual states and therefore quantify the population landscape. Both curl flux and coherence depend on steady state population landscape. Besides the environment-assistance which can give dramatic enhancement of coherence and quantum flux with high voltage at a fixed tunneling strength, the quantum flux is promoted by the coherence in the regime of small tunneling while reduced by the coherence in the regime of large tunneling, due to the non-monotonic relationship between the coherence and tunneling. This is in contrast to the previously found linear relationship. For the systems coupled to bosonic (photonic and phononic) reservoirs the flux is significantly promoted at large voltage while for fermionic (electronic) reservoirs the flux reaches a saturation after a significant enhancement at large voltage due to the Pauli exclusion principle. In view of the system as a quantum heat engine, we studied the non-equilibrium thermodynamics and established the analytical connections of curl quantum flux to the transport quantities such as energy (charge) transfer efficiency, chemical reaction efficiency, energy
Zhang, Zhedong; Wang, Jin; Zhang, Z D; Wang, J
2014-06-28
We established a theoretical framework in terms of the curl flux, population landscape, and coherence for non-equilibrium quantum systems at steady state, through exploring the energy and charge transport in molecular processes. The curl quantum flux plays the key role in determining transport properties and the system reaches equilibrium when flux vanishes. The novel curl quantum flux reflects the degree of non-equilibriumness and the time-irreversibility. We found an analytical expression for the quantum flux and its relationship to the environmental pumping (non-equilibriumness quantified by the voltage away from the equilibrium) and the quantum tunneling. Furthermore, we investigated another quantum signature, the coherence, quantitatively measured by the non-zero off diagonal element of the density matrix. Populations of states give the probabilities of individual states and therefore quantify the population landscape. Both curl flux and coherence depend on steady state population landscape. Besides the environment-assistance which can give dramatic enhancement of coherence and quantum flux with high voltage at a fixed tunneling strength, the quantum flux is promoted by the coherence in the regime of small tunneling while reduced by the coherence in the regime of large tunneling, due to the non-monotonic relationship between the coherence and tunneling. This is in contrast to the previously found linear relationship. For the systems coupled to bosonic (photonic and phononic) reservoirs the flux is significantly promoted at large voltage while for fermionic (electronic) reservoirs the flux reaches a saturation after a significant enhancement at large voltage due to the Pauli exclusion principle. In view of the system as a quantum heat engine, we studied the non-equilibrium thermodynamics and established the analytical connections of curl quantum flux to the transport quantities such as energy (charge) transfer efficiency, chemical reaction efficiency, energy
NASA Astrophysics Data System (ADS)
Groth, Clinton P. T.
1993-12-01
This study is concerned with the numerical solution of high-speed nonequilibrium gaseous flows with strong shocks. The extension of modern total-variation-diminishing (TVD) shock-capturing schemes to include thermochemical nonequilibrium high-temperature effects is of primary interest. Partially decoupled upwind-based TVD flux-difference split schemes for the solution of the conservation laws governing two-dimensional nonequilibrium vibrationally relaxing and chemically reacting flows of thermally-perfect gaseous mixtures are presented. Both time-split semi-implicit and factored implicit flux-limited TVD upwind schemes are described. The semi-implicit formulation is more appropriate for unsteady applications whereas the factored implicit form is useful for obtaining steady-state solutions. As well, a multigrid version of the fully implicit TVD scheme is also proposed for the more efficient computation of time-invariant solutions. The multigrid algorithm is based on the full approximation storage (FAS) and full multigrid (FMG) concepts and employs the partially-decoupled factored implicit scheme as the smoothing operator in conjunction with a four-level V-cycle coarsegrid-correction procedure. In the proposed methods, a novel partially-decoupled flux-difference splitting approach is adopted. The fluid conservation laws and the finite-rate species concentration and vibrational energy equations are decoupled by means of a frozen flow approximation. The resulting partially-decoupled gas dynamic and thermodynamic subsystems are then integrated alternately in lagged manner within a two-stage time marching procedure, thereby providing explicit coupling between the two equations sets. Extensions of Roe's approximate Riemann solvers, giving the eigenvalues and eigenvectors of the fully coupled systems, are used to evaluate the numerical flux functions. Additional modifications to the Riemann solutions are also described which ensure that the approximate solutions are not
Kreula, J M; Clark, S R; Jaksch, D
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case.
Kreula, J. M.; Clark, S. R.; Jaksch, D.
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case. PMID:27609673
Kreula, J M; Clark, S R; Jaksch, D
2016-01-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case. PMID:27609673
NASA Astrophysics Data System (ADS)
Kreula, J. M.; Clark, S. R.; Jaksch, D.
2016-09-01
We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical mean field theory (DMFT) and uses a digital quantum simulator to solve a quantum impurity problem whose parameters are iterated to self-consistency via a classically computed feedback loop where quantum gate errors can be partly accounted for. We analyse the performance of the scheme in an example case.
Quantum Coherence of Strongly Correlated Defects in Spin Chains
NASA Astrophysics Data System (ADS)
Bertaina, Sylvain; Dutoit, Charles-Emmanuel; Van Tol, Johan; Dressel, Martin; Barbara, Bernard; Stepanov, Anatoli
Most of qubit systems known to date are isolated paramagnetic centres in magnetically diluted samples since their dilution allows to considerably weaken the dipole-dipole inter-qubit interaction and thus to prevent the decoherence. Here we suggest an alternative approach for spin qubits which are built on spin S = 1/2 defects in magnetically concentrated strongly correlated systems - spin chains. The corresponding qubits are made of spin solitons resulting from local breaking of transitional symmetry associated with point-defects. We provide the first evidence for coherence and Rabi oscillations of spin solitons in isotropic Heisenberg chains, simple antiferromagnetic-Ńeel or spin-Peierls, proving that they can be manipulated as single spin S = 1/2. The entanglement of these many-body soliton states over macroscopic distances along chains gives rise to networks of coupled qubits which could easily be decoupled at will in extensions of this work.
J, Ashwin; Ganesh, R
2009-11-01
Using nonequilibrium molecular dynamics (MD) simulations behavior of three-dimensional (3D) Yukawa system has been studied in the presence of a small amplitude drive along one direction (say z[over ] ). This drive has the general form V=V_{0} cos(k_{L}z)Theta(t-t_{0}) , where Theta(t-t_{0}) is a Heaviside step function in time at t=t_{0} and k_{L}=2pi/L , L being the size of the system; V0 is considered small compared to average interparticle potential energy. In particular, a 3D equilibrated Yukawa crystal (bcc) near solid-liquid transition is subjected to an external drive at times t> or =t_{0} at the largest possible scale. For a given k_{L} it is observed that there exists a critical amplitude (V_{0};{c}) of the external drive below which the crystalline order is preserved and above which (V_{0}> or =V_{0};{c}) the transition from bcc to strongly coupled Yukawa liquid is observed. This critical amplitude (V_{0};{c}) is sensitive to the location of the Yukawa solid in the (kappa,Gamma) phase space. Various signatures of melting, transients, and steady state in the presence of this drive are elucidated using extensive MD diagnostics such as loss of long-range crystalline order, change in diffusion from subnormal to normal, and the fall of transversal shear peak in the Fourier transform of the velocity autocorrelation function. The mechanism of heating in the transient state is attributed to the local heating of the system where the forces are maximum. It is shown that these local hot regions dissipate heat into surrounding regions ultimately leading to a uniform temperature throughout the system. Ion streaming due to external field has been neglected.
Bold-line Monte Carlo and the nonequilibrium physics of strongly correlated many-body systems
NASA Astrophysics Data System (ADS)
Cohen, Guy
2015-03-01
This talk summarizes real time bold-line diagrammatic Monte-Carlo approaches to quantum impurity models, which make significant headway against the sign problem by summing over corrections to self-consistent diagrammatic expansions rather than a bare diagrammatic series. When the bold-line method is combined with reduced dynamics techniques both local single-time properties and two time correlators such as Green functions can be computed at very long timescales, enabling studies of nonequilibrium steady state behavior of quantum impurity models and creating new solvers for nonequilibrium dynamical mean field theory. This work is supported by NSF DMR 1006282, NSF CHE-1213247, DOE ER 46932, TG-DMR120085 and TG-DMR130036, and the Yad Hanadiv-Rothschild Foundation.
Universality of non-equilibrium fluctuations in strongly correlated quantum liquids
NASA Astrophysics Data System (ADS)
Ferrier, Meydi; Arakawa, Tomonori; Hata, Tokuro; Fujiwara, Ryo; Delagrange, Raphaëlle; Weil, Raphaël; Deblock, Richard; Sakano, Rui; Oguri, Akira; Kobayashi, Kensuke
2016-03-01
Interacting quantum many-body systems constitute a fascinating research field because they form quantum liquids with remarkable properties and universal behaviour. In fermionic systems, such quantum liquids are realized in helium-3 liquid, heavy fermion systems, neutron stars and cold gases. Their properties in the linear-response regime have been successfully described by the theory of Fermi liquids. The idea is that they behave as an ensemble of non-interacting `quasi-particles’. However, non-equilibrium properties have still to be established and remain a key issue of many-body physics. Here, we show a precise experimental demonstration of Landau Fermi liquid theory extended to the non-equilibrium regime in a zero-dimensional system. Combining transport and ultra-sensitive current noise measurements, we have unambiguously identified the SU(2) (ref. ) and SU(4) (refs ,,,,) symmetries of a quantum liquid in a carbon nanotube tuned in the universal Kondo regime. Whereas the free quasi-particle picture is found valid around equilibrium, an enhancement of the current fluctuations is detected out of equilibrium and perfectly explained by an effective charge induced by the residual interaction between quasi-particles. Moreover, an as-yet-unknown scaling law for the effective charge is discovered, suggesting a new non-equilibrium universality. Our method paves a new way to explore the exotic nature of quantum liquids out of equilibrium through their fluctuations in a wide variety of physical systems.
Reversal of nonlocal vortex motion in the regime of strong nonequilibrium.
Otto, Florian; Bilusić, Ante; Babić, Dinko; Vodolazov, Denis Yu; Sürgers, Christoph; Strunk, Christoph
2010-01-15
We investigate nonlocal vortex motion in weakly pinning a-NbGe nanostructures, which is driven by a transport current I and remotely detected as a nonlocal voltage V{nl}. At a high I of a given polarity, V{nl} changes sign dramatically. This is followed by V{nl} becoming even in I, with the opposite sign at low and high temperatures T. These findings can be explained by a Nernst-like effect resulting from local electron overheating (low T), and a magnetization enhancement due to a nonequilibrium quasiparticle distribution that leads to a gap enhancement near the vortex core (high T).
Theories of Strongly Nonequilibrium Phenomena, Especially Deformation and Fracture of Solids
Langer, J. S.
2013-02-13
The major focus of the research program supported by this grant was the development of the shear-transformation-zone (STZ) theory of amorphous plasticity and its application to theories of dynamic fracture. In retrospect, the project was remarkably successful. It produced a deep understanding of the formability and strength of bulk metallic glasses [see, especially, refs 5, 6, 19] , and a predictive theory of shear-banding instabilities [17] . The shear-band analysis led, peripherally, to a first understanding of the origin of sharp stress drops during large earthquakes [22]. An important theme that emerged during these studies was the role of an effective temperature as a quantitative measure of the state of disorder induced by shear deformations. This theme led to what now appears to be a fundamental advance in nonequilibrium thermodynamics [6,23,24,25]. Much of this work has been summarized in a review article [26].
Strong field coherent control of molecular torsions—Analytical models
Ashwell, Benjamin A.; Ramakrishna, S.; Seideman, Tamar
2015-08-14
We introduce analytical models of torsional alignment by moderately intense laser pulses that are applicable to the limiting cases of the torsional barrier heights. Using these models, we explore in detail the role that the laser intensity and pulse duration play in coherent torsional dynamics, addressing both experimental and theoretical concerns. Our results suggest strategies for minimizing the risk of off-resonant ionization, noting the qualitative differences between the case of torsional alignment subject to a field-free torsional barrier and that of torsional alignment of a barrier-less system (equivalent to a 2D rigid rotor). We also investigate several interesting torsional phenomena, including the onset of impulsive alignment of torsions, field-driven oscillations in quantum number space, and the disappearance of an alignment upper bound observed for a rigid rotor in the impulsive torsional alignment limit.
Universality of Non-equilibrium Fluctuations in Strongly Correlated Quantum Liquids
NASA Astrophysics Data System (ADS)
Ferrier, Meydi; Arakawa, Tomonori; Hata, Tokuro; Fujiwara, Ryo; Delagrange, Raphaelle; Deblock, Richard; Sakano, Rui; Oguri, Akira; Kobayashi, Kensuke
In a quantum dot, Kondo effect occurs when the spin of the confined electron is entangled with the electrons of the leads forming locally a strongly correlated Fermi-liquid. Our experiments were performed in such a dot formed in a single carbon nanotube, where Kondo effect with different symmetry groups, namely SU(2) and SU(4), shows up. In the latter case, as spin and orbital degrees of freedom are degenerate, two channels contribute to transport and Kondo resonance emerges for odd and even number of electrons. With our sample it was possible to investigate both symmetries near the unitary limit. In the Kondo regime, strong interaction creates a peculiar two-particle scattering which appears as an effective charge e* for the quasi-particles. We have extracted the signature of this effective charge in the shot noise for both symmetry in good agreement with theory. This result demonstrates that theory of the Kondo effect can be safely extended out of equilibrium even in the unconventional SU(4) symmetry.
Heller, Michal P; Janik, Romuald A; Spaliński, Michał; Witaszczyk, Przemysław
2014-12-31
Relativistic hydrodynamics simulations of quark-gluon plasma play a pivotal role in our understanding of heavy ion collisions at RHIC and LHC. They are based on a phenomenological description due to Müller, Israel, Stewart (MIS) and others, which incorporates viscous effects and ensures a well-posed initial value problem. Focusing on the case of conformal plasma we propose a generalization which includes, in addition, the dynamics of the least damped far-from-equilibrium degree of freedom found in strongly coupled plasmas through the AdS/CFT correspondence. We formulate new evolution equations for general flows and then test them in the case of N=4 super Yang-Mills plasma by comparing their solutions alongside solutions of MIS theory with numerical computations of isotropization and boost-invariant flow based on holography. In these tests the new equations reproduce the results of MIS theory when initialized close to the hydrodynamic stage of evolution, but give a more accurate description of the dynamics when initial conditions are set in the preequilibrium regime.
Strong thermal nonequilibrium in hypersonic CO and CH4 probed by CRDS.
Louviot, M; Suas-David, N; Boudon, V; Georges, R; Rey, M; Kassi, S
2015-06-01
A new experimental setup coupling a High Enthalpy Source (HES) reaching 2000 K to a cw-cavity ring-down spectrometer has been developed to investigate rotationally cold hot bands of polyatomic molecules in the [1.5, 1.7] μm region. The rotational and vibrational molecular degrees of freedom are strongly decoupled in the hypersonic expansion produced by the HES and probed by cavity ring-down spectroscopy. Carbon monoxide has been used as a first test molecule to validate the experimental approach. Its expansion in argon led to rotational and vibrational temperatures of 6.7 ± 0.8 K and 2006 ± 476 K, respectively. The tetradecad polyad of methane (1.67 μm) was investigated under similar conditions leading to rotational and vibrational temperatures of 13 ± 5 K and 750 ± 100 K, respectively. The rotationally cold structure of the spectra reveals many hot bands involving highly excited vibrational states of methane.
NASA Astrophysics Data System (ADS)
Heller, Michal P.; Janik, Romuald A.; Spaliński, Michał; Witaszczyk, Przemysław
2014-12-01
Relativistic hydrodynamics simulations of quark-gluon plasma play a pivotal role in our understanding of heavy ion collisions at RHIC and LHC. They are based on a phenomenological description due to Müller, Israel, Stewart (MIS) and others, which incorporates viscous effects and ensures a well-posed initial value problem. Focusing on the case of conformal plasma we propose a generalization which includes, in addition, the dynamics of the least damped far-from-equilibrium degree of freedom found in strongly coupled plasmas through the AdS/CFT correspondence. We formulate new evolution equations for general flows and then test them in the case of N =4 super Yang-Mills plasma by comparing their solutions alongside solutions of MIS theory with numerical computations of isotropization and boost-invariant flow based on holography. In these tests the new equations reproduce the results of MIS theory when initialized close to the hydrodynamic stage of evolution, but give a more accurate description of the dynamics when initial conditions are set in the preequilibrium regime.
Strong-field ionization inducing multi-electron-hole coherence probed by attosecond pulses
NASA Astrophysics Data System (ADS)
Zhao, Jing; Yuan, Jianmin; Zhao, Zengxiu
2016-05-01
Recent advances in attosecond spectroscopy has enabled resolving electron-hole dynamics in real time. The correlated electron-hole dynamics and the resulted coherence are directly related to how fast the ionization is completed. How the laser-induced electron-hole coherence evolves and whether it can be utilized to probe the core dynamics are among the key questions in attosecond physics or even attosecond chemistry. In this work, we propose a new scenario to apply IR-pump-XUV-probe schemes to resolving strong field ionization induced and attosecond pulse driven electron-hole dynamics and coherence in real time. The coherent driving of both the infrared laser and the attosecond pulse correlates the dynamics of the core-hole and the valence-hole which leads to the otherwise forbidden absorption and emission of XUV photon. An analytical model is developed based on the strong-field approximation by taking into account of the essential multielectron configurations. The emission spectra from the core-valence transition and the core-hole recombination are found modulating strongly as functions of the time delay between the two pulses, which provides a unique insight into the instantaneous ionization and the interplay of the multi-electron-hole coherence.
Complete Coherent Control of a Quantum Dot Strongly Coupled to a Nanocavity
Dory, Constantin; Fischer, Kevin A.; Müller, Kai; Lagoudakis, Konstantinos G.; Sarmiento, Tomas; Rundquist, Armand; Zhang, Jingyuan L.; Kelaita, Yousif; Vučković, Jelena
2016-01-01
Strongly coupled quantum dot-cavity systems provide a non-linear configuration of hybridized light-matter states with promising quantum-optical applications. Here, we investigate the coherent interaction between strong laser pulses and quantum dot-cavity polaritons. Resonant excitation of polaritonic states and their interaction with phonons allow us to observe coherent Rabi oscillations and Ramsey fringes. Furthermore, we demonstrate complete coherent control of a quantum dot-photonic crystal cavity based quantum-bit. By controlling the excitation power and phase in a two-pulse excitation scheme we achieve access to the full Bloch sphere. Quantum-optical simulations are in good agreement with our experiments and provide insight into the decoherence mechanisms. PMID:27112420
Complete Coherent Control of a Quantum Dot Strongly Coupled to a Nanocavity
NASA Astrophysics Data System (ADS)
Dory, Constantin; Fischer, Kevin A.; Müller, Kai; Lagoudakis, Konstantinos G.; Sarmiento, Tomas; Rundquist, Armand; Zhang, Jingyuan L.; Kelaita, Yousif; Vučković, Jelena
2016-04-01
Strongly coupled quantum dot-cavity systems provide a non-linear configuration of hybridized light-matter states with promising quantum-optical applications. Here, we investigate the coherent interaction between strong laser pulses and quantum dot-cavity polaritons. Resonant excitation of polaritonic states and their interaction with phonons allow us to observe coherent Rabi oscillations and Ramsey fringes. Furthermore, we demonstrate complete coherent control of a quantum dot-photonic crystal cavity based quantum-bit. By controlling the excitation power and phase in a two-pulse excitation scheme we achieve access to the full Bloch sphere. Quantum-optical simulations are in good agreement with our experiments and provide insight into the decoherence mechanisms.
Local Probing of Phase Coherence in a Strongly Interacting 2D Quantum Gas
NASA Astrophysics Data System (ADS)
Luick, Niclas; Siegl, Jonas; Hueck, Klaus; Morgener, Kai; Lompe, Thomas; Weimer, Wolf; Moritz, Henning
2016-05-01
The dimensionality of a quantum system has a profound impact on its coherence and superfluid properties. In 3D superfluids, bosonic atoms or Cooper pairs condense into a macroscopic wave function exhibiting long-range phase coherence. Meanwhile, 2D superfluids show a strikingly different behavior: True long-range coherence is precluded by thermal fluctuations, nevertheless Berezinskii-Kosterlitz-Thouless (BKT) theory predicts that 2D systems can still become superfluid. The superfluid state is characterized by an algebraic decay of phase correlations g1(r) ~r - τ / 4 , where the decay exponent τ is directly related to the superfluid density ns according to τ = 4 /(nsλdB2) . I will present local coherence measurements in a strongly interacting 2D gas of diatomic 6 Li molecules. A self-interference technique allows us to locally extract the algebraic decay exponent and to reconstruct the superfluid density. We determine the scaling of the decay exponent with phase space density to provide a benchmark for studies of 2D superfluids in the strongly interacting regime.
NASA Astrophysics Data System (ADS)
Temkin, A. Ya.
1989-10-01
The present work is the continuation of the previous works of the author on the non-equilibrium chemical kinetics. The consideration of direct and hot spot reactions provoked by the passage of fast particles through a liquid or solid medium is continued. It is shown that the model of quasi-particles permits us to detect and to consider a kinetic effect of primary fast particle reactions caused by the distribution of target molecules with respect to distance from the primary particle trajectory. It has been found what kinds of chemical kinetic experiments allow us to get rid of this effect to obtain correct values of the reaction elementary act parameters in the condensed phase. Spherical hot spot chemical kinetics of the reaction of two hot diatomic molecules is considered and compared with the one in cylindrical hot spots. It is shown that the creation of spherical hot spots can be stimulated by the addition of atoms having the mass close to that of the primary fast particle. In particular, this can be used to increase the selectivity of the radiation therapy by injection of such atoms to the tumor. Hot atom-polymer segment reaction kinetics in a cylindrical hot spot is considered. The obtained expressions for reaction product yields represent the hot spot contribution to polymer transformations by heavy fast ions. Their possible application to the DNA destruction by hot hydrogen atoms in a hot spot is discussed. Expressions for macroscopic yields of direct and hot spot reactions have been obtained. The hot spot evolution in the presence of laser radiation is considered. Various possibilities of fast particle and laser beams combining irradiation use are considered, especially for the laser material processing and metalworking as well as for the laser medicine.
NASA Astrophysics Data System (ADS)
Ponomarenko, Sergey A.; Wolf, Emil
2002-10-01
We investigate the inverse scattering problem for statistically homogeneous, isotropic random media under conditions of strong fluctuations of optical wavefields. We present a method for determining the spectral density of the dielectric constant fluctuations in such media from scattering of partially coherent light. The method may find applications to a wide class of turbulent media such as the turbulent atmosphere and certain turbulent plasmas where backscattering and depolarization effects are negligible.
Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium
Singh Dharodi, Vikram; Kumar Tiwari, Sanat; Das, Amita
2014-07-15
A generalized hydrodynamic model depicting the behaviour of visco-elastic fluids has often been invoked to explore the behaviour of a strongly coupled dusty plasma medium below their crystallization limit. The model has been successful in describing the collective normal modes of the strongly coupled dusty plasma medium observed experimentally. The paper focuses on the study of nonlinear dynamical characteristic features of this model. Specifically, the evolution of coherent vorticity patches is being investigated here within the framework of this model. A comparison with Newtonian fluids and molecular dynamics simulations treating the dust species interacting through the Yukawa potential has also been presented.
Single-Quantum Coherence Filter for Strongly Coupled Spin Systems for Localized 1H NMR Spectroscopy
NASA Astrophysics Data System (ADS)
Trabesinger, Andreas H.; Mueller, D. Christoph; Boesiger, Peter
2000-08-01
A pulse sequence for localized in vivo1H NMR spectroscopy is presented, which selectively filters single-quantum coherence built up by strongly coupled spin systems. Uncoupled and weakly coupled spin systems do not contribute to the signal output. Analytical calculations using a product operator description of the strongly coupled AB spin system as well as in vitro tests demonstrate that the proposed filter produces a signal output for a strongly coupled AB spin system, whereas the resonances of a weakly coupled AX spin system and of uncoupled spins are widely suppressed. As a potential application, the detection of the strongly coupled AA‧BB‧ spin system of taurine at 1.5 T is discussed.
Coherent optical spectroscopy of a strongly coupled semiconductor microcavity quantum-dot system
NASA Astrophysics Data System (ADS)
Srinivasan, Kartik; Painter, Oskar
2008-03-01
Chip-based systems involving a semiconductor microcavity coupled to an embedded quantum dot (QD) offer a scalable, stable platform for optical cavity quantum electrodynamics. To harness this potential in a manner consistent with many protocols for quantum information processing, the system must be coherently probed and manipulated. However, experiments in these systems have largely relied on incoherent excitation through photoluminescence (PL). Here, we describe recent experiments [1] in which a fiber taper waveguide is used to perform steady-state coherent linear and nonlinear optical spectroscopy of a strongly coupled microcavity-QD system, probing the system on its photonic channel (rather than its matter channel, as in PL). Under weak driving, vacuum Rabi splitting is observed, while increasing the drive strength reveals saturation for an average intracavity photon number of less than one. [1] K. Srinivasan and O. Painter (2007), to appear in Nature, Dec. 6, 2007 (preprint: physics/0707.3311).
Coherent Quantum Dynamics in Steady-State Manifolds of Strongly Dissipative Systems
NASA Astrophysics Data System (ADS)
Zanardi, Paolo; Campos Venuti, Lorenzo
2014-12-01
Recently, it has been realized that dissipative processes can be harnessed and exploited to the end of coherent quantum control and information processing. In this spirit, we consider strongly dissipative quantum systems admitting a nontrivial manifold of steady states. We show how one can enact adiabatic coherent unitary manipulations, e.g., quantum logical gates, inside this steady-state manifold by adding a weak, time-rescaled, Hamiltonian term into the system's Liouvillian. The effective long-time dynamics is governed by a projected Hamiltonian which results from the interplay between the weak unitary control and the fast relaxation process. The leakage outside the steady-state manifold entailed by the Hamiltonian term is suppressed by an environment-induced symmetrization of the dynamics. We present applications to quantum-computation in decoherence-free subspaces and noiseless subsystems and numerical analysis of nonadiabatic errors.
NASA Astrophysics Data System (ADS)
Najafi, Khadijeh; Freericks, James
We investigate the nonlinear electronic transport across a multilayered heterostructure which consists of Mott insulator layers connected to ballistic metal leads on both sides. To create current flow, we turn on an electric field in the leads for a finite period of time and then turn it off and let the system reach the steady state by adding an electric field over the correlated region. We use nonequilibrium dynamical mean-field theory to obtain the current-voltage relation. To do so, we current bias the device, and adjust the voltage profile to ensure current conservation and charge conservation throughout. The calculation ultimately works directly in the steady-state limit.
Li, Yuelin; Schaller, Richard D.; Zhu, Mengze; Walko, Donald A.; Kim, Jungho; Ke, Xianglin; Miao, Ludi; Mao, Z. Q.
2016-01-20
In correlated oxides the coupling of quasiparticles to other degrees of freedom such as spin and lattice plays critical roles in the emergence of symmetry-breaking quantum ordered states such as high temperature superconductivity. We report a strong lattice coupling of photon-induced quasiparticles in spin-orbital coupling Mott insulator Sr2IrO4 probed via optical excitation. Combining time-resolved x-ray diffraction and optical spectroscopy techniques, we reconstruct a spatiotemporal map of the diffusion of these quasiparticles. Lastly, due to the unique electronic configuration of the quasiparticles, the strong lattice correlation is unexpected but extends the similarity between Sr2IrO4 and cuprates to a new dimension ofmore » electron-phonon coupling which persists under highly non-equilibrium conditions.« less
Li, Yuelin; Schaller, Richard D.; Zhu, Mengze; Walko, Donald A.; Kim, Jungho; Ke, Xianglin; Miao, Ludi; Mao, Z. Q.
2016-01-01
In correlated oxides the coupling of quasiparticles to other degrees of freedom such as spin and lattice plays critical roles in the emergence of symmetry-breaking quantum ordered states such as high temperature superconductivity. We report a strong lattice coupling of photon-induced quasiparticles in spin-orbital coupling Mott insulator Sr2IrO4 probed via optical excitation. Combining time-resolved x-ray diffraction and optical spectroscopy techniques, we reconstruct a spatiotemporal map of the diffusion of these quasiparticles. Due to the unique electronic configuration of the quasiparticles, the strong lattice correlation is unexpected but extends the similarity between Sr2IrO4 and cuprates to a new dimension of electron-phonon coupling which persists under highly non-equilibrium conditions. PMID:26787094
Coherent beam combination of fiber lasers with a strongly confined waveguide: numerical model.
Tao, Rumao; Si, Lei; Ma, Yanxing; Zhou, Pu; Liu, Zejin
2012-08-20
Self-imaging properties of fiber lasers in a strongly confined waveguide (SCW) and their application in coherent beam combination (CBC) are studied theoretically. Analytical formulas are derived for the positions, amplitudes, and phases of the N images at the end of an SCW, which is important for quantitative analysis of waveguide CBC. The formulas are verified with experimental results and numerical simulation of a finite difference beam propagation method (BPM). The error of our analytical formulas is less than 6%, which can be reduced to less than 1.5% with Goos-Hahnchen penetration depth considered. Based on the theoretical model and BPM, we studied the combination of two laser beams based on an SCW. The effects of the waveguide refractive index and Gaussian beam waist are studied. We also simulated the CBC of nine and 16 fiber lasers, and a single beam without side lobes was achieved.
Karas, V. I. Vlasenko, A. M.; Sokolenko, V. I.; Zakharov, V. E.
2015-09-15
We present the results of a kinetic analysis of nonequilibrium dynamics of the electron–phonon system of a crystal in a strong electric field based on the proposed method of numerically solving a set of Boltzmann equations for electron and phonon distribution functions without expanding the electron distribution function into a series in the phonon energy. It is shown that the electric field action excites the electron subsystem, which by transferring energy to the phonon subsystem creates a large amount of short-wave phonons that effectively influence the lattice defects (point, lines, boundaries of different phases), which results in a redistribution of and decrease in the lattice defect density, in damage healing, in a decrease in the local peak stress, and a decrease in the degradation level of the construction material properties.
NASA Astrophysics Data System (ADS)
Karas, V. I.; Vlasenko, A. M.; Sokolenko, V. I.; Zakharov, V. E.
2015-09-01
We present the results of a kinetic analysis of nonequilibrium dynamics of the electron-phonon system of a crystal in a strong electric field based on the proposed method of numerically solving a set of Boltzmann equations for electron and phonon distribution functions without expanding the electron distribution function into a series in the phonon energy. It is shown that the electric field action excites the electron subsystem, which by transferring energy to the phonon subsystem creates a large amount of short-wave phonons that effectively influence the lattice defects (point, lines, boundaries of different phases), which results in a redistribution of and decrease in the lattice defect density, in damage healing, in a decrease in the local peak stress, and a decrease in the degradation level of the construction material properties.
Coherent structures in a zero-pressure-gradient and a strongly decelerated boundary layer
NASA Astrophysics Data System (ADS)
Simens, Mark P.; Gungor, Ayse G.; Maciel, Yvan
2016-04-01
Coherent structures in a strongly decelerated large-velocity-defect turbulent boundary layer (TBL) and a zero pressure gradient (ZPG) boundary layer are analysed by direct numerical simulation (DNS). The characteristics of the one-point velocity stastistics are also considered. The adverse pressure gradient (APG) TBL simulation is a new one carried out by the present authors. The APG TBL begins as a zero pressure gradient boundary layer, decelerates under a strong adverse pressure gradient, and separates near the end of the domain in the form of a very thin separation bubble. The one-point velocity statistics in the outer region of this large-defect boundary layer are compared to those of two other large-velocity-defect APG TBLs (one in dynamic equilibrium, the other in disequilibrium) and a mixing layer. In the upper half of the large-defect boundary layers, the velocity statistics are similar to those of the mixing layer. The dominant peaks of turbulence production and Reynolds stresses are located in the middle of the boundary layers. Three-dimensional spatial correlations of (u, u) and (u, v) show that coherence is lost in the streamwise and spanwise directions as the velocity defect increases. Near-wall streaks tend to disappear in the large-defect zone of the flow to be replaced by more disorganized u motions. Near-wall sweeps and ejections are also less numerous. In the outer region, the u structures tend to be shorter, less streaky, and more inclined with respect to the wall than in the ZPG TBL. The sweeps and ejections are generally bigger with respect to the boundary layer thickness in the large-defect boundary layer, even if the biggest structures are found in the ZPG TBL. Large sweeps and ejections that reach the wall region (wall-attached) are less streamwise elongated and they occupy less space than in the ZPG boundary layer. The distinction between wall-attached and wall-detached structures is not as pronounced in the large-defect TBL.
Chen, Deliang; Tian, Yudong; Yao, Tandong; Ou, Tinghai
2016-01-01
This study uses high-resolution, long-term satellite observations to evaluate the spatial scales of the climate variations across the Tibet Plateau (TP). Both land surface temperature and precipitation observations of more than 10 years were analysed with a special attention to eight existing ice-core sites in the TP. The temporal correlation for the monthly or annual anomalies between any two points decreases exponentially with their spatial distance, and we used the e-folding decay constant to quantify the spatial scales. We found that the spatial scales are strongly direction-dependent, with distinctive patterns in the west-east and south-north orientations, for example. Meanwhile, in the same directions the scales are largely symmetric backward and forward. Focusing on the west-east and south-north directions, we found the spatial coherence in the first is generally stronger than in the second. The annual surface temperature had typical spatial scales of 302-480 km, while the annual precipitation showed smaller scales of 111-182 km. The majority of the eight ice-core sites exhibit scales much smaller than the typical scales over the TP as a whole. These results provide important observational basis for the selection of appropriate downscaling strategies, deployment of climate-data collection networks, and interpreting paleoclimate reconstructions. PMID:27553388
NASA Astrophysics Data System (ADS)
Hernandez-Castillo, A. O.; Abeysekera, Chamara; Hays, Brian M.; Zwier, Timothy S.
2016-09-01
Using standard hardware available in chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy, an experimental method is introduced to selectively extract from the microwave spectrum of an otherwise complicated multicomponent mixture a set of transitions due to a single component, thereby speeding spectral assignment. The method operates the broadband chirped-pulse used to excite the sample in the strong-field limit through a combination of high power and control of the sweep rate. A procedure is introduced that leads to selection of three transition frequencies that can be incorporated as a set of resonant sequential single-frequency microwave pulses that follow broadband chirped-pulse excitation, resulting in a reduction in the coherent signal from a set of transitions ascribable to the component of interest. The difference in the CP-FTMW spectrum with and without this set of multi-resonant single-frequency pulses produces a set of transitions that can confidently be assigned to a single component of the mixture, aiding the analysis of its spectrum. The scheme is applied to (i) selectively extract the spectrum of one of five singly 13C-subsituted isotopologues of benzonitrile in natural abundance, (ii) obtain the microwave spectra of the two structural isomers (E)- and (Z)-phenylvinylnitrile, and (iii) obtain conformer-specific microwave spectra of methylbutyrate.
NASA Astrophysics Data System (ADS)
Chen, Deliang; Tian, Yudong; Yao, Tandong; Ou, Tinghai
2016-08-01
This study uses high-resolution, long-term satellite observations to evaluate the spatial scales of the climate variations across the Tibet Plateau (TP). Both land surface temperature and precipitation observations of more than 10 years were analysed with a special attention to eight existing ice-core sites in the TP. The temporal correlation for the monthly or annual anomalies between any two points decreases exponentially with their spatial distance, and we used the e-folding decay constant to quantify the spatial scales. We found that the spatial scales are strongly direction-dependent, with distinctive patterns in the west-east and south-north orientations, for example. Meanwhile, in the same directions the scales are largely symmetric backward and forward. Focusing on the west-east and south-north directions, we found the spatial coherence in the first is generally stronger than in the second. The annual surface temperature had typical spatial scales of 302–480 km, while the annual precipitation showed smaller scales of 111–182 km. The majority of the eight ice-core sites exhibit scales much smaller than the typical scales over the TP as a whole. These results provide important observational basis for the selection of appropriate downscaling strategies, deployment of climate-data collection networks, and interpreting paleoclimate reconstructions.
Chen, Deliang; Tian, Yudong; Yao, Tandong; Ou, Tinghai
2016-01-01
This study uses high-resolution, long-term satellite observations to evaluate the spatial scales of the climate variations across the Tibet Plateau (TP). Both land surface temperature and precipitation observations of more than 10 years were analysed with a special attention to eight existing ice-core sites in the TP. The temporal correlation for the monthly or annual anomalies between any two points decreases exponentially with their spatial distance, and we used the e-folding decay constant to quantify the spatial scales. We found that the spatial scales are strongly direction-dependent, with distinctive patterns in the west-east and south-north orientations, for example. Meanwhile, in the same directions the scales are largely symmetric backward and forward. Focusing on the west-east and south-north directions, we found the spatial coherence in the first is generally stronger than in the second. The annual surface temperature had typical spatial scales of 302–480 km, while the annual precipitation showed smaller scales of 111–182 km. The majority of the eight ice-core sites exhibit scales much smaller than the typical scales over the TP as a whole. These results provide important observational basis for the selection of appropriate downscaling strategies, deployment of climate-data collection networks, and interpreting paleoclimate reconstructions. PMID:27553388
Deng, Peng; Kavehrad, Mohsen; Liu, Zhiwen; Zhou, Zhou; Yuan, Xiuhua
2013-07-01
We study the average capacity performance for multiple-input multiple-output (MIMO) free-space optical (FSO) communication systems using multiple partially coherent beams propagating through non-Kolmogorov strong turbulence, assuming equal gain combining diversity configuration and the sum of multiple gamma-gamma random variables for multiple independent partially coherent beams. The closed-form expressions of scintillation and average capacity are derived and then used to analyze the dependence on the number of independent diversity branches, power law α, refractive-index structure parameter, propagation distance and spatial coherence length of source beams. Obtained results show that, the average capacity increases more significantly with the increase in the rank of MIMO channel matrix compared with the diversity order. The effect of the diversity order on the average capacity is independent of the power law, turbulence strength parameter and spatial coherence length, whereas these effects on average capacity are gradually mitigated as the diversity order increases. The average capacity increases and saturates with the decreasing spatial coherence length, at rates depending on the diversity order, power law and turbulence strength. There exist optimal values of the spatial coherence length and diversity configuration for maximizing the average capacity of MIMO FSO links over a variety of atmospheric turbulence conditions.
Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Mark, Alan E; Hush, Noel S
2009-03-17
In 1968, Fröhlich showed that a driven set of oscillators can condense with nearly all of the supplied energy activating the vibrational mode of lowest frequency. This is a remarkable property usually compared with Bose-Einstein condensation, superconductivity, lasing, and other unique phenomena involving macroscopic quantum coherence. However, despite intense research, no unambiguous example has been documented. We determine the most likely experimental signatures of Fröhlich condensation and show that they are significant features remote from the extraordinary properties normally envisaged. Fröhlich condensates are classified into 3 types: weak condensates in which profound effects on chemical kinetics are possible, strong condensates in which an extremely large amount of energy is channeled into 1 vibrational mode, and coherent condensates in which this energy is placed in a single quantum state. Coherent condensates are shown to involve extremely large energies, to not be produced by the Wu-Austin dynamical Hamiltonian that provides the simplest depiction of Fröhlich condensates formed using mechanically supplied energy, and to be extremely fragile. They are inaccessible in a biological environment. Hence the Penrose-Hameroff orchestrated objective-reduction model and related theories for cognitive function that embody coherent Fröhlich condensation as an essential element are untenable. Weak condensates, however, may have profound effects on chemical and enzyme kinetics, and may be produced from biochemical energy or from radio frequency, microwave, or terahertz radiation. Pokorný's observed 8.085-MHz microtubulin resonance is identified as a possible candidate, with microwave reactors (green chemistry) and terahertz medicine appearing as other feasible sources.
Coherent control of wavepacket launch and evolution in molecular cations in strong-field regime
NASA Astrophysics Data System (ADS)
Romanov(1, 3), Dmitri; Moore Tibbetts(2, 3), Katharine; Tarazkar(2, 3), Maryam; Bohinsky(2, 3), Timothy; Matsika(2, 3), Spiridoula; Levis(2, 3), Robert
2016-05-01
The time-resolved dissociative ionization dynamics for a family of acetophenone radical cations has been studied in pump-probe experiments. Modifications of the relative fragment yield have been measured as a function of the pump laser wavelength from 790 nm to 1500 nm. In the case of tunnel ionization (1150 - 1500 nm pump), the time-resolved transients of the parent and fragment ions probed with a weak 790 nm pulse reveal an order-of-magnitude enhancement of the peak-to-peak amplitude oscillations, ~ 100 fs longer coherence time, and an order-of-magnitude increase in the ratio of parent to fragment ions, as compared to the case of multiphoton ionization (790 nm pump). The results are quantitatively explained with a model of wavepacket evolution on the ground (D0) and excited (D1 and D2) ionic potential energy surfaces, with the probe-induced and conical-intersection-related transitions between the surfaces. The theory predicts the periods of fragment-ratio oscillations, thus confirming the ability to prepare and manipulate multiple wavepackets in the vicinity of a conical intersection for polyatomic molecules on the time scale of picoseconds.
Quantum dephasing of a two-state system by a nonequilibrium harmonic oscillator
Martens, Craig C.
2013-07-14
In this paper, we investigate coherent quantum dynamics in a nonequilibrium environment. We focus on a two-state quantum system strongly coupled to a single classical environmental oscillator, and explore the effect of nonstationary statistical properties of the oscillator on the quantum evolution. A simple nonequilibrium model, consisting of an oscillator with a well-defined initial phase which undergoes subsequent diffusion, is introduced and studied. Approximate but accurate analytic expressions for the evolution of the off-diagonal density matrix element of the quantum system are derived in the second-order cumulant approximation. The effect of the initial phase choice on the subsequent quantum evolution is quantified. It is observed that the initial phase can have a significant effect on the preservation of coherence on short time scales, suggesting this variable as a control parameter for optimizing coherence in many-body quantum systems.
Coherent extreme ultraviolet light amplification by strong-field-enhanced forward scattering.
Serrat, Carles
2013-09-27
We theoretically study the response of He atoms exposed simultaneously to an intense IR pulse and a weak extreme ultraviolet (XUV) pulse with photon energies far from the principal atomic He resonances. We find that XUV forward scattering from the nonstationary electronic wave packet promoted by the intense IR driving field is strongly enhanced as compared with the normal weak scattering from bound or free electrons. Based on this effect, we predict that large amplification of XUV radiation can be achieved in the cutoff spectral region of high-harmonic generation in He gas. PMID:24116781
Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime
NASA Astrophysics Data System (ADS)
Takemura, N.; Anderson, M. D.; Trebaol, S.; Biswas, S.; Oberli, D. Y.; Portella-Oberli, M. T.; Deveaud, B.
2015-12-01
Using femtosecond pump-probe spectroscopy, we identify excitation-induced dephasing as a major mechanism responsible for the breakdown of the strong coupling between excitons and photons in a semiconductor microcavity. The effects of dephasing are observed on the transmitted probe-pulse spectrum as a density-dependent broadening of the exciton-polariton resonances and the emergence of a third resonance at high excitation density. A striking asymmetry in the energy shift between the upper and the lower polaritons is also evidenced. Using the excitonic Bloch equations, we quantify the respective contributions to the energy shift of many-body effects associated with Coulomb fermion exchange and photon assisted exchange processes and the contribution to collisional broadening.
Nonequilibrium dynamics of emergent field configurations
NASA Astrophysics Data System (ADS)
Howell, Rafael Cassidy
The processes by which nonlinear physical systems approach thermal equilibrium is of great importance in many areas of science. Central to this is the mechanism by which energy is transferred between the many degrees of freedom comprising these systems. With this in mind, in this research the nonequilibrium dynamics of nonperturbative fluctuations within Ginzburg-Landau models are investigated. In particular, two questions are addressed. In both cases the system is initially prepared in one of two minima of a double-well potential. First, within the context of a (2 + 1) dimensional field theory, we investigate whether emergent spatio-temporal coherent structures play a dynamcal role in the equilibration of the field. We find that the answer is sensitive to the initial temperature of the system. At low initial temperatures, the dynamics are well approximated with a time-dependent mean-field theory. For higher temperatures, the strong nonlinear coupling between the modes in the field does give rise to the synchronized emergence of coherent spatio-temporal configurations, identified with oscillons. These are long-lived coherent field configurations characterized by their persistent oscillatory behavior at their core. This initial global emergence is seen to be a consequence of resonant behavior in the long wavelength modes in the system. A second question concerns the emergence of disorder in a highly viscous system modeled by a (3 + 1) dimensional field theory. An integro-differential Boltzmann equation is derived to model the thermal nucleation of precursors of one phase within the homogeneous background. The fraction of the volume populated by these precursors is computed as a function of temperature. This model is capable of describing the onset of percolation, characterizing the approach to criticality (i.e. disorder). It also provides a nonperturbative correction to the critical temperature based on the nonequilibrium dynamics of the system.
NASA Astrophysics Data System (ADS)
Hassouni, K.; Lombardi, G.; Gicquel, A.; Capitelli, M.; Shakhatov, V. A.; De Pascale, O.
2005-07-01
Vibrational and rotational experimental temperatures of molecular hydrogen obtained by coherent anti-Stokes Raman spectroscopy in radiofrequency inductive plasmas have been analyzed and interpreted in terms of vibration, electron, dissociation-recombination, and attachment kinetics by using a sophisticated kinetic model recently developed. The analysis clarifies the role of atomic hydrogen in affecting the vibrational content of the molecules. Theoretical plasma composition and population and electron energy distributions are presented as a function of the recombination coefficient γH of atomic hydrogen on the surfaces. The agreement between theoretical and experimental results is achieved for recombination coefficients consistent with those found in the literature.
Hassouni, K.; Lombardi, G.; Gicquel, A.; Capitelli, M.; Shakhatov, V.A.; De Pascale, O.
2005-07-15
Vibrational and rotational experimental temperatures of molecular hydrogen obtained by coherent anti-Stokes Raman spectroscopy in radiofrequency inductive plasmas have been analyzed and interpreted in terms of vibration, electron, dissociation-recombination, and attachment kinetics by using a sophisticated kinetic model recently developed. The analysis clarifies the role of atomic hydrogen in affecting the vibrational content of the molecules. Theoretical plasma composition and population and electron energy distributions are presented as a function of the recombination coefficient {gamma}{sub H} of atomic hydrogen on the surfaces. The agreement between theoretical and experimental results is achieved for recombination coefficients consistent with those found in the literature.
Theory of coherent resonance energy transfer
Jang, Seogjoo; Cheng, Y.-C.; Reichman, David R.; Eaves, Joel D.
2008-09-14
A theory of coherent resonance energy transfer is developed combining the polaron transformation and a time-local quantum master equation formulation, which is valid for arbitrary spectral densities including common modes. The theory contains inhomogeneous terms accounting for nonequilibrium initial preparation effects and elucidates how quantum coherence and nonequilibrium effects manifest themselves in the coherent energy transfer dynamics beyond the weak resonance coupling limit of the Foerster and Dexter (FD) theory. Numerical tests show that quantum coherence can cause significant changes in steady state donor/acceptor populations from those predicted by the FD theory and illustrate delicate cooperation of nonequilibrium and quantum coherence effects on the transient population dynamics.
Coherent quantum depletion of an interacting atom condensate
Kira, M.
2015-01-01
Sufficiently strong interactions promote coherent quantum transitions in spite of thermalization and losses, which are the adversaries of delicate effects such as reversibility and correlations. In atomic Bose–Einstein condensates (BECs), strong atom–atom interactions can eject atoms from the BEC to the normal component, yielding quantum depletion instead of temperature depletion. A recent experiment has already been verified to overcome losses. Here I show that it also achieves coherent quantum-depletion dynamics in a BEC swept fast enough from weak to strong atom–atom interactions. The elementary coherent process first excites the normal component into a liquid state that evolves into a spherical shell state, where the atom occupation peaks at a finite momentum to shield 50% of the BEC atoms from annihilation. The identified coherent processes resemble ultrafast semiconductor excitations expanding the scope of BEC explorations to many-body non-equilibrium studies. PMID:25767044
Coherent quantum depletion of an interacting atom condensate.
Kira, M
2015-03-13
Sufficiently strong interactions promote coherent quantum transitions in spite of thermalization and losses, which are the adversaries of delicate effects such as reversibility and correlations. In atomic Bose-Einstein condensates (BECs), strong atom-atom interactions can eject atoms from the BEC to the normal component, yielding quantum depletion instead of temperature depletion. A recent experiment has already been verified to overcome losses. Here I show that it also achieves coherent quantum-depletion dynamics in a BEC swept fast enough from weak to strong atom-atom interactions. The elementary coherent process first excites the normal component into a liquid state that evolves into a spherical shell state, where the atom occupation peaks at a finite momentum to shield 50% of the BEC atoms from annihilation. The identified coherent processes resemble ultrafast semiconductor excitations expanding the scope of BEC explorations to many-body non-equilibrium studies.
Glowacki, David R.; Orr-Ewing, Andrew J.; Harvey, Jeremy N.
2015-07-28
We describe a parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to explicitly correlated coupled cluster theory, we built a 64-state MS-EVB model designed to study the F + CD{sub 3}CN → DF + CD{sub 2}CN reaction in CD{sub 3}CN solvent (recently reported in Dunning et al. [Science 347(6221), 530 (2015)]). This approach allows us to build a reactive potential energy surface whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. We ran molecular dynamics simulations to examine a range of observables which follow in the wake of the reactive event: energy deposition in the nascent reaction products, vibrational relaxation rates of excited DF in CD{sub 3}CN solvent, equilibrium power spectra of DF in CD{sub 3}CN, and time dependent spectral shifts associated with relaxation of the nascent DF. Many of our results are in good agreement with time-resolved experimental observations, providing evidence for the accuracy of our MS-EVB framework in treating both the solute and solute/solvent interactions. The simulations provide additional insight into the dynamics at sub-picosecond time scales that are difficult to resolve experimentally. In particular, the simulations show that (immediately following deuterium abstraction) the nascent DF finds itself in a non-equilibrium regime in two different respects: (1) it is highly vibrationally excited, with ∼23 kcal mol{sup −1} localized in the stretch and (2) its post-reaction solvation environment, in which it is not yet hydrogen-bonded to CD{sub 3}CN solvent molecules, is intermediate between the non-interacting gas-phase limit and the solution-phase equilibrium limit. Vibrational
NASA Astrophysics Data System (ADS)
Glowacki, David R.; Orr-Ewing, Andrew J.; Harvey, Jeremy N.
2015-07-01
We describe a parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to explicitly correlated coupled cluster theory, we built a 64-state MS-EVB model designed to study the F + CD3CN → DF + CD2CN reaction in CD3CN solvent (recently reported in Dunning et al. [Science 347(6221), 530 (2015)]). This approach allows us to build a reactive potential energy surface whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. We ran molecular dynamics simulations to examine a range of observables which follow in the wake of the reactive event: energy deposition in the nascent reaction products, vibrational relaxation rates of excited DF in CD3CN solvent, equilibrium power spectra of DF in CD3CN, and time dependent spectral shifts associated with relaxation of the nascent DF. Many of our results are in good agreement with time-resolved experimental observations, providing evidence for the accuracy of our MS-EVB framework in treating both the solute and solute/solvent interactions. The simulations provide additional insight into the dynamics at sub-picosecond time scales that are difficult to resolve experimentally. In particular, the simulations show that (immediately following deuterium abstraction) the nascent DF finds itself in a non-equilibrium regime in two different respects: (1) it is highly vibrationally excited, with ˜23 kcal mol-1 localized in the stretch and (2) its post-reaction solvation environment, in which it is not yet hydrogen-bonded to CD3CN solvent molecules, is intermediate between the non-interacting gas-phase limit and the solution-phase equilibrium limit. Vibrational relaxation of the nascent DF results in a spectral
Glowacki, David R; Orr-Ewing, Andrew J; Harvey, Jeremy N
2015-07-28
We describe a parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to explicitly correlated coupled cluster theory, we built a 64-state MS-EVB model designed to study the F + CD3CN → DF + CD2CN reaction in CD3CN solvent (recently reported in Dunning et al. [Science 347(6221), 530 (2015)]). This approach allows us to build a reactive potential energy surface whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. We ran molecular dynamics simulations to examine a range of observables which follow in the wake of the reactive event: energy deposition in the nascent reaction products, vibrational relaxation rates of excited DF in CD3CN solvent, equilibrium power spectra of DF in CD3CN, and time dependent spectral shifts associated with relaxation of the nascent DF. Many of our results are in good agreement with time-resolved experimental observations, providing evidence for the accuracy of our MS-EVB framework in treating both the solute and solute/solvent interactions. The simulations provide additional insight into the dynamics at sub-picosecond time scales that are difficult to resolve experimentally. In particular, the simulations show that (immediately following deuterium abstraction) the nascent DF finds itself in a non-equilibrium regime in two different respects: (1) it is highly vibrationally excited, with ∼23 kcal mol(-1) localized in the stretch and (2) its post-reaction solvation environment, in which it is not yet hydrogen-bonded to CD3CN solvent molecules, is intermediate between the non-interacting gas-phase limit and the solution-phase equilibrium limit. Vibrational relaxation of the nascent DF results in a spectral
NASA Astrophysics Data System (ADS)
Korotin, M. A.; Pchelkina, Z. V.; Skorikov, N. A.; Efremov, A. V.; Anisimov, V. I.
2016-07-01
Based on the coherent potential approximation, the method of calculating the electronic structure of nonstoichiometric and hyperstoichiometric compounds with strong electron correlations and spin-orbit coupling has been developed. This method can be used to study both substitutional and interstitial impurities, which is demonstrated based on the example of the hyperstoichiometric UO2.12 compound. The influence of the coherent potential on the electronic structure of compounds has been shown for the nonstoichiometric UO1.87 containing vacancies in the oxygen sublattice as substitutional impurities, for stoichiometric UO2 containing vacancies in the oxygen sublattice and oxygen as an interstitial impurity, and for hyperstoichiometric UO2.12 with excess oxygen also as interstitial impurity. In the model of the uniform distribution of impurities, which forms the basis of the coherent potential approximation, the energy spectrum of UO2.12 has a metal-like character.
Atomic loss and gain as a resource for nonequilibrium phase transitions in optical lattices
NASA Astrophysics Data System (ADS)
Everest, B.; Marcuzzi, M.; Lesanovsky, I.
2016-02-01
Recent breakthroughs in the experimental manipulation of strongly interacting atomic Rydberg gases in lattice potentials have opened an avenue for the study of many-body phenomena. Considerable efforts are currently being undertaken to achieve clean experimental settings that show a minimal amount of noise and disorder and are close to zero temperature. A complementary direction investigates the interplay between coherent and dissipative processes. Recent experiments have revealed a glimpse into the emergence of a rich nonequilibrium behavior stemming from the competition of laser excitation, strong interactions, and radiative decay of Rydberg atoms. The aim of the present theoretical work is to show that local incoherent loss and gain of atoms can in fact be the source of interesting out-of-equilibrium dynamics. This perspective opens up paths for the exploration of nonequilibrium critical phenomena and, more generally, phase transitions, some of which so far have been rather difficult to study. To demonstrate the richness of the encountered dynamical behavior we consider here three examples. The first two feature local atom loss and gain together with an incoherent excitation of Rydberg states. In this setting either a continuous or a discontinuous phase transition emerges with the former being reminiscent of genuine nonequilibrium transitions of stochastic processes with multiple absorbing states. The third example considers the regime of coherent laser excitation. Here the many-body dynamics is dominated by an equilibrium transition of the "model A" universality class.
Egorov, V.S.; Lebedev, V.N.; Mekhov, I.B.; Moroshkin, P.V.; Chekhonin, I.A.; Bagayev, S.N.
2004-03-01
The nonstationary pump-probe interaction between short laser pulses propagating in a resonant optically dense coherent medium is considered. Special attention is paid to the case where the density of two-level particles is high enough that a considerable part of the energy of relatively weak external laser fields can be coherently absorbed and reemitted by the medium. Thus, the field of the medium reaction plays a key role in the interaction processes, which leads to collective behavior of an atomic ensemble in the strongly coupled light-matter system. Such behavior results in fast excitation interchanges between the field and a medium in the form of optical ringing, which is analogous to polariton beating in solid-state optics. This collective oscillating response, which can be treated as successive beats between light wave packets of different group velocities, is shown to significantly affect the propagation and amplification of the probe field under its nonlinear interaction with a nearly copropagating pump pulse. Depending on the probe-pump time delay, the probe transmission spectra show the appearance of either a specific doublet or coherent dip. The widths of these features are determined by the density-dependent field-matter coupling coefficient and increase during the propagation. Besides that, the widths of the coherent features, which appear close to resonance in the broadband probe spectrum, exceed the absorption-line width, since under the strong-coupling regime, the frequency of optical ringing exceeds the rate of incoherent relaxation. Contrary to stationary strong-field effects, the density- and coordinate-dependent transmission spectra of the probe manifest the importance of collective oscillations and cannot be obtained in the framework of a single-atom model.
Quantum thermodynamics: a nonequilibrium Green's function approach.
Esposito, Massimiliano; Ochoa, Maicol A; Galperin, Michael
2015-02-27
We establish the foundations of a nonequilibrium theory of quantum thermodynamics for noninteracting open quantum systems strongly coupled to their reservoirs within the framework of the nonequilibrium Green's functions. The energy of the system and its coupling to the reservoirs are controlled by a slow external time-dependent force treated to first order beyond the quasistatic limit. We derive the four basic laws of thermodynamics and characterize reversible transformations. Stochastic thermodynamics is recovered in the weak coupling limit. PMID:25768745
Non-equilibrium Kinematics in Merging Galaxies
NASA Astrophysics Data System (ADS)
Mihos, J. C.
Measurements of the kinematics of merging galaxies are often used to derive dynamical masses, study evolution onto the fundamental plane, or probe relaxation processes. These measurements are often compromised to some degree by strong non-equilibrium motions in the merging galaxies. This talk focuses on the evolution of the kinematics of merging galaxies, and highlights some pitfalls which occur when studying non-equilibrium systems.
NASA Technical Reports Server (NTRS)
Manning, Robert M.
2011-01-01
An expression for the mutual coherence function (MCF) of an electromagnetic beam wave propagating through atmospheric turbulence is derived within the confines of the Rytov approximation. It is shown that both the first and second Rytov approximations are required. The Rytov MCF is then compared to that which issues from the parabolic equation method of strong fluctuation theory. The agreement is found to be quite good in the weak fluctuation case. However, an instability is observed for the special case of beam wave intensities. The source of the instabilities is identified to be the characteristic way beam wave amplitudes are treated within the Rytov method.
NASA Astrophysics Data System (ADS)
Kirkpatrick, T. R.; Dorfman, J. R.
2015-08-01
Nonequilibrium and equilibrium fluid systems differ due to the existence of long-range correlations in nonequilibrium that are not present in equilibrium, except at critical points. Here we examine fluctuations of the temperature, of the pressure tensor, and of the heat current in a fluid maintained in a nonequilibrium stationary state (NESS) with a fixed temperature gradient, a system in which the nonequilibrium correlations are especially long-ranged. For this particular NESS, our results show that (i) the mean-squared fluctuations in nonequilibrium differ markedly in their system-size scaling compared to their equilibrium counterparts, and (ii) there are large, nonlocal correlations of the normal stress in this NESS. These terms provide important corrections to the fluctuating normal stress in linearized Landau-Lifshitz fluctuating hydrodynamics.
NASA Astrophysics Data System (ADS)
Lawrence, C. R.; Church, S.; Gaier, T.; Lai, R.; Ruf, C.; Wollack, E.
2009-03-01
Coherent systems offer significant advantages in simplicity, testability, control of systematics, and cost. Although quantum noise sets the fundamental limit to their performance at high frequencies, recent breakthroughs suggest that near-quantum-limited noise up to 150 or even 200 GHz could be realized within a few years. If the demands of component separation can be met with frequencies below 200 GHz, coherent systems will be strong competitors for a space CMB polarization mission. The rapid development of digital correlator capability now makes space interferometers with many hundreds of elements possible. Given the advantages of coherent interferometers in suppressing systematic effects, such systems deserve serious study.
NASA Astrophysics Data System (ADS)
Long, James P.; Owrutsky, Jeff C.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Compton, Ryan; Spann, Bryan; Simpkins, Blake S.
2015-09-01
Coherent coupling between an optical-transition and confined optical mode, when sufficiently strong, gives rise to new modes separated by the vacuum Rabi splitting. Such systems have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we bring strong polaritonic-coupling in cavities from the visible into the infrared where a new range of static and dynamic vibrational processes await investigation. First, we experimentally and numerically describe coupling between a Fabry-Perot cavity and carbonyl stretch (~1730 cm 1) in poly-methylmethacrylate. As is requisite for "strong coupling", the measured vacuum Rabi splitting of 132 cm 1 is much larger than the full width of the cavity (34 cm-1) and the inhomogeneously broadened carbonyl-stretch (24 cm-1). Agreement with classical theories providea evidence that the mixed-states are relatively immune to inhomogeneous broadening. Next, we investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of urethane. Rabi splittings increases from 0 to ~104 cm-1 with concentrations from 0-20 vol% and are in excellent agreement to an analytical description using no fitting parameters. Ultra-fast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band as well as modifications of energy relaxation times. Finally, we demonstrate coupling to liquids using the C-O stretching band (~1985 cm-1) of Mo(CO)6 in an aqueous solution. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied statically and dynamically.
Spectral coherence in windturbine wakes
Hojstrup, J.
1996-12-31
This paper describes an experiment at a Danish wind farm to investigate the lateral and vertical coherences in the nonequilibrium turbulence of a wind turbine wake. Two meteorological masts were instrumented for measuring profiles of mean speed, turbulence, and temperature. Results are provided graphically for turbulence intensities, velocity spectra, lateral coherence, and vertical coherence. The turbulence was somewhat influenced by the wake, or possibly from aggregated wakes further upstream, even at 14.5 diameters. Lateral coherence (separation 5m) seemed to be unaffected by the wake at 7.5 diameters, but the flow was less coherent in the near wake. The wake appeared to have little influence on vertical coherence (separation 13m). Simple, conventional models for coherence appeared to be adequate descriptions for wake turbulence except for the near wake situation. 3 refs., 7 figs., 1 tab.
Mandal, Dibyendu
2013-12-01
Development of steady state thermodynamics and statistical mechanics depends crucially on our ability to extend the notions of equilibrium thermodynamics to nonequilibrium steady states (NESS). The present paper considers the extension of heat capacity. A modified definition is proposed which continues to maintain the same relation to steady state Shannon entropy as in equilibrium, thus providing a thermodynamically consistent treatment of NESS heat capacity.
DSMC predictions of non-equilibrium reaction rates.
Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert
2010-04-01
A set of Direct Simulation Monte Carlo (DSMC) chemical-reaction models recently proposed by Bird and based solely on the collision energy and the vibrational energy levels of the species involved is applied to calculate nonequilibrium chemical-reaction rates for atmospheric reactions in hypersonic flows. The DSMC non-equilibrium model predictions are in good agreement with theoretical models and experimental measurements. The observed agreement provides strong evidence that modeling chemical reactions using only the collision energy and the vibrational energy levels provides an accurate method for predicting non-equilibrium chemical-reaction rates.
Nonlinear nonequilibrium quasiparticle relaxation in Josephson junctions.
Krasnov, V M
2009-11-27
I solve numerically a full set of nonlinear kinetic balance equations for stacked Josephson junctions, which allows analysis of strongly nonequilibrium phenomena. It is shown that nonlinearity becomes significant already at very small disequilibrium. The following new, nonlinear effects are obtained: (i) At even-gap voltages V = 2nDelta/e (n = 2, 3, ...) nonequilibrium bosonic bands overlap. This leads to enhanced emission of Omega = 2Delta bosons and to the appearance of dips in tunnel conductance. (ii) A new type of radiative solution is found at strong disequilibrium. It is characterized by the fast stimulated relaxation of quasiparticles. A stack in this state behaves as a light emitting diode and directly converts electric power to boson emission, without utilization of the ac-Josephson effect. The phenomenon can be used for realization of a new type of superconducting cascade laser in the THz frequency range.
NASA Astrophysics Data System (ADS)
Levi, Emanuele; Gutiérrez, Ricardo; Lesanovsky, Igor
2016-09-01
In the presence of strong dephasing noise the dynamics of Rydberg gases becomes effectively classical, due to the rapid decay of quantum superpositions between atomic levels. Recently a great deal of attention has been devoted to the stochastic dynamics that emerges in that limit, revealing several interesting features, including kinetically constrained glassy behaviour, self-similarity and aggregation effects. However, the non-equilibrium physics of these systems, in particular in the regime where coherent and dissipative processes contribute on equal footing, is yet far from being understood. To explore this we study the dynamics of a small one-dimensional Rydberg lattice gas subject to dephasing noise by numerically integrating the quantum master equation. We interpolate between the coherent and the strongly dephased regime by defining a generalised concept of a blockade length. We find indications that the main features observed in the strongly dissipative limit persist when the dissipation is not strong enough to annihilate quantum coherences at the dynamically relevant time scales. These features include the existence of a time-dependent Rydberg blockade radius, and a growth of the density of excitations which is compatible with the power-law behaviour expected in the classical limit.
Nonequilibrium superconducting detectors
NASA Astrophysics Data System (ADS)
Cristiano, R.; Ejrnaes, M.; Esposito, E.; Lisitskyi, M. P.; Nappi, C.; Pagano, S.; Perez de Lara, D.
2006-03-01
Nonequilibrium superconducting detectors exploit the early stages of the energy down cascade which occur after the absorption of radiation. They operate on a short temporal scale ranging from few microseconds down to tens of picoseconds. In such a way they provide fast counting capability, high time discrimination and also, for some devices, energy sensitivity. Nonequilibrium superconducting detectors are developed for their use both in basic science and in practical applications for detection of single photons or single ionized macromolecules. In this paper we consider two devices: distributed readout imaging detectors (DROIDs) based on superconducting tunnel junctions (STJs), which are typically used for high-speed energy spectroscopy applications, and hot-electron superconductive detectors (HESDs), which are typically used as fast counters and time discriminators. Implementation of the DROID geometry to use a single superconductor is discussed. Progress in the fabrication technology of NbN nanostructured HESDs is presented. The two detectors share the high sensitivity that makes them able to efficiently detect even single photons down to infrared energy.
Nonequilibrium Dynamical Mean-Field Theory for Bosonic Lattice Models
NASA Astrophysics Data System (ADS)
Strand, Hugo U. R.; Eckstein, Martin; Werner, Philipp
2015-01-01
We develop the nonequilibrium extension of bosonic dynamical mean-field theory and a Nambu real-time strong-coupling perturbative impurity solver. In contrast to Gutzwiller mean-field theory and strong-coupling perturbative approaches, nonequilibrium bosonic dynamical mean-field theory captures not only dynamical transitions but also damping and thermalization effects at finite temperature. We apply the formalism to quenches in the Bose-Hubbard model, starting from both the normal and the Bose-condensed phases. Depending on the parameter regime, one observes qualitatively different dynamical properties, such as rapid thermalization, trapping in metastable superfluid or normal states, as well as long-lived or strongly damped amplitude oscillations. We summarize our results in nonequilibrium "phase diagrams" that map out the different dynamical regimes.
Guo Jing; Liu Xueshen; Chu, Shih-I
2010-08-15
We extend the coupled coherent-state (CCS) approach to simulate the strong-field ionization of helium atoms at long wavelengths. This approach uses a basis of trajectories guided by frozen Gaussian coherent states, sampled from a Monte Carlo distribution, as the initial states of the quantum time-dependent Schroedinger equations. The CCS trajectories move over averaged potentials, which can remove the Columbic singularities exactly. The low-energy structure is predicted by our CCS calculation and a ''rescattering'' event is clearly identified in the higher-energy regime. In addition, the nonsequential double ionization is also explored and the rescattering event can be identified as the major mechanism. Finally, we also study the electron angular distribution of helium. It is found that the maximum angle between the electron and electric field directions becomes smaller with increase in the laser intensity and wavelength.
NASA Astrophysics Data System (ADS)
Wang, Jigang
2014-03-01
Research of non-equilibrium phase transitions of strongly correlated electrons is built around addressing an outstanding challenge: how to achieve ultrafast manipulation of competing magnetic/electronic phases and reveal thermodynamically hidden orders at highly non-thermal, femtosecond timescales? Recently we reveal a new paradigm called quantum femtosecond magnetism-photoinduced femtosecond magnetic phase transitions driven by quantum spin flip fluctuations correlated with laser-excited inter-atomic coherent bonding. We demonstrate an antiferromagnetic (AFM) to ferromagnetic (FM) switching during about 100 fs laser pulses in a colossal magneto-resistive manganese oxide. Our results show a huge photoinduced femtosecond spin generation, measured by magnetic circular dichroism, with photo-excitation threshold behavior absent in the picosecond dynamics. This reveals an initial quantum coherent regime of magnetism, while the optical polarization/coherence still interacts with the spins to initiate local FM correlations that compete with the surrounding AFM matrix. Our results thus provide a framework that explores quantum non-equilibrium kinetics to drive phase transitions between exotic ground states in strongly correlated elecrons, and raise fundamental questions regarding some accepted rules, such as free energy and adiabatic potential surface. This work is in collaboration with Tianqi Li, Aaron Patz, Leonidas Mouchliadis, Jiaqiang Yan, Thomas A. Lograsso, Ilias E. Perakis. This work was supported by the National Science Foundation (contract no. DMR-1055352). Material synthesis at the Ames Laboratory was supported by the US Department of Energy-Basic Energy Sciences (contract no. DE-AC02-7CH11358).
Landau superfluids as nonequilibrium stationary states
Wreszinski, Walter F.
2015-01-15
We define a superfluid state to be a nonequilibrium stationary state (NESS), which, at zero temperature, satisfies certain metastability conditions, which physically express that there should be a sufficiently small energy-momentum transfer between the particles of the fluid and the surroundings (e.g., pipe). It is shown that two models, the Girardeau model and the Huang-Yang-Luttinger (HYL) model, describe superfluids in this sense and, moreover, that, in the case of the HYL model, the metastability condition is directly related to Nozières’ conjecture that, due to the repulsive interaction, the condensate does not suffer fragmentation into two (or more) parts, thereby assuring its quantum coherence. The models are rigorous examples of NESS in which the system is not finite, but rather a many-body system.
Non-equilibrium quantum phase transition via entanglement decoherence dynamics
NASA Astrophysics Data System (ADS)
Lin, Yu-Chen; Yang, Pei-Yun; Zhang, Wei-Min
2016-10-01
We investigate the decoherence dynamics of continuous variable entanglement as the system-environment coupling strength varies from the weak-coupling to the strong-coupling regimes. Due to the existence of localized modes in the strong-coupling regime, the system cannot approach equilibrium with its environment, which induces a nonequilibrium quantum phase transition. We analytically solve the entanglement decoherence dynamics for an arbitrary spectral density. The nonequilibrium quantum phase transition is demonstrated as the system-environment coupling strength varies for all the Ohmic-type spectral densities. The 3-D entanglement quantum phase diagram is obtained.
Non-equilibrium quantum phase transition via entanglement decoherence dynamics
Lin, Yu-Chen; Yang, Pei-Yun; Zhang, Wei-Min
2016-01-01
We investigate the decoherence dynamics of continuous variable entanglement as the system-environment coupling strength varies from the weak-coupling to the strong-coupling regimes. Due to the existence of localized modes in the strong-coupling regime, the system cannot approach equilibrium with its environment, which induces a nonequilibrium quantum phase transition. We analytically solve the entanglement decoherence dynamics for an arbitrary spectral density. The nonequilibrium quantum phase transition is demonstrated as the system-environment coupling strength varies for all the Ohmic-type spectral densities. The 3-D entanglement quantum phase diagram is obtained. PMID:27713556
Theory of nonequilibrium superconductivity in cuprates
NASA Astrophysics Data System (ADS)
Oka, Takashi; Pietilä, Ville
2013-03-01
Recently, nonequilibrium properties of Hi Tc superconductors are attracting much interest. This is because new experimental methods such as time resolved ARPES has been applied to cuprates and succeeded in observing the dynamics of photo-excited quasiparticles as well as the temporal evolution of the d-wave superconducting order parameter (e.g.,). One can also realize nonequilibrium states in interfaces between cuprates and metal electrodes and control the superconducting order by changing the applied bias. In order to study the dynamics of superconductivity in strongly correlated systems, we developed a novel numerical method by combining the quantum kinetic equation with the fluctuation exchange approximation (FLEX, self-consistent T-matrix approximation). This method enables us to study the interplay between pair mediating fluctuations, e.g., antiferromagnetic and charge fluctuations, and the dynamics of quasiparticles and superconducting order parameter. In the presentation, we explain the physical insights we obtain by applying this method to nonequilibrium dynamics in d-wave superconductors.
Effective equilibrium theory of nonequilibrium quantum transport
Dutt, Prasenjit; Koch, Jens; Han, Jong; Le Hur, Karyn
2011-12-15
The theoretical description of strongly correlated quantum systems out of equilibrium presents several challenges and a number of open questions persist. Here, we focus on nonlinear electronic transport through an interacting quantum dot maintained at finite bias using a concept introduced by Hershfield [S. Hershfield, Phys. Rev. Lett. 70 2134 (1993)] whereby one can express such nonequilibrium quantum impurity models in terms of the system's Lippmann-Schwinger operators. These scattering operators allow one to reformulate the nonequilibrium problem as an effective equilibrium problem associated with a modified Hamiltonian. In this paper, we provide a pedagogical analysis of the core concepts of the effective equilibrium theory. First, we demonstrate the equivalence between observables computed using the Schwinger-Keldysh framework and the effective equilibrium approach, and relate Green's functions in the two theoretical frameworks. Second, we expound some applications of this method in the context of interacting quantum impurity models. We introduce a novel framework to treat effects of interactions perturbatively while capturing the entire dependence on the bias voltage. For the sake of concreteness, we employ the Anderson model as a prototype for this scheme. Working at the particle-hole symmetric point, we investigate the fate of the Abrikosov-Suhl resonance as a function of bias voltage and magnetic field. - Highlights: > Reformulation of steady-state nonequilibrium quantum transport, following Hershfield. > Derivation of effective equilibrium density operator using the 'open-system' approach. > Equivalence with the Keldysh description and formulas relating the two approaches. > Novel framework to treat interactions perturbatively. > Application to nonequilibrium Anderson model and fate of Abrikosov-Suhl resonance.
Kato, Akihito Tanimura, Yoshitaka
2015-08-14
We consider a system consisting of two interacting qubits that are individually coupled to separate heat baths at different temperatures. The quantum effects in heat transport are investigated in a numerically rigorous manner with a hierarchial equations of motion (HEOM) approach for non-perturbative and non-Markovian system-bath coupling cases under non-equilibrium steady-state conditions. For a weak interqubit interaction, the total system is regarded as two individually thermostatted systems, whereas for a strong interqubit interaction, the two-qubit system is regarded as a single system coupled to two baths. The roles of quantum coherence (or entanglement) between the two qubits (q-q coherence) and between the qubit and bath (q-b coherence) are studied through the heat current calculated for various strengths of the system-bath coupling and interqubit coupling for high and low temperatures. The same current is also studied using the time convolutionless (TCL) Redfield equation and using an expression derived from the Fermi golden rule (FGR). We find that the HEOM results exhibit turnover behavior of the heat current as a function of the system-bath coupling strength for all values of the interqubit coupling strength, while the results obtained with the TCL and FGR approaches do not exhibit such behavior, because they do not possess the capability of treating the q-b and q-q coherences. The maximum current is obtained in the case that the q-q coherence and q-b coherence are balanced in such a manner that coherence of the entire heat transport process is realized. We also find that the heat current does not follow Fourier’s law when the temperature difference is very large, due to the non-perturbative system-bath interactions.
Nonequilibrium ionization phenomena behind shock waves
Panesi, Marco; Magin, Thierry; Huo, Winifred
2011-05-20
An accurate investigation of the behavior of electronically excited states of atoms and molecules in the post shock relaxation zone of a trajectory point of the FIRE II flight experiment is carried out by means of a one-dimensional flow solver coupled to a collisional-radiative model. In the rapidly ionizing regime behind a strong shock wave, the high lying bound electronic states of atoms are depleted. This leads the electronic energy level populations of atoms to depart from Boltzmann distributions which strongly affects the non-equilibrium ionization process as well as the radiative signature. The importance of correct modeling of the interaction of radiation and matter is discussed showing a strong influence on the physico-chemical properties of the gas. The paper clearly puts forward the shortcomings of the simplified approach often used in literature which strongly relies on the escape factors to characterize the optical thickness of the gas.
Nonequilibrium Tuning of the Thermal Casimir Effect.
Dean, David S; Lu, Bing-Sui; Maggs, A C; Podgornik, Rudolf
2016-06-17
In net-neutral systems correlations between charge fluctuations generate strong attractive thermal Casimir forces and engineering these forces to optimize nanodevice performance is an important challenge. We show how the normal and lateral thermal Casimir forces between two plates containing Brownian charges can be modulated by decorrelating the system through the application of an electric field, which generates a nonequilibrium steady state with a constant current in one or both plates, reducing the ensuing fluctuation-generated normal force while at the same time generating a lateral drag force. This hypothesis is confirmed by detailed numerical simulations as well as an analytical approach based on stochastic density functional theory. PMID:27367374
Nonequilibrium Tuning of the Thermal Casimir Effect
NASA Astrophysics Data System (ADS)
Dean, David S.; Lu, Bing-Sui; Maggs, A. C.; Podgornik, Rudolf
2016-06-01
In net-neutral systems correlations between charge fluctuations generate strong attractive thermal Casimir forces and engineering these forces to optimize nanodevice performance is an important challenge. We show how the normal and lateral thermal Casimir forces between two plates containing Brownian charges can be modulated by decorrelating the system through the application of an electric field, which generates a nonequilibrium steady state with a constant current in one or both plates, reducing the ensuing fluctuation-generated normal force while at the same time generating a lateral drag force. This hypothesis is confirmed by detailed numerical simulations as well as an analytical approach based on stochastic density functional theory.
Nonequilibrium thermodynamics of nucleation
Schweizer, M.; Sagis, L. M. C.
2014-12-14
We present a novel approach to nucleation processes based on the GENERIC framework (general equation for the nonequilibrium reversible-irreversible coupling). Solely based on the GENERIC structure of time-evolution equations and thermodynamic consistency arguments of exchange processes between a metastable phase and a nucleating phase, we derive the fundamental dynamics for this phenomenon, based on continuous Fokker-Planck equations. We are readily able to treat non-isothermal nucleation even when the nucleating cores cannot be attributed intensive thermodynamic properties. In addition, we capture the dynamics of the time-dependent metastable phase being continuously expelled from the nucleating phase, and keep rigorous track of the volume corrections to the dynamics. Within our framework the definition of a thermodynamic nuclei temperature is manifest. For the special case of nucleation of a gas phase towards its vapor-liquid coexistence, we illustrate that our approach is capable of reproducing recent literature results obtained by more microscopic considerations for the suppression of the nucleation rate due to nonisothermal effects.
The fundamental role of quantized vibrations in coherent light harvesting by cryptophyte algae.
Kolli, Avinash; O'Reilly, Edward J; Scholes, Gregory D; Olaya-Castro, Alexandra
2012-11-01
The influence of fast vibrations on energy transfer and conversion in natural molecular aggregates is an issue of central interest. This article shows the important role of high-energy quantized vibrations and their non-equilibrium dynamics for energy transfer in photosynthetic systems with highly localized excitonic states. We consider the cryptophyte antennae protein phycoerythrin 545 and show that coupling to quantized vibrations, which are quasi-resonant with excitonic transitions is fundamental for biological function as it generates non-cascaded transport with rapid and wider spatial distribution of excitation energy. Our work also indicates that the non-equilibrium dynamics of such vibrations can manifest itself in ultrafast beating of both excitonic populations and coherences at room temperature, with time scales in agreement with those reported in experiments. Moreover, we show that mechanisms supporting coherent excitonic dynamics assist coupling to selected modes that channel energy to preferential sites in the complex. We therefore argue that, in the presence of strong coupling between electronic excitations and quantized vibrations, a concrete and important advantage of quantum coherent dynamics is precisely to tune resonances that promote fast and effective energy distribution.
The fundamental role of quantized vibrations in coherent light harvesting by cryptophyte algae
NASA Astrophysics Data System (ADS)
Kolli, Avinash; O'Reilly, Edward J.; Scholes, Gregory D.; Olaya-Castro, Alexandra
2012-11-01
The influence of fast vibrations on energy transfer and conversion in natural molecular aggregates is an issue of central interest. This article shows the important role of high-energy quantized vibrations and their non-equilibrium dynamics for energy transfer in photosynthetic systems with highly localized excitonic states. We consider the cryptophyte antennae protein phycoerythrin 545 and show that coupling to quantized vibrations, which are quasi-resonant with excitonic transitions is fundamental for biological function as it generates non-cascaded transport with rapid and wider spatial distribution of excitation energy. Our work also indicates that the non-equilibrium dynamics of such vibrations can manifest itself in ultrafast beating of both excitonic populations and coherences at room temperature, with time scales in agreement with those reported in experiments. Moreover, we show that mechanisms supporting coherent excitonic dynamics assist coupling to selected modes that channel energy to preferential sites in the complex. We therefore argue that, in the presence of strong coupling between electronic excitations and quantized vibrations, a concrete and important advantage of quantum coherent dynamics is precisely to tune resonances that promote fast and effective energy distribution.
Nonequilibrium fluctuation-dissipation inequality and nonequilibrium uncertainty principle.
Fleming, C H; Hu, B L; Roura, Albert
2013-07-01
The fluctuation-dissipation relation is usually formulated for a system interacting with a heat bath at finite temperature, and often in the context of linear response theory, where only small deviations from the mean are considered. We show that for an open quantum system interacting with a nonequilibrium environment, where temperature is no longer a valid notion, a fluctuation-dissipation inequality exists. Instead of being proportional, quantum fluctuations are bounded below by quantum dissipation, whereas classically the fluctuations vanish at zero temperature. The lower bound of this inequality is exactly satisfied by (zero-temperature) quantum noise and is in accord with the Heisenberg uncertainty principle, in both its microscopic origins and its influence upon systems. Moreover, it is shown that there is a coupling-dependent nonequilibrium fluctuation-dissipation relation that determines the nonequilibrium uncertainty relation of linear systems in the weak-damping limit.
The nonequilibrium glassy dynamics of self-propelled particles.
Flenner, Elijah; Szamel, Grzegorz; Berthier, Ludovic
2016-09-14
We study the glassy dynamics taking place in dense assemblies of athermal active particles that are driven solely by a nonequilibrium self-propulsion mechanism. Active forces are modeled as an Ornstein-Uhlenbeck stochastic process, characterized by a persistence time and an effective temperature, and particles interact via a Lennard-Jones potential that yields well-studied glassy behavior in the Brownian limit, which is obtained as the persistence time vanishes. By increasing the persistence time, the system departs more strongly from thermal equilibrium and we provide a comprehensive numerical analysis of the structure and dynamics of the resulting active fluid. Finite persistence times profoundly affect the static structure of the fluid and give rise to nonequilibrium velocity correlations that are absent in thermal systems. Despite these nonequilibrium features, for any value of the persistence time we observe a nonequilibrium glass transition as the effective temperature is decreased. Surprisingly, increasing departure from thermal equilibrium is found to promote (rather than suppress) the glassy dynamics. Overall, our results suggest that with increasing persistence time, microscopic properties of the active fluid change quantitatively, but the general features of the nonequilibrium glassy dynamics observed with decreasing the effective temperature remain qualitatively similar to those of thermal glass-formers. PMID:27499055
Nonequilibrium Growth Processes
NASA Astrophysics Data System (ADS)
Ramanlal, Pradipkumar
A number of issues in nonequilibrium aggregation and pattern formation are addressed. Using analytical, numerical, and computer simulation methods, an attempt is made to infer or conclude on a number of aspects of compact, fractal and dendritic growth. Using the ballistic aggregation model, we develop a mean-field continuum theory that successfully predicts the morphology of thin films formed by vapor deposition and aggregation on a seed. In addition, by relating the evolution of the surface of ballistic deposits to a problem of spin dynamics, we develop a theory for the roughness of the interface, showing it to be a self-affine fractal, and at the same time having a bounded interface length. We also develop a deterministic continuum model for the fractal growth of diffusion-limited aggregation (DLA), related to the problem of two-dimensional viscous fluid flow in a hele-shaw cell. With the introduction of a real-space renormalization scheme we solve the equations numerically to produce fractal growth and patterns reminiscent of real fluid flow experiments. In addition, we show the fractal patterns to have the same metric properties of DLA, with a prediction for the asymptotic value for the fractal dimension; D = 1.65. An important consequence of these results is that DLA is sufficiently unstable and sensitive to initial conditions to produce fractal growth in the absence of external noise present in computer simulation results. Further, we examine the effect of an underlying lattice on the growth process in both the discrete and continuum deterministic formulations of DLA. In both cases, the lattice anisotropy destroys the fractal characteristics and this is confirmed by studying large on-lattice DLA simulations. And finally, we infer a relationship between the lattice anisotropy and the phenomenological formulations of the interfacial anisotropy, and examine the nature of the transition between fractal and dendritic growth as a function of the interfacial
Nonequilibrium thermodynamics of an interface
NASA Astrophysics Data System (ADS)
Schweizer, Marco; Öttinger, Hans Christian; Savin, Thierry
2016-05-01
Interfacial thermodynamics has deep ramifications in understanding the boundary conditions of transport theories. We present a formulation of local equilibrium for interfaces that extends the thermodynamics of the "dividing surface," as introduced by Gibbs, to nonequilibrium settings such as evaporation or condensation. By identifying the precise position of the dividing surface in the interfacial region with a gauge degree of freedom, we exploit gauge-invariance requirements to consistently define the intensive variables for the interface. The model is verified under stringent conditions by employing high-precision nonequilibrium molecular-dynamics simulations of a coexisting vapor-liquid Lennard-Jones fluid. We conclude that the interfacial temperature is determined using the surface tension as a "thermometer," and it can be significantly different from the temperatures of the adjacent phases. Our findings lay foundations for nonequilibrium interfacial thermodynamics.
Nonequilibrium thermodynamics of an interface.
Schweizer, Marco; Öttinger, Hans Christian; Savin, Thierry
2016-05-01
Interfacial thermodynamics has deep ramifications in understanding the boundary conditions of transport theories. We present a formulation of local equilibrium for interfaces that extends the thermodynamics of the "dividing surface," as introduced by Gibbs, to nonequilibrium settings such as evaporation or condensation. By identifying the precise position of the dividing surface in the interfacial region with a gauge degree of freedom, we exploit gauge-invariance requirements to consistently define the intensive variables for the interface. The model is verified under stringent conditions by employing high-precision nonequilibrium molecular-dynamics simulations of a coexisting vapor-liquid Lennard-Jones fluid. We conclude that the interfacial temperature is determined using the surface tension as a "thermometer," and it can be significantly different from the temperatures of the adjacent phases. Our findings lay foundations for nonequilibrium interfacial thermodynamics.
Nonequilibrium thermodynamics of an interface.
Schweizer, Marco; Öttinger, Hans Christian; Savin, Thierry
2016-05-01
Interfacial thermodynamics has deep ramifications in understanding the boundary conditions of transport theories. We present a formulation of local equilibrium for interfaces that extends the thermodynamics of the "dividing surface," as introduced by Gibbs, to nonequilibrium settings such as evaporation or condensation. By identifying the precise position of the dividing surface in the interfacial region with a gauge degree of freedom, we exploit gauge-invariance requirements to consistently define the intensive variables for the interface. The model is verified under stringent conditions by employing high-precision nonequilibrium molecular-dynamics simulations of a coexisting vapor-liquid Lennard-Jones fluid. We conclude that the interfacial temperature is determined using the surface tension as a "thermometer," and it can be significantly different from the temperatures of the adjacent phases. Our findings lay foundations for nonequilibrium interfacial thermodynamics. PMID:27300960
Open problems in non-equilibrium physics
Kusnezov, D.
1997-09-22
The report contains viewgraphs on the following: approaches to non-equilibrium statistical mechanics; classical and quantum processes in chaotic environments; classical fields in non-equilibrium situations: real time dynamics at finite temperature; and phase transitions in non-equilibrium conditions.
Partially coherent ultrafast spectrography
Bourassin-Bouchet, C.; Couprie, M.-E.
2015-01-01
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080
Partially coherent ultrafast spectrography
NASA Astrophysics Data System (ADS)
Bourassin-Bouchet, C.; Couprie, M.-E.
2015-03-01
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter.
Nonequilibrium diagnostics of plasma thrusters
Eddy, T.L.; Grandy, J.D.
1990-01-01
This paper describes possible techniques by which the state of plasma thruster operation for space propulsion can be determined from a minimum set of experimental data in the laboratory. The kinetic properties of the nonequilibrium plasma plume usually can not be directly related to the observed radiation; hence, appropriate nonequilibrium diagnostic techniques must be employed. A newly developed multithermal, multichemical equilibrium method is discussed that uses measured line emission intensities and N equations to solve for N unknowns. The effect of arbitrarily changing the number of selected N unknowns and how one determines the optimum (minimum) number to be used for a given composition is also presented. The chemical nonequilibrium aspects and the application to molecular species have not yet been published. The important conclusions are that (1) complete thermodynamic systems in nonequilibrium can be described by relatively few variables if appropriate choices and filtering methods are used, (2) a few radiation measurements can yield valid kinetic properties, and (3) the major question in the relations to be used is in the form of the law of mass action. The results are substantiated in the laboratory by additional alternative methods of measurement of some of the kinetic properties. 13 refs., 1 fig.
Computer simulation of nonequilibrium processes
Hoover, W.G.; Moran, B.; Holian, B.L.; Posch, H.A.; Bestiale, S.
1987-01-01
Recent atomistic simulations of irreversible macroscopic hydrodynamic flows are illustrated. An extension of Nose's reversible atomistic mechanics makes it possible to simulate such non-equilibrium systems with completely reversible equations of motion. The new techniques show that macroscopic irreversibility is a natural inevitable consequence of time-reversible Lyapunov-unstable microscopic equations of motion.
Coherent transport and energy flow patterns in photosynthesis under incoherent excitation.
Pelzer, Kenley M; Can, Tankut; Gray, Stephen K; Morr, Dirk K; Engel, Gregory S
2014-03-13
Long-lived coherences have been observed in photosynthetic complexes after laser excitation, inspiring new theories regarding the extreme quantum efficiency of photosynthetic energy transfer. Whether coherent (ballistic) transport occurs in nature and whether it improves photosynthetic efficiency remain topics of debate. Here, we use a nonequilibrium Green's function analysis to model exciton transport after excitation from an incoherent source (as opposed to coherent laser excitation). We find that even with an incoherent source, the rate of environmental dephasing strongly affects exciton transport efficiency, suggesting that the relationship between dephasing and efficiency is not an artifact of coherent excitation. The Green's function analysis provides a clear view of both the pattern of excitonic fluxes among chromophores and the multidirectionality of energy transfer that is a feature of coherent transport. We see that even in the presence of an incoherent source, transport occurs by qualitatively different mechanisms as dephasing increases. Our approach can be generalized to complex synthetic systems and may provide a new tool for optimizing synthetic light harvesting materials.
Non-equilibrium many body dynamics
Creutz, M.; Gyulassy, M.
1997-09-22
This Riken BNL Research Center Symposium on Non-Equilibrium Many Body Physics was held on September 23-25, 1997 as part of the official opening ceremony of the Center at Brookhaven National Lab. A major objective of theoretical work at the center is to elaborate on the full spectrum of strong interaction physics based on QCD, including the physics of confinement and chiral symmetry breaking, the parton structure of hadrons and nuclei, and the phenomenology of ultra-relativistic nuclear collisions related to the up-coming experiments at RHIC. The opportunities and challenges of nuclear and particle physics in this area naturally involve aspects of the many body problem common to many other fields. The aim of this symposium was to find common theoretical threads in the area of non-equilibrium physics and modern transport theories. The program consisted of invited talks on a variety topics from the fields of atomic, condensed matter, plasma, astrophysics, cosmology, and chemistry, in addition to nuclear and particle physics. Separate abstracts have been indexed into the database for contributions to this workshop.
The influence of non-equilibrium pressure on rotating flows
NASA Astrophysics Data System (ADS)
Zardadkhan, Irfan Rashid
This study was undertaken to investigate the influence of pressure relaxation on steady, incompressible flows with strong streamline curvature. In the early part of this dissertation research, the significance of non-equilibrium pressure forces in controlling the structure of a steady, two dimensional axial vortex was demonstrated. In order to extend the study of pressure relaxation influences on more complex rotating flows, this dissertation has examined other rotating flow features that can be associated with hurricanes, tornadoes and dust devils. To model these flows, modified boundary layer equations were developed for a fluid column rotating near a solid plane including the influence of non-equilibrium pressure forces. The far-field boundary conditions were inferred using the asymptotic behavior of the governing equations, and the boundary conditions for the axial and radial components of velocity were shown to be dependent on the pressure relaxation coefficient, η
Nonequilibrium dynamical mean-field theory
NASA Astrophysics Data System (ADS)
Freericks, James
2007-03-01
Dynamical mean-field theory (DMFT) is establishing itself as one of the most powerful approaches to the quantum many-body problem in strongly correlated electron materials. Recently, the formalism has been generalized to study nonequilibrium problems [1,2], such as the evolution of Bloch oscillations in a material that changes from a diffusive metal to a Mott insulator [2,3]. Using a real-time formalism on the Kadanoff-Baym-Keldysh contour, the DMFT algorithm can be generalized to the case of systems that are not time-translation invariant. The computational algorithm has a parallel implementation with essentially a linear scale up when running on thousands of processors. Results on the decay of Bloch oscillations, their change of character within the Mott insulator, and movies on how electrons redistribute themselves due to their response to an external electrical field will be presented. In addition to solid-state applications, this work also applies to the behavior of mixtures of light and heavy cold atoms in optical lattices. [1] V. M. Turkowski and J. K. Freericks, Spectral moment sum rules for strongly correlated electrons in time-dependent electric fields, Phys. Rev. B 075108 (2006); Erratum, Phys. Rev. B 73, 209902(E) (2006). [2] J. K. Freericks, V. M. Turkowski , and V. Zlati'c, Nonlinear response of strongly correlated materials to large electric fields, in Proceedings of the HPCMP Users Group Conference 2006, Denver, CO, June 26--29, 2006 edited by D. E. Post (IEEE Computer Society, Los Alamitos, CA, 2006), to appear. [3] J. K. Freericks, V. M. Turkowski, and V. Zlati'c, Nonequilibrium dynamical mean-field theory, submitted to Phys. Rev. Lett. cond-mat//0607053.
Nonequilibrium landscape theory of neural networks.
Yan, Han; Zhao, Lei; Hu, Liang; Wang, Xidi; Wang, Erkang; Wang, Jin
2013-11-01
The brain map project aims to map out the neuron connections of the human brain. Even with all of the wirings mapped out, the global and physical understandings of the function and behavior are still challenging. Hopfield quantified the learning and memory process of symmetrically connected neural networks globally through equilibrium energy. The energy basins of attractions represent memories, and the memory retrieval dynamics is determined by the energy gradient. However, the realistic neural networks are asymmetrically connected, and oscillations cannot emerge from symmetric neural networks. Here, we developed a nonequilibrium landscape-flux theory for realistic asymmetrically connected neural networks. We uncovered the underlying potential landscape and the associated Lyapunov function for quantifying the global stability and function. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. We applied our theory to rapid-eye movement sleep cycle. We identified the key regulation factors for function through global sensitivity analysis of landscape topography against wirings, which are in good agreements with experiments.
Temporal Response of Nonequilibrium Correlated Electrons
Moritz, Brian; Devereaux, T.P.; Freericks, J.K.; /Georgetown U.
2010-08-26
In this work we examine the time-resolved, instantaneous current response for the spinless Falicov-Kimball model at half-filling, on both sides of the Mott-Hubbard metal-insulator transition, driven by a strong electric field pump pulse. The results are obtained using an exact, nonequilibrium, many-body impurity solution specifically designed to treat the out-of-equilibrium evolution of electrons in time-dependent fields. We provide a brief introduction to the method and its computational details. We find that the current develops Bloch oscillations, similar to the case of DC driving fields, with an additional amplitude modulation, characterized by beats and induced by correlation effects. Correlations primarily manifest themselves through an overall reduction in magnitude and shift in the onset time of the current response with increasing interaction strength.
Probing local equilibrium in nonequilibrium fluids.
del Pozo, J J; Garrido, P L; Hurtado, P I
2015-08-01
We use extensive computer simulations to probe local thermodynamic equilibrium (LTE) in a quintessential model fluid, the two-dimensional hard-disks system. We show that macroscopic LTE is a property much stronger than previously anticipated, even in the presence of important finite-size effects, revealing a remarkable bulk-boundary decoupling phenomenon in fluids out of equilibrium. This allows us to measure the fluid's equation of state in simulations far from equilibrium, with an excellent accuracy comparable to the best equilibrium simulations. Subtle corrections to LTE are found in the fluctuations of the total energy which strongly point to the nonlocality of the nonequilibrium potential governing the fluid's macroscopic behavior out of equilibrium.
Nonequilibrium spin crossover in copper phthalocyanine
NASA Astrophysics Data System (ADS)
Siegert, Benjamin; Donarini, Andrea; Grifoni, Milena
2016-03-01
We demonstrate the nonequilibrium tip induced control of the spin state of copper phthalocyanine on an insulator coated substrate. We find that, under the condition of energetic proximity of many-body neutral excited states to the anionic ground state, the system can undergo a population inversion towards these excited states. The resulting state of the system is accompanied by a change in the total spin quantum number. Experimental signatures of the crossover are the appearance of additional nodal planes in the topographical scanning tunneling microscopy images as well as a strong suppression of the current near the center of the molecule. The robustness of the effect against moderate charge conserving relaxation processes has also been tested.
Nonequilibrium itinerant-electron magnetism: A time-dependent mean-field theory
NASA Astrophysics Data System (ADS)
Secchi, A.; Lichtenstein, A. I.; Katsnelson, M. I.
2016-08-01
We study the dynamical magnetic susceptibility of a strongly correlated electronic system in the presence of a time-dependent hopping field, deriving a generalized Bethe-Salpeter equation that is valid also out of equilibrium. Focusing on the single-orbital Hubbard model within the time-dependent Hartree-Fock approximation, we solve the equation in the nonequilibrium adiabatic regime, obtaining a closed expression for the transverse magnetic susceptibility. From this, we provide a rigorous definition of nonequilibrium (time-dependent) magnon frequencies and exchange parameters, expressed in terms of nonequilibrium single-electron Green's functions and self-energies. In the particular case of equilibrium, we recover previously known results.
Nonequilibrium mesoscopic transport: a genealogy
NASA Astrophysics Data System (ADS)
Das, Mukunda P.; Green, Frederick
2012-05-01
Models of nonequilibrium quantum transport underpin all modern electronic devices, from the largest scales to the smallest. Past simplifications such as coarse graining and bulk self-averaging served well to understand electronic materials. Such particular notions become inapplicable at mesoscopic dimensions, edging towards the truly quantum regime. Nevertheless a unifying thread continues to run through transport physics, animating the design of small-scale electronic technology: microscopic conservation and nonequilibrium dissipation. These fundamentals are inherent in quantum transport and gain even greater and more explicit experimental meaning in the passage to atomic-sized devices. We review their genesis, their theoretical context, and their governing role in the electronic response of meso- and nanoscopic systems.
Computer simulation of nonequilibrium processes
Wallace, D.C.
1985-07-01
The underlying concepts of nonequilibrium statistical mechanics, and of irreversible thermodynamics, will be described. The question at hand is then, how are these concepts to be realize in computer simulations of many-particle systems. The answer will be given for dissipative deformation processes in solids, on three hierarchical levels: heterogeneous plastic flow, dislocation dynamics, an molecular dynamics. Aplication to the shock process will be discussed.
Theory of coherent resonance energy transfer for coherent initial condition.
Jang, Seogjoo
2009-10-28
A theory of coherent resonance energy transfer [Jang et al., J. Chem. Phys. 129, 101104 (2008)] is extended for coherent initial condition. For the situation where the initial excitation is an arbitrary linear combination of donor and acceptor excitations, a second order time local quantum master equation combined with polaron transformation is derived. Inhomogeneous terms in the resulting equation have contributions not only from initial donor and acceptor populations but also from their coherence terms. Numerical tests are performed for general super Ohmic spectral density where the bath degrees of freedom coupled to donor and acceptor can be correlated with each other. Calculation results demonstrate sensitivity of early nonstationary population dynamics on the relative sign of initial donor and acceptor excitation states. It is shown that contribution of inhomogeneous terms is more significant for coherent initial condition than for localized one. The overall model calculations provide details of the interplay between quantum coherence and nonequilibrium/non-Markovian effects in the time dependent donor population dynamics.
Nonequilibrium chemistry boundary layer integral matrix procedure
NASA Technical Reports Server (NTRS)
Tong, H.; Buckingham, A. C.; Morse, H. L.
1973-01-01
The development of an analytic procedure for the calculation of nonequilibrium boundary layer flows over surfaces of arbitrary catalycities is described. An existing equilibrium boundary layer integral matrix code was extended to include nonequilibrium chemistry while retaining all of the general boundary condition features built into the original code. For particular application to the pitch-plane of shuttle type vehicles, an approximate procedure was developed to estimate the nonequilibrium and nonisentropic state at the edge of the boundary layer.
Nonequilibrium volumetric response of shocked polymers
Clements, B E
2009-01-01
Polymers are well known for their non-equilibrium deviatoric behavior. However, investigations involving both high rate shock experiments and equilibrium measured thermodynamic quantities remind us that the volumetric behavior also exhibits a non-equilibrium response. Experiments supporting the notion of a non-equilibrium volumetric behavior will be summarized. Following that discussion, a continuum-level theory is proposed that will account for both the equilibrium and non-equilibrium response. Upon finding agreement with experiment, the theory is used to study the relaxation of a shocked polymer back towards its shocked equilibrium state.
Theoretical description of nonequilibrium behavior in charge density wave systems
NASA Astrophysics Data System (ADS)
Shen, Wen
The fast development of time resolved photoemission (TRPES) techniques allow us to discover the rich features of nonequilibrium phenomena which may not appear in equilibrium. One of the most explored topics is the nonequilibrium behavior of a charge density wave (CDW) material. Being an ordered phase at low temperature, the CDW state provides a fertile ground to study electron-electron and electron-ion interactions. By driving this material out of equilibrium and taking ultrafast time resolution snapshots of its behavior, TRPES helps us understand these interactions and sheds light on the mechanisms behind these and other complex material properties, such as metal-insulator transitions, high temperature superconductivity, and magnetic phenomena. Recent experiments on TRPES in CDW materials show an ultrafast CDW gap closure in systems such as 1T--TaS2 and TbTe3 and the subsequent separation of time scales for the electron-electron interaction and the electron-lattice interaction. But it is still not clear what happens during the ultrashort period (in first 100 femtosecond). In this dissertation, we solve a two band model describing this ultrafast process in a CDW system. By fixing the lattice distortion effect in the CDW, we studied the nonequilibrium excitations of the electrons under a strong electric field. This research is performed by calculating nonequilibrium Green's functions (NGF) along the Kadanoff-Baym-Keldysh contour. We solved this nonequilibrium problem exactly. We show non-perturbative results and explore the nonlinear electronic behavior under an ultrashort light pulses. In addition to the TRPES problem, we also examined the behavior of Bloch oscillations under a large DC field, the response to an AC electric field, high harmonic generation from solids, and the crossover between frequency-driven excitation and amplitude-driven excitation.
Phonon coherence in isotopic silicon superlattices
Frieling, R.; Radek, M.; Eon, S.; Bracht, H.; Wolf, D. E.
2014-09-29
Recent experimental and theoretical investigations have confirmed that a reduction in thermal conductivity of silicon is achieved by isotopic silicon superlattices. In the present study, non-equilibrium molecular dynamics simulations are performed to identify the isotope doping and isotope layer ordering with minimum thermal conductivity. Furthermore, the impact of isotopic intermixing at the superlattice interfaces on phonon transport is investigated. Our results reveal that the coherence of phonons in isotopic Si superlattices is prevented if interfacial mixing of isotopes is considered.
Nonequilibrium transport in superconducting filaments
NASA Technical Reports Server (NTRS)
Arutyunov, K. YU.; Danilova, N. P.; Nikolaeva, A. A.
1995-01-01
The step-like current-voltage characteristics of highly homogeneous single-crystalline tin and indium thin filaments has been measured. The length of the samples L approximately 1 cm was much greater than the nonequilibrium quasiparticle relaxation length Lambda. It was found that the activation of a successive i-th voltage step occurs at current significantly greater than the one derived with the assumption that the phase slip centers are weakly interacting on a scale L much greater than Lambda. The observation of 'subharmonic' fine structure on the voltage-current characteristics of tin filaments confirms the hypothesis of the long-range phase slip centers interaction.
Coherence dynamics in photosynthesis: protein protection of excitonic coherence.
Lee, Hohjai; Cheng, Yuan-Chung; Fleming, Graham R
2007-06-01
The role of quantum coherence in promoting the efficiency of the initial stages of photosynthesis is an open and intriguing question. We performed a two-color photon echo experiment on a bacterial reaction center that enabled direct visualization of the coherence dynamics in the reaction center. The data revealed long-lasting coherence between two electronic states that are formed by mixing of the bacteriopheophytin and accessory bacteriochlorophyll excited states. This coherence can only be explained by strong correlation between the protein-induced fluctuations in the transition energy of neighboring chromophores. Our results suggest that correlated protein environments preserve electronic coherence in photosynthetic complexes and allow the excitation to move coherently in space, enabling highly efficient energy harvesting and trapping in photosynthesis.
Nonequilibrium thermodynamics of dilute polymer solutions in flow
Latinwo, Folarin; Hsiao, Kai-Wen; Schroeder, Charles M.
2014-11-07
Modern materials processing applications and technologies often occur far from equilibrium. To this end, the processing of complex materials such as polymer melts and nanocomposites generally occurs under strong deformations and flows, conditions under which equilibrium thermodynamics does not apply. As a result, the ability to determine the nonequilibrium thermodynamic properties of polymeric materials from measurable quantities such as heat and work is a major challenge in the field. Here, we use work relations to show that nonequilibrium thermodynamic quantities such as free energy and entropy can be determined for dilute polymer solutions in flow. In this way, we determine the thermodynamic properties of DNA molecules in strong flows using a combination of simulations, kinetic theory, and single molecule experiments. We show that it is possible to calculate polymer relaxation timescales purely from polymer stretching dynamics in flow. We further observe a thermodynamic equivalence between nonequilibrium and equilibrium steady-states for polymeric systems. In this way, our results provide an improved understanding of the energetics of flowing polymer solutions.
INTRODUCTION: Nonequilibrium Processes in Plasmas
NASA Astrophysics Data System (ADS)
Petrović, Zoran; Marić, Dragana; Malović, Gordana
2009-07-01
This book aims to give a cross section from a wide range of phenomena that, to different degrees, fall under the heading of non-equilibrium phenomenology. The selection is, of course, biased by the interests of the members of the scientific committee and of the FP6 Project 026328 IPB-CNP Reinforcing Experimental Centre for Non-equilibrium Studies with Application in Nano-technologies, Etching of Integrated Circuits and Environmental Research. Some of the papers included here are texts based on selected lectures presented at the Second International Workshop on Non-equilibrium Processes in Plasmas and Environmental Science. However, this volume is not just the proceedings of that conference as it contains a number of papers from authors that did not attend the conference. The goal was to put together a volume that would cover the interests of the project and support further work. It is published in the Institute of Physics journal Journal of Physics: Conference Series to ensure a wide accessibility of the articles. The texts presented here range from in-depth reviews of the current status and past achievements to progress reports of currently developed experimental devices and recently obtained still unpublished results. All papers have been refereed twice, first when speakers were selected based on their reputation and recently published results, and second after the paper was submitted both by the editorial board and individual assigned referees according to the standards of the conference and of the journal. Nevertheless, we still leave the responsibility (and honours) for the contents of the papers to the authors. The papers in this book are review articles that give a summary of the already published work or present the work in progress that will be published in full at a later date (or both). In the introduction to the first volume, in order to show how far reaching, ubiquitous and important non-equilibrium phenomena are, we claimed that ever since the early
Non-equilibrium phase transitions
Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.
1998-12-31
This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken.
Thermochemical nonequilibrium in atomic hydrogen at elevated temperatures
NASA Technical Reports Server (NTRS)
Scott, R. K.
1972-01-01
A numerical study of the nonequilibrium flow of atomic hydrogen in a cascade arc was performed to obtain insight into the physics of the hydrogen cascade arc. A rigorous mathematical model of the flow problem was formulated, incorporating the important nonequilibrium transport phenomena and atomic processes which occur in atomic hydrogen. Realistic boundary conditions, including consideration of the wall electrostatic sheath phenomenon, were included in the model. The governing equations of the asymptotic region of the cascade arc were obtained by writing conservation of mass and energy equations for the electron subgas, an energy conservation equation for heavy particles and an equation of state. Finite-difference operators for variable grid spacing were applied to the governing equations and the resulting system of strongly coupled, stiff equations were solved numerically by the Newton-Raphson method.
Non-equilibrium Hybridization Expansion Impurity-solver
NASA Astrophysics Data System (ADS)
Dong, Qiaoyuan
2015-03-01
The study of non-equilibrium phenomena in strongly correlated systems has developed into one of the most active and exciting branches of condensed matter physics. Meanwhile, quantum impurity models play a prominent role as mathematical representations of quantum dots, single-molecule devices, and effective models for the dynamical mean field theory. We show results for a generalization of the hybridization expansion diagrammatic Monte Carlo technique for the Anderson impurity model. And we perform non-equilibrium calculations on the full Keldysh contour, where a dynamical sign problem vastly increases the complexity of real-time simulation. By further combining this method with a non-crossing approximation, our ``bold-line'' Monte Carlo can reach substantially longer times out of equilibrium than previously accessible, and provides an accurate description of quench and driven dynamics of correlated systems. Sponsored by the Department of Energy.
Thermodynamics of Stability of Nonequilibrium Steady States.
ERIC Educational Resources Information Center
Rastogi, R. P.; Shabd, Ram
1983-01-01
Presented is a concise and critical account of developments in nonequilibrium thermodynamics. The criterion for stability of nonequilibrium steady states is critically examined for consecutive and monomolecular triangular reactions, autocatalytic reactions, auto-inhibited reactions, and the Lotka-Volterra model. (JN)
Nonequilibrium Dynamics of Ultracold Neutral Plasmas
NASA Astrophysics Data System (ADS)
Pohl, Thomas; Pattard, Thomas; Rost, Jan-Michael
2006-03-01
In a number of recent experiments ultracold plasmas (UNPs) have been produced by photoionizing laser-cooled atomic ensembles [1]. Their very low initial kinetic energies suggest that they are created deeply in the strongly correlated regime. Moreover, UNPs are produced far from equilibrium, leading to a complex relaxation dynamics. We present a hybrid-molecular dynamics approach [2], to describe the long-time plasma evolution while fully taking into account the strongly correlated character of the ionic motion. We demonstrate that the method yields an accurate description of recent measurements [2,3] and allows to address problems beyond present experimental capabilities [3]. It turns out that under the conditions in UNPs the commonly applied Bogoliubov assumption about a hierarchy of relaxation timescale becomes invalid, resulting in an unusual relaxation dynamics connected with a wave-like temperature evolution and an ultimate relaxation to a non-equilibrium undercorrelated state.(1) Y.C. Chen et al., Phys. Rev. Lett. 93, 265003 (2004).(2) T. Pohl, T. Pattard and J.M. Rost, Phys. Rev. A 70, 033416 (2004).(3) T. Pohl, T. Pattard and J.M. Rost, Phys. Rev. Lett. 94, 205003 (2005); Phys. Rev. Lett. 92, 205003 (2004).
Holographic microscopy in low coherence
NASA Astrophysics Data System (ADS)
Chmelík, Radim; Petráček, Jiří; Slabá, Michala; Kollárová, Věra; Slabý, Tomáš; Čolláková, Jana; Komrska, Jiří; Dostál, Zbyněk.; Veselý, Pavel
2016-03-01
Low coherence of the illumination substantially improves the quality of holographic and quantitative phase imaging (QPI) by elimination of the coherence noise and various artefacts and by improving the lateral resolution compared to the coherent holographic microscopy. Attributes of coherence-controlled holographic microscope (CCHM) designed and built as an off-axis holographic system allowing QPI within the range from complete coherent to incoherent illumination confirmed these expected advantages. Low coherence illumination also furnishes the coherence gating which constraints imaging of some spatial frequencies of an object axially thus forming an optical section in the wide sense. In this way the depth discrimination capability of the microscope is introduced at the price of restricting the axial interval of possible numerical refocusing. We describe theoretically these effects for the whole range of illumination coherence. We also show that the axial refocusing constraints can be overcome using advanced mode of imaging based on mutual lateral shift of reference and object image fields in CCHM. Lowering the spatial coherence of illumination means increasing its numerical aperture. We study how this change of the illumination geometry influences 3D objects QPI and especially the interpretation of live cells QPI in terms of the dry mass density measurement. In this way a strong dependence of the imaging process on the light coherence is demonstrated. The theoretical calculations and numerical simulations are supported by experimental data including a chance of time-lapse watching of live cells even in optically turbid milieu.
Strongly magnetized classical plasma models
NASA Technical Reports Server (NTRS)
Montgomery, D.; Peyraud, J.; Dewitt, C.
1974-01-01
Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).
Coherence current, coherence vortex, and the conservation law of coherence.
Wang, Wei; Takeda, Mitsuo
2006-06-01
Introducing scalar and vector densities for a mutual coherence function, we present a new conservation law for optical coherence of scalar wave fields in the form of a continuity equation. This coherence conservation law provides new insights into topological phenomena for the complex coherence function. Some properties related to the newly introduced coherence vector density, such as a circulating coherence current associated with a coherence vortex, are investigated both theoretically and experimentally for the first time.
INTRODUCTION: Nonequilibrium Processes in Plasmas
NASA Astrophysics Data System (ADS)
Petrović, Zoran; Marić, Dragana; Malović, Gordana
2009-07-01
This book aims to give a cross section from a wide range of phenomena that, to different degrees, fall under the heading of non-equilibrium phenomenology. The selection is, of course, biased by the interests of the members of the scientific committee and of the FP6 Project 026328 IPB-CNP Reinforcing Experimental Centre for Non-equilibrium Studies with Application in Nano-technologies, Etching of Integrated Circuits and Environmental Research. Some of the papers included here are texts based on selected lectures presented at the Second International Workshop on Non-equilibrium Processes in Plasmas and Environmental Science. However, this volume is not just the proceedings of that conference as it contains a number of papers from authors that did not attend the conference. The goal was to put together a volume that would cover the interests of the project and support further work. It is published in the Institute of Physics journal Journal of Physics: Conference Series to ensure a wide accessibility of the articles. The texts presented here range from in-depth reviews of the current status and past achievements to progress reports of currently developed experimental devices and recently obtained still unpublished results. All papers have been refereed twice, first when speakers were selected based on their reputation and recently published results, and second after the paper was submitted both by the editorial board and individual assigned referees according to the standards of the conference and of the journal. Nevertheless, we still leave the responsibility (and honours) for the contents of the papers to the authors. The papers in this book are review articles that give a summary of the already published work or present the work in progress that will be published in full at a later date (or both). In the introduction to the first volume, in order to show how far reaching, ubiquitous and important non-equilibrium phenomena are, we claimed that ever since the early
Shapiro step at nonequilibrium conditions
NASA Astrophysics Data System (ADS)
Shukrinov, Yu. M.; Nashaat, M.; Kulikov, K. V.; Dawood, R.; El Samman, H.; El Sherbini, Th. M.
2016-07-01
Detailed numerical simulations of intrinsic Josephson junctions of high-temperature superconductors under external electromagnetic radiation are performed taking into account a charge imbalance effect. We demonstrate that the charge imbalance is responsible for a slope in the Shapiro step in the IV-characteristic. The value of slope increases with a nonequilibrium parameter. Coupling between junctions leads to the distribution of the slope's values along the stack. The nonperiodic boundary conditions shift the Shapiro step from the canonical position determined by Vss=\\hbar f /(2e) , where f is a frequency of external radiation. This fact makes the interpretation of the experimentally found Shapiro step shift by the charge imbalance effect ambiguous.
Nonequilibrium structure in sequential assembly
NASA Astrophysics Data System (ADS)
Popov, Alexander V.; Craven, Galen T.; Hernandez, Rigoberto
2015-11-01
The assembly of monomeric constituents into molecular superstructures through sequential-arrival processes has been simulated and theoretically characterized. When the energetic interactions allow for complete overlap of the particles, the model is equivalent to that of the sequential absorption of soft particles on a surface. In the present work, we consider more general cases by including arbitrary aggregating geometries and varying prescriptions of the connectivity network. The resulting theory accounts for the evolution and final-state configurations through a system of equations governing structural generation. We find that particle geometries differ significantly from those in equilibrium. In particular, variations of structural rigidity and morphology tune particle energetics and result in significant variation in the nonequilibrium distributions of the assembly in comparison to the corresponding equilibrium case.
Nonequilibrium migration in human history.
Wakeley, J
1999-01-01
A nonequilibrium migration model is proposed and applied to genetic data from humans. The model assumes symmetric migration among all possible pairs of demes and that the number of demes is large. With these assumptions it is straightforward to allow for changes in demography, and here a single abrupt change is considered. Under the model this change is identical to a change in the ancestral effective population size and might be caused by changes in deme size, in the number of demes, or in the migration rate. Expressions for the expected numbers of sites segregating at particular frequencies in a multideme sample are derived. A maximum-likelihood analysis of independent polymorphic restriction sites in humans reveals a decrease in effective size. This is consistent with a change in the rates of migration among human subpopulations from ancient low levels to present high ones. PMID:10581291
Nonequilibrium interfaces in colloidal fluids
NASA Astrophysics Data System (ADS)
Bier, Markus; Arnold, Daniel
2013-12-01
The time-dependent structure, interfacial tension, and evaporation of an oversaturated colloid-rich (liquid) phase in contact with an undersaturated colloid-poor (vapor) phase of a colloidal dispersion is investigated theoretically during the early-stage relaxation, where the interface is relaxing towards a local equilibrium state while the bulk phases are still out of equilibrium. Since systems of this type exhibit a clear separation of colloidal and solvent relaxation time scales with typical times of interfacial tension measurements in between, they can be expected to be suitable for analogous experimental studies, too. The major finding is that, irrespective of how much the bulk phases differ from two-phase coexistence, the interfacial structure and the interfacial tension approach those at two-phase coexistence during the early-stage relaxation process. This is a surprising observation since it implies that the relaxation towards global equilibrium of the interface is not following but preceding that of the bulk phases. Scaling forms for the local chemical potential, the flux, and the dissipation rate exhibit qualitatively different leading order contributions depending on whether an equilibrium or a nonequilibrium system is considered. The degree of nonquilibrium between the bulk phases is found to not influence the qualitative relaxation behavior (i.e., the values of power-law exponents), but to determine the quantitative deviation of the observed quantities from their values at two-phase coexistence. Whereas the underlying dynamics differs between colloidal and molecular fluids, the behavior of quantities such as the interfacial tension approaching the equilibrium values during the early-stage relaxation process, during which nonequilibrium conditions of the bulk phases are not changed, can be expected to occur for both types of systems.
Transient Orthogonality Catastrophe in a Time Dependent Nonequilibrium Environment
NASA Astrophysics Data System (ADS)
Schiro, Marco; Mitra, Aditi; 0 Team
2015-03-01
We study the response of a highly-excited time dependent quantum many-body state to a sudden local perturbation, a sort of orthogonality catastrophe problem in a transient non-equilibrium environment. To this extent we consider, as key quantity, the overlap between time dependent wave-functions, that we write in terms of a novel two-time correlator generalizing the standard Loschmidt Echo. We discuss its physical meaning, general properties, and its connection with experimentally measurable quantities probed through non-equilibrium Ramsey interferometry schemes. Then we present explicit calculations for a one dimensional interacting Fermi system brought out of equilibrium by a sudden change of the interaction, and perturbed by the switching on of a local static potential. We show that different scattering processes give rise to remarkably different behaviors at long times, quite opposite from the equilibrium situation. In particular, while the forward scattering contribution retains its power law structure even in the presence of a large non-equilibrium perturbation, with an exponent that is strongly affected by the transient nature of the bath, the backscattering term is a source of non-linearity which generates an exponential decay in time of the Loschmidt Echo, reminiscent of
Transient Orthogonality Catastrophe in a Time-Dependent Nonequilibrium Environment
NASA Astrophysics Data System (ADS)
Schiró, Marco; Mitra, Aditi
2014-06-01
We study the response of a highly excited time-dependent quantum many-body state to a sudden local perturbation, a sort of orthogonality catastrophe problem in a transient nonequilibrium environment. To this extent we consider, as a key quantity, the overlap between time-dependent wave functions, which we write in terms of a novel two-time correlator generalizing the standard Loschmidt echo. We discuss its physical meaning, general properties, and its connection with experimentally measurable quantities probed through nonequilibrium Ramsey interferometry schemes. Then we present explicit calculations for a one-dimensional interacting Fermi system brought out of equilibrium by a sudden change of the interaction, and perturbed by the switching on of a local static potential. We show that different scattering processes give rise to remarkably different behaviors at long times, quite opposite from the equilibrium situation. In particular, while the forward scattering contribution retains its power-law structure even in the presence of a large nonequilibrium perturbation, with an exponent that is strongly affected by the transient nature of the bath, the backscattering term is a source of nonlinearity which generates an exponential decay in time of the Loschmidt Echo, reminiscent of an effective thermal behavior.
Novel mapping in non-equilibrium stochastic processes
NASA Astrophysics Data System (ADS)
Heseltine, James; Kim, Eun-jin
2016-04-01
We investigate the time-evolution of a non-equilibrium system in view of the change in information and provide a novel mapping relation which quantifies the change in information far from equilibrium and the proximity of a non-equilibrium state to the attractor. Specifically, we utilize a nonlinear stochastic model where the stochastic noise plays the role of incoherent regulation of the dynamical variable x and analytically compute the rate of change in information (information velocity) from the time-dependent probability distribution function. From this, we quantify the total change in information in terms of information length { L } and the associated action { J }, where { L } represents the distance that the system travels in the fluctuation-based, statistical metric space parameterized by time. As the initial probability density function’s mean position (μ) is decreased from the final equilibrium value {μ }* (the carrying capacity), { L } and { J } increase monotonically with interesting power-law mapping relations. In comparison, as μ is increased from {μ }*,{ L } and { J } increase slowly until they level off to a constant value. This manifests the proximity of the state to the attractor caused by a strong correlation for large μ through large fluctuations. Our proposed mapping relation provides a new way of understanding the progression of the complexity in non-equilibrium system in view of information change and the structure of underlying attractor.
Photosynthetic light harvesting: excitons and coherence
Fassioli, Francesca; Dinshaw, Rayomond; Arpin, Paul C.; Scholes, Gregory D.
2014-01-01
Photosynthesis begins with light harvesting, where specialized pigment–protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques. PMID:24352671
Photosynthetic light harvesting: excitons and coherence.
Fassioli, Francesca; Dinshaw, Rayomond; Arpin, Paul C; Scholes, Gregory D
2014-03-01
Photosynthesis begins with light harvesting, where specialized pigment-protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.
General nonequilibrium theory of colloid dynamics.
Ramírez-González, Pedro; Medina-Noyola, Magdaleno
2010-12-01
A nonequilibrium extension of Onsager's canonical theory of thermal fluctuations is employed to derive a self-consistent theory for the description of the statistical properties of the instantaneous local concentration profile n(r,t) of a colloidal liquid in terms of the coupled time-evolution equations of its mean value n(r,t) and of the covariance [Formula in text] of its fluctuations δn(r,t)=n(r,t)-n(r,t). These two coarse-grained equations involve a local mobility function b(r,t) which, in its turn, is written in terms of the memory function of the two-time correlation function [Formula in text]. For given effective interactions between colloidal particles and applied external fields, the resulting self-consistent theory is aimed at describing the evolution of a strongly correlated colloidal liquid from an initial state with arbitrary mean and covariance n(0)(r) and σ(0)(r,r') toward its equilibrium state characterized by the equilibrium local concentration profile n(eq)(r) and equilibrium covariance σ(eq)(r,r'). This theory also provides a general theoretical framework to describe irreversible processes associated with dynamic arrest transitions, such as aging, and the effects of spatial heterogeneities.
Xu, Liufang; Shi, Hualin; Feng, Haidong; Wang, Jin
2012-04-28
The global stability of dynamical systems and networks is still challenging to study. We developed a landscape and flux framework to explore the global stability. The potential landscape is directly linked to the steady state probability distribution of the non-equilibrium dynamical systems which can be used to study the global stability. The steady state probability flux together with the landscape gradient determines the dynamics of the system. The non-zero probability flux implies the breaking down of the detailed balance which is a quantitative signature of the systems being in non-equilibrium states. We investigated the dynamics of several systems from monostability to limit cycle and explored the microscopic origin of the probability flux. We discovered that the origin of the probability flux is due to the non-equilibrium conditions on the concentrations resulting energy input acting like non-equilibrium pump or battery to the system. Another interesting behavior we uncovered is that the probabilistic flux is closely related to the steady state deterministic chemical flux. For the monostable model of the kinetic cycle, the analytical expression of the probabilistic flux is directly related to the deterministic flux, and the later is directly generated by the chemical potential difference from the adenosine triphosphate (ATP) hydrolysis. For the limit cycle of the reversible Schnakenberg model, we also show that the probabilistic flux is correlated to the chemical driving force, as well as the deterministic effective flux. Furthermore, we study the phase coherence of the stochastic oscillation against the energy pump, and argue that larger non-equilibrium pump results faster flux and higher coherence. This leads to higher robustness of the biological oscillations. We also uncovered how fluctuations influence the coherence of the oscillations in two steps: (1) The mild fluctuations influence the coherence of the system mainly through the probability flux while
Spence, W.L.
1987-11-01
The radiation coherently emitted by a high energy bunched beam suffering an arbitrarily large disruption in a collision with an idealized undisrupted beam is calculated. The near-luminal velocity of the beam - such that the emitted radiation moves very slowly with respect to the bunch - implies that only a small part of the bunch radiates coherently and necessitates a careful treatment of the disrupted beam phase space during emission. The angular distribution and spectral density are presented. It is found that most of the radiation is at wave lengths greater than or equal to the bunch length and that the total energy lost by the beam due to coherent effects should be negligible in high energy-high luminosity linear colliders. 4 refs.
Nonequilibrium molecular dynamics: The first 25 years
Hoover, W.G. |
1992-08-01
Equilibrium Molecular Dynamics has been generalized to simulate Nonequilibrium systems by adding sources of thermodynamic heat and work. This generalization incorporates microscopic mechanical definitions of macroscopic thermodynamic and hydrodynamic variables, such as temperature and stress, and augments atomistic forces with special boundary, constraint, and driving forces capable of doing work on, and exchanging heat with, an otherwise Newtonian system. The underlying Lyapunov instability of these nonequilibrium equations of motion links microscopic time-reversible deterministic trajectories to macroscopic time-irreversible hydrodynamic behavior as described by the Second Law of Thermodynamics. Green-Kubo linear-response theory has been checked. Nonlinear plastic deformation, intense heat conduction, shockwave propagation, and nonequilibrium phase transformation have all been simulated. The nonequilibrium techniques, coupled with qualitative improvements in parallel computer hardware, are enabling simulations to approximate real-world microscale and nanoscale experiments.
Nonequilibrium quantum dissipation in spin-fermion systems
NASA Astrophysics Data System (ADS)
Segal, Dvira; Reichman, David R.; Millis, Andrew J.
2007-11-01
Dissipative processes in nonequilibrium many-body systems are fundamentally different than their equilibrium counterparts. Such processes are of great importance for the understanding of relaxation in single-molecule devices. As a detailed case study, we investigate here a generic spin-fermion model, where a two-level system couples to two metallic leads with different chemical potentials. We present results for the spin relaxation rate in the nonadiabatic limit for an arbitrary coupling to the leads using both analytical and exact numerical methods. The nonequilibrium dynamics is reflected by an exponential relaxation at long times and via complex phase shifts, leading in some cases to an “antiorthogonality” effect. In the limit of strong system-lead coupling at zero temperature we demonstrate the onset of a Marcus-like Gaussian decay with voltage difference activation. This is analogous to the equilibrium spin-boson model, where at strong coupling and high temperatures, the spin excitation rate manifests temperature activated Gaussian behavior. We find that there is no simple linear relationship between the role of the temperature in the bosonic system and a voltage drop in a nonequilibrium electronic case. The two models also differ by the orthogonality-catastrophe factor existing in a fermionic system, which modifies the resulting line shapes. Implications for current characteristics are discussed. We demonstrate the violation of pairwise Coulomb gas behavior for strong coupling to the leads. The results presented in this paper form the basis of an exact, nonperturbative description of steady-state quantum dissipative systems.
Low-temperature thermodynamics with quantum coherence
Narasimhachar, Varun; Gour, Gilad
2015-01-01
Thermal operations are an operational model of non-equilibrium quantum thermodynamics. In the absence of coherence between energy levels, exact state transition conditions under thermal operations are known in terms of a mathematical relation called thermo-majorization. But incorporating coherence has turned out to be challenging, even under the relatively tractable model wherein all Gibbs state-preserving quantum channels are included. Here we find a mathematical generalization of thermal operations at low temperatures, ‘cooling maps', for which we derive the necessary and sufficient state transition condition. Cooling maps that saturate recently discovered bounds on coherence transfer are realizable as thermal operations, motivating us to conjecture that all cooling maps are thermal operations. Cooling maps, though a less-conservative generalization to thermal operations, are more tractable than Gibbs-preserving operations, suggesting that cooling map-like models at general temperatures could be of use in gaining insight about thermal operations. PMID:26138621
The nonequilibrium thermodynamics of small systems
NASA Astrophysics Data System (ADS)
Ritort, Felix
2007-03-01
Nonequilibrium behavior is widespread and rich in nature. Yet our understanding of the fundamental principles underlying nonequilibrium behavior is still poor as shown by the fact that non-equilibrium theories tend to be ad-hoc and specific (1). Recently there has been a lot of interest in applying single-molecule techniques to scrutinize nonequilibrium theories (2). The use of new micromanipulation tools in the exploration of the behavior of tiny objects (such as biomolecules and motors) embedded in a thermal environment opens the possibility to investigate how these systems exchange energy with their environment. The study of such questions, nowadays referred to as ``Nonequilibrium thermodynamics of small systems,'' is becoming quite popular among statistical physicists who recognize there new aspects of thermodynamics where large Brownian fluctuations are of pivotal importance as compared to fluctuations in macroscopic (or large) systems (3). Nonequilibrium small systems are characterized by large deviations in work/heat distributions that satisfy some relations called fluctuation theorems. In this talk I will discuss single-molecule experiments where some of these fluctuation theorems have been tested (4). REFERENCES: (1) F. Ritort, Nonequilibrium fluctuations in small sytems: From physics to biology, To be published in Advances in Chemical Physics, volume 137; (2) F. Ritort, Single molecule experiments in biological physics: methods and applications, Journal of Physics C (Condensed Matter),18 (2006) R531-R583; (3) C. Bustamante, J. Liphardt and F. Ritort, The nonequilibrium thermodynamics of small systems, Physics Today,58 (2005) 43-48; (4) D. Collin, F. Ritort, C. Jarzynski, S. B. Smith, I. Tinoco Jr and C. Bustamante, Verification of the Crooks fluctuation theorem and recovery of RNA folding free energies, Nature, 437 (2005) 231-234.
Non-equilibrium Aspects of Quantum Integrable Systems
NASA Astrophysics Data System (ADS)
Andrei, Natan
The study of non-equilibrium dynamics of interacting many body systems is currently one of the main challenges of modern condensed matter physics, driven by the spectacular progress in the ability to create experimental systems - trapped cold atomic gases are a prime example - that can be isolated from their environment and be highly controlled. Many old and new questions can be addressed: thermalization of isolated systems, nonequilibrium steady states, the interplay between non equilibrium currents and strong correlations, quantum phase transitions in time, universality among others. In this talk I will describe nonequilibrium quench dynamics in integrable quantum systems. I'll discuss the time evolution of the Lieb-Liniger system, a gas of interacting bosons moving on the continuous infinite line and interacting via a short range potential. Considering a finite number of bosons on the line we find that for any value of repulsive coupling the system asymptotes towards a strongly repulsive gas for any initial state, while for an attractive coupling, the system forms a maximal bound state that dominates at longer times. In the thermodynamic limit -with the number of bosons and the system size sent to infinity at a constant density and the long time limit taken subsequently- I'll show that the density and density-density correlation functions for strong but finite positive coupling are described by GGE for translationally invariant initial states with short range correlations. As examples I'll discuss quenches from a Mott insulator initial state or a Newton's Cradle. Then I will show that if the initial state is strongly non translational invariant, e.g. a domain wall configuration, the system does not equilibrate but evolves into a nonequilibrium steady state (NESS). A related NESS arises when the quench consists of coupling a quantum dot to two leads held at different chemical potential, leading in the long time limit to a steady state current. Time permitting I
Measurement of spin coherence using Raman scattering
NASA Astrophysics Data System (ADS)
Sun, Z.; Delteil, A.; Faelt, S.; Imamoǧlu, A.
2016-06-01
Ramsey interferometry provides a natural way to determine the coherence time of most qubit systems. Recent experiments on quantum dots, however, demonstrated that dynamical nuclear spin polarization can strongly influence the measurement process, making it difficult to extract the T2* coherence time using standard optical Ramsey pulses. Here, we demonstrate an alternative method for spin coherence measurement that is based on first-order coherence of photons generated in spin-flip Raman scattering. We show that if a quantum emitter is driven by a weak monochromatic laser, Raman coherence is determined exclusively by spin coherence, allowing for a direct determination of spin T2* time. When combined with coherence measurements on Rayleigh scattered photons, our technique enables us to identify coherent and incoherent contributions to resonance fluorescence, and to minimize the latter. We verify the validity of our technique by comparing our results to those determined from Ramsey interferometry for electron and heavy-hole spins.
Matveev, O. P.; Shvaika, A. M.; Devereaux, T. P.; Freericks, J. K.
2015-12-08
Nonequilibrium dynamical mean-field theory (DMFT) is developed for the case of the charge-density-wave ordered phase. We consider the spinless Falicov-Kimball model which can be solved exactly. This strongly correlated system is then placed in an uniform external dc electric field. We present a complete derivation for nonequilibrium dynamical mean-field theory Green’s functions defined on the Keldysh-Schwinger time contour. We also discuss numerical issues involved in solving the coupled equations.
Coherent amplified optical coherence tomography
NASA Astrophysics Data System (ADS)
Zhang, Jun; Rao, Bin; Chen, Zhongping
2007-07-01
A technique to improve the signal-to-noise ratio (SNR) of a high speed 1300 nm swept source optical coherence tomography (SSOCT) system was demonstrated. A semiconductor optical amplifier (SOA) was employed in the sample arm to coherently amplify the weak light back-scattered from sample tissue without increasing laser power illuminated on the sample. The image quality improvement was visualized and quantified by imaging the anterior segment of a rabbit eye at imaging speed of 20,000 A-lines per second. The theory analysis of SNR gain is given followed by the discussion on the technologies that can further improve the SNR gain.
Theory of chemical kinetics and charge transfer based on nonequilibrium thermodynamics.
Bazant, Martin Z
2013-05-21
the past 7 years, which is capable of answering these questions. The reaction rate is a nonlinear function of the thermodynamic driving force, the free energy of reaction, expressed in terms of variational chemical potentials. The theory unifies and extends the Cahn-Hilliard and Allen-Cahn equations through a master equation for nonequilibrium chemical thermodynamics. For electrochemistry, I have also generalized both Marcus and Butler-Volmer kinetics for concentrated solutions and ionic solids. This new theory provides a quantitative description of LFP phase behavior. Concentration gradients and elastic coherency strain enhance the intercalation rate. At low currents, the charge-transfer rate is focused on exposed phase boundaries, which propagate as "intercalation waves", nucleated by surface wetting. Unexpectedly, homogeneous reactions are favored above a critical current and below a critical size, which helps to explain the rate capability of LFP nanoparticles. Contrary to other mechanisms, elevated temperatures and currents may enhance battery performance and lifetime by suppressing phase separation. The theory has also been extended to porous electrodes and could be used for battery engineering with multiphase active materials. More broadly, the theory describes nonequilibrium chemical systems at mesoscopic length and time scales, beyond the reach of molecular simulations and bulk continuum models. The reaction rate is consistently defined for inhomogeneous, nonequilibrium states, for example, with phase separation, large electric fields, or mechanical stresses. This research is also potentially applicable to fluid extraction from nanoporous solids, pattern formation in electrophoretic deposition, and electrochemical dynamics in biological cells. PMID:23520980
Theory of chemical kinetics and charge transfer based on nonequilibrium thermodynamics.
Bazant, Martin Z
2013-05-21
the past 7 years, which is capable of answering these questions. The reaction rate is a nonlinear function of the thermodynamic driving force, the free energy of reaction, expressed in terms of variational chemical potentials. The theory unifies and extends the Cahn-Hilliard and Allen-Cahn equations through a master equation for nonequilibrium chemical thermodynamics. For electrochemistry, I have also generalized both Marcus and Butler-Volmer kinetics for concentrated solutions and ionic solids. This new theory provides a quantitative description of LFP phase behavior. Concentration gradients and elastic coherency strain enhance the intercalation rate. At low currents, the charge-transfer rate is focused on exposed phase boundaries, which propagate as "intercalation waves", nucleated by surface wetting. Unexpectedly, homogeneous reactions are favored above a critical current and below a critical size, which helps to explain the rate capability of LFP nanoparticles. Contrary to other mechanisms, elevated temperatures and currents may enhance battery performance and lifetime by suppressing phase separation. The theory has also been extended to porous electrodes and could be used for battery engineering with multiphase active materials. More broadly, the theory describes nonequilibrium chemical systems at mesoscopic length and time scales, beyond the reach of molecular simulations and bulk continuum models. The reaction rate is consistently defined for inhomogeneous, nonequilibrium states, for example, with phase separation, large electric fields, or mechanical stresses. This research is also potentially applicable to fluid extraction from nanoporous solids, pattern formation in electrophoretic deposition, and electrochemical dynamics in biological cells.
Quench Dynamics and Nonequilibrium Phase Diagram of the Bose-Hubbard Model
Kollath, Corinna; Laeuchli, Andreas M.; Altman, Ehud
2007-05-04
We investigate the time evolution of correlations in the Bose-Hubbard model following a quench from the superfluid to the Mott insulator. For large values of the final interaction strength the system approaches a distinctly nonequilibrium steady state that bears strong memory of the initial conditions. In contrast, when the final interaction strength is comparable to the hopping, the correlations are rather well approximated by those at thermal equilibrium. The existence of two distinct nonequilibrium regimes is surprising given the nonintegrability of the Bose-Hubbard model. We relate this phenomenon to the role of quasiparticle interactions in the Mott insulator.
Coherence in Turbulence: New Perspective
NASA Astrophysics Data System (ADS)
Levich, Eugene
2009-07-01
It is claimed that turbulence in fluids is inherently coherent phenomenon. The coherence shows up clearly as strongly correlated helicity fluctuations of opposite sign. The helicity fluctuations have cellular structure forming clusters that are actually observed as vorticity bands and coherent structures in laboratory turbulence, direct numerical simulations and most obviously in atmospheric turbulence. The clusters are named BCC - Beltrami Cellular Clusters - because of the observed nearly total alignment of the velocity and vorticity fields in each particular cell, and hence nearly maximal possible helicity in each cell; although when averaged over all the cells the residual mean helicity in general is small and does not play active dynamical role. The Beltrami like fluctuations are short-lived and stabilize only in small and generally contiguous sub-domains that are tending to a (multi)fractal in the asymptotic limit of large Reynolds numbers, Re → ∞. For the model of homogeneous isotropic turbulence the theory predicts the leading fractal dimension of BCC to be: DF = 2.5. This particular BCC is responsible for generating the Kolmogorov -5/3 power law energy spectrum. The most obvious role that BCC play dynamically is that the nonlinear interactions in them are relatively reduced, due to strong spatial alignment between the velocity field v(r, t) and the vorticity field ω(r, t) = curlv(r, t), while the physical quantities typically best characterizing turbulence intermittency, such as entrophy, vorticity stretching and generation, and energy dissipation are maximized in and near them. The theory quantitatively relates the reduction of nonlinear inter-actions to the BCC fractal dimension DF and subsequent turbulence intermittency. It is further asserted that BCC is a fundamental feature of all turbulent flows, e.g., wall bounded turbulent flows, atmospheric and oceanic flows, and their leading fractal dimension remains invariant and universal in these flows
Equilibrium sampling by reweighting nonequilibrium simulation trajectories.
Yang, Cheng; Wan, Biao; Xu, Shun; Wang, Yanting; Zhou, Xin
2016-03-01
Based on equilibrium molecular simulations, it is usually difficult to efficiently visit the whole conformational space of complex systems, which are separated into some metastable regions by high free energy barriers. Nonequilibrium simulations could enhance transitions among these metastable regions and then be applied to sample equilibrium distributions in complex systems, since the associated nonequilibrium effects can be removed by employing the Jarzynski equality (JE). Here we present such a systematical method, named reweighted nonequilibrium ensemble dynamics (RNED), to efficiently sample equilibrium conformations. The RNED is a combination of the JE and our previous reweighted ensemble dynamics (RED) method. The original JE reproduces equilibrium from lots of nonequilibrium trajectories but requires that the initial distribution of these trajectories is equilibrium. The RED reweights many equilibrium trajectories from an arbitrary initial distribution to get the equilibrium distribution, whereas the RNED has both advantages of the two methods, reproducing equilibrium from lots of nonequilibrium simulation trajectories with an arbitrary initial conformational distribution. We illustrated the application of the RNED in a toy model and in a Lennard-Jones fluid to detect its liquid-solid phase coexistence. The results indicate that the RNED sufficiently extends the application of both the original JE and the RED in equilibrium sampling of complex systems. PMID:27078486
Equilibrium sampling by reweighting nonequilibrium simulation trajectories.
Yang, Cheng; Wan, Biao; Xu, Shun; Wang, Yanting; Zhou, Xin
2016-03-01
Based on equilibrium molecular simulations, it is usually difficult to efficiently visit the whole conformational space of complex systems, which are separated into some metastable regions by high free energy barriers. Nonequilibrium simulations could enhance transitions among these metastable regions and then be applied to sample equilibrium distributions in complex systems, since the associated nonequilibrium effects can be removed by employing the Jarzynski equality (JE). Here we present such a systematical method, named reweighted nonequilibrium ensemble dynamics (RNED), to efficiently sample equilibrium conformations. The RNED is a combination of the JE and our previous reweighted ensemble dynamics (RED) method. The original JE reproduces equilibrium from lots of nonequilibrium trajectories but requires that the initial distribution of these trajectories is equilibrium. The RED reweights many equilibrium trajectories from an arbitrary initial distribution to get the equilibrium distribution, whereas the RNED has both advantages of the two methods, reproducing equilibrium from lots of nonequilibrium simulation trajectories with an arbitrary initial conformational distribution. We illustrated the application of the RNED in a toy model and in a Lennard-Jones fluid to detect its liquid-solid phase coexistence. The results indicate that the RNED sufficiently extends the application of both the original JE and the RED in equilibrium sampling of complex systems.
Equilibrium sampling by reweighting nonequilibrium simulation trajectories
NASA Astrophysics Data System (ADS)
Yang, Cheng; Wan, Biao; Xu, Shun; Wang, Yanting; Zhou, Xin
2016-03-01
Based on equilibrium molecular simulations, it is usually difficult to efficiently visit the whole conformational space of complex systems, which are separated into some metastable regions by high free energy barriers. Nonequilibrium simulations could enhance transitions among these metastable regions and then be applied to sample equilibrium distributions in complex systems, since the associated nonequilibrium effects can be removed by employing the Jarzynski equality (JE). Here we present such a systematical method, named reweighted nonequilibrium ensemble dynamics (RNED), to efficiently sample equilibrium conformations. The RNED is a combination of the JE and our previous reweighted ensemble dynamics (RED) method. The original JE reproduces equilibrium from lots of nonequilibrium trajectories but requires that the initial distribution of these trajectories is equilibrium. The RED reweights many equilibrium trajectories from an arbitrary initial distribution to get the equilibrium distribution, whereas the RNED has both advantages of the two methods, reproducing equilibrium from lots of nonequilibrium simulation trajectories with an arbitrary initial conformational distribution. We illustrated the application of the RNED in a toy model and in a Lennard-Jones fluid to detect its liquid-solid phase coexistence. The results indicate that the RNED sufficiently extends the application of both the original JE and the RED in equilibrium sampling of complex systems.
Electron and phonon drag in thermoelectric transport through coherent molecular conductors
NASA Astrophysics Data System (ADS)
Lü, Jing-Tao; Wang, Jian-Sheng; Hedegârd, Per; Brandbyge, Mads
2016-05-01
We study thermoelectric transport through a coherent molecular conductor connected to two electron and two phonon baths using the nonequilibrium Green's function method. We focus on the mutual drag between electron and phonon transport as a result of `momentum' transfer, which happens only when there are at least two phonon degrees of freedom. After deriving expressions for the linear drag coefficients, obeying the Onsager relation, we further investigate their effect on nonequilibrium transport. We show that the drag effect is closely related to two other phenomena: (1) adiabatic charge pumping through a coherent conductor; (2) the current-induced nonconservative and effective magnetic forces on phonons.
NASA Astrophysics Data System (ADS)
Bogatskaya, A. V.; Bin, Hou; Popov, A. M.; Smetanin, I. V.
2016-09-01
We developed the analytical model of relaxation of a low-density plasma channel produced in noble gases (Xe, Ar) by a femtosecond KrF laser pulse and investigated the temporal evolution of its dielectric permittivity. It was demonstrated that the strong nonequilibrium of the photoelectron energy spectrum and the presence of Ramsauer minimum in transport scattering cross section make such a plasma channel an optically denser medium in comparison with non-ionized gas in the microwave frequency band and consequently such a channel appears to be a waveguide. In xenon this nonequilibrium state of a plasma leads to both transportation and amplification of the microwave signal during the relaxation of the photoelectron energy spectrum. It was also shown that a circular metal waveguide partially filled with such a nonequilibrium Xe plasma provides efficient amplification of the sub-THz microwave signal.
de Oliveira, M M; da Luz, M G E; Fiore, C E
2015-12-01
Based on quasistationary distribution ideas, a general finite size scaling theory is proposed for discontinuous nonequilibrium phase transitions into absorbing states. Analogously to the equilibrium case, we show that quantities such as response functions, cumulants, and equal area probability distributions all scale with the volume, thus allowing proper estimates for the thermodynamic limit. To illustrate these results, five very distinct lattice models displaying nonequilibrium transitions-to single and infinitely many absorbing states-are investigated. The innate difficulties in analyzing absorbing phase transitions are circumvented through quasistationary simulation methods. Our findings (allied to numerical studies in the literature) strongly point to a unifying discontinuous phase transition scaling behavior for equilibrium and this important class of nonequilibrium systems. PMID:26764651
On the structure, stress fields and energy of nonequilibrium grain boundaries
Nazarov, A.A.; Valiev, R.Z. . Inst. for Metals Superplasticity Problems); Romanov, A.E. . A.F. Ioffe Physico-Technical Inst.)
1993-04-01
The changes of grain boundary (GB) structure caused by the absorption of lattice dislocations are analyzed. The typical result of the absorption is the disordering of networks of disclination dipoles/grain boundary dislocations (GBDs). It is shown that the variance of GBD spacings is a good quantitative measure of the degree of GB structure nonequilibrium. By the use of Monte Carlo technique the abating law of x[sup [minus]1/2] for long range stress fields of disordered GBD networks is obtained. Excess energies of nonequilibrium boundaries are also calculated. In strongly exited state of GBs characterized by the maximum value of the variance of GBD spacings the excess energy can exceed the equilibrium GB energy. Such high-nonequilibrium boundaries can exist in ultrafine grained materials.
Nonequilibrium dynamical mean-field theory: an auxiliary quantum master equation approach.
Arrigoni, Enrico; Knap, Michael; von der Linden, Wolfgang
2013-02-22
We introduce a versatile method to compute electronic steady-state properties of strongly correlated extended quantum systems out of equilibrium. The approach is based on dynamical mean-field theory (DMFT), in which the original system is mapped onto an auxiliary nonequilibrium impurity problem imbedded in a Markovian environment. The steady-state Green's function of the auxiliary system is solved by full diagonalization of the corresponding Lindblad equation. The approach can be regarded as the nontrivial extension of the exact-diagonalization-based DMFT to the nonequilibrium case. As a first application, we consider an interacting Hubbard layer attached to two metallic leads and present results for the steady-state current and the nonequilibrium density of states.
NASA Astrophysics Data System (ADS)
Shen, Tongye; Wolynes, Peter G.
2005-10-01
The cytoskeleton is not an equilibrium structure. To develop theoretical tools to investigate such nonequilibrium assemblies, we study a statistical physical model of motorized spherical particles. Though simple, it captures some of the key nonequilibrium features of the cytoskeletal networks. Variational solutions of the many-body master equation for a set of motorized particles accounts for their thermally induced Brownian motion as well as for the motorized kicking of the structural elements. These approximations yield stability limits for crystalline phases and for frozen amorphous structures. The methods allow one to compute the effects of nonequilibrium behavior and adhesion (effective cross-linking) on the mechanical stability of localized phases as a function of density, adhesion strength, and temperature. We find that nonequilibrium noise does not necessarily destabilize mechanically organized structures. The nonequilibrium forces strongly modulate the phase behavior and have comparable effect as the adhesion due to cross-linking. Modeling transitions such as these allows the mechanical properties of cytoskeleton to rapidly and adaptively change. The present model provides a statistical mechanical underpinning for a tensegrity picture of the cytoskeleton.
Non-equilibrium Helium Ionization in an MHD Simulation of the Solar Atmosphere
NASA Astrophysics Data System (ADS)
Golding, Thomas Peter; Leenaarts, Jorrit; Carlsson, Mats
2016-02-01
The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only included non-equilibrium hydrogen ionization by performing a 2D radiation-magnetohydrodynamics simulation featuring non-equilibrium ionization of both hydrogen and helium. The simulation includes the effect of hydrogen Lyα and the EUV radiation from the corona on the ionization and heating of the atmosphere. Details on code implementation are given. We obtain helium ion fractions that are far from their equilibrium values. Comparison with models with local thermodynamic equilibrium (LTE) ionization shows that non-equilibrium helium ionization leads to higher temperatures in wavefronts and lower temperatures in the gas between shocks. Assuming LTE ionization results in a thermostat-like behavior with matter accumulating around the temperatures where the LTE ionization fractions change rapidly. Comparison of DEM curves computed from our models shows that non-equilibrium ionization leads to more radiating material in the temperature range 11-18 kK, compared to models with LTE helium ionization. We conclude that non-equilibrium helium ionization is important for the dynamics and thermal structure of the upper chromosphere and transition region. It might also help resolve the problem that intensities of chromospheric lines computed from current models are smaller than those observed.
Effects of Nonequilibrium at Edge of Boundary Layer on Convective Heat Transfer to a Blunt Body
NASA Technical Reports Server (NTRS)
Goekcen, Tahir; Edwards, Thomas A. (Technical Monitor)
1996-01-01
This investigation is a continuation of a previous study on nonequilibrium convective heat transfer to a blunt body. In the previous study, for relatively high Reynolds number flows, it was found that: nonequilibrium convective heat transfer to a blunt body is not strongly dependent on freestream parameters, provided that the thermochemical equilibrium is reached at the edge of boundary layer; and successful testing of convective heat transfer in an arc-jet environment is possible by duplicating the surface pressure and total enthalpy. The nonequilibrium convective heat transfer computations are validated against the results of Fay and Riddell/Goulard theory. Present work investigates low Reynolds number conditions which are typical in an actual arc-jet flow environment. One expects that there will be departures from the Fay and Riddell/Goulard result since certain assumptions of the classical theory are not satisfied. These departures are of interest because the Fay and Riddell/Goulard formulas are extensively used in arc-jet testing (e.g., to determine the enthalpy of the flow and the catalytic efficiency of heat shield materials). For practical sizes of test materials, density of the test flow (and Reynolds number) in an arc-jet is such that thermochemical equilibrium may not be reached at the edge of boundary layer. For blunt body flows of nitrogen and air, computations will be presented to show the effects of thermochemical nonequilibrium at the boundary layer edge on nonequilibrium heat transfer.
Thermal response of nonequilibrium R C circuits
NASA Astrophysics Data System (ADS)
Baiesi, Marco; Ciliberto, Sergio; Falasco, Gianmaria; Yolcu, Cem
2016-08-01
We analyze experimental data obtained from an electrical circuit having components at different temperatures, showing how to predict its response to temperature variations. This illustrates in detail how to utilize a recent linear response theory for nonequilibrium overdamped stochastic systems. To validate these results, we introduce a reweighting procedure that mimics the actual realization of the perturbation and allows extracting the susceptibility of the system from steady-state data. This procedure is closely related to other fluctuation-response relations based on the knowledge of the steady-state probability distribution. As an example, we show that the nonequilibrium heat capacity in general does not correspond to the correlation between the energy of the system and the heat flowing into it. Rather, also nondissipative aspects are relevant in the nonequilibrium fluctuation-response relations.
Thermal response of nonequilibrium RC circuits.
Baiesi, Marco; Ciliberto, Sergio; Falasco, Gianmaria; Yolcu, Cem
2016-08-01
We analyze experimental data obtained from an electrical circuit having components at different temperatures, showing how to predict its response to temperature variations. This illustrates in detail how to utilize a recent linear response theory for nonequilibrium overdamped stochastic systems. To validate these results, we introduce a reweighting procedure that mimics the actual realization of the perturbation and allows extracting the susceptibility of the system from steady-state data. This procedure is closely related to other fluctuation-response relations based on the knowledge of the steady-state probability distribution. As an example, we show that the nonequilibrium heat capacity in general does not correspond to the correlation between the energy of the system and the heat flowing into it. Rather, also nondissipative aspects are relevant in the nonequilibrium fluctuation-response relations. PMID:27627283
Nonequilibrium combustion effects in supersonic streams
NASA Technical Reports Server (NTRS)
Jensen, R. M.; Bryce, C. A.; Reese, B. A.
1972-01-01
This research program is a theoretical and experimental investigation of the effect of nonequilibrium conditions upon the performance of combustors employing supersonic flows. Calculations and experiments are made regarding the effects on the ignition of hydrogen of the nonequilibrium species (free radicals, atoms, water vapor, etc.) obtained using vitiated air. Results of this investigation show that the nonequilibrium free-radical content from a supersonic vitiated air source will cause early ignition of the hydrogen. An analysis of heated air expended from a high temperature source to test section conditions also indicates that there is sufficient free radical content in the incoming flow to cause early ignition. Water vapor, an inherent contaminant in the generation of vitiated air, was found to reduce the ignition delay period under the experimental conditions considered.
Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator
NASA Technical Reports Server (NTRS)
Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir
2012-01-01
In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.
Exploring the nonequilibrium dynamics of ultracold quantum gases by using numerical tools
NASA Astrophysics Data System (ADS)
Heidrich-Meisner, Fabian
Numerical tools such as exact diagonalization or the density matrix renormalization group method have been vital for the study of the nonequilibrium dynamics of strongly correlated many-body systems. Moreover, they provided unique insight for the interpretation of quantum gas experiments, whenever a direct comparison with theory is possible. By considering the example of the experiment by Ronzheimer et al., in which both an interaction quench and the release of bosons from a trap into an empty optical lattice (sudden expansion) was realized, I discuss several nonequilibrium effects of strongly interacting quantum gases. These include the thermalization of a closed quantum system and its connection to the eigenstate thermalization hypothesis, nonequilibrium mass transport, dynamical fermionization, and transient phenomena such as quantum distillation or dynamical quasicondensation. I highlight the role of integrability in giving rise to ballistic transport in strongly interacting 1D systems and in determining the asymptotic state after a quantum quench. The talk concludes with a perspective on open questions concerning 2D systems and the numerical simulation of their nonequilibrium dynamics. Supported by Deutsche Forschungsgemeinschaft (DFG) via FOR 801.
Improved molecular collision models for nonequilibrium rarefied gases
NASA Astrophysics Data System (ADS)
Parsons, Neal
The Direct Simulation Monte Carlo (DSMC) method typically used to model thermochemical nonequilibrium rarefied gases requires accurate total collision cross sections, reaction probabilities, and molecular internal energy exchange models. However, the baseline total cross sections are often determined from extrapolations of relatively low-temperature viscosity data, reaction probabilities are defined such that experimentally determined equilibrium reaction rates are replicated, and internal energy relaxation models are phenomenological in nature. Therefore, these models have questionable validity in modeling strongly nonequilibrium gases with temperatures greater than those possible in experimental test facilities. To rectify this deficiency, the Molecular Dynamics/Quasi-Classical Trajectories (MD/QCT) method can be used to accurately compute total collision cross sections, reaction probabilities, and internal energy exchange models based on first principles for hypervelocity collision conditions. In this thesis, MD/QCT-based models were used to improve simulations of two unique nonequilibrium rarefied gas systems: the Ionian atmosphere and hypersonic shocks in Earth's atmosphere. The Jovian plasma torus flows over Io at ≈ 57 km/s, inducing high-speed collisions between atmospheric SO2 and the hypervelocity plasma's O atoms and ions. The DSMC method is well-suited to model the rarefied atmosphere, so MD/QCT studies are therefore conducted to improve DSMC collision models of the critical SO2-O collision pair. The MD/QCT trajectory simulations employed a new potential energy surface that was developed using a ReaxFF fit to a set of ab initio calculations. Compared to the MD/QCT results, the baseline DSMC models are found to significantly under-predict total cross sections, use reaction probabilities that are unrealistically high, and give unphysical internal energies above the dissociation energy for non-reacting inelastic collisions and under-predicts post
Coherent diffractive imaging and partial coherence
NASA Astrophysics Data System (ADS)
Williams, Garth J.; Quiney, Harry M.; Peele, Andrew G.; Nugent, Keith A.
2007-03-01
We formulate coherent diffractive imaging in the framework of partially spatially coherent diffraction. We find that the reconstruction can be critically dependent on the degree of coherence in the illuminating field and that even a small departure from full coherence may invalidate the conventional assumption that a mapping exists between an exit surface wave of finite support and a far field diffraction pattern. We demonstrate that the introduction of sufficient phase curvature in the illumination can overcome the adverse effects of partial coherence.
Nonequilibrium spin polarization induced charge Hall effect
NASA Astrophysics Data System (ADS)
Hou, Dazhi; Qiu, Z.; Iguchi, R.; Sato, K.; Uchida, K.; Bauer, G. W.; Saitoh, Eiji
2015-03-01
The nonequilibrium spin polarization lies at the heart of information processing in spin-based devices. The generation and manipulation of the spin polarization have been realized by various approaches, however, the spin polarization is usually considered to have negligible effect on the electric transport property, especially for systems of high electron concentration like metals (ɛF ~ eV). Here we show that the nonequilibrium spin polarization can cause a novel Hall voltage in a conventional metallic alloy at room temperature, which is due to a new mechanism and closely related to the spin Nernst effect.
Nonequilibrium air radiation (Nequair) program: User's manual
NASA Astrophysics Data System (ADS)
Park, C.
1985-07-01
A supplement to the data relating to the calculation of nonequilibrium radiation in flight regimes of aeroassisted orbital transfer vehicles contains the listings of the computer code NEQAIR (Nonequilibrium Air Radiation), its primary input data, and explanation of the user-supplied input variables. The user-supplied input variables are the thermodynamic variables of air at a given point, i.e., number densities of various chemical species, translational temperatures of heavy particles and electrons, and vibrational temperature. These thermodynamic variables do not necessarily have to be in thermodynamic equilibrium. The code calculates emission and absorption characteristics of air under these given conditions.
Mesoscopic virial equation for nonequilibrium statistical mechanics
NASA Astrophysics Data System (ADS)
Falasco, G.; Baldovin, F.; Kroy, K.; Baiesi, M.
2016-09-01
We derive a class of mesoscopic virial equations governing energy partition between conjugate position and momentum variables of individual degrees of freedom. They are shown to apply to a wide range of nonequilibrium steady states with stochastic (Langevin) and deterministic (Nosé-Hoover) dynamics, and to extend to collective modes for models of heat-conducting lattices. A macroscopic virial theorem ensues upon summation over all degrees of freedom. It allows for the derivation of generalised (nonequilibrium) equations of state that involve average dissipative heat flows besides genuine state variables, as exemplified for inertial Brownian motion with solid friction and overdamped active Brownian particles subject to inhomogeneous pressure.
Fluctuation theorem for partially masked nonequilibrium dynamics.
Shiraishi, Naoto; Sagawa, Takahiro
2015-01-01
We establish a generalization of the fluctuation theorem for partially masked nonequilibrium dynamics. We introduce a partial entropy production with a subset of all possible transitions, and show that the partial entropy production satisfies the integral fluctuation theorem. Our result reveals the fundamental properties of a broad class of autonomous as well as nonautonomous nanomachines. In particular, our result gives a unified fluctuation theorem for both autonomous and nonautonomous Maxwell's demons, where mutual information plays a crucial role. Furthermore, we derive a fluctuation-dissipation theorem that relates nonequilibrium stationary current to two kinds of equilibrium fluctuations. PMID:25679593
Fluctuation theorem for partially masked nonequilibrium dynamics
NASA Astrophysics Data System (ADS)
Shiraishi, Naoto; Sagawa, Takahiro
2015-01-01
We establish a generalization of the fluctuation theorem for partially masked nonequilibrium dynamics. We introduce a partial entropy production with a subset of all possible transitions, and show that the partial entropy production satisfies the integral fluctuation theorem. Our result reveals the fundamental properties of a broad class of autonomous as well as nonautonomous nanomachines. In particular, our result gives a unified fluctuation theorem for both autonomous and nonautonomous Maxwell's demons, where mutual information plays a crucial role. Furthermore, we derive a fluctuation-dissipation theorem that relates nonequilibrium stationary current to two kinds of equilibrium fluctuations.
Nonequilibrium air radiation (Nequair) program: User's manual
NASA Technical Reports Server (NTRS)
Park, C.
1985-01-01
A supplement to the data relating to the calculation of nonequilibrium radiation in flight regimes of aeroassisted orbital transfer vehicles contains the listings of the computer code NEQAIR (Nonequilibrium Air Radiation), its primary input data, and explanation of the user-supplied input variables. The user-supplied input variables are the thermodynamic variables of air at a given point, i.e., number densities of various chemical species, translational temperatures of heavy particles and electrons, and vibrational temperature. These thermodynamic variables do not necessarily have to be in thermodynamic equilibrium. The code calculates emission and absorption characteristics of air under these given conditions.
Nonequilibrium temperature response for stochastic overdamped systems
NASA Astrophysics Data System (ADS)
Falasco, G.; Baiesi, M.
2016-04-01
The thermal response of nonequilibrium systems requires the knowledge of concepts that go beyond entropy production. This is showed for systems obeying overdamped Langevin dynamics, either in steady states or going through a relaxation process. Namely, we derive the linear response to perturbations of the noise intensity, mapping it onto the quadratic response to a constant small force. The latter, displaying divergent terms, is explicitly regularised with a novel path-integral method. The nonequilibrium equivalents of heat capacity and thermal expansion coefficient are two applications of this approach, as we show with numerical examples.
Thermodynamic model of nonequilibrium phase transitions.
Martyushev, L M; Konovalov, M S
2011-07-01
Within the scope of a thermodynamic description using the maximum entropy production principle, transitions from one nonequilibrium (kinetic) regime to another are considered. It is shown that in the case when power-law dependencies of thermodynamic flux on force are similar for two regimes, only a transition accompanied by a positive jump of thermodynamic flux is possible between them. It is found that the difference in powers of the dependencies of thermodynamic fluxes on forces results in a number of interesting nonequilibrium transitions between kinetic regimes, including the reentrant one with a negative jump of thermodynamic flux. PMID:21867119
Karsch, F.; Vogelsang, V.
2009-09-29
We will give here an overview of our theory of the strong interactions, Quantum Chromo Dynamics (QCD) and its properties. We will also briefly review the history of the study of the strong interactions, and the discoveries that ultimately led to the formulation of QCD. The strong force is one of the four known fundamental forces in nature, the others being the electromagnetic, the weak and the gravitational force. The strong force, usually referred to by scientists as the 'strong interaction', is relevant at the subatomic level, where it is responsible for the binding of protons and neutrons to atomic nuclei. To do this, it must overcome the electric repulsion between the protons in an atomic nucleus and be the most powerful force over distances of a few fm (1fm=1 femtometer=1 fermi=10{sup -15}m), the typical size of a nucleus. This property gave the strong force its name.
Strongly interacting ultracold polar molecules
NASA Astrophysics Data System (ADS)
Gadway, Bryce; Yan, Bo
2016-08-01
This paper reviews recent advances in the study of strongly interacting systems of dipolar molecules. Heteronuclear molecules feature large and tunable electric dipole moments, which give rise to long-range and anisotropic dipole-dipole interactions. Ultracold samples of dipolar molecules with long-range interactions offer a unique platform for quantum simulations and the study of correlated many-body physics. We provide an introduction to the physics of dipolar quantum gases, both electric and magnetic, and summarize the multipronged efforts to bring dipolar molecules into the quantum regime. We discuss in detail the recent experimental progress in realizing and studying strongly interacting systems of polar molecules trapped in optical lattices, with particular emphasis on the study of interacting spin systems and non-equilibrium quantum magnetism. Finally, we conclude with a brief discussion of the future prospects for studies of strongly interacting dipolar molecules.
Strongly interacting ultracold polar molecules
NASA Astrophysics Data System (ADS)
Gadway, Bryce; Yan, Bo
2016-08-01
This paper reviews recent advances in the study of strongly interacting systems of dipolar molecules. Heteronuclear molecules feature large and tunable electric dipole moments, which give rise to long-range and anisotropic dipole–dipole interactions. Ultracold samples of dipolar molecules with long-range interactions offer a unique platform for quantum simulations and the study of correlated many-body physics. We provide an introduction to the physics of dipolar quantum gases, both electric and magnetic, and summarize the multipronged efforts to bring dipolar molecules into the quantum regime. We discuss in detail the recent experimental progress in realizing and studying strongly interacting systems of polar molecules trapped in optical lattices, with particular emphasis on the study of interacting spin systems and non-equilibrium quantum magnetism. Finally, we conclude with a brief discussion of the future prospects for studies of strongly interacting dipolar molecules.
Shape characteristics of equilibrium and non-equilibrium fractal clusters.
Mansfield, Marc L; Douglas, Jack F
2013-07-28
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Shape characteristics of equilibrium and non-equilibrium fractal clusters.
Mansfield, Marc L; Douglas, Jack F
2013-07-28
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Shape characteristics of equilibrium and non-equilibrium fractal clusters
NASA Astrophysics Data System (ADS)
Mansfield, Marc L.; Douglas, Jack F.
2013-07-01
It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other
Ergodicity: a historical perspective. Equilibrium and Nonequilibrium
NASA Astrophysics Data System (ADS)
Gallavotti, Giovanni
2016-10-01
A view on the physical meaning of the so called ergodic hypothesis: its role on the foundations of equilibrium statistical mechanics in mid '1800, its interpretations and hints at its relevance for modern nonequilibrium statistical mechanics. Followed by appendices with detailed comments on the original papers.
Axisymmetric reacting gas nonequilibrium performance program
NASA Technical Reports Server (NTRS)
Kliegel, J. R.; Melde, J. E.; Nickerson, G. R.; Quan, V.
1968-01-01
Computer program calculates the inviscid one-dimensional equilibrium, frozen, and nonequilibrium nozzle expansion of propellant exhaust mixtures containing these six elements - carbon, hydrogen, oxygen, nitrogen, fluorine, and chlorine plus either aluminum, beryllium, boron or lithium. This program will perform calculations for contoured and conical nozzles.
Boundary stability under nonequilibrium conditions. Final report
Hackney, S.A.; Lee, J.K.; Plichta, M.R.
1999-08-01
Summaries of research accomplished are given for the following areas: Morphological (Diffusional) Stability; A New Algorithm for Numerical Modeling of Non-equilibrium Materials Behavior; A Unified Treatment of Single and Microcrystalline Film Edge Instabilities; and Validation of the Structure Based Grain Boundary Diffusion/Migration Model.
Ergodicity: a historical perspective. Equilibrium and Nonequilibrium
NASA Astrophysics Data System (ADS)
Gallavotti, Giovanni
2016-09-01
A view on the physical meaning of the so called ergodic hypothesis: its role on the foundations of equilibrium statistical mechanics in mid '1800, its interpretations and hints at its relevance for modern nonequilibrium statistical mechanics. Followed by appendices with detailed comments on the original papers.
Non-equilibrium Thermodynamics of Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Sengupta, Tapan K.; Sengupta, Aditi; Sengupta, Soumyo; Bhole, Ashish; Shruti, K. S.
2016-04-01
Here, the fundamental problem of Rayleigh-Taylor instability (RTI) is studied by direct numerical simulation (DNS), where the two air masses at different temperatures, kept apart initially by a non-conducting horizontal interface in a 2D box, are allowed to mix. Upon removal of the partition, mixing is controlled by RTI, apart from mutual mass, momentum, and energy transfer. To accentuate the instability, the top chamber is filled with the heavier (lower temperature) air, which rests atop the chamber containing lighter air. The partition is positioned initially at mid-height of the box. As the fluid dynamical system considered is completely isolated from outside, the DNS results obtained without using Boussinesq approximation will enable one to study non-equilibrium thermodynamics of a finite reservoir undergoing strong irreversible processes. The barrier is removed impulsively, triggering baroclinic instability by non-alignment of density, and pressure gradient by ambient disturbances via the sharp discontinuity at the interface. Adopted DNS method has dispersion relation preservation properties with neutral stability and does not require any external initial perturbations. The complete inhomogeneous problem with non-periodic, no-slip boundary conditions is studied by solving compressible Navier-Stokes equation, without the Boussinesq approximation. This is important as the temperature difference between the two air masses considered is high enough (Δ T = 70 K) to invalidate Boussinesq approximation. We discuss non-equilibrium thermodynamical aspects of RTI with the help of numerical results for density, vorticity, entropy, energy, and enstrophy.
Consistent Modeling of Hypersonic Nonequilibrium Flows using Direct Simulation Monte Carlo
NASA Astrophysics Data System (ADS)
Zhang, Chonglin
Hypersonic flows involve strong thermal and chemical nonequilibrium due to steep gradients in gas properties in the shock layer, wake, and next to vehicle surfaces. Accurate simulation of hypersonic nonequilibrium flows requires consideration of the molecular nature of the gas including internal energy excitation (translational, rotational, and vibrational energy modes) as well as chemical reaction processes such as dissociation. Both continuum and particle simulation methods are available to simulate such complex flow phenomena. Specifically, the direct simulation Monte Carlo (DSMC) method is widely used to model such complex nonequilibrium phenomena within a particle-based numerical method. This thesis describes in detail how the different types of DSMC thermochemical models should be implemented in a rigorous and consistent manner. In the process, new algorithms are developed including a new framework for phenomenological models able to incorporate results from computational chemistry. Using this framework, a new DSMC model for rotational energy exchange is constructed. General algorithms are developed for the various types of methods that inherently satisfy microscopic reversibility, detailed balance, and equipartition of energy in equilibrium. Furthermore, a new framework for developing rovibrational state-to-state DSMC collision models is proposed, and a vibrational state-to-state model is developed along the course. The overall result of this thesis is a rigorous and consistent approach to bridge molecular physics and computational chemistry through stochastic molecular simulation to continuum models for gases in strong thermochemical nonequilibrium.
Non-equilibrium calcium ionisation in the solar atmosphere
NASA Astrophysics Data System (ADS)
Wedemeyer-Böhm, S.; Carlsson, M.
2011-04-01
Context. The chromosphere of the Sun is a temporally and spatially very varying medium for which the assumption of ionisation equilibrium is questionable. Aims: Our aim is to determine the dominant processes and timescales for the ionisation equilibrium of calcium under solar chromospheric conditions. Methods: The study is based on numerical simulations with the RADYN code, which combines hydrodynamics with a detailed solution of the radiative transfer equation. The calculations include a detailed non-equilibrium treatment of hydrogen, calcium, and helium. Next to an hour long simulation sequence, additional simulations are produced, for which the stratification is slightly perturbed so that a ionisation relaxation timescale can be determined. The simulations are characterised by upwards propagating shock waves, which cause strong temperature fluctuations and variations of the (non-equilibrium) ionisation degree of calcium. Results: The passage of a hot shock front leads to a strong net ionisation of Ca II, rapidly followed by net recombination. The relaxation timescale of the calcium ionisation state is found to be of the order of a few seconds at the top of the photosphere and 10 to 30 s in the upper chromosphere. At heights around 1 Mm, we find typical values around 60 s and in extreme cases up to ~150 s. Generally, the timescales are significantly reduced in the wakes of ubiquitous hot shock fronts. The timescales can be reliably determined from a simple analysis of the eigenvalues of the transition rate matrix. The timescales are dominated by the radiative recombination from Ca III into the metastable Ca II energy levels of the 4d 2D term. These transitions depend strongly on the density of free electrons and therefore on the (non-equilibrium) ionisation degree of hydrogen, which is the main electron donor. Conclusions: The ionisation/recombination timescales derived here are too long for the assumption of an instantaneous ionisation equilibrium to be valid
Kempa, K.; Bakshi, P.; Gornik, E.
1996-09-01
We show theoretically that strong plasma mode generation is possible in a nonequilibrium steady-state quasi-one-dimensional bounded solid-state plasma, in which a nonequilibrium distribution is maintained by appropriate injection/extraction of carriers. We calculate the density response of realistic model systems using the random-phase approximation, determine the normal modes of the bounded carrier plasma, and show that strong plasma instabilities can be generated under suitable conditions. Such stimulated plasma oscillations could lead to sources of terahertz electromagnetic radiation. {copyright} {ital 1996 The American Physical Society.}
Marx, Christoph A.; Harbola, Upendra; Mukamel, Shaul
2010-01-01
Nonlinear optical signals from an assembly of N noninteracting particles consist of an incoherent and a coherent component, whose magnitudes scale ~ N and ~ N(N − 1), respectively. A unified microscopic description of both types of signals is developed using a quantum electrodynamical (QED) treatment of the optical fields. Closed nonequilibrium Green’s function expressions are derived that incorporate both stimulated and spontaneous processes. General (n + 1)-wave mixing experiments are discussed as an example of spontaneously generated signals. When performed on a single particle, such signals cannot be expressed in terms of the nth order polarization, as predicted by the semiclassical theory. Stimulated processes are shown to be purely incoherent in nature. Within the QED framework, heterodyne-detected wave mixing signals are simply viewed as incoherent stimulated emission, whereas homodyne signals are generated by coherent spontaneous emission. PMID:21037933
A study of non-equilibrium phonons in GaAs/AlAs quantum wells
Su, Zhenpeng
1996-11-01
In this thesis we have studied the non-equilibrium phonons in GaAs/AlAs quantum wells via Raman scattering. We have demonstrated experimentally that by taking into account the time-reversal symmetry relation between the Stokes and anti-Stokes Raman cross sections, one can successfully measure the non-equilibrium phonon occupancy in quantum wells. Using this technique, we have studied the subject of resonant intersubband scattering of optical phonons. We find that interface roughness plays an important role in resonant Raman scattering in quantum wells. The lateral size of the smooth regions in such interface is estimated to be of the order of 100 {Angstrom}. Through a study of photoluminescence of GaAs/AlAs quantum wells under high intensity laser excitation, we have found that band nonparabolicity has very little effect on the electron subband energies even for subbands as high as a few hundred meV above the lowest one. This finding may require additional theoretical study to understand its origin. We have also studied phonon confinement and propagation in quantum wells. We show that Raman scattering of non-equilibrium phonons in quantum wells can be a sensitive measure of the spatial extent of the longitudinal optical (LO) phonons. We deduce the coherence length of LO phonons in GaAs/Al{sub x}Ga{sub 1-x}As quantum wells as a function of the Al concentration x.
Measuring nonequilibrium retarded spin-spin Green's functions in an ion-trap-based quantum simulator
NASA Astrophysics Data System (ADS)
Yoshimura, Bryce T.; Freericks, J. K.
2016-05-01
Recently a variant on Ramsey interferometry for coupled spin-1 /2 systems was proposed to directly measure the retarded spin-spin Green's function. In conventional experimental situations, the spin system is initially in a nonequilibrium state before the Ramsey interferometry is performed, so we examine the nonequilibrium retarded spin-spin Green's functions within the transverse-field Ising model. We derive the lowest four spectral moments to understand the short-time behavior and we employ a Lehmann-like representation to determine the spectral behavior. We simulate a Ramsey protocol for a nonequilibrium quantum spin system that consists of a coherent superposition of the ground state and diabatically excited higher-energy states via a temporally ramped transverse magnetic field. We then apply the Ramsey spectroscopy protocol to the final Hamiltonian, which has a constant transverse field. The short time allows us to extract the initial transport of many-body correlations, while the long-time behavior relates to the excitation spectra of the Hamiltonian. Compressive sensing is employed in the data analysis to efficiently extract that spectra.
Nonequilibrium functional renormalization for driven-dissipative Bose-Einstein condensation
NASA Astrophysics Data System (ADS)
Sieberer, L. Â. M.; Huber, S. Â. D.; Altman, E.; Diehl, S.
2014-04-01
We present a comprehensive analysis of critical behavior in the driven-dissipative Bose condensation transition in three spatial dimensions. The starting point is a microscopic description of the system in terms of a many-body quantum master equation, where coherent and driven-dissipative dynamics occur on an equal footing. An equivalent Keldysh real-time functional integral reformulation opens up the problem to a practical evaluation using the tools of quantum field theory. In particular, we develop a functional renormalization group approach to quantitatively explore the universality class of this stationary nonequilibrium system. Key results comprise the emergence of an asymptotic thermalization of the distribution function, while manifest nonequilibrium properties are witnessed in the response properties in terms of a new, independent critical exponent. Thus, the driven-dissipative microscopic nature is seen to bear observable consequences on the largest length scales. The absence of two symmetries present in closed equilibrium systems—underlying particle number conservation and detailed balance, respectively—is identified as the root of this new nonequilibrium critical behavior. Our results are relevant for broad ranges of open quantum systems on the interface of quantum optics and many-body physics, from exciton-polariton condensates to cold atomic gases.
NASA Astrophysics Data System (ADS)
Chang, Po-Hao; Mahfouzi, Farzad; Nagaosa, Naoto; Nikolić, Branislav K.
2014-05-01
We study the transverse spin-Seebeck effect (SSE) on the surface of a three-dimensional topological insulator (TI) thin film, such as Bi2Se3, which is sandwiched between two normal metal leads. The temperature bias ΔT applied between the leads generates surface charge current which becomes spin polarized due to strong spin-orbit coupling on the TI surface, with polarization vector acquiring a component Px≃60% parallel to the direction of transport. When the third nonmagnetic voltage probe is attached to the portion of the TI surface across its width Ly, pure spin current will be injected into the probe where the inverse spin Hall effect (ISHE) converts it into a voltage signal |VISHE|max/ΔT ≃2.5μV/K (assuming the SH angle of the Pt voltage probe and Ly=1 mm). The existence of predicted nonequilibrium spin polarization parallel to the direction of electronic transport and the corresponding electron-driven SSE crucially relies on orienting quintuple layers (QLs) of Bi2Se3 orthogonal to the TI surface and tilted by 45∘ with respect to the direction of transport. Our analysis is based on the Landauer-Büttiker-type formula for spin currents in the leads of a multiterminal quantum-coherent junction, which is constructed by using nonequilibrium Green function formalism within which we show how to take into account arbitrary orientation of QLs via the self-energy describing coupling between semi-infinite normal metal leads and the TI sample.
NASA Astrophysics Data System (ADS)
Asher, D. J.; Clube, S. V. M.; Napier, W. M.; Steel, D. I.
We review the theoretical and observational evidence that, on timescales relevant to mankind, the prime collision hazard is posed by temporally correlated impacts (coherent catastrophism, Δt ˜ 10 2-10 4 yr) rather than random ones (stochastic catastrophism, Δt ˜ 10 5-10 8 yr). The mechanism whereby coherent incursions into and through the terrestrial atmosphere occur is described as being the result of giant cometary bodies arriving in orbits with perihelia in the inner solar system. Hierarchical fragmentation of such large (100 km-plus) bodies — due to thermal stresses near perihelion, collisions in the asteroid belt, or passages through the Jovian Roche radius — results in numerous ˜kilometre-sized objects being left in short-period orbits, and appearing in telescopic searches as Apollo-type asteroids. Many more smaller objects, in the 10-100 metre size range and only recently observed, by the Spacewatch team, are expected to be in replenished clusters in particular orbits as a result of continuing disintegrations of large, differentiated, cometary objects. Gravitational perturbations by Jupiter bring these clusters around to have a node at 1 AU in a cyclic fashion, leading to impacts at certain times of year every few years during active periods lasting a few centuries, such periods being separated by intervals of a few millennia. Furthermore, fragmentations within the hierarchy result in significant bombardment commensurabilities ( Δt ˜ 10-10 2 yr) during active periods occurring at random intervals ( Δt ˜ 10 2-10 3 yr). It appears that the Earth has been subject to such impacts since the break-up of such a comet ˜2×10 4 years ago; currently we are not passing through a high-risk epoch, although some phenomena originating in the products of this break-up have been observed in the 20th century. This most recent hierarchical disintegration, associated with four well-known meteor showers and termed the Taurid Complex, is now recognized as resulting
Neural Correlates of Bridging Inferences and Coherence Processing
ERIC Educational Resources Information Center
Kim, Sung-il; Yoon, Misun; Kim, Wonsik; Lee, Sunyoung; Kang, Eunjoo
2012-01-01
We explored the neural correlates of bridging inferences and coherence processing during story comprehension using Positron Emission Tomography (PET). Ten healthy right-handed volunteers were visually presented three types of stories (Strong Coherence, Weak Coherence, and Control) consisted of three sentences. The causal connectedness among…
Nonequilibrium thermodynamics of wealth condensation
NASA Astrophysics Data System (ADS)
Braun, Dieter
2006-09-01
We analyze wealth condensation for a wide class of stochastic economy models on the basis of the economic analog of thermodynamic potentials, termed transfer potentials. The economy model is based on three common transfers modes of wealth: random transfer, profit proportional to wealth and motivation of poor agents to work harder. The economies never reach steady state. Wealth condensation is the result of stochastic tunneling through a metastable transfer potential. In accordance with reality, both wealth and income distribution transiently show Pareto tails for high-income subjects. For metastable transfer potentials, exponential wealth condensation is a robust feature. For example with 10% annual profit 1% of the population owns 50% of the wealth after 50 years. The time to reach such a strong wealth condensation is a hyperbolic function of the annual profit rate.
Plasma wave instabilities in nonequilibrium graphene
NASA Astrophysics Data System (ADS)
Aryal, Chinta M.; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka
2016-09-01
We study two-stream instabilities in a nonequilibrium system in which a stream of electrons is injected into doped graphene. As with equivalent nonequilibrium parabolic band systems, we find that the graphene systems can support unstable charge-density waves whose amplitudes grow with time. We determine the range of wave vectors q that are unstable, and their growth rates. We find no instability for waves with wave vectors parallel or perpendicular to the direction of the injected carriers. We find that, within the small-wave-vector approximation, the angle between q and the direction of the injected electrons that maximizes the growth rate increases with increasing |q | . We compare the range and strength of the instability in graphene to that of two- and three-dimensional parabolic band systems.
Nonequilibrium diagrammatic technique for nanoscale devices
NASA Astrophysics Data System (ADS)
Zebrev, G. I.
2006-05-01
A general approach based on gauge invariance requirements has been developed for automatic construction of quantum kinetic equation in electron systems, far for equilibrium. Proposed theoretical scheme has high generality and automatism and capable to treat nonequilibrium effects of electron transport, quantum interference and energy dissipation. Dissipative and quantum-interference effects can be consequentially incorporated in the computational scheme through solution of dynamic Dyson equation for self-energies in the framework of conventional diagrammatic technique.
Efficiency bounds for nonequilibrium heat engines
Mehta, Pankaj; Polkovnikov, Anatoli
2013-05-15
We analyze the efficiency of thermal engines (either quantum or classical) working with a single heat reservoir like an atmosphere. The engine first gets an energy intake, which can be done in an arbitrary nonequilibrium way e.g. combustion of fuel. Then the engine performs the work and returns to the initial state. We distinguish two general classes of engines where the working body first equilibrates within itself and then performs the work (ergodic engine) or when it performs the work before equilibrating (non-ergodic engine). We show that in both cases the second law of thermodynamics limits their efficiency. For ergodic engines we find a rigorous upper bound for the efficiency, which is strictly smaller than the equivalent Carnot efficiency. I.e. the Carnot efficiency can be never achieved in single reservoir heat engines. For non-ergodic engines the efficiency can be higher and can exceed the equilibrium Carnot bound. By extending the fundamental thermodynamic relation to nonequilibrium processes, we find a rigorous thermodynamic bound for the efficiency of both ergodic and non-ergodic engines and show that it is given by the relative entropy of the nonequilibrium and initial equilibrium distributions. These results suggest a new general strategy for designing more efficient engines. We illustrate our ideas by using simple examples. -- Highlights: ► Derived efficiency bounds for heat engines working with a single reservoir. ► Analyzed both ergodic and non-ergodic engines. ► Showed that non-ergodic engines can be more efficient. ► Extended fundamental thermodynamic relation to arbitrary nonequilibrium processes.
Nonequilibrium self-energy functional theory
NASA Astrophysics Data System (ADS)
Hofmann, Felix; Eckstein, Martin; Arrigoni, Enrico; Potthoff, Michael
2013-10-01
The self-energy functional theory (SFT) is generalized to describe the real-time dynamics of correlated lattice-fermion models far from thermal equilibrium. This is achieved by starting from a reformulation of the original equilibrium theory in terms of double-time Green's functions on the Keldysh-Matsubara contour. With the help of a generalized Luttinger-Ward functional, we construct a functional Ω̂[Σ] which is stationary at the physical (nonequilibrium) self-energy Σ and which yields the grand potential of the initial thermal state Ω at the physical point. Nonperturbative approximations can be defined by specifying a reference system that serves to generate trial self-energies. These self-energies are varied by varying the reference system's one-particle parameters on the Keldysh-Matsubara contour. In the case of thermal equilibrium, this approach reduces to the conventional SFT. Contrary to the equilibrium theory, however, “unphysical” variations, i.e., variations that are different on the upper and the lower branches of the Keldysh contour, must be considered to fix the time dependence of the optimal physical parameters via the variational principle. Functional derivatives in the nonequilibrium SFT Euler equation are carried out analytically to derive conditional equations for the variational parameters that are accessible to a numerical evaluation via a time-propagation scheme. Approximations constructed by means of the nonequilibrium SFT are shown to be inherently causal, internally consistent, and to respect macroscopic conservation laws resulting from gauge symmetries of the Hamiltonian. This comprises the nonequilibrium dynamical mean-field theory but also dynamical-impurity and variational-cluster approximations that are specified by reference systems with a finite number of degrees of freedom. In this way, nonperturbative and consistent approximations can be set up, the numerical evaluation of which is accessible to an exact
Nonequilibrium invariant measure under heat flow.
Delfini, Luca; Lepri, Stefano; Livi, Roberto; Politi, Antonio
2008-09-19
We provide an explicit representation of the nonequilibrium invariant measure for a chain of harmonic oscillators with conservative noise in the presence of stationary heat flow. By first determining the covariance matrix, we are able to express the measure as the product of Gaussian distributions aligned along some collective modes that are spatially localized with power-law tails. Numerical studies show that such a representation applies also to a purely deterministic model, the quartic Fermi-Pasta-Ulam chain.
NASA Astrophysics Data System (ADS)
Jiang, Shi-xiao W.; Lu, Hai-hao; Zhou, Douglas; Cai, David
2014-09-01
We study the nonlinear dispersive characteristics in β-Fermi-Pasta-Ulam (FPU) chains in both thermal equilibrium and nonequilibrium steady state. By applying a multiple scale analysis to the FPU chain, we analyze the contribution of the trivial and nontrivial resonance to the renormalization of the dispersion relation. Our results show that the contribution of the nontrivial resonance remains significant to the renormalization, in particular, in strongly nonlinear regimes. We contrast our results with the dispersion relations obtained from the Zwanzig-Mori formalism and random phase approximation to further illustrate the role of resonances. Surprisingly, these theoretical dispersion relations can be generalized to describe dispersive characteristics well at the nonequilibrium steady state of the FPU chain with driving-damping in real space. Through numerical simulation, we confirm that the theoretical renormalized dispersion relations are valid for a wide range of nonlinearities in thermal equilibrium as well as in nonequilibrium steady state. We further show that the dispersive characteristics persist in nonequilibrium steady state driven-damped in Fourier space.
NASA Astrophysics Data System (ADS)
Greenshields, Christopher J.; Reese, Jason M.
2012-07-01
This paper investigates the use of Navier-Stokes-Fourier equations with non-equilibrium boundary conditions (BCs) for simulation of rarefied hypersonic flows. It revisits a largely forgotten derivation of velocity slip and temperature jump by Patterson, based on Grad's moment method. Mach 10 flow around a cylinder and Mach 12.7 flow over a flat plate are simulated using both computational fluid dynamics using the temperature jump BCs of Patterson and Smoluchowski and the direct simulation Monte-Carlo (DSMC) method. These flows exhibit such strongly non-equilibrium behaviour that, following Patterson's analysis, they are strictly beyond the range of applicability of the BCs. Nevertheless, the results using Patterson's temperature jump BC compare quite well with the DSMC and are consistently better than those using the standard Smoluchowski temperature jump BC. One explanation for this better performance is that an assumption made by Patterson, based on the flow being only slightly non-equilibrium, introduces an additional constraint to the resulting BC model in the case of highly non-equilibrium flows.
NASA Astrophysics Data System (ADS)
Bijie, Yang; Ning, Zhou; Quanhua, Sun
2016-01-01
The capacitively coupled plasma in the gaseous electronics conference reference reactor is numerically investigated for argon flow using a non-equilibrium plasma fluid model. The finite rate chemistry is adopted for the chemical non-equilibrium among species including neutral metastable, whereas a two-temperature model is employed to resolve the thermal non-equilibrium between electrons and heavy species. The predicted plasma density agrees very well with experimental data for the validation case. A strong thermal non-equilibrium is observed between heavy particles and electrons due to its low collision frequency, where the heavy species remains near ambient temperature for low pressure and low voltage conditions (0.1 Torr, 100 V). The effects of the operating parameters on the ion flux are also investigated, including the electrode voltage, chamber pressure, and gas flow rate. It is found that the ion flux can be increased by either elevating the electrode voltage or lowering the gas pressure. Project supported by the National Natural Science Foundation of China (Nos. 11372325, 11475239).
Nonequilibrium quantum dynamics in optomechanical systems
NASA Astrophysics Data System (ADS)
Patil, Yogesh Sharad; Cheung, Hil F. H.; Shaffer, Airlia; Wang, Ke; Vengalattore, Mukund
2016-05-01
The thermalization dynamics of isolated quantum systems has so far been explored in the context of cold atomic systems containing a large number of particles and modes. Quantum optomechanical systems offer prospects of studying such dynamics in a qualitatively different regime - with few individually addressable modes amenable to continuous quantum measurement and thermalization times that vastly exceed those observed in cold atomic systems. We have experimentally realized a dynamical continuous phase transition in a quantum compatible nondegenerate mechanical parametric oscillator. This system is formally equivalent to the optical parametric amplifiers whose dynamics have been a subject of intense theoretical study. We experimentally verify its phase diagram and observe nonequilibrium behavior that was only theorized, but never directly observed, in the context of optical parametric amplifiers. We discuss prospects of using nonequilibrium protocols such as quenches in optomechanical systems to amplify weak nonclassical correlations and to realize macroscopic nonclassical states. This work was supported by the DARPA QuASAR program through a Grant from the ARO and the ARO MURI on non-equilibrium manybody dynamics.
Fresnel diffractive imaging: Experimental study of coherence and curvature
NASA Astrophysics Data System (ADS)
Whitehead, L. W.; Williams, G. J.; Quiney, H. M.; Nugent, K. A.; Peele, A. G.; Paterson, D.; de Jonge, M. D.; McNulty, I.
2008-03-01
A Fresnel coherent diffractive imaging experiment is performed using a pinhole as a test object. The experimental parameters of the beam curvature and coherence length of the illuminating radiation are varied to investigate their effects on the reconstruction process. It is found that a sufficient amount of curvature across the sample strongly ameliorates the effects of low coherence, even when the sample size exceeds the coherence length.
NASA Astrophysics Data System (ADS)
Zhai, Cuili; Zhang, Ting
2016-09-01
In this article, we consider the global existence and uniqueness of the solution to the 2D incompressible non-resistive MHD system with non-equilibrium background magnetic field. Our result implies that a strong enough non-equilibrium background magnetic field will guarantee the stability of the nonlinear MHD system. Beside the classical energy method, the interpolation inequalities and the algebraic structure of the equations coming from the incompressibility of the fluid are crucial in our arguments.
PREFACE: Progress in Nonequilibrium Green's Functions IV
NASA Astrophysics Data System (ADS)
Bonitz, Michael; Balzer, Karsten
2010-04-01
This is the fourth volume1 of articles on the theory of Nonequilibrium Green's functions (NEGF) and their modern application in various fields such as plasma physics, semiconductor physics, molecular electronics and high energy physics. It contains 23 articles written by experts in many-body theory and quantum transport who summarize recent progress in their respective area of research. The articles are based on talks given at the interdisciplinary conference Progress in Nonequilibrium Green's functions IV which was held 17-21 August 2009 at the University of Glasgow, Scotland. This conference continues the tradition of the previous meetings which started in 1999 and which aimed at an informal exchange across field boundaries. The previous meetings and the earlier proceedings proved to be very stimulating not only for young researchers but also for experienced scientists, and we are convinced that this fourth volume will be as successful as the previous ones. As before, this volume includes only extended review-type papers which are written in a way that they are understandable to a broad interdisciplinary audience. All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administrated by the Editors assuring highest scientific standards. In the review process some papers were substantially revised and improved and some were rejected. This conference would not have been possible without the remarkable work of the local organizing team around John Barker and Scott Roy and the generous financial support from the University of Glasgow and the Deutsche Forschungsgemeinschaft via SFB-Transregio 24. Michael Bonitz and Karsten Balzer Kiel, February 2010 1 The first two volumes are Progress in Nonequilibrium Green's functions, M Bonitz (ed) and Progress in Nonequilibrium Green's functions II, M Bonitz and D Semkat (eds), which were published by World Scientific (Singapore), in 2000 and 2003, respectively (ISBN
Spatial and spectral shape of inhomogeneous nonequilibrium exciton-polariton condensates
Wouters, Michiel; Carusotto, Iacopo; Ciuti, Cristiano
2008-03-15
We develop a mean-field theory of the spatial profile and the spectral properties of polariton condensates in nonresonantly pumped semiconductor microcavities in the strong coupling regime. Specific signatures of the nonequilibrium character of the condensation process are pointed out: a striking sensitivity of the condensate shape on the optical pump spot size is demonstrated by analytical and numerical calculations, in good quantitative agreement with recent experimental observations.
Anomalies of a nonequilibrium spinor polariton condensate in a magnetic field.
Fischer, J; Brodbeck, S; Chernenko, A V; Lederer, I; Rahimi-Iman, A; Amthor, M; Kulakovskii, V D; Worschech, L; Kamp, M; Durnev, M; Schneider, C; Kavokin, A V; Höfling, S
2014-03-01
We observe a strong variation of the Zeeman splitting of exciton polaritons in microcavities when switching between the linear regime, the polariton lasing, and photon lasing regimes. In the polariton lasing regime the sign of Zeeman splitting changes compared to the linear regime, while in the photon lasing regime the splitting vanishes. We additionally observe an increase of the diamagnetic shift in the polariton lasing regime. These effects are explained in terms of the nonequilibrium "spin Meissner effect." PMID:24655252
A coupled implicit method for chemical non-equilibrium flows at all speeds
NASA Technical Reports Server (NTRS)
Shuen, Jian-Shun; Chen, Kuo-Huey; Choi, Yunho
1993-01-01
The present time-accurate coupled-solution procedure addresses the chemical nonequilibrium Navier-Stokes equations over a wide Mach-number range uses, in conjunction with the strong conservation form of the governing equations, five unknown primitive variables. The numerical tests undertaken address steady convergent-divergent nozzle flows with air dissociation/recombination, dump combustor flows with n-pentane/air chemistry, and unsteady nonreacting cavity flows.
Nonequilibrium Bose-Einstein condensation of hot magnons
Vannucchi, Fabio Stucchi; Vasconcellos, Aurea Rosas; Luzzi, Roberto
2010-10-01
We present an analysis of the emergence of a nonequilibrium Bose-Einstein-type condensation of magnons in radio-frequency pumped magnetic thin films, which has recently been experimentally observed. A complete description of all the nonequilibrium processes involved is given. It is demonstrated that the phenomenon is another example of the emergence of Bose-Einstein-type condensation in nonequilibrium many-boson systems embedded in a thermal bath, a phenomenon evidenced decades ago by the renowned late Herbert Froehlich.
Nonequilibrium Phase Chemistry in High Temperature Structure Alloys
NASA Technical Reports Server (NTRS)
Wang, R.
1991-01-01
Titanium and nickel aluminides of nonequilibrium microstructures and in thin gauge thickness were identified, characterized and produced for potential high temperature applications. A high rate sputter deposition technique for rapid surveillance of the microstructures and nonequilibrium phase is demonstrated. Alloys with specific compositions were synthesized with extended solid solutions, stable dispersoids, and specific phase boundaries associated with different heat treatments. Phase stability and mechanical behavior of these nonequilibrium alloys were investigated and compared.
Non-equilibrium diffusion combustion of a fuel droplet
NASA Astrophysics Data System (ADS)
Tyurenkova, Veronika V.
2012-06-01
A mathematical model for the non-equilibrium combustion of droplets in rocket engines is developed. This model allows to determine the divergence of combustion rate for the equilibrium and non-equilibrium model. Criterion for droplet combustion deviation from equilibrium is introduced. It grows decreasing droplet radius, accommodation coefficient, temperature and decreases on decreasing diffusion coefficient. Also divergence from equilibrium increases on reduction of droplet radius. Droplet burning time essentially increases under non-equilibrium conditions. Comparison of theoretical and experimental data shows that to have adequate solution for small droplets it is necessary to use the non-equilibrium model.
Nonequilibrium 2-Hydroxyoctadecanoic Acid Monolayers: Effect of Electrolytes
Lendrum, Conrad D.; Ingham, Bridget; Lin, Binhua; Meron, Mati; Toney, Michael F.; McGrath, Kathryn M.
2012-02-06
2-Hydroxyacids display complex monolayer phase behavior due to the additional hydrogen bonding afforded by the presence of the second hydroxy group. The placement of this group at the position {alpha} to the carboxylic acid functionality also introduces the possibility of chelation, a utility important in crystallization including biomineralization. Biomineralization, like many biological processes, is inherently a nonequilibrium process. The nonequilibrium monolayer phase behavior of 2-hydroxyoctadecanoic acid was investigated on each of pure water, calcium chloride, sodium bicarbonate and calcium carbonate crystallizing subphases as a precursor study to a model calcium carbonate biomineralizing system, each at a pH of {approx}6. The role of the bicarbonate co-ion in manipulating the monolayer structure was determined by comparison with monolayer phase behavior on a sodium chloride subphase. Monolayer phase behavior was probed using surface pressure/area isotherms, surface potential, Brewster angle microscopy, and synchrotron-based grazing incidence X-ray diffraction and X-ray reflectivity. Complex phase behavior was observed for all but the sodium chloride subphase with hydrogen bonding, electrostatic and steric effects defining the symmetry of the monolayer. On a pure water subphase hydrogen bonding dominates with three phases coexisting at low pressures. Introduction of calcium ions into the aqueous subphase ensures strong cation binding to the surfactant head groups through chelation. The monolayer becomes very unstable in the presence of bicarbonate ions within the subphase due to short-range hydrogen bonding interactions between the monolayer and bicarbonate ions facilitated by the sodium cation enhancing surfactant solubility. The combined effects of electrostatics and hydrogen bonding are observed on the calcium carbonate crystallizing subphase.
Non-equilibrium Dynamics of DNA Nanotubes
NASA Astrophysics Data System (ADS)
Hariadi, Rizal Fajar
Can the fundamental processes that underlie molecular biology be understood and simulated by DNA nanotechnology? The early development of DNA nanotechnology by Ned Seeman was driven by the desire to find a solution to the protein crystallization problem. Much of the later development of the field was also driven by envisioned applications in computing and nanofabrication. While the DNA nanotechnology community has assembled a versatile tool kit with which DNA nanostructures of considerable complexity can be assembled, the application of this tool kit to other areas of science and technology is still in its infancy. This dissertation reports on the construction of non-equilibrium DNA nanotube dynamic to probe molecular processes in the areas of hydrodynamics and cytoskeletal behavior. As the first example, we used DNA nanotubes as a molecular probe for elongational flow measurement in different micro-scale flow settings. The hydrodynamic flow in the vicinity of simple geometrical objects, such as a rigid DNA nanotube, is amenable to rigorous theoretical investigation. We measured the distribution of elongational flows produced in progressively more complex settings, ranging from the vicinity of an orifice in a microfluidic chamber to within a bursting bubble of Pacific ocean water. This information can be used to constrain theories on the origin of life in which replication involves a hydrodynamically driven fission process, such as the coacervate fission proposed by Oparin. A second theme of this dissertation is the bottom-up construction of a de novo artificial cytoskeleton with DNA nanotubes. The work reported here encompasses structural, locomotion, and control aspects of non-equilibrium cytoskeletal behavior. We first measured the kinetic parameters of DNA nanotube assembly and tested the accuracy of the existing polymerization models in the literature. Toward recapitulation of non-equilibrium cytoskeletal dynamics, we coupled the polymerization of DNA
Nonequilibrium Kinetics of Rydberg Atomic States
Bureyeva, L. A.; Kadomtsev, M. B.; Levashova, M. G.; Lisitsa, V. S.
2008-10-22
Two-dimensional quasi-classical model of the radiative-collisional cascade for hydrogen-like systems is developed. The model establishes the correspondence between the quantum and classical approaches. Our calculations of the two-dimensional populations of highly excited atomic hydrogen states for three-body and photorecombination sources of population allow the data of one-dimensional kinetic models to be refined. The calculated intensities of recombination lines demonstrate the degree of nonequilibrium of the Rydberg state populations under typical astrophysical plasma conditions.
Adaptive Implicit Non-Equilibrium Radiation Diffusion
Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael
2013-01-01
We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
Non-equilibrium processes in interstellar molecules
NASA Technical Reports Server (NTRS)
Strelnitskiy, V. S.
1979-01-01
The types of nonequilibrium emission and absorption by interstellar molecules are summarized. The observed brightness emission temperatures of compact OH and H2O sources are discussed using the concept of maser amplification. A single thermodynamic approach was used in which masers and anti-masers are considered as heat engines for the theoretical interpretation of the cosmic maser and anti-maser phenomena. The requirements for different models of pumping are formulated and a classification is suggested for the mechanisms of pumping, according to the source and discharge of energy.
Conserved moments in nonequilibrium field dynamics
Mineev-Weinstein, M.B.; Alexander, F.J.
1995-06-01
We demonstrate with the example of Cahn-Hilliard dynamics that the macroscopic kinetics of first-order phase transitions exhibits an infinite number of constants of motion. Moreover, this results holds in any space dimension for a broad class of nonequilibrium processes whose macroscopic behavior is governed by equations of the form {partial_derivative}{phi}/{partial_derivative}t = LW({phi}), where {phi} is an {open_quotes}order parameter,{close_quotes} W is an arbitrary function of {phi}, and L is a linear Hermitian operator. We speculate on the implications of this result.
Non-Equilibrium Transitions of Heliospheric plasma
NASA Astrophysics Data System (ADS)
Livadiotis, G.; McComas, D. J.
2011-12-01
Recent advances in Space Physics theory have established the connection between non-extensive Statistical Mechanics and space plasmas by providing a theoretical basis for the empirically derived kappa distributions commonly used to describe the phase space distribution functions of these systems [1]. The non-equilibrium temperature and the kappa index that govern these distributions are the two independent controlling parameters of non-equilibrium systems [1-3]. The significance of the kappa index is primarily given by its role in identifying the non-equilibrium stationary states, and measuring their "thermodynamic distance" from thermal equilibrium [4], while its physical meaning is connected to the correlation between the system's particles [5]. For example, analysis of the IBEX high Energetic Neutral Atom spectra [6] showed that the vast majority of measured kappa indices are between ~1.5 and ~2.5, consistent with the far-equilibrium "cavity" of minimum entropy discovered by Livadiotis & McComas [2]. Spontaneous procedures that can increase the entropy, move the system gradually toward equilibrium, that is the state with the maximum (infinite) kappa index. Other external factors that may decrease the entropy, move the system back to states further from equilibrium where the kappa indices are smaller. Newly formed pick-up ions can play this critical role in the solar wind and other space plasmas. We have analytically shown that their highly ordered motion can reduce the average entropy in the plasma beyond the termination shock, inside the inner heliosheath [7]. Non-equilibrium transitions have a key role in understanding the governing thermodynamical processes of space plasmas. References 1. Livadiotis, G., & McComas, D. J. 2009, JGR, 114, 11105. 2. Livadiotis, G., & McComas, D. J. 2010a, ApJ, 714, 971. 3. Livadiotis, G., & McComas, D. J. 2010c, in AIP Conf. Proc. 9, Pickup Ions Throughout the Heliosphere and Beyond, ed. J. LeRoux, V. Florinski, G. P. Zank, & A
Nonequilibrium Interlayer Transport in Pulsed Laser Deposition
Tischler, Jonathan Zachary; Eres, Gyula; Larson, Ben C; Rouleau, Christopher M; Zschack, P.; Lowndes, Douglas H
2006-01-01
We use time-resolved surface x-ray diffraction measurements with microsecond range resolution to study the growth kinetics of pulsed laser deposited SrTiO3. Time-dependent surface coverages corresponding to single laser shots were determined directly from crystal truncation rod intensity transients. Analysis of surface coverage evolution shows that extremely fast nonequilibrium interlayer transport, which occurs concurrently with the arrival of the laser plume, dominates the deposition process. A much smaller fraction of material, which is governed by the dwell time between successive laser shots, is transferred by slow, thermally driven interlayer transport processes.
Nonlinear and nonequilibrium dynamics in geomaterials.
TenCate, James A; Pasqualini, Donatella; Habib, Salman; Heitmann, Katrin; Higdon, David; Johnson, Paul A
2004-08-01
The transition from linear to nonlinear dynamical elasticity in rocks is of considerable interest in seismic wave propagation as well as in understanding the basic dynamical processes in consolidated granular materials. We have carried out a careful experimental investigation of this transition for Berea and Fontainebleau sandstones. Below a well-characterized strain, the materials behave linearly, transitioning beyond that point to a nonlinear behavior which can be accurately captured by a simple macroscopic dynamical model. At even higher strains, effects due to a driven nonequilibrium state, and relaxation from it, complicate the characterization of the nonlinear behavior.
Ma, Li; Zhang, Fan; Allen, Andrew; Levine, Lyle
2014-07-01
It is a scientific and engineering challenge to characterize materials under nonequilibrium conditions. In recent years, X-ray photon correlation spectroscopy (XPCS), a synchrotron-based coherent X-ray scattering technique, has been found useful in determining the timescales associated with various nonequilibrium processes, with detailed descriptions of the underlying processes lacking. Here, both static ultra small angle X-ray scattering (USAXS) and dynamic USAXS-based XPCS were used to investigate a transient structural change (a nonequilibrium process) associated with an isothermal anneal in a glass polymer composite system. While the bulk USAXS technique lacked the required sensitivity to detect the change in the microstructures, the local structural reorganization was apparent in the XPCS study. The structural changes were modeled using a three-dimensional finite element analysis approach and wave-propagation theory was used to simulate the resulting reciprocal-space coherent scattering intensity. Qualitative agreement was found between the modeling and experimental results, which validates that stress relaxation in the viscous polymer matrix was responsible for the observed changes. This analysis demonstrates that multi-physics modeling of complex systems can be used to interpret XPCS measurements of nonequilibrium processes. PMID:25970190
Collisional-Radiative Nonequilibrium and Precursor Effects in a Nitrogen Shock Wave
NASA Technical Reports Server (NTRS)
Cambier, Jean-Luc; Edwards, Thomas A. (Technical Monitor)
1994-01-01
Improvements to a plasma code with a Collisional-Radiative (CR) non-equilibrium model are made, allowing for a more accurate description of the physical processes. The code allows for non-Boltzmann distributions of the electronic excited states by convecting separately each excited state, as a pseudo-specie. Each molecular state has also its own vibrational temperature, while a global rotational temperature is assumed. The free electron temperature is different from those of the excited states, and the electron heat conduction is also included. The CR model also uses a unique coupling between chemistry and vibrational energy (C-V coupling), which is fully coherent, and has the property of establishing thermal equilibrium as well as chemical equilibrium, on its own. We have also included a coupling between electronic excitations and vibrational energy (X-V coupling), which can have a strong influence on the vibrational temperature of some states. The recent improvements include the multi- temperature dependence of the chemical rates for associative ionization, as well as the estimation of the internal energies transferred during this process. Additionally, the distribution of energy into different translational modes (electron and heavy particles) is now correctly modeled. This provides a very rapid heating mechanism for the free electrons, since it is found that the electrons are generated with an average thermal energy of the same order as the heavy particle translational energy. This effect was observed by Gorelov et al in a recent paper, and lead to pronounced peaks in electron temperature immediately behind the shock. We will attempt ro reproduce this phenomenon. The last modification concerns the inclusion of the radiative terms into the calculations, thus enabling us to observe the effect of radiative losses and radiation transport. Preliminary tests have shown that the radiative losses are not negligible, i.e. the shock velocity drops when the radiative
Nonequilibrium electron-vibration coupling and conductance fluctuations in a C60 junction
NASA Astrophysics Data System (ADS)
Ulstrup, Søren; Frederiksen, Thomas; Brandbyge, Mads
2012-12-01
We investigate chemical bond formation and conductance in a molecular C60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong coupling between the C60 motion and the molecular electronic structure. This is only seen for positive sample bias, although the conductance itself is not strongly polarity dependent. The nonequilibrium effect is traced back to a sudden shift in the position of the voltage drop with a small C60 displacement. Combined with a vibrational heating mechanism we construct a model from our results that explain the polarity-dependent two-level conductance fluctuations observed in recent scanning tunneling microscopy (STM) experiments [N. Néel , Nano Lett.NALEFD1530-698410.1021/nl201327c 11, 3593 (2011)]. These findings highlight the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics.
On Typicality in Nonequilibrium Steady States
NASA Astrophysics Data System (ADS)
Evans, Denis J.; Williams, Stephen R.; Searles, Debra J.; Rondoni, Lamberto
2016-08-01
From the statistical mechanical viewpoint, relaxation of macroscopic systems and response theory rest on a notion of typicality, according to which the behavior of single macroscopic objects is given by appropriate ensembles: ensemble averages of observable quantities represent the measurements performed on single objects, because " almost all" objects share the same fate. In the case of non-dissipative dynamics and relaxation toward equilibrium states, " almost all" is referred to invariant probability distributions that are absolutely continuous with respect to the Lebesgue measure. In other words, the collection of initial micro-states (single systems) that do not follow the ensemble is supposed to constitute a set of vanishing, phase space volume. This approach is problematic in the case of dissipative dynamics and relaxation to nonequilibrium steady states, because the relevant invariant distributions attribute probability 1 to sets of zero volume, while evolution commonly begins in equilibrium states, i.e., in sets of full phase space volume. We consider the relaxation of classical, thermostatted particle systems to nonequilibrium steady states. We show that the dynamical condition known as Ω T-mixing is necessary and sufficient for relaxation of ensemble averages to steady state values. Moreover, we find that the condition known as weak T-mixing applied to smooth observables is sufficient for ensemble relaxation to be independent of the initial ensemble. Lastly, we show that weak T-mixing provides a notion of typicality for dissipative dynamics that is based on the (non-invariant) Lebesgue measure, and that we call physical ergodicity.
Viscosity of confined inhomogeneous nonequilibrium fluids
NASA Astrophysics Data System (ADS)
Zhang, Junfang; Todd, B. D.; Travis, Karl P.
2004-12-01
We use the nonlocal linear hydrodynamic constitutive model, proposed by Evans and Morriss [Statistical Mechanics of Nonequilibrium Liquids (Academic, London, 1990)], for computing an effective spatially dependent shear viscosity of inhomogeneous nonequilibrium fluids. The model is applied to a simple atomic fluid undergoing planar Poiseuille flow in a confined channel of several atomic diameters width. We compare the spatially dependent viscosity with a local generalization of Newton's law of viscosity and the Navier-Stokes viscosity, both of which are known to suffer extreme inaccuracies for highly inhomogeneous systems. The nonlocal constitutive model calculates effective position dependent viscosities that are free from the notorious singularities experienced by applying the commonly used local constitutive model. It is simple, general, and has widespread applicability in nanofluidics where experimental measurement of position dependent transport coefficients is currently inaccessible. In principle the method can be used to predict approximate flow profiles of any arbitrary inhomogeneous system. We demonstrate this by predicting the flow profile for a simple fluid undergoing planar Couette flow in a confined channel of several atomic diameters width.
Phase transitions in nonequilibrium traffic theory
Zhang, H.M.
2000-02-01
This paper uses the center difference scheme of Lax-Friedrichs to numerically solve a newly developed continuum traffic flow theory and the kinematic theory of Lighthill and Whitham, and Richards, and it studies the flow-concentration phase transitions in flow containing both shock and rarefaction waves. A homogeneous road with finite length was modeled by both theories. Numerical simulations show that both theories yield nearly identical results for two representative Riemann problems--one has a shock solution and the other a rarefaction wave solution. Their phase transition curves, however, are different: those derived from the new theory have two branches--one for acceleration flow and one for deceleration flow, whereas those derived from the LWR theory comprise a single curve--the equilibrium curve. The phase transition curves in the shock case agree well with certain experimental observations but disagree with others. This disagreement may be resolved by studying transitions among nonequilibrium states, which awaits further development of a more accurate finite difference approximation of the nonequilibrium theory.
Can Thermal Nonequilibrium Explain Coronal Loops?
NASA Technical Reports Server (NTRS)
Klimchuk, James A.; Karpen, Judy T.; Antiochos, Spiro K.
2010-01-01
Any successful model of coronal loops must explain a number of observed properties. For warm (approx. 1 MK) loops, these include: 1. excess density, 2. flat temperature profile, 3. super-hydrostatic scale height, 4. unstructured intensity profile, and 5. 1000-5000 s lifetime. We examine whether thermal nonequilibrium can reproduce the observations by performing hydrodynamic simulations based on steady coronal heating that decreases exponentially with height. We consider both monolithic and multi-stranded loops. The simulations successfully reproduce certain aspects of the observations, including the excess density, but each of them fails in at least one critical way. -Xonolithic models have far too much intensity structure, while multi-strand models are either too structured or too long-lived. Storms of nanoflares remain the only viable explanation for warm loops that has been proposed so far. Our results appear to rule out the widespread existence of heating that is both highly concentrated low in the corona and steady or quasi-steady (slowly varying or impulsive with a rapid cadence). Active regions would have a very different appearance if the dominant heating mechanism had these properties. Thermal nonequilibrium may nonetheless play an important role in prominences and catastrophic cooling e(veen.gts..,coronal rain) that occupy a small fraction of the coronal volume. However, apparent inconsistencies between the models and observations of cooling events have yet to be understood.
Turbulence modeling for non-equilibrium flow
NASA Technical Reports Server (NTRS)
Durbin, P. A.
1995-01-01
The work performed during this year has involved further assessment and extension of the k-epsilon-v(exp 2) model, and initiation of work on scalar transport. The latter is introduced by the contribution of Y. Shabany to this volume. Flexible, computationally tractable models are needed for engineering CFD. As computational technology has progressed, the ability and need to use elaborate turbulence closure models has increased. The objective of our work is to explore and develop new analytical frameworks that might extend the applicability of the modeling techniques. In past years the development of a method for near-wall modeling was described. The method has been implemented into a CFD code and its viability has been demonstrated by various test cases. Further tests are reported herein. Non-equilibrium near-wall models are needed for some heat transfer applications. Scalar transport seems generally to be more sensitive to non-equilibrium effects than is momentum transport. For some applications turbulence anisotropy plays a role and an estimate of the full Reynolds stress tensor is needed. We have begun work on scalar transport per se, but in this brief I will only report on an extension of the k-epsilon-v(exp 2) model to predict the Reynolds stress tensor.
In command of non-equilibrium.
Roduner, Emil; Radhakrishnan, Shankara Gayathri
2016-05-21
The second law of thermodynamics is well known for determining the direction of spontaneous processes in the laboratory, life and the universe. It is therefore often called the arrow of time. Less often discussed but just as important is the effect of kinetic barriers which intercept equilibration and preserve highly ordered, high energy non-equilibrium states. Examples of such states are many modern materials produced intentionally for technological applications. Furthermore, all living organisms fuelled directly by photosynthesis and those fuelled indirectly by living on high energy nutrition represent preserved non-equilibrium states. The formation of these states represents the local reversal of the arrow of time which only seemingly violates the second law. It has been known since the seminal work of Prigogine that the stabilisation of these states inevitably requires the dissipation of energy in the form of waste heat. It is this feature of waste heat dissipation following the input of energy that drives all processes occurring at a non-zero rate. Photosynthesis, replication of living organisms, self-assembly, crystal shape engineering and distillation have this principle in common with the well-known Carnot cycle in the heat engine. Drawing on this analogy, we subsume these essential and often sophisticated driven processes under the term machinery of life. PMID:27146424
Temperature Anisotropies of Thermal Non-equilibrium Ions by a Nonresonant AlfvÉn Wave
NASA Astrophysics Data System (ADS)
Liu, Hai-Feng; Tang, Chang-Jian; Wang, Xian-Qu; Zhang, Xin; Zhao, Yong
2016-09-01
From a significant view, considering the thermal non-equilibrium factor, we investigate Kappa (κ) ion temperature anisotropies induced by a low-frequency parallel propagating Alfvén wave by combining quasi-linear theory and test particle simulation. Analytic expressions for the ion temperature ratios {T}\\perp i/{T}//i and {T}\\perp i/{T}\\perp j are derived for the solar wind, where {T}\\perp i,{T}//i and {T}\\perp j denote the perpendicular temperature of species i, parallel temperature of species i, and perpendicular temperature of species j, respectively. The results of our model are broadly consistent, compared to observations of solar-wind measurements. Solar wind helium that meets the condition for strong core heating is nearly seven times hotter than hydrogen, on average. Furthermore, we note that we are able to predict the temperature anisotropies of ions based on their thermal non-equilibrium factors.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Yildiz, Bilge; Herbert, F. William; Senanayake, Sanjaya D.
2015-03-09
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr{sup 1+}, Zr{sup 2+}, and Zr{sup 3+} as non-equilibrium oxidation states, in addition to Zr{sup 4+} in the stoichiometric ZrO{sub 2}. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr{sup 0} and Zr{sup 4+} at the metal-oxide interface. The presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.
NASA Astrophysics Data System (ADS)
Jiang, Shixiao W.; Lu, Haihao; Zhou, Douglas; Cai, David
2016-08-01
Characterizing dispersive wave turbulence in the long time dynamics is central to understanding of many natural phenomena, e.g., in atmosphere ocean dynamics, nonlinear optics, and plasma physics. Using the β-Fermi-Pasta-Ulam nonlinear system as a prototypical example, we show that in thermal equilibrium and non-equilibrium steady state the turbulent state even in the strongly nonlinear regime possesses an effective linear stochastic structure in renormalized normal variables. In this framework, we can well characterize the spatiotemporal dynamics, which are dominated by long-wavelength renormalized waves. We further demonstrate that the energy flux is nearly saturated by the long-wavelength renormalized waves in non-equilibrium steady state. The scenario of such effective linear stochastic dynamics can be extended to study turbulent states in other nonlinear wave systems.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Senanayake, Sanjaya D.; Herbert, F. William; Yildiz, Bilge
2015-03-11
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr1+, Zr2+, and Zr3+ as non-equilibrium oxidation states, in addition to Zr4+ in the stoichiometric ZrO2. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr0 and Zr4+ at the metal-oxide interface. As a result, the presence of local strong electric fields andmore » the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.« less
Critical wetting of a class of nonequilibrium interfaces: a mean-field picture.
de Los Santos, Francisco; Romera, Elvira; Al Hammal, Omar; Muñoz, Miguel Angel
2007-03-01
A self-consistent mean-field method is used to study critical wetting transitions under nonequilibrium conditions by analyzing Kardar-Parisi-Zhang (KPZ) interfaces in the presence of a bounding substrate. In the case of positive KPZ nonlinearity a single (Gaussian) regime is found. On the contrary, interfaces corresponding to negative nonlinearities lead to three different regimes of critical behavior for the surface order parameter: (i) a trivial Gaussian regime, (ii) a weak-fluctuation regime with a trivially located critical point and nontrivial exponents, and (iii) a highly nontrivial strong-fluctuation regime, for which we provide a full solution by finding the zeros of parabolic-cylinder functions. These analytical results are also verified by solving numerically the self-consistent equation in each case. Analogies with and differences from equilibrium critical wetting as well as nonequilibrium complete wetting are also discussed.
Altaner, Bernhard; Wachtel, Artur; Vollmer, Jürgen
2015-10-01
Unlike macroscopic engines, the molecular machinery of living cells is strongly affected by fluctuations. Stochastic thermodynamics uses Markovian jump processes to model the random transitions between the chemical and configurational states of these biological macromolecules. A recently developed theoretical framework [A. Wachtel, J. Vollmer, and B. Altaner, Phys. Rev. E 92, 042132 (2015)] provides a simple algorithm for the determination of macroscopic currents and correlation integrals of arbitrary fluctuating currents. Here we use it to discuss energy conversion and nonequilibrium response in different models for the molecular motor kinesin. Methodologically, our results demonstrate the effectiveness of the algorithm in dealing with parameter-dependent stochastic models. For the concrete biophysical problem our results reveal two interesting features in experimentally accessible parameter regions: the validity of a nonequilibrium Green-Kubo relation at mechanical stalling as well as a negative differential mobility for superstalling forces.
Partially coherent contrast-transfer-function approximation.
Nesterets, Yakov I; Gureyev, Timur E
2016-04-01
The contrast-transfer-function (CTF) approximation, widely used in various phase-contrast imaging techniques, is revisited. CTF validity conditions are extended to a wide class of strongly absorbing and refracting objects, as well as to nonuniform partially coherent incident illumination. Partially coherent free-space propagators, describing amplitude and phase in-line contrast, are introduced and their properties are investigated. The present results are relevant to the design of imaging experiments with partially coherent sources, as well as to the analysis and interpretation of the corresponding images. PMID:27140752
Properties of coherence-gated wavefront sensing.
Rueckel, Markus; Denk, Winfried
2007-11-01
Coherence-gated wavefront sensing (CGWS) allows the determination of wavefront aberrations in strongly scattering tissue and their correction by adaptive optics. This allows, e.g., the restoration of the diffraction limit in light microscopy. Here, we develop a model, based on ray tracing of ballistic light scattered from a set of discrete scatterers, to characterize CGWS performance as it depends on coherence length, scatterer density, coherence-gate position, and polarization. The model is evaluated by using Monte Carlo simulation and verified against experimental measurements. We show, in particular, that all aberrations needed for adaptive wavefront restoration are correctly sensed if circularly polarized light is used. PMID:17975579
Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1991-01-01
The primary tasks performed are: (1) the development of a second order local thermodynamic nonequilibrium (LTNE) model for atoms; (2) the continued development of vibrational nonequilibrium models; and (3) the development of a new multicomponent diffusion model. In addition, studies comparing these new models with previous models and results were conducted and reported.
Three-dimensional AOTV flowfields in chemical nonequilibrium
NASA Technical Reports Server (NTRS)
Gnoffo, P. A.; Mccandless, R. S.
1986-01-01
A technique for upwind differencing of the three-dimensional species continuity equations is presented which permits computation of steady flows in chemical equilibrium and nonequilibrium. The capabilities and shortcomings of the present approach for equilibrium and nonequilibrium flows is discussed. Modifications now being investigated to improve computational time are outlined.
Recent advances of strong-strong beam-beam simulation
Qiang, Ji; Furman, Miguel A.; Ryne, Robert D.; Fischer, Wolfram; Ohmi,Kazuhito
2004-09-15
In this paper, we report on recent advances in strong-strong beam-beam simulation. Numerical methods used in the calculation of the beam-beam forces are reviewed. A new computational method to solve the Poisson equation on nonuniform grid is presented. This method reduces the computational cost by a half compared with the standard FFT based method on uniform grid. It is also more accurate than the standard method for a colliding beam with low transverse aspect ratio. In applications, we present the study of coherent modes with multi-bunch, multi-collision beam-beam interactions at RHIC. We also present the strong-strong simulation of the luminosity evolution at KEKB with and without finite crossing angle.
Design and Synthesis of Nonequilibrium Systems.
Cheng, Chuyang; McGonigal, Paul R; Stoddart, J Fraser; Astumian, R Dean
2015-09-22
The active transport of ions and molecules across cell membranes is essential to creating the concentration gradients that sustain life in all living organisms, be they bacteria, fungi, plants, animals or Homo sapiens. Nature uses active transport everywhere for everything. Molecular biologists have long been attracted to the study of active transport and continue to this day to investigate and elucidate the tertiary structures of the complex motor proteins that sustain it, while physicists, interested in nonequilibrium statistical mechanics, have developed theoretical models to describe the driven ratcheting motions that are crucial to its function. The increasingly detailed understanding that contemporary science has acquired relating to active transport, however, has yet to lead to the design and construction of artificial molecular motors capable of employing ratchet-driven motions that can also perform work against concentration gradients. Mechanically interlocked molecules (MIMs) in the form of pseudo- and semirotaxanes are showing some encouraging signs in meeting these goals. This review summarizes recent progress in making artificial molecular motors that can perform work by "pumping" tetracationic rings into high-energy states. The launching pad is a bistable [2]rotaxane whose dumbbell component contains two electron-donating recognition sites, one, a tetrathiafulvalene (TTF) unit, which interacts more strongly with the ring component, cyclobis(paraquat-p-phenylene) (CBPQT(4+)), containing two electron-accepting bipyridinium units, than does the other 1,5-dioxynaphthalene (DNP) unit. Switching can be induced electrochemically by oxidizing the TTF unit to a TTF(•+) radical cation, whereupon Coulombic repulsion takes care of moving the ring to the DNP unit. Reduction of the radical cation resets the switch. Molecular switches operate at, or close to, equilibrium. Any work done during one switching event is undone during the reset. Molecular motors, on the
Conditional reversibility in nonequilibrium stochastic systems.
Bonança, Marcus V S; Jarzynski, Christopher
2016-02-01
For discrete-state stochastic systems obeying Markovian dynamics, we establish the counterpart of the conditional reversibility theorem obtained by Gallavotti for deterministic systems [Ann. de l'Institut Henri Poincaré (A) 70, 429 (1999)]. Our result states that stochastic trajectories conditioned on opposite values of entropy production are related by time reversal, in the long-time limit. In other words, the probability of observing a particular sequence of events, given a long trajectory with a specified entropy production rate σ, is the same as the probability of observing the time-reversed sequence of events, given a trajectory conditioned on the opposite entropy production, -σ, where both trajectories are sampled from the same underlying Markov process. To obtain our result, we use an equivalence between conditioned ("microcanonical") and biased ("canonical") ensembles of nonequilibrium trajectories. We provide an example to illustrate our findings. PMID:26986282
Stochastic approach to equilibrium and nonequilibrium thermodynamics
NASA Astrophysics Data System (ADS)
Tomé, Tânia; de Oliveira, Mário J.
2015-04-01
We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions.
Nonequilibrium phases of nanoparticle Langmuir films.
Vegso, Karol; Siffalovic, Peter; Majkova, Eva; Jergel, Matej; Benkovicova, Monika; Kocsis, Teodora; Weis, Martin; Luby, Stefan; Nygård, Kim; Konovalov, Oleg
2012-07-17
We report on an in-situ observation of the colloidal silver nanoparticle self-assembly into a close-packed monolayer at the air/water interface followed by a 2D to 3D transition. Using the fast tracking GISAXS technique, we were able to observe the immediate response to the compression of the self-assembled nanoparticle layer at the air/water interface and to identify all relevant intermediate stages including those far from the equilibrium. In particular, a new nonequilibrium phase before the monolayer collapse via the 2D to 3D transition was found that is inaccessible by the competing direct space imaging techniques such as the scanning and transmission electron microscopies due to the high water vapor pressure and surface tension. PMID:22724517
Thermodynamics of Nonequilibrium Systems with Feedback Control
NASA Astrophysics Data System (ADS)
Sagawa, Takahiro
2015-03-01
In modern nonequilibrium physics, ``Maxwell's demon'' has attracted renewed attentions in both terms of theory and experiment. The demon plays a key role to unify thermodynamics and information theory, which can extract the useful work from a heat bath by using the obtained information via feedback control. In this talk, I will talk about the recent development of thermodynamics of information. In particular, I will focus on the generalizations of the second law of thermodynamics and the Jarzynski equality in the presence of feedback control, where information contents and thermodynamic quantities are treated on an equal footing. I will also discuss recent experimental results that realized Maxwell's demon by colloidal particles and single electrons.
Specific mass increment and nonequilibrium crystal growth
NASA Astrophysics Data System (ADS)
Martyushev, Leonid M.; Terentiev, Pavel S.
2013-09-01
Unsteady nonequilibrium crystallization of ammonium chloride from an aqueous solution resulting in the formation of irregular, so-called seaweed, structures is experimentally investigated. It is shown that specific increment of mass for the coexisting structures (or parts thereof) is the same and changes with time (t) according to the power law a/t-b, where the factor a=1.87±0.09 and the factor b is determined by the system relaxation time. The normalization of the power law to the total time of structure growth allows obtaining a universal law that describes the specific mass increment with time for both seaweed and dendrite structures (including the non-coexisting ones).
Conditional reversibility in nonequilibrium stochastic systems.
Bonança, Marcus V S; Jarzynski, Christopher
2016-02-01
For discrete-state stochastic systems obeying Markovian dynamics, we establish the counterpart of the conditional reversibility theorem obtained by Gallavotti for deterministic systems [Ann. de l'Institut Henri Poincaré (A) 70, 429 (1999)]. Our result states that stochastic trajectories conditioned on opposite values of entropy production are related by time reversal, in the long-time limit. In other words, the probability of observing a particular sequence of events, given a long trajectory with a specified entropy production rate σ, is the same as the probability of observing the time-reversed sequence of events, given a trajectory conditioned on the opposite entropy production, -σ, where both trajectories are sampled from the same underlying Markov process. To obtain our result, we use an equivalence between conditioned ("microcanonical") and biased ("canonical") ensembles of nonequilibrium trajectories. We provide an example to illustrate our findings.
Water in Renewable Polymers: Nonequilibrium Thermodynamics
NASA Astrophysics Data System (ADS)
Elabd, Yossef
2015-03-01
The design of polymers derived from sustainable resources (renewable polymers) as replacements to nonrenewable plastics for various applications will require an accurate assessment and fundamental understanding of the dynamics water sorption in glassy polymers. In this work, water sorption and diffusion in a number of glassy polymers (including the renewable polymer poly(lactide)) were measured using gravimetric and spectroscopic techniques. Non-Fickian diffusion was observed in all polymers studied, which was indicated by rapid, initial water uptake (driven by a concentration gradient), followed by continuous, gradual uptake of water at later experimental times (driven by slow polymer relaxation). Additionally, water sorption in these glassy polymers was predicted using two nonequilibrium thermodynamic models, where excellent agreement between the model prediction and experimental data was achieved for both models. Furthermore, contrasting physical pictures of water clustering were obtained between the Zimm-Lundberg theory and direct measurements. National Science Foundation.
Nonequilibrium bubbles in a flowing langmuir monolayer.
Muruganathan, Rm; Khattari, Z; Fischer, Th M
2005-11-24
We investigate the nonequilibrium behavior of two-dimensional gas bubbles in Langmuir monolayers. A cavitation bubble is induced in liquid expanded phase by locally heating a Langmuir monolayer with an IR-laser. At low IR-laser power the cavitation bubble is immersed in quiescent liquid expanded monolayer. At higher IR-laser power thermo capillary flow around the laser-induced cavitation bubble sets in. The thermo capillary flow is caused by a temperature dependence of the gas/liquid line tension. The slope of the line tension with temperature is determined by measuring the thermo capillary flow velocity. Thermodynamically stable satellite bubbles are generated by increasing the surface area of the monolayer. Those satellite bubbles collide with the cavitation bubble. Upon collision the satellite bubbles either coalesce with the cavitation bubble or slide past the cavitation bubble. Moreover we show that the satellite bubbles can also be produced by the emission from the laser-induced cavitation bubbles.
Nanoscale imaging of nonequilibrium polymer films
NASA Astrophysics Data System (ADS)
King, John; Granick, Steve
2015-03-01
In recent years there have been exciting advances in sub-diffraction limited imaging based on fluorescence microscopy. While most applications of super-resolution microscopy focus on static biological imaging, we are interested in extending these techniques to the study of polymer dynamics. To this end, we couple stimulated emission depletion (STED) with spectroscopic detection, relying on spectral features of fluorescence emission to serve as the imaging contrast agent. We aim to adapt fluorescent dyes responsive to environmental properties (polarity, mobility, current, temperature, ect.) to STED imaging. Using the fluorescent spectral response as a contrast agent allows for nanoscopic environments to be directly imaged without the need for specific labeling. Rapid acquisition of images allows for slow dynamic processes in nonequilibrium polymer films to be imaged in real time. We demonstrate the power of super-resolution spectroscopic imaging by directly imaging several topical problems in materials science.
Flowing crystals: nonequilibrium structure of foam.
Garstecki, Piotr; Whitesides, George M
2006-07-14
Bubbles pushed through a quasi-two-dimensional channel self-organize into a variety of periodic lattices. The structures of these lattices correspond to local minima of the interfacial energy. The "flowing crystals" are long-lived metastable states, a small subset of possible local minima of confined quasi-two-dimensional foams [P. Garstecki and G. M. Whitesides, Phys. Rev. E 73, 031603 (2006)10.1103/PhysRevE.73.031603]. Experimental results suggest that the choice of the structures that we observe is dictated by the dynamic stability of the cyclic processes of their formation. Thus, the dynamic system that we report provides a unique example of nonequilibrium self-organization that results in structures that correspond to local minima of the relevant energy functional. PMID:16907453
Stochastic approach to equilibrium and nonequilibrium thermodynamics.
Tomé, Tânia; de Oliveira, Mário J
2015-04-01
We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions. PMID:25974471
Non-equilibrium quantum heat machines
NASA Astrophysics Data System (ADS)
Alicki, Robert; Gelbwaser-Klimovsky, David
2015-11-01
Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.
Nonequilibrium phase transitions in biomolecular signal transduction
NASA Astrophysics Data System (ADS)
Smith, Eric; Krishnamurthy, Supriya; Fontana, Walter; Krakauer, David
2011-11-01
We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework.
Conditional reversibility in nonequilibrium stochastic systems
NASA Astrophysics Data System (ADS)
Bonança, Marcus V. S.; Jarzynski, Christopher
2016-02-01
For discrete-state stochastic systems obeying Markovian dynamics, we establish the counterpart of the conditional reversibility theorem obtained by Gallavotti for deterministic systems [Ann. de l'Institut Henri Poincaré (A) 70, 429 (1999)]. Our result states that stochastic trajectories conditioned on opposite values of entropy production are related by time reversal, in the long-time limit. In other words, the probability of observing a particular sequence of events, given a long trajectory with a specified entropy production rate σ , is the same as the probability of observing the time-reversed sequence of events, given a trajectory conditioned on the opposite entropy production, -σ , where both trajectories are sampled from the same underlying Markov process. To obtain our result, we use an equivalence between conditioned ("microcanonical") and biased ("canonical") ensembles of nonequilibrium trajectories. We provide an example to illustrate our findings.
Stochastic approach to equilibrium and nonequilibrium thermodynamics.
Tomé, Tânia; de Oliveira, Mário J
2015-04-01
We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions.
Nonequilibrium microstructures for Ag-Ni nanowires.
Rai, Rajesh K; Srivastava, Chandan
2015-04-01
This work illustrates that a variety of nanowire microstructures can be obtained either by controlling the nanowire formation kinetics or by suitable thermal processing of as-deposited nanowires with nonequilibrium metastable microstructure. In the present work, 200-nm diameter Ag-Ni nanowires with similar compositions, but with significantly different microstructures, were electrodeposited. A 15 mA deposition current produced nanowires in which Ag-rich crystalline nanoparticles were embedded in a Ni-rich amorphous matrix. A 3 mA deposition current produced nanowires in which an Ag-rich crystalline phase formed a backbone-like configuration in the axial region of the nanowire, whereas the peripheral region contained Ni-rich nanocrystalline and amorphous phases. Isothermal annealing of the nanowires illustrated a phase evolution pathway that was extremely sensitive to the initial nanowire microstructure.
Harmonic oscillator in presence of nonequilibrium environment
Chaudhuri, Jyotipratim Ray; Chaudhury, Pinaki; Chattopadhyay, Sudip
2009-06-21
Based on a microscopic Hamiltonian picture where the system is coupled with the nonequilibrium environment, comprising of a set of harmonic oscillators, the Langevin equation with proper microscopic specification of Langevin force is formulated analytically. In our case, the reservoir is perturbed by an external force, either executing rapid or showing periodic fluctuations, hence the reservoir is not in thermal equilibrium. In the presence of external fluctuating force, using Shapiro-Loginov procedure, we arrive at the linear coupled first order differential equations for the two-time correlations and examine the time evolution of the same considering the system as a simple harmonic oscillator. We study the stochastic resonance phenomena of a Kubo-type oscillator (assumed to be the system) when the bath is modulated by a periodic force. The result(s) obtained here is of general significance and can be used to analyze the signature of stochastic resonance.
Discriminatory Proofreading Regimes in Nonequilibrium Systems
NASA Astrophysics Data System (ADS)
Murugan, Arvind; Huse, David A.; Leibler, Stanislas
2014-04-01
We use ideas from kinetic proofreading, an error-correcting mechanism in biology, to identify new kinetic regimes in nonequilibrium systems. These regimes are defined by the sensitivity of the occupancy of a state of the system to a change in its energy. In biological contexts, higher sensitivity corresponds to stronger discrimination between molecular substrates with different energetics competing in the same reaction. We study this discriminatory ability in systems with discrete states that are connected by a general network of transitions. We find multiple regimes of different discriminatory ability when the energy of a given state of the network is varied. Interestingly, the occupancy of the state can even increase with its energy, corresponding to an "antiproofreading" regime. The number and properties of such discriminatory regimes are limited by the topology of the network. Finally, we find that discriminatory regimes can be changed without modifying any "hard-wired" structural aspects of the system but rather by simply changing external chemical potentials.
Nonequilibrium route to nanodiamond with astrophysical implications.
Marks, N A; Lattemann, M; McKenzie, D R
2012-02-17
Nanometer-sized diamond grains are commonly found in primitive chondritic meteorites, but their origin is puzzling. Using evidence from atomistic simulation, we establish a mechanism by which nanodiamonds form abundantly in space in a two-stage process involving condensation of vapor to form carbon onions followed by transformation to nanodiamond in an energetic impact. This nonequilibrium process is consistent with common environments in space and invokes the fewest assumptions of any proposed model. Accordingly, our model can explain nanodiamond formation in both presolar and solar environments. The model provides an attractive framework for understanding noble gas incorporation and explains all key features of meteoritic nanodiamond, including size, shape, and polytype. By understanding the creation of nanodiamonds, new opportunities arise for their exploitation as a powerful astrophysical probe. PMID:22401225
Nonequilibrium Route to Nanodiamond with Astrophysical Implications
NASA Astrophysics Data System (ADS)
Marks, N. A.; Lattemann, M.; McKenzie, D. R.
2012-02-01
Nanometer-sized diamond grains are commonly found in primitive chondritic meteorites, but their origin is puzzling. Using evidence from atomistic simulation, we establish a mechanism by which nanodiamonds form abundantly in space in a two-stage process involving condensation of vapor to form carbon onions followed by transformation to nanodiamond in an energetic impact. This nonequilibrium process is consistent with common environments in space and invokes the fewest assumptions of any proposed model. Accordingly, our model can explain nanodiamond formation in both presolar and solar environments. The model provides an attractive framework for understanding noble gas incorporation and explains all key features of meteoritic nanodiamond, including size, shape, and polytype. By understanding the creation of nanodiamonds, new opportunities arise for their exploitation as a powerful astrophysical probe.
NASA Astrophysics Data System (ADS)
Richings, A. J.; Schaye, Joop
2016-05-01
We present a series of hydrodynamic simulations of isolated galaxies with stellar mass of 109 M⊙. The models use a resolution of 750 M⊙ per particle and include a treatment for the full non-equilibrium chemical evolution of ions and molecules (157 species in total), along with gas cooling rates computed self-consistently using the non-equilibrium abundances. We compare these to simulations evolved using cooling rates calculated assuming chemical (including ionization) equilibrium, and we consider a wide range of metallicities and UV radiation fields, including a local prescription for self-shielding by gas and dust. We find higher star formation rates and stronger outflows at higher metallicity and for weaker radiation fields, as gas can more easily cool to a cold (few hundred Kelvin) star-forming phase under such conditions. Contrary to variations in the metallicity and the radiation field, non-equilibrium chemistry generally has no strong effect on the total star formation rates or outflow properties. However, it is important for modelling molecular outflows. For example, the mass of H2 outflowing with velocities {>}50 {km} {s}^{-1} is enhanced by a factor ˜20 in non-equilibrium. We also compute the observable line emission from C II and CO. Both are stronger at higher metallicity, while C II and CO emission are higher for stronger and weaker radiation fields, respectively. We find that C II is generally unaffected by non-equilibrium chemistry. However, emission from CO varies by a factor of ˜2-4. This has implications for the mean XCO conversion factor between CO emission and H2 column density, which we find is lowered by up to a factor ˜2.3 in non-equilibrium, and for the fraction of CO-dark molecular gas.
Quantum simulation of non-equilibrium dynamical maps with trapped ions
NASA Astrophysics Data System (ADS)
Schindler, Philipp; Müller, Markus; Nigg, Daniel; Monz, Thomas; Barreiro, Julio; Martinez, Esteban; Hennrich, Markus; Diehl, Sebastian; Zoller, Peter; Blatt, Rainer
2013-03-01
Dynamical maps are central for the understanding of general state transformations of physical systems. Prime examples include classical nonlinear systems undergoing transitions to chaos, or single particle quantum mechanical counterparts showing intriguing phenomena such as dynamical localization. Here, we extend the concept of dynamical maps to an open-system, many-particle context and experimentally explore the stroboscopic dynamics of a complex many-body spin model in a universal quantum simulator using up to five ions. We generate quantum mechanical long range order by an iteration of purely dissipative maps, reveal the characteristic features of a combined coherent and dissipative non-equilibrium evolution, and develop and implement various error detection and reduction techniques that will facilitate the faithful quantum simulation of larger systems.
Non-equilibrium critical properties of the Ising model on product graphs
NASA Astrophysics Data System (ADS)
Burioni, Raffaella; Corberi, Federico; Vezzani, Alessandro
2010-12-01
We study numerically the non-equilibrium critical properties of the Ising model defined on direct products of graphs, obtained from factor graphs without phase transition (Tc = 0). On this class of product graphs, the Ising model features a finite temperature phase transition, and we find a pattern of scaling behaviors analogous to the one known on regular lattices: observables take a scaling form in terms of a function L(t) of time, with the meaning of a growing length inside which a coherent fractal structure, the critical state, is progressively formed. Computing universal quantities, such as the critical exponents and the limiting fluctuation-dissipation ratio X_\\infty , allows us to comment on the possibility to extend universality concepts to the critical behavior on inhomogeneous substrates.
Light steering in a strongly nonlocal nonlinear medium
Ouyang Shigen; Hu Wei; Guo Qi
2007-11-15
With a strongly nonlocal model, we present an analytical solution of the coherent interaction of two Gaussian beams with an arbitrary phase difference and arbitrary incident angles. Numerical simulations show that the analytical solution can describe the interaction of two Gaussian beams very well in the strongly nonlocal case. It is theoretically shown that one can steer lights in strongly nonlocal media by tuning the incident conditions of coherently interacting beams like the phase difference between beams and their relative amplitude.
Göppel, Tobias; Palyulin, Vladimir V; Gerland, Ulrich
2016-07-27
An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting.
Nonequilibrium statistical mechanics of mixtures of particles in contact with different thermostats
NASA Astrophysics Data System (ADS)
Grosberg, A. Y.; Joanny, J.-F.
2015-09-01
We introduce a novel type of locally driven systems made of two types of particles (or a polymer with two types of monomers) subject to a chaotic drive with approximately white noise spectrum, but different intensity; in other words, particles of different types are in contact with thermostats at different temperatures. We present complete systematic statistical mechanics treatment starting from first principles. Although we consider only corrections to the dilute limit due to pairwise collisions between particles, meaning we study a nonequilibrium analog of the second virial approximation, we find that the system exhibits a surprisingly rich behavior. In particular, pair correlation function of particles has an unusual quasi-Boltzmann structure governed by an effective temperature distinct from that of any of the two thermostats. We also show that at sufficiently strong drive the uniformly mixed system becomes unstable with respect to steady states consisting of phases enriched with different types of particles. In the second virial approximation, we define nonequilibrium "chemical potentials" whose gradients govern diffusion fluxes and a nonequilibrium "osmotic pressure," which governs the mechanical stability of the interface.
Nonequilibrium statistical mechanics of mixtures of particles in contact with different thermostats.
Grosberg, A Y; Joanny, J-F
2015-09-01
We introduce a novel type of locally driven systems made of two types of particles (or a polymer with two types of monomers) subject to a chaotic drive with approximately white noise spectrum, but different intensity; in other words, particles of different types are in contact with thermostats at different temperatures. We present complete systematic statistical mechanics treatment starting from first principles. Although we consider only corrections to the dilute limit due to pairwise collisions between particles, meaning we study a nonequilibrium analog of the second virial approximation, we find that the system exhibits a surprisingly rich behavior. In particular, pair correlation function of particles has an unusual quasi-Boltzmann structure governed by an effective temperature distinct from that of any of the two thermostats. We also show that at sufficiently strong drive the uniformly mixed system becomes unstable with respect to steady states consisting of phases enriched with different types of particles. In the second virial approximation, we define nonequilibrium "chemical potentials" whose gradients govern diffusion fluxes and a nonequilibrium "osmotic pressure," which governs the mechanical stability of the interface. PMID:26465437
NASA Astrophysics Data System (ADS)
Pan, D.; Pepe, G. P.; Pagliarulo, V.; Lisio, C. De; Parlato, L.; Khafizov, M.; Komissarov, I.; Sobolewski, Roman
2008-11-01
Time-resolved optical pump-probe and photoimpedance studies of proximized ferromagnet/superconductor nanobilayers are presented. The weak ferromagnetic nature of an ultrathin Ni0.48Cu0.52 film makes it possible to observe the dynamics of the nonequilibrium superconductivity in NiCu/Nb hybrids through time-resolved measurements of a near-surface optical reflectivity change, which is generated by femtosecond optical pump pulses and discussed within a nonequilibrium two-temperature electron-heating model. We observed that the NiCu overlay significantly reduced the slow bolometric contribution present in the photoresponse of a pure Nb film, resulting in a strong enhancement of the nonequilibrium kinetic-inductive component of the transient photoimpedance, measured as an ˜700-ps -wide voltage waveform generated across an optically excited current-biased NiCu/Nb bilayer microbridge. The sensitive picosecond photoresponse makes our NiCu/Nb heterostructures suitable for “engineered” ultrafast superconducting photodetectors since the photoimpedance signals observed in plain Nb bridges were at least 10ns long and were due to the light-induced simple-heating effect.
Coherent-state-induced transparency
NASA Astrophysics Data System (ADS)
Gogyan, A.; Malakyan, Yu.
2016-04-01
We examine electromagnetically induced transparency (EIT) in an ensemble of cold Λ -type atoms induced by a quantum control field in multimode coherent states and compare it with the transparency created by the classical light of the same intensity. We show that the perfect coincidence is achieved only in the case of a single-mode coherent state, whereas the transparency sharply decreases, when the number of the modes exceeds the mean number of control photons in the medium. The origin of the effect is the modification of photon statistics in the control field with increasing the number of the modes that weakens its interaction with atoms resulting in a strong probe absorption. For the same reason, the probe pulse transforms from EIT-based slow light into superluminal propagation caused by the absorption.
Development of unified Reynolds stress models for non-equilibrium turbulent flows
NASA Astrophysics Data System (ADS)
Xu, Xiang-Hua
Turbulence modeling has played a major role in the calculation of turbulent flows of engineering importance. To solve the flow problems that arise in both nature and engineering, a variety of Reynolds stress models--including simple eddy viscosity models based on the Prandtl mixing length hypothesis, one-equation and two-equation models, nonlinear two-equation and explicit algebraic stress models, as well as full second-order closures--have been proposed during the past few decades. These models, which are typically based on benchmark near-equilibrium turbulence experimental data, perform fairly well in a variety of turbulent flows that are not far from equilibrium. However, it is now well recognized that these models cannot correctly predict turbulent flows that are far from equilibrium. In this dissertation, it is shown that they cannot even properly predict homogeneous turbulent flows that are in strongly strained non-equilibrium states. Two benchmark flows--homogeneous turbulent shear flow and homogeneous plane strain turbulence--are chosen to evaluate the performance of existing turbulence models since these two benchmark flows constitute idealizations of real engineering turbulent flows. It is found that none of the existing Reynolds stress models (including a recent version of a non-equilibrium, near-wall model) can predict results that compare favorably with Rapid Distortion Theory (RDT) in strongly distorted turbulent flows that are far from equilibrium. Moreover, it is demonstrated that the standard linear and nonlinear two-equation models can predict enormous negative values of the normal Reynolds stresses in non-equilibrium homogeneous turbulence that strongly violate basic realizability constraints. In light of the poor performance of existing Reynolds stress models in non-equilibrium homogeneous turbulence, two new Reynolds stress models are developed herein--an explicit algebraic stress model and a full second-order closure--that can correctly
Investigations of eddy coherence in jet flows
NASA Technical Reports Server (NTRS)
Yule, A. J.
1980-01-01
In turbulent shear flow the term coherent structures refers to eddies which are both spatially coherent, i.e., large eddies, aand also temporally coherent, i.e., they retain their identities for times which are long compared with their time scales in fixed point measurements. In transitional flows, the existence of such structures is evident from flow visualizations. In many other flows, such structures are not so evident. The reasons for the existence of these two classes of flows are discussed and attention is focused upon the more difficult flows, where coherent structures are not so evident. Techniques by which the existence (or nonexistence) of such structures in these flows can be established from point measurements, are also discussed. A major problem is shown to be the need to discriminate between real losses in eddy coherence and apparent losses in coherence introduced by phase scrambling effects which 'smear' multipoint correlations. The analysis of multiprobe time dependent data in cold and reacting round turbulent jets is described and it is shown how evidence of strong eddy coherence can be extracted from data.
Quasicritical brain dynamics on a nonequilibrium Widom line
NASA Astrophysics Data System (ADS)
Williams-García, Rashid V.; Moore, Mark; Beggs, John M.; Ortiz, Gerardo
2014-12-01
Is the brain really operating at a critical point? We study the nonequilibrium properties of a neural network which models the dynamics of the neocortex and argue for optimal quasicritical dynamics on the Widom line where the correlation length and information transmission are optimized. We simulate the network and introduce an analytical mean-field approximation, characterize the nonequilibrium phase transitions, and present a nonequilibrium phase diagram, which shows that in addition to an ordered and disordered phase, the system exhibits a "quasiperiodic" phase corresponding to synchronous activity in simulations, which may be related to the pathological synchronization associated with epilepsy.
Random paths and current fluctuations in nonequilibrium statistical mechanics
Gaspard, Pierre
2014-07-15
An overview is given of recent advances in nonequilibrium statistical mechanics about the statistics of random paths and current fluctuations. Although statistics is carried out in space for equilibrium statistical mechanics, statistics is considered in time or spacetime for nonequilibrium systems. In this approach, relationships have been established between nonequilibrium properties such as the transport coefficients, the thermodynamic entropy production, or the affinities, and quantities characterizing the microscopic Hamiltonian dynamics and the chaos or fluctuations it may generate. This overview presents results for classical systems in the escape-rate formalism, stochastic processes, and open quantum systems.
Nonequilibrium radiation and dissociation of CO molecules in shock-heated flows
NASA Astrophysics Data System (ADS)
Macdonald, R. L.; Munafò, A.; Johnston, C. O.; Panesi, M.
2016-08-01
This work addresses the study of the behavior of the excited electronic states of CO molecules in the nonequilibrium relaxation zone behind a normal shock for a CO2-N2 mixture representative of the Mars atmosphere. The hybrid state-to-state (StS) model developed accounts for thermal nonequilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The electronic states of CO molecules are treated as separate species, allowing for non-Boltzmann distributions of their populations. The StS model is coupled with a nonequilibrium radiation solver, hpc-rad, allowing for the calculation of the radiation signature from the molecular and atomic species in the gas. This study focuses on the radiation from the fourth positive system of CO, which dominates the radiation heating on the forebody for higher speed Mars entry applications. In the rapidly dissociating regime behind strong shock waves, the population of the ground electronic state of CO [ CO(X 1Σ )], departs from Maxwell-Boltzmann distributions, owing to the efficient collisional excitation to the electronically excited CO(A 1Π ) state. In general the assumption of the equilibrium between electronic and vibration fails when the excitation of electronic states is driven by heavy particles. The comparison of the radiation heating predictions obtained using the conventional quasi-steady-state (QSS) approach and the physics-based StS approach revealed differences in radiative heating predictions of up to 50%. These results demonstrate that the choice of nonequilibrium model can have a significant impact on radiative heating simulations, and more importantly, they cast serious doubts on the validity of the QSS assumption for the condition of interest to this work.
A probability theory for non-equilibrium gravitational systems
NASA Astrophysics Data System (ADS)
Peñarrubia, Jorge
2015-08-01
This paper uses dynamical invariants to describe the evolution of collisionless systems subject to time-dependent gravitational forces without resorting to maximum-entropy probabilities. We show that collisionless relaxation can be viewed as a special type of diffusion process in the integral-of-motion space. In time-varying potentials with a fixed spatial symmetry the diffusion coefficients are closely related to virial quantities, such as the specific moment of inertia, the virial factor and the mean kinetic and potential energy of microcanonical particle ensembles. The non-equilibrium distribution function is found by convolving the initial distribution function with the Green function that solves Einstein's equation for freely diffusing particles. Such a convolution also yields a natural solution to the Fokker-Planck equations in the energy space. Our mathematical formalism can be generalized to potentials with a time-varying symmetry, where diffusion extends over multiple dimensions of the integral-of-motion space. The new probability theory is in many ways analogous to stochastic calculus, with two significant differences: (i) the equations of motion that govern the trajectories of particles are fully deterministic, and (ii) the diffusion coefficients can be derived self-consistently from microcanonical phase-space averages without relying on ergodicity assumptions. For illustration we follow the cold collapse of N-body models in a time-dependent logarithmic potential. Comparison between the analytical and numerical results shows excellent agreement in regions where the potential evolution does not depart too strongly from the adiabatic regime.
Bibliography on Small Systems: Nonequilibrium Phenomena and Anomalous Behavior
NASA Astrophysics Data System (ADS)
LIU, Fei; Lamberto, Rondoni; TANG, Lei-Han; ZHOU, Hai-Jun; WANG, Yan-Ting
2014-10-01
The workshop and satellite conference held in July 2013 at the Kavli Institute for Theoretical Physics China (KITPC) of the Chinese Academy of Sciences (CAS) brought together experts of a variety of different fields, and constituted a unique opportunity to share ideas and breed new ones in a strongly interdisciplinary fashion. At the same time, the breadth of the scope of these two meetings was so wide that the need for a collection of reference books and papers was pointed out, in order to help the interested professionals, as well as graduate students, both to tackle the technically advanced issues and to bridge the gaps, necessarily present in each other's background. Therefore, we invited some of the participants to produce a bibliography containing the most relevant works in their own fields, and to complement this bibliography with a short explanation of the content of those books and papers. We are thus very grateful to Igor Goychuk, David Lacoste, Annick Lesne, Andrea Puglisi, Hong Qian and Hugo Touchette for having accepted our invitation and for having produced what we consider a very useful tool for all those who want to learn or to understand more deeply the current theories concerning small and nonequilibrium systems.
State-resolved thermochemical nonequilibrium analysis of hydrogen mixture flows
NASA Astrophysics Data System (ADS)
Gang Kim, Jae; Boyd, Iain D.
2012-08-01
The complete sets of state-to-state transition rate coefficients for both target and projectile molecules of hydrogen are derived from the predicted response surface designed by the ordinary Kriging model. A system of master equations is constructed for bound-bound and bound-free transitions with these designed transition rate coefficients, and the rovibrational number densities are numerically evaluated by implicitly integrating a system of master equations. In these master equation studies, relaxation of rotation and vibration modes, number density relaxation, reaction rate coefficients, and average rotational and vibrational energy losses due to dissociation are each considered in strong nonequilibrium conditions. A system of master equations is coupled with one-dimensional flow equations to analyze the relaxations of hydrogen in post-normal shock and nozzle expanding flows. In post-normal shock flows, at high temperature, the relaxation of the rotational mode is similar to the relaxation of the vibrational mode. In nozzle expanding flows, the relaxations of both rotational and vibrational modes appear to be frozen.
Beretta, Gian Paolo
2014-10-01
By suitable reformulations, we cast the mathematical frameworks of several well-known different approaches to the description of nonequilibrium dynamics into a unified formulation valid in all these contexts, which extends to such frameworks the concept of steepest entropy ascent (SEA) dynamics introduced by the present author in previous works on quantum thermodynamics. Actually, the present formulation constitutes a generalization also for the quantum thermodynamics framework. The analysis emphasizes that in the SEA modeling principle a key role is played by the geometrical metric with respect to which to measure the length of a trajectory in state space. In the near-thermodynamic-equilibrium limit, the metric tensor is directly related to the Onsager's generalized resistivity tensor. Therefore, through the identification of a suitable metric field which generalizes the Onsager generalized resistance to the arbitrarily far-nonequilibrium domain, most of the existing theories of nonequilibrium thermodynamics can be cast in such a way that the state exhibits the spontaneous tendency to evolve in state space along the path of SEA compatible with the conservation constraints and the boundary conditions. The resulting unified family of SEA dynamical models is intrinsically and strongly consistent with the second law of thermodynamics. The non-negativity of the entropy production is a general and readily proved feature of SEA dynamics. In several of the different approaches to nonequilibrium description we consider here, the SEA concept has not been investigated before. We believe it defines the precise meaning and the domain of general validity of the so-called maximum entropy production principle. Therefore, it is hoped that the present unifying approach may prove useful in providing a fresh basis for effective, thermodynamically consistent, numerical models and theoretical treatments of irreversible conservative relaxation towards equilibrium from far nonequilibrium
Li, Hai; Zou, Jian; Yu, Wen-Li; Xu, Bao-Ming; Li, Jun-Gang; Shao, Bin
2014-05-01
We consider a model of an optical cavity with a nonequilibrium reservoir consisting of a beam of identical two-level atom pairs (TLAPs) in the general X state. We find that coherence of multiparticle nonequilibrium reservoir plays a central role on the potential work capability of the cavity. We show that no matter whether there are quantum correlations in each TLAP (including quantum entanglement and quantum discord) or not, the coherence of the TLAPs has an effect on the work capability of the cavity. Additionally, constructive and destructive interferences could be induced to influence the work capability of the cavity by adjusting only the relative phase, with which quantum correlations have nothing to do. In this paper, the coherence of the reservoir, rather than the quantum correlations, effectively reflecting the effects of the reservoir on the system's work capability is demonstrated clearly. PMID:25353764
High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter.
Green, B; Kovalev, S; Asgekar, V; Geloni, G; Lehnert, U; Golz, T; Kuntzsch, M; Bauer, C; Hauser, J; Voigtlaender, J; Wustmann, B; Koesterke, I; Schwarz, M; Freitag, M; Arnold, A; Teichert, J; Justus, M; Seidel, W; Ilgner, C; Awari, N; Nicoletti, D; Kaiser, S; Laplace, Y; Rajasekaran, S; Zhang, L; Winnerl, S; Schneider, H; Schay, G; Lorincz, I; Rauscher, A A; Radu, I; Mährlein, S; Kim, T H; Lee, J S; Kampfrath, T; Wall, S; Heberle, J; Malnasi-Csizmadia, A; Steiger, A; Müller, A S; Helm, M; Schramm, U; Cowan, T; Michel, P; Cavalleri, A; Fisher, A S; Stojanovic, N; Gensch, M
2016-01-01
Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution. PMID:26924651
High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter
Green, B.; Kovalev, S.; Asgekar, V.; Geloni, G.; Lehnert, U.; Golz, T.; Kuntzsch, M.; Bauer, C.; Hauser, J.; Voigtlaender, J.; et al
2016-02-29
Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields andmore » the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. In conclusion, we benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution.« less
High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter
Green, B.; Kovalev, S.; Asgekar, V.; Geloni, G.; Lehnert, U.; Golz, T.; Kuntzsch, M.; Bauer, C.; Hauser, J.; Voigtlaender, J.; Wustmann, B.; Koesterke, I.; Schwarz, M.; Freitag, M.; Arnold, A.; Teichert, J.; Justus, M.; Seidel, W.; Ilgner, C.; Awari, N.; Nicoletti, D.; Kaiser, S.; Laplace, Y.; Rajasekaran, S.; Zhang, L.; Winnerl, S.; Schneider, H.; Schay, G.; Lorincz, I.; Rauscher, A. A.; Radu, I.; Mährlein, S.; Kim, T. H.; Lee, J. S.; Kampfrath, T.; Wall, S.; Heberle, J.; Malnasi-Csizmadia, A.; Steiger, A.; Müller, A. S.; Helm, M.; Schramm, U.; Cowan, T.; Michel, P.; Cavalleri, A.; Fisher, A. S.; Stojanovic, N.; Gensch, M.
2016-01-01
Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution. PMID:26924651
NASA Astrophysics Data System (ADS)
Reggiani, L.; Bordone, P.; Brunetti, R.
2004-02-01
The International Conference on Nonequilibrium Carrier Dynamics in Semiconductors (HCIS-13) celebrates 30 years since it first took place in Modena. Nonequilibrium dynamics of charge carriers, pioneered by the hot-electron concept, is an important issue for understanding electro-optic transport properties in semiconductor materials and structures. In these 30 years several topics have matured, and new ones have emerged thus fertilizing the field with a variety of physical problems and new ideas. The history of the conference is summarized in the opening paper `30 years of HCIS'. The future of the conference seems secure considering the continued lively interest of the participants. The conference addressed eleven major topics which constitute the backbone of the proceedings and are summarized as follows: carrier transport in low dimensional and nanostructure systems, nonequilibrium carriers in superlattices and devices, small devices and related phenomena, carrier dynamics and fluctuations, carrier quantum dynamics, coherent/incoherent carrier dynamics of optical excitations and ultra-fast optical phenomena, nonlinear optical effects, transport in organic matter, semiconductor-based spintronics, coherent dynamics in solid state systems for quantum processing and communication, novel materials and devices. Nanometric space scale and femtosecond time scale represent the ultimate domains of theoretical, experimental and practical interest. Traditional fields such as bulk properties, quantum transport, fluctuations and chaotic phenomena, etc, have received thorough and continuous attention. Emerging fields from previous conferences, such as quantum processing and communication, have been better assessed. New fields, such as spintronics and electron transport in organic matter, have appeared for the first time. One plenary talk, 11 invited talks, 230 submitted abstracts covering all these topics constituted a single-session conference. Following scientific selection
Nonequilibrium and nonlinear defect states in microcavity-polariton condensates.
Chen, Ting-Wei; Jheng, Shih-Da; Hsieh, Wen-Feng; Cheng, Szu-Cheng
2016-05-01
The nonequilibrium and nonlinear defect modes (NNDMs), localized by a defect in a nonequilibrium microcavity-polariton condensate (MPC), are studied. There are three analytic solutions of NNDMs in a point defect: the bright NNDM, a bound state with two dark solitons for an attractive potential, and a gray soliton bound by a defect for a repulsive potential. We find that the stable NNDMs in a nonequilibrium MPC are the bright NNDM and gray soliton bound by a defect. The bright NNDM, which has the hyperbolic cotangent form, is a bright localized state existing in a uniform MPC. The bright NNDM is a unique state occurring in a nonequilibrium MPC that has pump-dissipation and repulsive-nonlinearity characters. No such state can exist in an equilibrium system with repulsive nonlinearity. PMID:27300887
Electrolytes: transport properties and non-equilibrium thermodynamics
Miller, D.G.
1980-12-01
This paper presents a review on the application of non-equilibrium thermodynamics to transport in electrolyte solutions, and some recent experimental work and results for mutual diffusion in electrolyte solutions.
Nonequilibrium phonon effects in midinfrared quantum cascade lasers
Shi, Y. B. Knezevic, I.
2014-09-28
We investigate the effects of nonequilibrium phonon dynamics on the operation of a GaAs-based midinfrared quantum cascade laser over a range of temperatures (77–300 K) via a coupled ensemble Monte Carlo simulation of electron and optical-phonon systems. Nonequilibrium phonon effects are shown to be important below 200 K. At low temperatures, nonequilibrium phonons enhance injection selectivity and efficiency by drastically increasing the rate of interstage electron scattering from the lowest injector state to the next-stage upper lasing level via optical-phonon absorption. As a result, the current density and modal gain at a given field are higher and the threshold current density lower and considerably closer to experiment than results obtained with thermal phonons. By amplifying phonon absorption, nonequilibrium phonons also hinder electron energy relaxation and lead to elevated electronic temperatures.
One-dimensional reacting gas nonequilibrium performance program
NASA Technical Reports Server (NTRS)
Frey, H. M.; Kliegel, J. R.
1968-01-01
Computer program calculates the inviscid one-dimensional equilibrium, frozen, and nonequilibrium nozzle expansion of gaseous propellant exhaust mixtures containing the elements - carbon, hydrogen, oxygen, nitrogen, fluorine and chlorine. The program performs calculations for conical nozzles only.
Electron Systems Out of Equilibrium: Nonequilibrium Green's Function Approach
NASA Astrophysics Data System (ADS)
Špička, Václav Velický, Bedřich Kalvová, Anděla
2015-10-01
This review deals with the state of the art and perspectives of description of non-equilibrium many body systems using the non-equilibrium Green's function (NGF) method. The basic aim is to describe time evolution of the many-body system from its initial state over its transient dynamics to its long time asymptotic evolution. First, we discuss basic aims of transport theories to motivate the introduction of the NGF techniques. Second, this article summarizes the present view on construction of the electron transport equations formulated within the NGF approach to non-equilibrium. We discuss incorporation of complex initial conditions to the NGF formalism, and the NGF reconstruction theorem, which serves as a tool to derive simplified kinetic equations. Three stages of evolution of the non-equilibrium, the first described by the full NGF description, the second by a Non-Markovian Generalized Master Equation and the third by a Markovian Master Equation will be related to each other.
Statistical physics of shear flow: a non-equilibrium problem
NASA Astrophysics Data System (ADS)
Evans, R. M. L.
2010-09-01
Complex fluids are easily and reproducibly driven into non-equilibrium steady states by the action of shear flow. The statistics of the microstructure of non-equilibrium fluids is important to the material properties of every complex fluid that flows, e.g. axle grease on a rotating bearing; blood circulating in capillaries; molten plastic flowing into a mould; the non-equilibrium onion phase of amphiphiles used for drug delivery; the list is endless. Such states are as diverse and interesting as equilibrium states, but are not governed by the same statistics as equilibrium materials. I review some recently discovered principles governing the probabilities of various types of molecular re-arrangements taking place within a sheared fluid. As well as providing new foundations for the study of non-equilibrium matter, the principles are applied to some simple models of particles interacting under flow, showing that the theory exhibits physically convincing behaviour.
Nonequilibrium and nonlinear defect states in microcavity-polariton condensates
NASA Astrophysics Data System (ADS)
Chen, Ting-Wei; Jheng, Shih-Da; Hsieh, Wen-Feng; Cheng, Szu-Cheng
2016-05-01
The nonequilibrium and nonlinear defect modes (NNDMs), localized by a defect in a nonequilibrium microcavity-polariton condensate (MPC), are studied. There are three analytic solutions of NNDMs in a point defect: the bright NNDM, a bound state with two dark solitons for an attractive potential, and a gray soliton bound by a defect for a repulsive potential. We find that the stable NNDMs in a nonequilibrium MPC are the bright NNDM and gray soliton bound by a defect. The bright NNDM, which has the hyperbolic cotangent form, is a bright localized state existing in a uniform MPC. The bright NNDM is a unique state occurring in a nonequilibrium MPC that has pump-dissipation and repulsive-nonlinearity characters. No such state can exist in an equilibrium system with repulsive nonlinearity.
Ordering states with coherence measures
NASA Astrophysics Data System (ADS)
Liu, C. L.; Yu, Xiao-Dong; Xu, G. F.; Tong, D. M.
2016-10-01
The quantification of quantum coherence has attracted a growing attention, and based on various physical contexts, several coherence measures have been put forward. An interesting question is whether these coherence measures give the same ordering when they are used to quantify the coherence of quantum states. In this paper, we consider the two well-known coherence measures, the l_1 norm of coherence and the relative entropy of coherence, to show that there are the states for which the two measures give a different ordering. Our analysis can be extended to other coherence measures, and as an illustration of the extension we further consider the formation of coherence to show that the l_1 norm of coherence and the formation of coherence, as well as the relative entropy of coherence and the coherence of formation, do not give the same ordering too.
Ordering states with coherence measures
NASA Astrophysics Data System (ADS)
Liu, C. L.; Yu, Xiao-Dong; Xu, G. F.; Tong, D. M.
2016-07-01
The quantification of quantum coherence has attracted a growing attention, and based on various physical contexts, several coherence measures have been put forward. An interesting question is whether these coherence measures give the same ordering when they are used to quantify the coherence of quantum states. In this paper, we consider the two well-known coherence measures, the l_1 norm of coherence and the relative entropy of coherence, to show that there are the states for which the two measures give a different ordering. Our analysis can be extended to other coherence measures, and as an illustration of the extension we further consider the formation of coherence to show that the l_1 norm of coherence and the formation of coherence, as well as the relative entropy of coherence and the coherence of formation, do not give the same ordering too.
Coherent Pump-Probe Interactions and Terahertz Intersubband Gain in Semiconductor Quantum Wells
NASA Technical Reports Server (NTRS)
Liu, Ansheng; Ning, Cun-Zheng
1999-01-01
In recent years there has been considerable interest in intersubband-transition-based infrared semiconductor quantum well (QW) lasers because of their potential applications. In the mid-infrared range, both electrically-injected quantum cascade lasers [1] and optically-pumped multiple QW lasers [2] have been experimentally realized. In these studies, optical gain is due to population inversion between the lasing subbands. It was also proposed that stimulated Raman scattering in QW systems can produce net infrared optical gain [3j. In such a nonlinear optical scheme, the appearance of optical gain that may lead to intersubband Raman lasers does not rely on the population inversion. Since, in tile resonant Raman process (Raman gain is the largest in this case), the pump field induces population redistribution among subbands in the QW s ystem, it seems that a realistic estimate of the optical gain has to include this effect. Perturbative calculations used in the previous work [3] may overestimate the Raman gain. In this paper we present a nonperturbative calculation of terahertz gain of optically-pumped semiconductor step quantum wells. Limiting optical transitions within the conduction band of QW, we solve the pump-field-induced nonequilibrium distribution function for each subband of the QW system from a set of coupled rate equations. Both intrasubband and intersubband relaxation processes in the quantum well system are included. Taking into account the coherent interactions between pump and THz (signal) waves, we we derive the susceptibility of the QW system for the THz field. For a GaAs/AlGaAs step QW, we calculate the Thz gain spectrum for different pump frequencies and intensities. Under moderately strong pumping (approximately 0.3 MW/sq cm), a significant THz gain (approximately 300/m) is predicted. It is also shown that the coherent wave interactions (resonant stimulated Raman processes) contribute significantly to the THz gain.
Combined physical and chemical nonequilibrium transport model for solution conduits
NASA Astrophysics Data System (ADS)
Field, Malcolm S.; Leij, Feike J.
2014-02-01
Solute transport in karst aquifers is primarily constrained to relatively complex and inaccessible solution conduits where transport is often rapid, turbulent, and at times constrictive. Breakthrough curves generated from tracer tests in solution conduits are typically positively-skewed with long tails evident. Physical nonequilibrium models to fit breakthrough curves for tracer tests in solution conduits are now routinely employed. Chemical nonequilibrium processes are likely important interactions, however. In addition to partitioning between different flow domains, there may also be equilibrium and nonequilibrium partitioning between the aqueous and solid phases. A combined physical and chemical nonequilibrium (PCNE) model was developed for an instantaneous release similar to that developed by Leij and Bradford (2009) for a pulse release. The PCNE model allows for partitioning open space in solution conduits into mobile and immobile flow regions with first-order mass transfer between the two regions to represent physical nonequilibrium in the conduit. Partitioning between the aqueous and solid phases proceeds either as an equilibrium process or as a first-order process and represents chemical nonequilibrium for both the mobile and immobile regions. Application of the model to three example breakthrough curves demonstrates the applicability of the combined physical and chemical nonequilibrium model to tracer tests conducted in karst aquifers, with exceptionally good model fits to the data. The three models, each from a different state in the United States, exhibit very different velocities, dispersions, and other transport properties with most of the transport occurring via the fraction of mobile water. Fitting the model suggests the potentially important interaction of physical and chemical nonequilibrium processes.
Effects of nonequilibrium ablation chemistry on Viking radio blackout.
NASA Technical Reports Server (NTRS)
Evans, J. S.; Schexnayder, C. J., Jr.; Grose, W. L.
1973-01-01
The length of the entry blackout period during descent of the Viking Lander into the Mars atmosphere is predicted from calculated profiles of electron density in the shock layer over the aeroshell. Nonequilibrium chemistry plays a key role in the calculation, both in the inviscid flow and in the boundary layer. This is especially true in the boundary layer contaminated with ablation material, for which nonequilibrium chemistry predicts electron densities two decades lower than the same case calculated with equilibrium chemistry.
Separated transonic airfoil flow calculations with a nonequilibrium turbulence model
NASA Technical Reports Server (NTRS)
King, L. S.; Johnson, D. A.
1985-01-01
Navier-Stokes transonic airfoil calculations based on a recently developed nonequilibrium, turbulence closure model are presented for a supercritical airfoil section at transonic cruise conditions and for a conventional airfoil section at shock-induced stall conditions. Comparisons with experimental data are presented which show that this nonequilibrium closure model performs significantly better than the popular Baldwin-Lomax and Cebeci-Smith equilibrium algebraic models when there is boundary-layer separation that results from the inviscid-viscous interactions.
The Anomalous Distributions and Soret Coefficient in a Nonequilibrium Colloidal System
NASA Astrophysics Data System (ADS)
Zhou, Yanjun; Du, Jiulin
2016-02-01
We study the density distribution and Soret coefficient in a nonequilibrium colloidal system by using the overdamped Langevin equation for Brownian motion in an inhomogeneous strong friction medium. Based on the relation between the temperature gradient, the interaction potential and the q-parameter in nonextensive statistics, we show that the colloidal particle density can be a function of the temperature and anomalously follows the noted α-distribution, or equivalently it can also be a function of the potential energy following Tsallis distribution. With the q-parameter we can establish a new formula of Soret coefficient and thus, bridge the gap between the ideally theoretical Soret coefficient and available experiments.
Fleming, R M T; Maes, C M; Saunders, M A; Ye, Y; Palsson, B Ø
2012-01-01
We derive a convex optimization problem on a steady-state nonequilibrium network of biochemical reactions, with the property that energy conservation and the second law of thermodynamics both hold at the problem solution. This suggests a new variational principle for biochemical networks that can be implemented in a computationally tractable manner. We derive the Lagrange dual of the optimization problem and use strong duality to demonstrate that a biochemical analogue of Tellegen's theorem holds at optimality. Each optimal flux is dependent on a free parameter that we relate to an elementary kinetic parameter when mass action kinetics is assumed.
Numerical simulations of a nonequilibrium argon plasma in a shock-tube experiment
NASA Technical Reports Server (NTRS)
Cambier, Jean-Luc
1991-01-01
A code developed for the numerical modeling of nonequilibrium radiative plasmas is applied to the simulation of the propagation of strong ionizing shock waves in argon gas. The simulations attempt to reproduce a series of shock-tube experiments which will be used to validate the numerical models and procedures. The ability to perform unsteady simulations makes it possible to observe some fluctuations in the shock propagation, coupled to the kinetic processes. A coupling mechanism by pressure waves, reminiscent of oscillation mechanisms observed in detonation waves, is described. The effect of upper atomic levels is also briefly discussed.
Synthesis of silane and silicon in a non-equilibrium plasma jet
NASA Technical Reports Server (NTRS)
Calcote, H. F.; Felder, W.
1977-01-01
The feasibility of using a non-equilibrium hydrogen plasma jet as a chemical synthesis tool was investigated. Four possible processes were identified for further study: (1) production of polycrystalline silicon photovoltaic surfaces, (2) production of SiHCl3 from SiCl4, (3) production of SiH4 from SiHCl3, and (4) purification of SiCl4 by metal impurity nucleation. The most striking result was the recognition that the strongly adhering silicon films, amorphous or polycrystalline, produced in our studies could be the basis for preparing a photovoltaic surface directly; this process has potential advantages over other vapor deposition processes.
Non-equilibrium slave bosons approach to quantum pumping in interacting quantum dots
NASA Astrophysics Data System (ADS)
Citro, Roberta; Romeo, Francesco
2016-03-01
We review a time-dependent slave bosons approach within the non-equilibrium Green's function technique to analyze the charge and spin pumping in a strongly interacting quantum dot. We study the pumped current as a function of the pumping phase and of the dot energy level and show that a parasitic current arises, beyond the pure pumping one, as an effect of the dynamical constraints. We finally illustrate an all-electrical mean for spin-pumping and discuss its relevance for spintronics applications.
Density Functional Theory for Steady-State Nonequilibrium Molecular Junctions
Liu, Shuanglong; Nurbawono, Argo; Zhang, Chun
2015-01-01
We present a density functional theory (DFT) for steady-state nonequilibrium quantum systems such as molecular junctions under a finite bias. Based on the steady-state nonequilibrium statistics that maps nonequilibrium to an effective equilibrium, we show that ground-state DFT (GS-DFT) is not applicable in this case and two densities, the total electron density and the density of current-carrying electrons, are needed to uniquely determine the properties of the corresponding nonequilibrium system. A self-consistent mean-field approach based on two densities is then derived. The theory is implemented into SIESTA computational package and applied to study nonequilibrium electronic/transport properties of a realistic carbon-nanotube (CNT)/Benzene junction. Results obtained from our steady-state DFT (SS-DFT) are compared with those of conventional GS-DFT based transport calculations. We show that SS-DFT yields energetically more stable nonequilibrium steady state, predicts significantly lower electric current, and is able to produce correct electronic structures in local equilibrium under a limiting case. PMID:26472080
Effect of thermal nonequilibrium on reactions in hydrogen combustion
NASA Astrophysics Data System (ADS)
Voelkel, S.; Raman, V.; Varghese, P. L.
2016-09-01
The presence of shocks in scramjet internal flows introduces nonequilibrium of internal energy modes of the molecules. Here, the effect of vibrational nonequilibrium on key reactions of hydrogen-air combustion is studied. A quasi-classical trajectory (QCT) approach is used to derive reaction probability for nonequilibrium conditions using ab initio-derived potential energy surfaces. The reaction rates under nonequilibrium are studied using a two-temperature description, where the vibrational modes are assumed to be distributed according to a Boltzmann distribution at a characteristic vibrational temperature, in addition to a translational temperature describing the translational and rotational population distribution. At scramjet-relevant conditions, it is found that the nonequilibrium reaction rate depends not only on the level of vibrational excitation, but also on the reactants involved. Conventional two-temperature models for reaction rates, often derived using empirical means, were found to be inaccurate under these conditions, and modified parameters are proposed based on the QCT calculations. It is also found that models that include details of the reaction process through dissociation energy, for instance, provide a better description of nonequilibrium effects.
Global coherence of dust density waves
Killer, Carsten; Melzer, André
2014-06-15
The coherence of self-excited three-dimensional dust density waves has been experimentally investigated by comparing global and local wave properties. For that purpose, three-dimensional dust clouds have been confined in a radio frequency plasma with thermophoretic levitation. Global wave properties have been measured from the line-of-sight integrated dust density obtained from homogenous light extinction measurements. Local wave properties have been obtained from thin, two-dimensional illuminated laser slices of the cloud. By correlating the simultaneous global and local wave properties, the spatial coherence of the waves has been determined. We find that linear waves with small amplitudes tend to be fragmented, featuring an incoherent wave field. Strongly non-linear waves with large amplitudes, however, feature a strong spatial coherence throughout the dust cloud, indicating a high level of synchronization.
Coherent control near metallic nanostructures
Efimov, Ilya; Efimov, Anatoly
2008-01-01
We study coherent control in the vicinity of metallic nanostructures. Unlike in the case of control in gas or liquid phase, the collective response of electrons in a metallic nanostructure can significantly enhance different frequency components of the control field. This enhancement strongly depends on the geometry of the nanostructure and can substantially modify the temporal profile of the local control field. The changes in the amplitude and phase of the control field near the nanostructure are studied using linear response theory. The inverse problem of finding the external electromagnetic field to generate the desired local control field is considered and solved.
Coherent Control of Quantum Matter
Cavalleri, Andrea
2011-10-05
This talk addresses some recent work aimed at controlling the low-lying electrodynamics of quantum solids using strong field transients. The excitation of selected vibrational resonances to manipulate the many-body physics of one dimensional Mott Hubbard Insulators and to perturb competing orders in High-Tc superconductors is also covered. Finally, the speaker shows how the electrodynamics of layered superconductors can be driven through the orderparameter phase gradient, demonstrating ultrafast transistor action in a layered superconductor. Advances in the use of coherent optics, from tabletop sources to THz and x-ray free-electron lasers are also discussed.
Coherent control of molecular torsion.
Parker, Shane M; Ratner, Mark A; Seideman, Tamar
2011-12-14
We propose a coherent, strong-field approach to control the torsional modes of biphenyl derivatives, and develop a numerical scheme to simulate the torsional dynamics. By choice of the field parameters, the method can be applied either to drive the torsion angle to an arbitrary configuration or to induce free internal rotation. Transient absorption spectroscopy is suggested as a probe of torsional control and the usefulness of this approach is numerically explored. Several consequences of our ability to manipulate molecular torsional motions are considered. These include a method for the inversion of molecular chirality and an ultrafast chiral switch.
Stoichiometric network theory for nonequilibrium biochemical systems.
Qian, Hong; Beard, Daniel A; Liang, Shou-dan
2003-02-01
We introduce the basic concepts and develop a theory for nonequilibrium steady-state biochemical systems applicable to analyzing large-scale complex isothermal reaction networks. In terms of the stoichiometric matrix, we demonstrate both Kirchhoff's flux law sigma(l)J(l)=0 over a biochemical species, and potential law sigma(l) mu(l)=0 over a reaction loop. They reflect mass and energy conservation, respectively. For each reaction, its steady-state flux J can be decomposed into forward and backward one-way fluxes J = J+ - J-, with chemical potential difference deltamu = RT ln(J-/J+). The product -Jdeltamu gives the isothermal heat dissipation rate, which is necessarily non-negative according to the second law of thermodynamics. The stoichiometric network theory (SNT) embodies all of the relevant fundamental physics. Knowing J and deltamu of a biochemical reaction, a conductance can be computed which directly reflects the level of gene expression for the particular enzyme. For sufficiently small flux a linear relationship between J and deltamu can be established as the linear flux-force relation in irreversible thermodynamics, analogous to Ohm's law in electrical circuits.
Nonequilibrium in a low power arcjet nozzle
NASA Technical Reports Server (NTRS)
Zube, Dieter M.; Myers, Roger M.
1991-01-01
Emission spectroscopy measurements were made of the plasma flow inside the nozzle of a 1 kW class arcjet thruster. The thruster propellant was a hydrogen-nitrogen mixture used to simulate fully decomposed hydrazine. The 0.25 mm diameter holes were drilled into the diverging section of the tungsten thruster nozzle to provide optical access to the internal flow. Atomic electron excitation, vibrational, and rotational temperatures were determined for the expanding plasma using relative line intensity techniques. The atomic excitation temperatures decreased from 18,000K at a location 3 mm downstream of the constrictor to 9,000K at a location 9 mm from the constrictor, while the molecular vibrational and rotational temperatures decreased from 6,500K to 2,500K and from 8,000K to 3,000K, respectively, between the same locations. The electron density measured using hydrogen H line Stark broadening decreased from about 10(exp 15) cm(-3) to about 2 times 10(exp 14) cm(-3) during the expansion. The results show that the plasma is highly nonequilibrium throughout the nozzle, with most relaxation times equal or exceeding the particle residence time.
Vibrational nonequilibrium effects on diatomic dissociation rates
NASA Technical Reports Server (NTRS)
Hansen, C. F.
1993-01-01
The collision-induced dissociation rate of diatomic molecules from a ladder of rotational and anharmonic vibrational states is developed, and the correction for vibrational nonequilibrium is considered. The result is similar to an analytic correction derived by Hammerling et al. (1959) for harmonic oscillators. An empirical correction algorithm suggested by Park (1987, 1990) gives similar results when vibrational temperature is comparable to kinetic temperature but underestimates the dissociation rate when vibrational temperature is small compared with the kinetic temperature. This algorithm uses an effective temperature in the experimentally determined Arrhenius expression for the rate coefficient, which is a weighted average of the vibrational and kinetic temperature, whereas theory indicates that kinetic temperature should appear only in the exponential term of the Arrhenius expression. Nevertheless, an effective temperature can always be found that will numerically duplicate the proper rate coefficient at any given condition, but a constant weighting factor cannot be expected to provide this. However, the algorithm can he adjusted to give reasonable results over a range of conditions if the geometric weighting factor is taken to be a simple linear function of the ratio of vibrational to kinetic temperature in the gas.
ERIC Educational Resources Information Center
Zheng, Yanping
2009-01-01
In the thesis a coherent text is defined as a continuity of senses of the outcome of combining concepts and relations into a network composed of knowledge space centered around main topics. And the author maintains that in order to obtain the coherence of a target language text from a source text during the process of translation, a translator can…
NASA Astrophysics Data System (ADS)
García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.
2009-04-01
We define a family of entanglement distribution protocols assisted by classical feedback communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This protocol family leads to the definition of a new entanglement distribution capacity that exceeds the unassisted entanglement distribution capacity for some interesting channels.
NASA Astrophysics Data System (ADS)
García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.
2009-05-01
In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.
Catalytic coherence transformations
NASA Astrophysics Data System (ADS)
Bu, Kaifeng; Singh, Uttam; Wu, Junde
2016-04-01
Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.
García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H
2009-05-29
In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.
Andrianov, A. V. Alekseev, P. S.; Klimko, G. V.; Ivanov, S. V.; Shcheglov, V. L.; Sedova, M. A.; Zakhar'in, A. O.
2013-11-15
The generation of coherent terahertz radiation upon the band-to-band femtosecond laser photoexcitation of GaAs/AlGaAs multiple-quantum-well structures in a transverse electric field at room temperature is investigated. The properties of the observed terahertz radiation suggest that it is generated on account of the excitation of a time-dependent dipole moment as a result of the polarization of nonequilibrium electron-hole pairs in quantum wells by the electric field. The proposed theoretical model taking into account the dynamic screening of the electric field in the quantum wells by nonequilibrium charge carriers describes the properties of the observed terahertz signal.
Alnaes, K.; Kristiansen, E.H. ); Gustavson, D.B. ); James, D.V. )
1990-01-01
The Scalable Coherent Interface (IEEE P1596) is establishing an interface standard for very high performance multiprocessors, supporting a cache-coherent-memory model scalable to systems with up to 64K nodes. This Scalable Coherent Interface (SCI) will supply a peak bandwidth per node of 1 GigaByte/second. The SCI standard should facilitate assembly of processor, memory, I/O and bus bridge cards from multiple vendors into massively parallel systems with throughput far above what is possible today. The SCI standard encompasses two levels of interface, a physical level and a logical level. The physical level specifies electrical, mechanical and thermal characteristics of connectors and cards that meet the standard. The logical level describes the address space, data transfer protocols, cache coherence mechanisms, synchronization primitives and error recovery. In this paper we address logical level issues such as packet formats, packet transmission, transaction handshake, flow control, and cache coherence. 11 refs., 10 figs.
Rehder, B; Ross, B H
2001-09-01
Many studies have demonstrated the importance of the knowledge that interrelates features in people's mental representation of categories and that makes our conception of categories coherent. This article focuses on abstract coherent categories, coherent categories that are also abstract because they are defined by relations independently of any features. Four experiments demonstrate that abstract coherent categories are learned more easily than control categories with identical features and statistical structure, and also that participants induced an abstract representation of the category by granting category membership to exemplars with completely novel features. The authors argue that the human conceptual system is heavily populated with abstract coherent concepts, including conceptions of social groups, societal institutions, legal, political, and military scenarios, and many superordinate categories, such as classes of natural kinds. PMID:11550753
Nasel'skii, P.D.; Polnarev, A.G.
1987-11-01
The formation of small-scale anisotropy and polarization in a model of nonstationary ionization of the pregalactic plasma is considered. It is shown that the ratio of the degree of polarization to the degree of anisotropy is rather insensitive to the actual regime of ionization and is 7-8%. However, the characteristic correlation angle is in the distribution of the anisotropy and polarization of the background radiation on the celestial sphere depends strongly on the parameters of the nonequilibrium.
Non-equilibrium radiation nuclear reactor
NASA Technical Reports Server (NTRS)
Thom, K.; Schneider, R. T. (Inventor)
1978-01-01
An externally moderated thermal nuclear reactor is disclosed which is designed to provide output power in the form of electromagnetic radiation. The reactor is a gaseous fueled nuclear cavity reactor device which can operate over wide ranges of temperature and pressure, and which includes the capability of processing and recycling waste products such as long-lived transuranium actinides. The primary output of the device may be in the form of coherent radiation, so that the reactor may be utilized as a self-critical nuclear pumped laser.
Nonequilibrium dynamics of the Ising chain in a fluctuating transverse field
NASA Astrophysics Data System (ADS)
Roósz, Gergő; Juhász, Róbert; Iglói, Ferenc
2016-04-01
We study nonequilibrium dynamics of the quantum Ising chain at zero temperature when the transverse field is varied stochastically. In the equivalent fermion representation, the equation of motion of Majorana operators is derived in the form of a one-dimensional, continuous-time quantum random walk with stochastic, time-dependent transition amplitudes. This type of external noise gives rise to decoherence in the associated quantum walk and the semiclassical wave packet generally has a diffusive behavior. As a consequence, in the quantum Ising chain, the average entanglement entropy grows in time as t1 /2 and the logarithmic average magnetization decays in the same form. In the case of a dichotomous noise, when the transverse field is changed in discrete time steps, τ , there can be excitation modes, for which coherence is maintained, provided their energy satisfies ɛkτ ≈n π with a positive integer n . If the dispersion of ɛk is quadratic, the long-time behavior of the entanglement entropy and the logarithmic magnetization is dominated by these ballistically traveling coherent modes and both will have a t3 /4 time dependence.
Using nonequilibrium dynamics to probe competing orders in a Mott-Peierls system
Wang, Y.; Moritz, B.; Chen, C. -C.; Jia, C. J.; van Veenendaal, M.; Devereaux, T. P.
2016-02-24
Competition between ordered phases, and their associated phase transitions, are significant in the study of strongly correlated systems. Here, we examine one aspect, the nonequilibrium dynamics of a photoexcited Mott-Peierls system, using an effective Peierls-Hubbard model and exact diagonalization. Near a transition where spin and charge become strongly intertwined, we observe antiphase dynamics and a coupling-strength-dependent suppression or enhancement in the static structure factors. The renormalized bosonic excitations coupled to a particular photoexcited electron can be extracted, which provides an approach for characterizing the underlying bosonic modes. The results from this analysis for different electronic momenta show an uneven softeningmore » due to a stronger coupling near kF. As a result, this behavior reflects the strong link between the fermionic momenta, the coupling vertices, and ultimately, the bosonic susceptibilities when multiple phases compete for the ground state of the system.« less
The Global Coherence Initiative: Creating a Coherent Planetary Standing Wave
Deyhle, Annette; Childre, Doc
2012-01-01
ABSTRACT The much anticipated year of 2012 is now here. Amidst the predictions and cosmic alignments that many are aware of, one thing is for sure: it will be an interesting and exciting year as the speed of change continues to increase, bringing both chaos and great opportunity. One benchmark of these times is a shift in many people from a paradigm of competition to one of greater cooperation. All across the planet, increasing numbers of people are practicing heart-based living, and more groups are forming activities that support positive change and creative solutions for manifesting a better world. The Global Coherence Initiative (GCI) is a science-based, co-creative project to unite people in heart-focused care and intention. GCI is working in concert with other initiatives to realize the increased power of collective intention and consciousness. The convergence of several independent lines of evidence provides strong support for the existence of a global information field that connects all living systems and consciousness. Every cell in our bodies is bathed in an external and internal environment of fluctuating invisible magnetic forces that can affect virtually every cell and circuit in biological systems. Therefore, it should not be surprising that numerous physiological rhythms in humans and global collective behaviors are not only synchronized with solar and geomagnetic activity, but disruptions in these fields can create adverse effects on human health and behavior. The most likely mechanism for explaining how solar and geomagnetic influences affect human health and behavior are a coupling between the human nervous system and resonating geomagnetic frequencies, called Schumann resonances, which occur in the earth-ionosphere resonant cavity and Alfvén waves. It is well established that these resonant frequencies directly overlap with those of the human brain and cardiovascular system. If all living systems are indeed interconnected and communicate with
The global coherence initiative: creating a coherent planetary standing wave.
McCraty, Rollin; Deyhle, Annette; Childre, Doc
2012-03-01
The much anticipated year of 2012 is now here. Amidst the predictions and cosmic alignments that many are aware of, one thing is for sure: it will be an interesting and exciting year as the speed of change continues to increase, bringing both chaos and great opportunity. One benchmark of these times is a shift in many people from a paradigm of competition to one of greater cooperation. All across the planet, increasing numbers of people are practicing heart-based living, and more groups are forming activities that support positive change and creative solutions for manifesting a better world. The Global Coherence Initiative (GCI) is a science-based, co-creative project to unite people in heart-focused care and intention. GCI is working in concert with other initiatives to realize the increased power of collective intention and consciousness. The convergence of several independent lines of evidence provides strong support for the existence of a global information field that connects all living systems and consciousness. Every cell in our bodies is bathed in an external and internal environment of fluctuating invisible magnetic forces that can affect virtually every cell and circuit in biological systems. Therefore, it should not be surprising that numerous physiological rhythms in humans and global collective behaviors are not only synchronized with solar and geomagnetic activity, but disruptions in these fields can create adverse effects on human health and behavior. The most likely mechanism for explaining how solar and geomagnetic influences affect human health and behavior are a coupling between the human nervous system and resonating geomagnetic frequencies, called Schumann resonances, which occur in the earth-ionosphere resonant cavity and Alfvén waves. It is well established that these resonant frequencies directly overlap with those of the human brain and cardiovascular system. If all living systems are indeed interconnected and communicate with each other
Quench dynamics of a strongly interacting resonant Bose gas
NASA Astrophysics Data System (ADS)
Yin, Xiao; Radzihovsky, Leo
2013-12-01
We explore the dynamics of a Bose gas following its quench to a strongly interacting regime near a Feshbach resonance. Within a self-consistent Bogoliubov analysis we find that after the initial condensate-quasiparticle Rabi oscillations, at long time scales the gas is characterized by a nonequilibrium steady-state momentum distribution function, with depletion, condensate density, and contact that deviate strongly from their corresponding equilibrium values. These are in a qualitative agreement with recent experiments on 85Rb by Makotyn Our analysis also suggests that for sufficiently deep quenches close to the resonance the nonequilibrium state undergoes a phase transition to a fully depleted state, characterized by a vanishing condensate density.
Quench dynamics of a strongly interacting resonant Bose gas
NASA Astrophysics Data System (ADS)
Yin, Xiao; Radzihovsky, Leo
2014-03-01
We explore the dynamics of a Bose gas following its quench to a strongly interacting regime near a Feshbach resonance. Within a self-consistent Bogoliubov analysis we find that after the initial condensate-quasiparticle Rabi oscillations, at long time scales the gas is characterized by a nonequilibrium steady-state momentum distribution function, with depletion, condensate density and contact that deviate strongly from their corresponding equilibrium values. These are in a qualitative agreement with recent experiments on 85Rb by Makotyn. Our analysis also suggests that for sufficiently deep quenches close to the resonance the nonequilibrium state undergoes a phase transition to a fully depleted state, characterized by a vanishing condensate density. This research was supported by the NSF through DMR-0321848.
Radiation temperature of non-equilibrium plasmas
Arunasalam, V.
1991-07-01
In fusion devices measurements of the radiation temperature T{sub r} ({omega}, k) near the electron cyclotron frequency {omega}{sub C} and the second harmonic 2{omega}{sub C} in directions nearly perpendicular to the confining magnetic field B (i.e., k {approx} k {perpendicular}) serve to map out the electron temperature profiles T{sub e}(r,t). For optically thick plasma at thermodynamic equilibrium T{sub r} = T{sub e}. However, there is increasing experimental evidence for the presence of non-equilibrium electron distributions (such as a drifting Maxwellian with appreciable values of the streaming parameter {omicron} = v{sub d}/v{sub t}, a bi- Maxwellian, and anisotropic Maxwellian with T {perpendicular} {ne} T {parallel}, etc.,) in tokamak plasmas, especially in the presence of radio-frequency heating. Here, we examine (both non-relativistically and relativistically) the dependence of T{sub r} on {omicron}, T{perpendicular}/T{parallel}, T{sub h}/T{sub b}, n{sub h}/n{sub b}etc., where n{sub b}, n{sub h}, T{sub b}, T{sub h} are the densities and temperatures, respectively, of the bulk and the hot components of the bi-Maxwellian plasma. Our bi-Maxwellian results predict that the ratio T{sub r}/T{sub e} is a very sensitive function of the ratios n{sub h}/n{sub b} and T{sub h}/T{sub b}. Further, these relativistic and non-relativistic results satisfy the well-known limit c {yields} {infinity} correspondence principle'', showing that the intensity of the emission and absorption line is independent of the line broadening mechanism. 44 refs., 2 figs.
Multiple quantum coherence spectroscopy.
Mathew, Nathan A; Yurs, Lena A; Block, Stephen B; Pakoulev, Andrei V; Kornau, Kathryn M; Wright, John C
2009-08-20
Multiple quantum coherences provide a powerful approach for studies of complex systems because increasing the number of quantum states in a quantum mechanical superposition state increases the selectivity of a spectroscopic measurement. We show that frequency domain multiple quantum coherence multidimensional spectroscopy can create these superposition states using different frequency excitation pulses. The superposition state is created using two excitation frequencies to excite the symmetric and asymmetric stretch modes in a rhodium dicarbonyl chelate and the dynamic Stark effect to climb the vibrational ladders involving different overtone and combination band states. A monochromator resolves the free induction decay of different coherences comprising the superposition state. The three spectral dimensions provide the selectivity required to observe 19 different spectral features associated with fully coherent nonlinear processes involving up to 11 interactions with the excitation fields. The different features act as spectroscopic probes of the diagonal and off-diagonal parts of the molecular potential energy hypersurface. This approach can be considered as a coherent pump-probe spectroscopy where the pump is a series of excitation pulses that prepares a multiple quantum coherence and the probe is another series of pulses that creates the output coherence. PMID:19507812
Quantum-classical correspondence principles for locally nonequilibrium driven systems.
Smith, Eric
2008-02-01
Many of the core concepts and (especially field-theoretic) tools of statistical mechanics have developed within the context of thermodynamic equilibrium, where state variables are all taken to be charges, meaning that their values are inherently preserved under reversal of the direction of time. A principle concern of nonequilibrium statistical mechanics is to understand the emergence and stability of currents, quantities whose values change sign under time reversal. Whereas the correspondence between classical charge-valued state variables and their underlying statistical or quantum ensembles is quite well understood, the study of currents away from equilibrium has been more fragmentary, with classical descriptions relying on the asymmetric auxiliary-field formalism of Martin, Siggia, and Rose (and often restricted to the Markovian assumption of Doi and Peliti), while quantum descriptions employ a symmetric two-field formalism introduced by Schwinger and further clarified by Keldysh. In this paper we demonstrate that for quantum ensembles in which superposition is not violated by very strong conditions of decoherence, there is a large natural generalization of the principles and tools of equilibrium, which not only admits but requires the introduction of current-valued state variables. For these systems, not only do Martin-Siggia-Rose (MSR) and Schwinger-Keldysh (SK) field methods both exist, in some cases they provide inequivalent classical and quantum descriptions of identical ensembles. With these systems for examples, we can both study the correspondence between classical and quantum descriptions of currents, and also clarify the nature of the mapping between the structurally homologous but interpretationally different MSR and SK formalisms.
Nonequilibrium dynamics of laser-generated plasma channels
NASA Astrophysics Data System (ADS)
Petrova, Tz. B.; Ladouceur, H. D.; Baronavski, A. P.
2008-05-01
A time-dependent nonequilibrium kinetics model based upon the time-dependent electron Boltzmann equation coupled with an extensive air chemistry model accounting for gas heating and vibrational kinetics is developed. The model is applied to the temporal evolution of femtosecond laser-generated air plasma channels at atmospheric pressure in an external electric field. The plasma channel dynamics depend upon the initial free electron density, the initial electron energy of the plasma, and upon the externally applied electric field strength. The model predicts an electric breakdown field strength of 5-10kV/cm with a delay time of hundreds of nanoseconds when the electron density drops to the optimum value of ˜1012-1013cm-3. The experimentally observed breakdown field is ˜5.7kV/cm with a statistical breakdown delay time of ˜200ns. The reduction in the breakdown field strength in natural air from ˜30to5kV/cm is attributed to a combination of processes such as enhanced ionization due to relaxation of the initial electron energy distribution function toward a Maxwellian distribution, strong electron detachment, and gas heating. The calculated electron density decay of the laser-generated plasma channel in both pure nitrogen and dry air is in good agreement with the NRL experiments. The derived rate constant for recombination in dry air is bBair=3.9×10-8cm3s-1 and in pure nitrogen it is bBN2=4.4×10-8cm3s-1. The attachment rate coefficient in dry air is ηBair=7.5×106s-1.
Temperature equilibration in strongly coupled plasma
Thode, L. E.; Chang, C. H.; Snell, C. M.; Daughton, W. S.; Csanak, G. Y.
2002-01-01
A laser-driven experiment investigating electron-ion equilibration in strongly coupled plasma was performed in 1995. At that time, standard estimates for the electron-ion equilibration time were two-to-three orders of magnitude faster than observed experimentally. As a result, the electron-ion equilibration time was taken as a fitting parameter to understand the experimental results. Based upon guidance from nonequilibrium molecular dynamics mixture calculations 121 and comparison with strongly coupled resistivity experiments, we have developed a consistent binary collision model to understand the electron-ion equilibration experiment. The model has been implemented in a newly developed multi-species, multi-temperature physics code, which was used for simulation of the experiment. The resulting electron-ion exchange rate is close to the experiment, which is about three orders-of-magnitude slower than given by standard estimates, most of which is the result of a modified coulomb logarithm.
Non-Equilibrium Effects on Hypersonic Turbulent Boundary Layers
NASA Astrophysics Data System (ADS)
Kim, Pilbum
Understanding non-equilibrium effects of hypersonic turbulent boundary layers is essential in order to build cost efficient and reliable hypersonic vehicles. It is well known that non-equilibrium effects on the boundary layers are notable, but our understanding of the effects are limited. The overall goal of this study is to improve the understanding of non-equilibrium effects on hypersonic turbulent boundary layers. A new code has been developed for direct numerical simulations of spatially developing hypersonic turbulent boundary layers over a flat plate with finite-rate reactions. A fifth-order hybrid weighted essentially non-oscillatory scheme with a low dissipation finite-difference scheme is utilized in order to capture stiff gradients while resolving small motions in turbulent boundary layers. The code has been validated by qualitative and quantitative comparisons of two different simulations of a non-equilibrium flow and a spatially developing turbulent boundary layer. With the validated code, direct numerical simulations of four different hypersonic turbulent boundary layers, perfect gas and non-equilibrium flows of pure oxygen and nitrogen, have been performed. In order to rule out uncertainties in comparisons, the same inlet conditions are imposed for each species, and then mean and turbulence statistics as well as near-wall turbulence structures are compared at a downstream location. Based on those comparisons, it is shown that there is no direct energy exchanges between internal and turbulent kinetic energies due to thermal and chemical non-equilibrium processes in the flow field. Instead, these non-equilibria affect turbulent boundary layers by changing the temperature without changing the main characteristics of near-wall turbulence structures. This change in the temperature induces the changes in the density and viscosity and the mean flow fields are then adjusted to satisfy the conservation laws. The perturbation fields are modified according to
NASA Astrophysics Data System (ADS)
Bondi, James F.
reacting Au nanoparticle seeds with n-butyllithium. The reaction yielded the thermodynamically stable phase Au3Li, a polar intermetallic which adopts the L12 structure type. Interestingly, the Au3Li nanoparticles decompose in water to regenerate Au. The Au3Li phase gives insight to a plausible template-driven reaction pathway for the non-equilibrium Au3M 1-x phases. The synthetic achievement of both non-equilibrium phases and polar intermetallics shows that n-butyllithium is capable of affecting nucleation kinetics and lithium intercalation. Finally, n-butyllithium was used as a strong reducing agent in the solution-based synthesis of elemental Mn nanoparticles. The particles were synthesized using air-free techniques by reacting n-butyllithium with MnCl2 and oleic acid in diphenyl ether. The nanoparticles were found to adopt the alpha-Mn structure and contained a thin amorphous MnO layer bound by oleate ligands to help render them air-stable. Unlike antiferromagnetic bulk Mn, the as-made nanoparticles were paramagnetic. With little modification, crystalline Mo and amorphous W nanoparticles were synthesized using the same n-butyllithium procedure. Using the thermal decomposition of metal-carbonyls was shown to yield W, Mo-based alloys, and tetrapod-like MnO nanoparticles.
Reconsidering harmonic and anharmonic coherent states: Partial differential equations approach
Toutounji, Mohamad
2015-02-15
This article presents a new approach to dealing with time dependent quantities such as autocorrelation function of harmonic and anharmonic systems using coherent states and partial differential equations. The approach that is normally used to evaluate dynamical quantities involves formidable operator algebra. That operator algebra becomes insurmountable when employing Morse oscillator coherent states. This problem becomes even more complicated in case of Morse oscillator as it tends to exhibit divergent dynamics. This approach employs linear partial differential equations, some of which may be solved exactly and analytically, thereby avoiding the cumbersome noncommutative algebra required to manipulate coherent states of Morse oscillator. Additionally, the arising integrals while using the herein presented method feature stability and high numerical efficiency. The correctness, applicability, and utility of the above approach are tested by reproducing the partition and optical autocorrelation function of the harmonic oscillator. A closed-form expression for the equilibrium canonical partition function of the Morse oscillator is derived using its coherent states and partial differential equations. Also, a nonequilibrium autocorrelation function expression for weak electron–phonon coupling in condensed systems is derived for displaced Morse oscillator in electronic state. Finally, the utility of the method is demonstrated through further simplifying the Morse oscillator partition function or autocorrelation function expressions reported by other researchers in unevaluated form of second-order derivative exponential. Comparison with exact dynamics shows identical results.
Reconsidering harmonic and anharmonic coherent states: Partial differential equations approach
NASA Astrophysics Data System (ADS)
Toutounji, Mohamad
2015-02-01
This article presents a new approach to dealing with time dependent quantities such as autocorrelation function of harmonic and anharmonic systems using coherent states and partial differential equations. The approach that is normally used to evaluate dynamical quantities involves formidable operator algebra. That operator algebra becomes insurmountable when employing Morse oscillator coherent states. This problem becomes even more complicated in case of Morse oscillator as it tends to exhibit divergent dynamics. This approach employs linear partial differential equations, some of which may be solved exactly and analytically, thereby avoiding the cumbersome noncommutative algebra required to manipulate coherent states of Morse oscillator. Additionally, the arising integrals while using the herein presented method feature stability and high numerical efficiency. The correctness, applicability, and utility of the above approach are tested by reproducing the partition and optical autocorrelation function of the harmonic oscillator. A closed-form expression for the equilibrium canonical partition function of the Morse oscillator is derived using its coherent states and partial differential equations. Also, a nonequilibrium autocorrelation function expression for weak electron-phonon coupling in condensed systems is derived for displaced Morse oscillator in electronic state. Finally, the utility of the method is demonstrated through further simplifying the Morse oscillator partition function or autocorrelation function expressions reported by other researchers in unevaluated form of second-order derivative exponential. Comparison with exact dynamics shows identical results.
Nonequilibrium chemical and radiation coupling phenomena in AOTV flowfields
NASA Technical Reports Server (NTRS)
Carlson, Leland A.; Gally, Thomas A.
1991-01-01
A flowfield model for the nonequilibrium stagnation region of high altitude entry vehicles which includes nonequilibrium chemistry, multitemperature, viscous, conduction, and diffusion effects is presented. It contains coupled nongray nonequilibrium radiative transfer for atoms and molecules and local thermodynamic nonequilibrium phenomena. Comparison with Fire 2 flight data verifies that the model is reasonably accurate; and it has been applied to two AFE trajectory points, a high speed return from Mars, a series of points at 80 km for 12 to 16 km/sec, and three altitudes at 16 km/sec. Based on these results shock slip is significant, radiation cooling/coupling is minor at AFE conditions but important by 14 km/sec and dominant at 16 km/sec, radiation for the AFE is small but important and primarily molecular, above 12 km/sec atomic radiation is a significant or dominant portion of the total heating, and local thermodynamic nonequilibrium is important and should be included in all models.
Free coherent spinons in quantum square ice
NASA Astrophysics Data System (ADS)
Kourtis, Stefanos; Castelnovo, Claudio
2016-09-01
We investigate the quantum dynamics of monopolelike excitations in quantum square ice, as captured by the strongly anisotropic spin-1/2 XXZ model on the checkerboard lattice. We obtain exact results for excitation dynamics in both analytically solvable effective models and a fully interacting model of quantum square ice on finite clusters. We find that the dispersive lower bound of the dynamic response of freely propagating spinons is recovered in the dynamic structure factor of the interacting system, yielding a marked fingerprint of coherent spinon dispersion. Our results provide unbiased evidence for the formation of coherent quasiparticles propagating freely in the correlated "vacuum" of quantum square ice.
Quantum speed limits of a qubit system interacting with a nonequilibrium environment
NASA Astrophysics Data System (ADS)
He, Zhi; Yao, Chun-Mei; Li, Li; Wang, Qiong
2016-08-01
The speed of evolution of a qubit undergoing a nonequilibrium environment with spectral density of general ohmic form is investigated. First we reveal non-Markovianity of the model, and find that the non-Markovianity quantified by information backflow of Breuer et al. [Phys. Rev. Lett. 103 210401 (2009)] displays a nonmonotonic behavior for different values of the ohmicity parameter s in fixed other parameters and the maximal non-Markovianity can be achieved at a specified value s. We also find that the non-Markovianity displays a nonmonotonic behavior with the change of a phase control parameter. Then we further discuss the relationship between quantum speed limit (QSL) time and non-Markovianity of the open-qubit system for any initial states including pure and mixed states. By investigation, we find that the QSL time of a qubit with any initial states can be expressed by a simple factorization law: the QSL time of a qubit with any qubit-initial states are equal to the product of the coherence of the initial state and the QSL time of maximally coherent states, where the QSL time of the maximally coherent states are jointly determined by the non-Markovianity, decoherence factor and a given driving time. Moreover, we also find that the speed of quantum evolution can be obviously accelerated in the wide range of the ohmicity parameter, i.e., from sub-Ohmic to Ohmic and super-Ohmic cases, which is different from the thermal equilibrium environment case. Project supported by the National Natural Science Foundation of China (Grants Nos. 61505053 and 61475045), the Natural Science Foundation of Hunan Province, China(Grant No. 2015JJ3092), the School Foundation from the Hunan University of Arts and Science (Grant No. 14ZD01), the Fund from the Key Laboratory of Photoelectric Information Integration and Optical Manufacturing Technology of Hunan Province, China, and the Construction Program of the Key Discipline in Hunan University of Arts and Science (Optics).
... Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Diagnostic Tests and Procedures Echocardiography Electrocardiogram ... Ultrasound Nuclear Stress Test Nuclear Ventriculography Positron Emission Tomography (PET) Stress ... Optical Coherence Tomography | ...
Undergraduate Coherent Optics Laboratory
ERIC Educational Resources Information Center
Yu, F. T. S.; Wang, E. Y.
1973-01-01
Discusses the use of a set of experiments to provide undergraduate electrical engineering students with a knowledge of the state of the art in modern coherent optics from an engineering standpoint. (CC)
Fresnel Coherent Diffractive Imaging
NASA Astrophysics Data System (ADS)
Williams, G. J.; Quiney, H. M.; Dhal, B. B.; Tran, C. Q.; Nugent, K. A.; Peele, A. G.; Paterson, D.; de Jonge, M. D.
2006-07-01
We present an x-ray coherent diffractive imaging experiment utilizing a nonplanar incident wave and demonstrate success by reconstructing a nonperiodic gold sample at 24 nm resolution. Favorable effects of the curved beam illumination are identified.
NASA Astrophysics Data System (ADS)
Thomson, D. J.; Maclennan, C. G.; Lanzerotti, L. J.
2006-12-01
The EPAM charged particle instrument on ACE is the backup for the HISCALE instrument on Ulysses making the two ideally suited for spatial coherence studies over large heliosphere distances. Fluxes of low-energy ( ~50 - 200 keV) electrons are detected in eight spatial sectors on both spacecraft. A spherical harmonic description of the particle flux as a function of time using only the l=0 and l=1 degree coefficients describes most of the observed flux. Here we concentrate on the three l=1 coefficients for the 60--100 kev electrons.Between the two spacecraft these result in nine coherence estimates that are all typically moderately coherent, but the fact that the different coefficients at each spacecraft are also coherent with each other makes interpretation difficult. To avoid this difficulty we estimated the canonical coherences between the two groups of three series. This, in effect, chooses an optimum coordinate system at each spacecraft and for each frequency and estimates the coherence in this frame. Using one--minute data, we find that the canonical coherences are generally larger at high frequencies (3 mHz and above) than they are at low frequencies. This appears to be generally true and does not depend particularly on time, range, etc. However, if the data segment is chosen too long, say > 30 days with 1--minute sampling, the coherence at high frequencies drops. This may be because the spatial and temporal features of the mode are confounded, or possibly because the solar modes p--modes are known to change frequency with solar activity, so do not appear coherent on long blocks.The coherences are not smooth functions of frequency, but have a bimodal distribution particularly in the 100 μHz to 5 mHz range. Classifying the data at frequencies where the canonical coherences are high in terms of apparent polarization and orientation, we note two major families of modes that appear to be organized by the Parker spiral. The magnetic field data on the two
NASA Astrophysics Data System (ADS)
Chapman, H. N.; Bajt, S.; Barty, A.; Benner, W. H.; Bogan, M. J.; Boutet, S.; Cavalleri, A.; Duesterer, S.; Frank, M.; Hajdu, J.; Hau-Riege, S. P.; Iwan, B.; Marchesini, S.; Sakdinawat, A.; Sokolowski-Tinten, K.; Seibert, M. M.; Timneanu, N.; Treusch, R.; Woods, B. W.
2009-09-01
We have carried out high-resolution single-pulse coherent diffractive imaging at the FLASH free-electron laser. The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of an object before that object turns into a plasma and explodes. In particular we are developing imaging of biological specimens beyond conventional radiation damage resolution limits, developing imaging of ultrafast processes, and testing methods to characterize and perform single-particle imaging.
Detection of Non-Equilibrium Fluctuations in Active Gels
NASA Astrophysics Data System (ADS)
Bacanu, Alexandru; Broedersz, Chase; Gladrow, Jannes; Mackintosh, Fred; Schmidt, Christoph; Fakhri, Nikta
Active force generation at the molecular scale in cells can result in stochastic non-equilibrium dynamics on mesoscpopic scales. Molecular motors such as myosin can drive steady-state stress fluctuations in cytoskeletal networks. Here, we present a non-invasive technique to probe non-equilibrium fluctuations in an active gel using single-walled carbon nanotubes (SWNTs). SWNTs are semiflexible polymers with intrinsic fluorescence in the near infrared. Both thermal and active motor-induced forces in the network induce transverse fluctuations of SWNTs. We demonstrate that active driven shape fluctuations of the SWNTs exhibit dynamics that reflect the non-equilibrium activity, in particular the emergence of correlations between the bending modes. We discuss the observation of breaking of detailed balance in this configurational space of the SWNT probes. Supported by National Defense Science and Engineering Graduate Student Fellowship (NDSEG).
Analysis of slow transitions between nonequilibrium steady states
NASA Astrophysics Data System (ADS)
Mandal, Dibyendu; Jarzynski, Christopher
2016-06-01
Transitions between nonequilibrium steady states obey a generalized Clausius inequality, which becomes an equality in the quasistatic limit. For slow but finite transitions, we show that the behavior of the system is described by a response matrix whose elements are given by a far-from-equilibrium Green–Kubo formula, involving the decay of correlations evaluated in the nonequilibrium steady state. This result leads to a fluctuation-dissipation relation between the mean and variance of the nonadiabatic entropy production, Δ {{s}\\text{na}} . Furthermore, our results extend—to nonequilibrium steady states—the thermodynamic metric structure introduced by Sivak and Crooks for analyzing minimal-dissipation protocols for transitions between equilibrium states.
Analysis of slow transitions between nonequilibrium steady states
NASA Astrophysics Data System (ADS)
Mandal, Dibyendu; Jarzynski, Christopher
2016-06-01
Transitions between nonequilibrium steady states obey a generalized Clausius inequality, which becomes an equality in the quasistatic limit. For slow but finite transitions, we show that the behavior of the system is described by a response matrix whose elements are given by a far-from-equilibrium Green-Kubo formula, involving the decay of correlations evaluated in the nonequilibrium steady state. This result leads to a fluctuation-dissipation relation between the mean and variance of the nonadiabatic entropy production, Δ {{s}\\text{na}} . Furthermore, our results extend—to nonequilibrium steady states—the thermodynamic metric structure introduced by Sivak and Crooks for analyzing minimal-dissipation protocols for transitions between equilibrium states.
Adiabatic Hamiltonian deformation, linear response theory, and nonequilibrium molecular dynamics
Hoover, W.G.
1980-05-28
Although Hamiltonians of various kinds have previously been used to derive Green-Kubo relations for the transport coefficients, the particular choice described is uniquely related to thermodynamics. This nonequilibrium Hamiltonian formulation of fluid flow provides pedagogically simple routes to nonequilibrium fluxes and distribution functions, to theoretical understanding of long-time effects, and to new numerical methods for simulating systems far from equilibrium. The same methods are now being applied to solid-phase problems. At the relatively high frequencies used in the viscous fluid calculations described, solids typically behave elastically. Lower frequencies lead to the formation of dislocations and other defects, making it possible to study plastic flow. A property of the nonequilibrium equations of motion which might be profitably explored is their effective irreversibility. Because only a few particles are necessary to generate irreversible behavior, simulations using adiabatic deformations of the kind described here could perhaps elucidate the instability in the equations of motion responsible for irreversibility.
NASA Technical Reports Server (NTRS)
Bose, Deepak
2012-01-01
The design of entry vehicles requires predictions of aerothermal environment during the hypersonic phase of their flight trajectories. These predictions are made using computational fluid dynamics (CFD) codes that often rely on physics and chemistry models of nonequilibrium processes. The primary processes of interest are gas phase chemistry, internal energy relaxation, electronic excitation, nonequilibrium emission and absorption of radiation, and gas-surface interaction leading to surface recession and catalytic recombination. NASAs Hypersonics Project is advancing the state-of-the-art in modeling of nonequilibrium phenomena by making detailed spectroscopic measurements in shock tube and arcjets, using ab-initio quantum mechanical techniques develop fundamental chemistry and spectroscopic databases, making fundamental measurements of finite-rate gas surface interactions, implementing of detailed mechanisms in the state-of-the-art CFD codes, The development of new models is based on validation with relevant experiments. We will present the latest developments and a roadmap for the technical areas mentioned above
Mankind as society, an example of a nonequilibrium system
Fliedner, D.
1992-12-31
Like every biotic, species mankind constitutes an extremely complex nonequilibrium system. This paper tries to gain an insight into its structure. Recognizable organizational patterns are the definable social populations (family, community, urban population, people, cultural population, etc.); they are ordered hierarchically. The social population is in itself a nonequilibrium system. Its structure can most appropriately be achieved by reducing it to the essentials and establishing a model. Within this {open_quotes}basic system{close_quotes} the flow of information and energy, the structuring processes connected with self-organization etc. is described by a set of formulae. The {open_quotes}basic system{close_quotes} can be regarded as a module that can also be used to form complex structures, above all the superior nonequilibrium system: mankind as society. This is a task for the future. 15 refs.
Detailed balance, nonequilibrium states, and dissipation in symbolic sequences
NASA Astrophysics Data System (ADS)
Nicolis, G.; Nicolis, C.
2016-05-01
Symbolic sequences arising from the coarse graining of deterministic dynamical systems continuous in phase space are considered. The extent to which signatures of the time irreversibility and of the nonequilibrium constraints at the level of the original system, such as fluxes or dissipation, can be identified at the coarse-grained level is analyzed. The roles of the partition, of the time window, and of time averaging in distinguishing in a clear-cut way the equilibrium versus nonequilibrium character of the sequence are brought out.
Experimental approaches for studying non-equilibrium atmospheric plasma jets
Shashurin, A.; Keidar, M.
2015-12-15
This work reviews recent research efforts undertaken in the area non-equilibrium atmospheric plasma jets with special focus on experimental approaches. Physics of small non-equilibrium atmospheric plasma jets operating in kHz frequency range at powers around few Watts will be analyzed, including mechanism of breakdown, process of ionization front propagation, electrical coupling of the ionization front with the discharge electrodes, distributions of excited and ionized species, discharge current spreading, transient dynamics of various plasma parameters, etc. Experimental diagnostic approaches utilized in the field will be considered, including Rayleigh microwave scattering, Thomson laser scattering, electrostatic streamer scatterers, optical emission spectroscopy, fast photographing, etc.
Gravitational energy, local holography and non-equilibrium thermodynamics
NASA Astrophysics Data System (ADS)
Freidel, Laurent
2015-03-01
We study the properties of gravitational systems in finite regions bounded by gravitational screens. We present a detailed construction of the total energy of such regions and of the energy and momentum balance equations due to the flow of matter and gravitational radiation through the screen. We establish that the gravitational screen possesses analogs of surface tension, internal energy, and viscous stress tensor, while the conservations are analogs of nonequilibrium balance equations for a viscous system. This gives a precise correspondence between gravity in finite regions and nonequilibrium thermodynamics.
Carbon vaporization into a nonequilibrium, stagnation-point boundary layer
NASA Technical Reports Server (NTRS)
Suzuki, T.
1978-01-01
The heat transfer to the stagnation point of an ablating carbonaceous heat shield, where both the gas-phase boundary layer and the heterogeneous surface reactions are not in chemical equilibrium, is examined. Specifically, the nonequilibrium changes in the mass fraction profiles of carbon species calculated for frozen flow are studied. A set of equations describing the steady-state, nonequilibrium laminar boundary layer in the axisymmetric stagnation region, over an ablating graphite surface, is solved, with allowance for the effects of finite rate of carbon vaporization.
Free energy functional for nonequilibrium systems: an exactly solvable case.
Derrida, B; Lebowitz, J L; Speer, E R
2001-10-01
We consider the steady state of an open system in which there is a flux of matter between two reservoirs at different chemical potentials. For a large system of size N, the probability of any macroscopic density profile rho(x) is exp[-NF([rho])]; F thus generalizes to nonequilibrium systems the notion of free energy density for equilibrium systems. Our exact expression for F is a nonlocal functional of rho, which yields the macroscopically long range correlations in the nonequilibrium steady state previously predicted by fluctuating hydrodynamics and observed experimentally. PMID:11580688
Time Dependent Hartree Fock Equation: Gateway to Nonequilibrium Plasmas
James W. Dufty
2007-04-28
This is the Final Technical Report for DE-FG02-2ER54677 award “Time Dependent Hartree Fock Equation - Gateway to Nonequilibrium Plasmas”. Research has focused on the nonequilibrium dynamics of electrons in the presence of ions, both via basic quantum theory and via semi-classical molecular dynamics (MD) simulation. In addition, fundamental notions of dissipative dynamics have been explored for models of grains and dust, and for scalar fields (temperature) in turbulent edge plasmas. The specific topics addressed were Quantum Kinetic Theory for Metallic Clusters, Semi-classical MD Simulation of Plasmas , and Effects of Dissipative Dynamics.
Physical origin of nonequilibrium fluctuation-induced forces in fluids.
Kirkpatrick, T R; Ortiz de Zárate, J M; Sengers, J V
2016-01-01
Long-range thermal fluctuations appear in fluids in nonequilibrium states leading to fluctuation-induced Casimir-like forces. Two distinct mechanisms have been identified for the origin of the long-range nonequilibrium fluctuations in fluids subjected to a temperature or concentration gradient. One is a coupling between the heat or mass-diffusion mode with a viscous mode in fluids subjected to a temperature or concentration gradient. Another one is the spatial inhomogeneity of thermal noise in the presence of a gradient. We show that in fluids fluctuation-induced forces arising from mode coupling are several orders of magnitude larger than those from inhomogeneous noise.
A nonequilibrium model for dynamic simulation of tray distillation columns
Kooijman, H.A.; Taylor, R.
1995-08-01
A nonequilibrium model for the dynamic simulation of distillation columns is described. The nonequilibrium model includes the direct calculation of the rates of mass and energy transfer and is better able to model the actual physical processes occurring on a real distillation tray than is the conventional equilibrium stage model. Example calculations show that heat-transfer limitations and the vapor holdup above the froth cannot be neglected at elevated pressures. Back-computed Murphree tray efficiencies are not constant over time, which implies that the equilibrium model should not be used for dynamic simulations.
Normal and superfluid fractions of inhomogeneous nonequilibrium quantum fluids
NASA Astrophysics Data System (ADS)
Gladilin, Vladimir N.; Wouters, Michiel
2016-04-01
We present a theoretical analysis of the normal and superfluid fractions of quantum fluids described by a nonequilibrium extension of the Gross-Pitaevskii equation in the presence of an external potential. Both disordered and regular potentials are considered. The normal and superfluid fractions are defined by the response of the nonequilibrium quantum fluid to a vector potential, in analogy with the equilibrium case. We find that the physical meaning of these definitions breaks down out of equilibrium. The normal and superfluid fractions no longer add up to one and for some types of external potentials they can even become negative.
a Nonequilibrium Plasmadynamics Model for Nitrogen/hydrogen Arcjets
NASA Astrophysics Data System (ADS)
Megli, Thomas W.
Electrothermal arcjets offer significant cost advantage over conventional satellite propulsion systems. In these devices, the propellant is electrically heated, allowing for higher temperatures and specific impulse than chemical rockets. Despite the relative simplicity of the basic design, many complex physical processes are poorly understood. Less than 50% of the electrical power is converted to thrust kinetic power. A numerical model is developed to study arcjet plasma flowfields. The model employs a modified set of Navier-Stokes equations, which includes separate energy equations for the electrons and heavy species. A thermal nonequilibrium, chemical equilibrium model is first developed, and then generalized to chemical nonequilibrium. A seven -species plasma of molecules, atoms, and ions is assumed for a variable mixture ratio of nitrogen and hydrogen. This permits simulation of various propellants, including hydrogen, ammonia, and hydrazine. Equations for charge continuity and Ohm's Law are employed to predict the arc current distribution. A thermal model for the nozzle is also included. The combined features of thermal nonequilibrium, chemical nonequilibrium, and propellant flexibility distinguish this model from previous research efforts. Model calculations are presented for 1-2 kW-class arcjets operating with hydrogen and hydrazine propellants. Thermal equilibrium is predicted in the highly ionized arc core, while electron temperatures near the electrodes are an order of magnitude greater than heavy species temperatures. The thermal nonequilibrium enhances ionization and electrical conductivity, and thus governs the current attachment to the nozzle. A comparison of chemical equilibrium and nonequilibrium simulations indicates that ambipolar diffusion of electrons and ions also controls the current conduction. The model is compared with experimental measurements. Respective calculations for specific impulse and exhaust velocities are within approximately 5
Hypersonic Viscous Shock Layer of Nonequilibrium Dissociating Gas
NASA Technical Reports Server (NTRS)
Chung, Paul M.
1961-01-01
The nonequilibrium chemical reaction of dissociation and recombination is studied theoretically for air in the viscous shock layer at the stagnation region af axisymmetric bodies. The flight regime considered is for speeds near satellite speed and for altitudes between 200,000 and 300,000 feet. The convective heat transfer to noncatalytic walls is obtained. The effects of nose radius, wall temperature, and flight altitude on the chemical state of the shock layer are studied. An analysis is also made on the simultaneous effect of nonequilibrium chemical reaction and air rarefaction on the shock layer thickness.
Nonequilibrium work energy relation for non-Hamiltonian dynamics
NASA Astrophysics Data System (ADS)
Mandal, Dibyendu; DeWeese, Michael R.
2016-04-01
Recent years have witnessed major advances in our understanding of nonequilibrium processes. The Jarzynski equality, for example, provides a link between equilibrium free energy differences and finite-time nonequilibrium dynamics. We propose a generalization of this relation to non-Hamiltonian dynamics, relevant for active matter systems, continuous feedback, and computer simulation. Surprisingly, this relation allows us to calculate the free energy difference between the desired initial and final equilibrium states using arbitrary dynamics. As a practical matter, this dissociation between the dynamics and the initial and final states promises to facilitate a range of techniques for free energy estimation in a single universal expression.
Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1990-01-01
The primary tasks during January 1990 to June 1990 have been the development and evaluation of various electron and electron-electronic energy equation models, the continued development of improved nonequilibrium radiation models for molecules and atoms, and the continued development and investigation of precursor models and their effects. In addition, work was initiated to develop a vibrational model for the viscous shock layer (VSL) nonequilibrium chemistry blunt body engineering code. Also, an effort was started associated with the effects of including carbon species, say from an ablator, in the flowfield.
Introduction to Nonequilibrium Statistical Mechanics with Quantum Field Theory
NASA Astrophysics Data System (ADS)
Kita, T.
2010-04-01
In this article, we present a concise and self-contained introduction to nonequilibrium statistical mechanics with quantum field theory by considering an ensemble of interacting identical bosons or fermions as an example. Readers are assumed to be familiar with the Matsubara formalism of equilibrium statistical mechanics such as Feynman diagrams, the proper self-energy, and Dyson's equation. The aims are threefold: (i) to explain the fundamentals of nonequilibrium quantum field theory as simple as possible on the basis of the knowledge of the equilibrium counterpart; (ii) to elucidate the hierarchy in describing nonequilibrium systems from Dyson's equation on the Keldysh contour to the Navier-Stokes equation in fluid mechanics via quantum transport equations and the Boltzmann equation; (iii) to derive an expression of nonequilibrium entropy that evolves with time. In stage (i), we introduce nonequilibrium Green's function and the self-energy uniquely on the round-trip Keld ysh contour, thereby avoiding possible confusions that may arise from defining multiple Green's functions at the very beginning. We try to present the Feynman rules for the perturbation expansion as simple as possible. In particular, we focus on the self-consistent perturbation expansion with the Luttinger-Ward thermodynamic functional, i.e., Baym's Phi-derivable approximation, which has a crucial property for nonequilibrium systems of obeying various conservation laws automatically. We also show how the two-particle correlations can be calculated within the Phi-derivable approximation, i.e., an issue of how to handle the ``Bogoliubov-Born-Green-Kirkwood-Yvons (BBGKY) hierarchy''. Aim (ii) is performed through successive reductions of relevant variables with the Wigner transformation, the gradient expansion based on the Groenewold-Moyal product, and Enskog's expansion from local equilibrium. This part may be helpful for convincing readers that nonequilibrium systems ca n be handled
Formation of an interphase boundary under highly nonequilibrium conditions
Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.
2007-12-15
The results of comparison studies of the CdTe-CdS interphase boundary in Au/CdTe/CdS sandwich structures synthesized on a substrate of artificial fluorophlogopite mica in highly nonequilibrium conditions (with a substrate temperature T{sub s} = 125 K) and in quasi-equilibrium conditions (T{sub s} > 720 K) are reported. The X-ray diffraction patterns and a capacitance-voltage characteristic are also reported. It is shown that highly nonequilibrium conditions allow synthesis of structures with excellent crystalline quality and with an interphase boundary that is no worse than in the structures grown under equilibrium conditions.
Skewness of steady-state current fluctuations in nonequilibrium systems.
Belousov, Roman; Cohen, E G D; Wong, Chun-Shang; Goree, John A; Feng, Yan
2016-04-01
A skewness of the probability for instantaneous current fluctuations, in a nonequilibrium steady state, is observed experimentally in a dusty plasma. This skewness is attributed to the spatial asymmetry, which is imminent to the nonequilibrium systems due to the external hydrodynamic gradient. Using the modern framework of the large deviation theory, we extend the Onsager-Machlup ansatz for equilibrium fluctuations to systems with a preferred spatial direction, and provide a modulated Gaussian probability distribution, which is tested by simulations. This probability distribution is also of potential interest for other statistical disciplines. Connections with the principles of statistical mechanics, due to Boltzmann and Gibbs, are discussed as well. PMID:27176272
Comparison of methodologies for describing relaxation in nonequilibrium gaseous systems
NASA Technical Reports Server (NTRS)
Schreiber, Willard C.
1992-01-01
The heat transfer process in hypervelocity vehicles is dominated by nonequilibrium gas dynamics. One model used in computational fluid dynamics (CFD) codes to predict hypervelocity heat transfer is the 'two-temperature' model. An analysis has been made to test the validity of the two-temperature model for predicting another nonequilibrium phenomenon, sound absorption and deviation of signal speed in a high temperature gas. It is found that the two temperature model's prediction capabilities degenerate with increasing temperature. These results are felt to have significance concerning the two-temperature's ability to predict heat transfer in hypervelocity flows.
Strongly Coupled Nanotube Electromechanical Resonators.
Deng, Guang-Wei; Zhu, Dong; Wang, Xin-He; Zou, Chang-Ling; Wang, Jiang-Tao; Li, Hai-Ou; Cao, Gang; Liu, Di; Li, Yan; Xiao, Ming; Guo, Guang-Can; Jiang, Kai-Li; Dai, Xing-Can; Guo, Guo-Ping
2016-09-14
Coupling an electromechanical resonator with carbon-nanotube quantum dots is a significant method to control both the electronic charge and the spin quantum states. By exploiting a novel microtransfer technique, we fabricate two separate strongly coupled and electrically tunable mechanical resonators for the first time. The frequency of the two resonators can be individually tuned by the bottom gates, and in each resonator, the electron transport through the quantum dot can be strongly affected by the phonon mode and vice versa. Furthermore, the conductance of either resonator can be nonlocally modulated by the other resonator through phonon-phonon interaction between the two resonators. Strong coupling is observed between the phonon modes of the two resonators, where the coupling strength larger than 200 kHz can be reached. This strongly coupled nanotube electromechanical resonator array provides an experimental platform for future studies of the coherent electron-phonon interaction, the phonon-mediated long-distance electron interaction, and entanglement state generation.
The global coherence initiative: creating a coherent planetary standing wave.
McCraty, Rollin; Deyhle, Annette; Childre, Doc
2012-03-01
The much anticipated year of 2012 is now here. Amidst the predictions and cosmic alignments that many are aware of, one thing is for sure: it will be an interesting and exciting year as the speed of change continues to increase, bringing both chaos and great opportunity. One benchmark of these times is a shift in many people from a paradigm of competition to one of greater cooperation. All across the planet, increasing numbers of people are practicing heart-based living, and more groups are forming activities that support positive change and creative solutions for manifesting a better world. The Global Coherence Initiative (GCI) is a science-based, co-creative project to unite people in heart-focused care and intention. GCI is working in concert with other initiatives to realize the increased power of collective intention and consciousness. The convergence of several independent lines of evidence provides strong support for the existence of a global information field that connects all living systems and consciousness. Every cell in our bodies is bathed in an external and internal environment of fluctuating invisible magnetic forces that can affect virtually every cell and circuit in biological systems. Therefore, it should not be surprising that numerous physiological rhythms in humans and global collective behaviors are not only synchronized with solar and geomagnetic activity, but disruptions in these fields can create adverse effects on human health and behavior. The most likely mechanism for explaining how solar and geomagnetic influences affect human health and behavior are a coupling between the human nervous system and resonating geomagnetic frequencies, called Schumann resonances, which occur in the earth-ionosphere resonant cavity and Alfvén waves. It is well established that these resonant frequencies directly overlap with those of the human brain and cardiovascular system. If all living systems are indeed interconnected and communicate with each other
The Global Coherence Initiative: Creating a Coherent Planetary Standing Wave
Deyhle, Annette; Childre, Doc
2012-01-01
ABSTRACT The much anticipated year of 2012 is now here. Amidst the predictions and cosmic alignments that many are aware of, one thing is for sure: it will be an interesting and exciting year as the speed of change continues to increase, bringing both chaos and great opportunity. One benchmark of these times is a shift in many people from a paradigm of competition to one of greater cooperation. All across the planet, increasing numbers of people are practicing heart-based living, and more groups are forming activities that support positive change and creative solutions for manifesting a better world. The Global Coherence Initiative (GCI) is a science-based, co-creative project to unite people in heart-focused care and intention. GCI is working in concert with other initiatives to realize the increased power of collective intention and consciousness. The convergence of several independent lines of evidence provides strong support for the existence of a global information field that connects all living systems and consciousness. Every cell in our bodies is bathed in an external and internal environment of fluctuating invisible magnetic forces that can affect virtually every cell and circuit in biological systems. Therefore, it should not be surprising that numerous physiological rhythms in humans and global collective behaviors are not only synchronized with solar and geomagnetic activity, but disruptions in these fields can create adverse effects on human health and behavior. The most likely mechanism for explaining how solar and geomagnetic influences affect human health and behavior are a coupling between the human nervous system and resonating geomagnetic frequencies, called Schumann resonances, which occur in the earth-ionosphere resonant cavity and Alfvén waves. It is well established that these resonant frequencies directly overlap with those of the human brain and cardiovascular system. If all living systems are indeed interconnected and communicate with
Nonlinear optics in non-equilibrium microplasmas
NASA Astrophysics Data System (ADS)
Compton, Ryan E.
2011-12-01
This dissertation details the nature of subnanosecond laser-induced microplasma dynamics, particularly concerning the evolution of the electron temperature and concentration. Central to this development is the advent of a femtosecond four-wave mixing (FWM) spectroscopic method. FWM (in the form of coherent anti-Stokes Raman scattering (CARS)) measurements are performed on the fundamental oxygen vibrational transition. An analytical expression is provided that accounts for the resonant and nonresonant contributions to the CARS signal generated from the interaction of broadband pump and Stokes pulses. The inherent phase mismatch is also accounted for, resulting in quantitative agreement between experiment and theory. FWM is then used to measure the early-time electron dynamics in the noble gas series from He to Xe following irradiation by an intense (1014 Wcm-2) nonresonant 80 fs laser pulse. An electron impact ionization cooling model is presented to determine the evolution of electron kinetic energies following ionization. Kinetic energies are predicted to evolve from > 20 eV to < 1 eV in the first 1.5 ns. The initial degree of ionization is determined experimentally via measurement of the Bremsstrahlung background emission, and modeled with a modified ADK theory based on tunnel ionization. Combined, these two descriptions account for the evolution of both the electron temperature and concentration and provide quantitative agreement with the FWM measurements. The model is further tested with measurements of the gas pressure and pump laser intensity on the electron dynamics. The FWM experiments are concluded with a qualitative discussion of dissociative recombination dynamics occurring in molecular microplasmas. The microplasma environment is used as a source for the generation of two-level systems in the excited state manifold of atomic oxygen and argon. These two-level systems are coupled using moderately intense ˜1 ps near-infrared (and near-resonant) pulses
Interferometric phase reconstruction using simplified coherence network
NASA Astrophysics Data System (ADS)
Zhang, Kui; Song, Ruiqing; Wang, Hui; Wu, Di; Wang, Hua
2016-09-01
Interferometric time-series analysis techniques, which extend the traditional differential radar interferometry, have demonstrated a strong capability for monitoring ground surface displacement. Such techniques are able to obtain the temporal evolution of ground deformation within millimeter accuracy by using a stack of synthetic aperture radar (SAR) images. In order to minimize decorrelation between stacked SAR images, the phase reconstruction technique has been developed recently. The main idea of this technique is to reform phase observations along a SAR stack by taking advantage of a maximum likelihood estimator which is defined on the coherence matrix estimated from each target. However, the phase value of a coherence matrix element might be considerably biased when its corresponding coherence is low. In this case, it will turn to an outlying sample affecting the corresponding phase reconstruction process. In order to avoid this problem, a new approach is developed in this paper. This approach considers a coherence matrix element to be an arc in a network. A so-called simplified coherence network (SCN) is constructed to decrease the negative impact of outlying samples. Moreover, a pointed iterative strategy is designed to resolve the transformed phase reconstruction problem defined on a SCN. For validation purposes, the proposed method is applied to 29 real SAR images. The results demonstrate that the proposed method has an excellent computational efficiency and could obtain more reliable phase reconstruction solutions compared to the traditional method using phase triangulation algorithm.
Understanding Nonequilibrium and Correlated Electron Behavior in Molecular Junctions
NASA Astrophysics Data System (ADS)
Wegewijs, Maarten
2010-03-01
I present an overview of the effects of the strong correlations in single-molecule junctions on non-linear transport, focusing on theory while comparing with several recent experiments. In the brief introduction I outline our real-time diagrammatic transport theory and its renormalization group extensions. In this approach a kinetic equation (generalized master equation) for the molecular density matrix incorporates both the quantum coherence and the strong correlations between electronic, vibrational and spin degrees of freedom of the device. The molecular state and non-linear current are calculated perturbatively beyond the lowest order in the coupling to the electrodes. As a first example, a detailed comparison with recent measurements on carbon-nanotube ``peapod'' devices is presented, indicating non-trivial hybridization and Coulomb interaction with the host nanotube quantum dot. The remainder of the talk focuses on predictions for specific electromechanical (electron-vibration coupling) and magnetic effects (spin-orbit coupling). I discuss non-linear transport signatures of vibrations when going beyond the simplified pictures of sequential tunneling (which breaks down due to quantum fluctuations) and the Born-Oppenheimer separation (its breakdown resulting in pseudo-Jahn-Teller coupling). Both effects have recently been observed. Finally, I address the interplay of transport with various aspects of molecular magnetism, such as antisymmetric (Dzyaloshinskii-Moriya) exchange and magnetic anisotropy. A comparison with recent transport experiments reveals the possibility of electric-field tunable molecular magnetism in an ``ferric-star'' molecular device.
Coherent combination of slab-coupled optical waveguide lasers
NASA Astrophysics Data System (ADS)
Huang, Robin K.; Chann, Bien; Missaggia, Leo J.; Augst, Steven J.; Connors, Michael K.; Turner, George W.; Sanchez-Rubio, Antonio; Donnelly, Joseph P.; Hostetler, John L.; Miester, Carl; Dorsch, Friedhelm
2009-02-01
A long-standing challenge for semiconductor lasers is scaling the optical power and brightness of many diode lasers by coherent beam combination. Because single-mode semiconductor lasers have limited power available from a single element, there is a strong motivation to coherently combine the outputs of many elements for applications including industrial lasers for materials processing, free space optical communications, and defense. Despite the fact that such a coherently-combined source is potentially the most efficient laser, coherent combination of semiconductor lasers is generally considered to be difficult, since precise phase control is required between elements. We describe our approach to coherent combination of semiconductor lasers. The Slab-Coupled Optical Waveguide Laser (SCOWL), invented at Lincoln Laboratory, is used as the single-mode diode laser element for coherent combination. With a 10-element SCOWL array, coherently combined output power as high as 7 W in continuous wave using an external cavity has been demonstrated, which is the highest output level achieved using a coherent array of semiconductor lasers. We are currently working on a related approach to scale the coherent power up to 100 W.
SAR image effects on coherence and coherence estimation.
Bickel, Douglas Lloyd
2014-01-01
Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.
Optical coherency matrix tomography
NASA Astrophysics Data System (ADS)
Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.
2015-10-01
The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes.
Optical coherency matrix tomography
Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.
2015-01-01
The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes. PMID:26478452
Vibrational non-equilibrium in the hydrogen-oxygen reaction. Comparison with experiment
NASA Astrophysics Data System (ADS)
Skrebkov, Oleg V.
2015-03-01
A theoretical model is proposed for the chemical and vibrational kinetics of hydrogen oxidation based on consistent accounting of the vibrational non-equilibrium of the HO2 radical that forms as a result of the bimolecular recombination H+O2 → HO2. In the proposed model, the chain branching H+O2 = O+OH and inhibiting H+O2+M = HO2+M formal reactions are treated (in the terms of elementary processes) as a single multi-channel process of forming, intramolecular energy redistribution between modes, relaxation, and unimolecular decay of the comparatively long-lived vibrationally excited HO2 radical, which is able to react and exchange energy with the other components of the mixture. The model takes into account the vibrational non-equilibrium of the starting (primary) H2 and O2 molecules, as well as the most important molecular intermediates HO2, OH, O2(1Δ), and the main reaction product H2O. It is shown that the hydrogen-oxygen reaction proceeds in the absence of vibrational equilibrium, and the vibrationally excited HO2(v) radical acts as a key intermediate in a fundamentally important chain branching process and in the generation of electronically excited species O2(1Δ), O(1D), and OH(2Σ+). The calculated results are compared with the shock tube experimental data for strongly diluted H2-O2 mixtures at 1000 < T < 2500 K, 0.5 < p < 4 atm. It is demonstrated that this approach is promising from the standpoint of reconciling the predictions of the theoretical model with experimental data obtained by different authors for various compositions and conditions using different methods. For T < 1500 K, the nature of the hydrogen-oxygen reaction is especially non-equilibrium, and the vibrational non-equilibrium of the HO2 radical is the essence of this process. The quantitative estimation of the vibrational relaxation characteristic time of the HO2 radical in its collisions with H2 molecules has been obtained as a result of the comparison of different experimental data on
NASA Astrophysics Data System (ADS)
Hell, M.; Wegewijs, M. R.; DiVincenzo, D. P.
2016-01-01
We theoretically investigate the backaction of a sensor quantum dot with strong local Coulomb repulsion on the transient dynamics of a qubit that is probed capacitively. We show that the measurement backaction induced by the noise of electron cotunneling through the sensor is surprisingly mitigated by the recently identified coherent backaction [M. Hell, M. R. Wegewijs, and D. P. DiVincenzo, Phys. Rev. B 89, 195405 (2014), 10.1103/PhysRevB.89.195405] arising from quantum fluctuations. This indicates that a sensor with quantized states may be switched off better than naively expected. This renormalization effect is missing in semiclassical stochastic fluctuator models and typically also in Born-Markov approaches, which try to avoid the calculation of the nonstationary, nonequilibrium state of the qubit plus sensor. Technically, we integrate out the current-carrying electrodes to obtain kinetic equations for the joint, nonequilibrium detector-qubit dynamics. We show that the sensor current response, level renormalization, cotunneling broadening, and leading non-Markovian corrections always appear together and cannot be turned off individually in an experiment or ignored theoretically. We analyze the backaction on the reduced qubit state—capturing the full non-Markovian effects imposed by the sensor quantum dot on the qubit—by applying a Liouville-space decomposition into quasistationary and rapidly decaying modes. Importantly, the sensor cannot be eliminated completely even in the simplest high-temperature, weak-measurement limit since the qubit state experiences an initial slip depending on the initial preparation of qubit plus sensor quantum dot. The slip persists over many qubit cycles, i.e., also on the time scale of the qubit decoherence induced by the backaction. A quantum-dot sensor can thus not be modeled as usual as a "black box" without accounting for its dynamical variables; it is part of the quantum circuit. We furthermore find that the Bloch vector
Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma
NASA Technical Reports Server (NTRS)
Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander
2007-01-01
As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.
Nonequilibrium Enhances Adaptation Efficiency of Stochastic Biochemical Systems
Jia, Chen; Qian, Minping
2016-01-01
Adaptation is a crucial biological function possessed by many sensory systems. Early work has shown that some influential equilibrium models can achieve accurate adaptation. However, recent studies indicate that there are close relationships between adaptation and nonequilibrium. In this paper, we provide an explanation of these two seemingly contradictory results based on Markov models with relatively simple networks. We show that as the nonequilibrium driving becomes stronger, the system under consideration will undergo a phase transition along a fixed direction: from non-adaptation to simple adaptation then to oscillatory adaptation, while the transition in the opposite direction is forbidden. This indicates that although adaptation may be observed in equilibrium systems, it tends to occur in systems far away from equilibrium. In addition, we find that nonequilibrium will improve the performance of adaptation by enhancing the adaptation efficiency. All these results provide a deeper insight into the connection between adaptation and nonequilibrium. Finally, we use a more complicated network model of bacterial chemotaxis to validate the main results of this paper. PMID:27195482
Caloric and entropic temperatures in non-equilibrium steady states
NASA Astrophysics Data System (ADS)
Jou, D.; Restuccia, L.
2016-10-01
We examine the non-equilibrium consequences of two different definitions of temperature in systems out of equilibrium: one is based on the internal energy (caloric temperature), and the other one on the entropy (entropic temperature). We discuss the relation between the values obtained from these two definitions in ideal gases and in two-level systems.
Model for nonequilibrium segregation during pulsed laser annealing
Wood, R.F.
1980-08-01
Highly nonequilibrium thermodynamic processes occur during the ultrarapid recrystallization characteristic of pulsed laser annealing. Values of interface segregation coefficients are observed to differ from equilibrium values by as much as three orders of magnitude and equilibrium solubility limits may be exceeded by similar magnitudes. In this letter, a model is developed which accounts quantitatively for these effects.
Note on two theorems in nonequilibrium statistical mechanics
Cohen, E.G.D.; Gallavotti, G.
1999-09-01
An attempt is made to clarify the difference between a theorem derived by Evans and Searles in 1994 on the statistics of trajectories in phase space and a theorem proved by the authors in 1995 on the statistics of fluctuations on phase space trajectory segments in a nonequilibrium stationary state.
Simulations of nonequilibrium warm dense gold produced by ultrafast heating
NASA Astrophysics Data System (ADS)
Holst, B.; Recoules, V.; Torrent, M.; Chen, Z.; Sametoglu, V.; Tsui, Y. Y.; Kirkwood, S. E.; Reid, M.; Mazevet, S.; Ng, A.
2013-03-01
The interaction of femtosecond laser pulses with metals produces nonequilibrium states consisting of hot electrons and cold ions. These can last for many picoseconds before relaxing to a thermodynamic equilibrium. Recent experiments using a chirped pulse probe technique provided AC conductivity data of gold at a sufficient time resolution to observe this relaxation process. We developed an ab-initio model that characterizes thermodynamic properties of warm dense matter states in nonequilibrium. Our theoretical scheme combines a standard two temperature model with temperature dependent material parameters and an energy transfer rate that are obtained by means of ab-initio simulations. This enables us to give a prediction for the temperature evolution during the relaxation process. Additionally, we derive the AC conductivity of the nonequilibrium states from our simulations using the Kubo-Greenwood formula. It is used to test our model against measurements. We observe agreement with experiment using an energy relaxation rate, that is smaller than predicted, giving us reason to revisit its determination. We can furthermore provide thermodynamical and structural data of nonequilibrium warm dense gold which are not accessible in experiment.
EQUILIBRIUM AND NONEQUILIBRIUM FOUNDATIONS OF FREE ENERGY COMPUTATIONAL METHODS
C. JARZYNSKI
2001-03-01
Statistical mechanics provides a rigorous framework for the numerical estimation of free energy differences in complex systems such as biomolecules. This paper presents a brief review of the statistical mechanical identities underlying a number of techniques for computing free energy differences. Both equilibrium and nonequilibrium methods are covered.
Measures of trajectory ensemble disparity in nonequilibrium statistical dynamics
Crooks, Gavin; Sivak, David
2011-06-03
Many interesting divergence measures between conjugate ensembles of nonequilibrium trajectories can be experimentally determined from the work distribution of the process. Herein, we review the statistical and physical significance of several of these measures, in particular the relative entropy (dissipation), Jeffreys divergence (hysteresis), Jensen-Shannon divergence (time-asymmetry), Chernoff divergence (work cumulant generating function), and Renyi divergence.
Dynamic coherent backscattering mirror
Xu, M.
2016-01-01
The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation. PMID:26937296
Nonequilibrium solidification in undercooled Ti{sub 45}Al{sub 55} melts
Hartmann, H.; Galenko, P. K.; Holland-Moritz, D.; Kolbe, M.; Herlach, D. M.; Shuleshova, O.
2008-04-01
Ti-Al alloys are of high technological interest as light-weight high-performance materials. When produced by solidification from the liquid state, the material properties of as-solidified materials are strongly dependent on the conditions governing the solidification process. Nonequilibrium solidification from the state of an undercooled liquid may result to the formation of metastable solid materials. On the one hand undercooling under special cases may influence the phase selection behavior during solidification, and on the other hand during rapid growth of solid phases in undercooled melts nonequilibrium effects such as solute trapping and disorder trapping may occur. In the present work containerless processing by electromagnetic levitation is used to undercool Ti{sub 45}Al{sub 55} melts deeply below the liquidus temperature. The dendrite growth velocity during the solidification is measured as a function of undercooling by application of a high-speed video camera. In situ diffraction experiments at ESRF in Grenoble and microstructure investigations are performed in order to identify the primary solidified phases. The experimental findings are interpreted within current theoretical models for dendritic growth and solute trapping.
NASA Astrophysics Data System (ADS)
English, Niall J.; Clarke, Elaine T.
2013-09-01
Equilibrium and non-equilibrium molecular dynamics (MD) simulations have been performed to investigate thermal-driven break-up of planar CO2 hydrate interfaces in liquid water at 300-320 K. Different guest compositions, at 85%, 95%, and 100% of maximum theoretical occupation, led to statistically-significant differences in the observed initial dissociation rates. The melting temperatures of each interface were estimated, and dissociation rates were observed to be strongly dependent on temperature, with higher dissociation rates at larger over-temperatures vis-à-vis melting. A simple coupled mass and heat transfer model developed previously was applied to fit the observed dissociation profiles, and this helps to identify clearly two distinct régimes of break-up; a second well-defined region is essentially independent of composition and temperature, in which the remaining nanoscale, de facto two-dimensional system's lattice framework is intrinsically unstable. From equilibrium MD of the two-phase systems at their melting point, the relaxation times of the auto-correlation functions of fluctuations in number of enclathrated guest molecules were used as a basis for comparison of the variation in the underlying, non-equilibrium, thermal-driven dissociation rates via Onsager's hypothesis, and statistically significant differences were found, confirming the value of a fluctuation-dissipation approach in this case.
NASA Astrophysics Data System (ADS)
Shafranjuk, S.; Nevirkovets, I. P.; Mukhanov, O. A.; Ketterson, J. B.
2016-08-01
We report a theoretical and experimental study on the use of nonequilibrium tunneling injection to control the local Cooper pair amplitude ΦS in an S F sandwich involving superconducting (S ) and ferromagnetic (F ) layers coupled by the proximity effect. In an SISFIFS structure (where I is an insulator), this same S F sandwich serves as the acceptor electrode of an S I S F Josephson junction whose critical current Ica depends on ΦS . We derive the self-consistency equation describing the critical temperature Tc of the S F sandwich under nonequilibrium conditions. In addition, we compute Ica by solving the Boltzmann equation for the electron distribution function fɛ , which then allows a determination of the relative change of δ Ica/δ Ii(Vi) versus the bias voltage Vi and the injection current Ii(Vi) . The computed gain δ Ica/δ Ii(Vi) strongly depends on δ Ica/δ Ii(Vi) , and agrees well with the experimental data.
Stability of high-speed boundary layers in oxygen including chemical non-equilibrium effects
NASA Astrophysics Data System (ADS)
Klentzman, Jill; Tumin, Anatoli
2013-11-01
The stability of high-speed boundary layers in chemical non-equilibrium is examined. A parametric study varying the edge temperature and the wall conditions is conducted for boundary layers in oxygen. The edge Mach number and enthalpy ranges considered are relevant to the flight conditions of reusable hypersonic cruise vehicles. Both viscous and inviscid stability formulations are used and the results compared to gain insight into the effects of viscosity and thermal conductivity on the stability. It is found that viscous effects have a strong impact on the temperature and mass fraction perturbations in the critical layer and in the viscous sublayer near the wall. Outside of these areas, the perturbations closely match in the viscous and inviscid models. The impact of chemical non-equilibrium on the stability is investigated by analyzing the effects of the chemical source term in the stability equations. The chemical source term is found to influence the growth rate of the second Mack mode instability but not have much of an effect on the mass fraction eigenfunction for the flow parameters considered. This work was supported by the AFOSR/NASA/National Center for Hypersonic Laminar-Turbulent Transition Research.
Nonequilibrium self-energy functional approach to the dynamical Mott transition
NASA Astrophysics Data System (ADS)
Hofmann, Felix; Eckstein, Martin; Potthoff, Michael
2016-06-01
The real-time dynamics of the Fermi-Hubbard model, driven out of equilibrium by quenching or ramping the interaction parameter, is studied within the framework of the nonequilibrium self-energy functional theory. A dynamical impurity approximation with a single auxiliary bath site is considered as a reference system, and the time-dependent hybridization is optimized as prescribed by the variational principle. The dynamical two-site approximation turns out to be useful to study the real-time dynamics on short and intermediate time scales. Depending on the strength of the interaction in the final state, two qualitatively different response regimes are observed. For both weak and strong couplings, qualitative agreement with previous results of nonequilibrium dynamical mean-field theory is found. The two regimes are sharply separated by a critical point at which the low-energy bath degree of freedom decouples in the course of time. We trace the dependence of the critical interaction of the dynamical Mott transition on the duration of the interaction ramp from sudden quenches to adiabatic dynamics and therewith link the dynamical to the equilibrium Mott transition.
NASA Astrophysics Data System (ADS)
Assis, Vladimir R. V.; Copelli, Mauro
2009-12-01
We study a modified version of the stochastic susceptible-infected-refractory-susceptible (SIRS) model by employing a nonlinear (exponential) reinforcement in the contagion rate and no diffusion. We run simulations for complete and random graphs as well as d -dimensional hypercubic lattices (for d=3,2,1 ). For weak nonlinearity, a continuous nonequilibrium phase transition between an absorbing and an active phase is obtained, such as in the usual stochastic SIRS model [Joo and Lebowitz, Phys. Rev. E 70, 036114 (2004)]. However, for strong nonlinearity, the nonequilibrium transition between the two phases can be discontinuous for d≥2 , which is confirmed by well-characterized hysteresis cycles and bistability. Analytical mean-field results correctly predict the overall structure of the phase diagram. Furthermore, contrary to what was observed in a model of phase-coupled stochastic oscillators with a similar nonlinearity in the coupling [Wood , Phys. Rev. Lett. 96, 145701 (2006)], we did not find a transition to a stable (partially) synchronized state in our nonlinearly pulse-coupled excitable elements. For long enough refractory times and high enough nonlinearity, however, the system can exhibit collective excitability and unstable stochastic oscillations.
Non-equilibrium oxidation states of zirconium during early stages of metal oxidation
Ma, Wen; Senanayake, Sanjaya D.; Herbert, F. William; Yildiz, Bilge
2015-03-11
The chemical state of Zr during the initial, self-limiting stage of oxidation on single crystal zirconium (0001), with oxide thickness on the order of 1 nm, was probed by synchrotron x-ray photoelectron spectroscopy. Quantitative analysis of the Zr 3d spectrum by the spectrum reconstruction method demonstrated the formation of Zr^{1+}, Zr^{2+}, and Zr^{3+} as non-equilibrium oxidation states, in addition to Zr^{4+} in the stoichiometric ZrO_{2}. This finding resolves the long-debated question of whether it is possible to form any valence states between Zr^{0} and Zr^{4+} at the metal-oxide interface. As a result, the presence of local strong electric fields and the minimization of interfacial energy are assessed and demonstrated as mechanisms that can drive the formation of these non-equilibrium valence states of Zr.
Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1994-01-01
The primary accomplishments of the project were as follows: (1) From an overall standpoint, the primary accomplishment of this research was the development of a complete gasdynamic-radiatively coupled nonequilibrium viscous shock layer solution method for axisymmetric blunt bodies. This method can be used for rapid engineering modeling of nonequilibrium re-entry flowfields over a wide range of conditions. (2) Another significant accomplishment was the development of an air radiation model that included local thermodynamic nonequilibrium (LTNE) phenomena. (3) As part of this research, three electron-electronic energy models were developed. The first was a quasi-equilibrium electron (QEE) model which determined an effective free electron temperature and assumed that the electronic states were in equilibrium with the free electrons. The second was a quasi-equilibrium electron-electronic (QEEE) model which computed an effective electron-electronic temperature. The third model was a full electron-electronic (FEE) differential equation model which included convective, collisional, viscous, conductive, vibrational coupling, and chemical effects on electron-electronic energy. (4) Since vibration-dissociation coupling phenomena as well as vibrational thermal nonequilibrium phenomena are important in the nonequilibrium zone behind a shock front, a vibrational energy and vibration-dissociation coupling model was developed and included in the flowfield model. This model was a modified coupled vibrational dissociation vibrational (MCVDV) model and also included electron-vibrational coupling. (5) Another accomplishment of the project was the usage of the developed models to investigate radiative heating. (6) A multi-component diffusion model which properly models the multi-component nature of diffusion in complex gas mixtures such as air, was developed and incorporated into the blunt body model. (7) A model was developed to predict the magnitude and characteristics of the shock
Spectral properties of strongly correlated systems
NASA Astrophysics Data System (ADS)
Monien, H.
1998-01-01
The pseudogap and the suppression of coherent transport in the direction perpendicular to the CuO planes of the high-temperature superconductors are clearly related to strong correlations. We study the suppression of coherent transport modelling the layered structure of the high-temperature superconductors by a pair of strongly correlated planes which are connected by a hopping transfer integral t⊥ in the limit of large in-plane coordination number. The suppression of low-energy density of states (pseudogap) by low-energy fluctuation close to a phase transition can be studied in one dimension using techniques introduced by Abrikosova and Ryzhkin. We present results which are exact in the limit of large correlation lengths which differ significantly from results obtained earlier. Our results may be relevant to the “pseudogap” phenomenon occurring in underdoped high- Tc superconductors and quasi-one-dimensional organic conductors and to the theory of liquid metals.
Coherent soliton communication lines
Yushko, O. V. Redyuk, A. A.; Fedoruk, M. P.; Turitsyn, S. K.
2014-11-15
The data transmission in coherent fiber-optical communication lines using solitons with a variable phase is studied. It is shown that nonlinear coherent structures (solitons) can be applied for effective signal transmission over a long distance using amplitude and optical-phase keying of information. The optimum ratio of the pulse width to the bit slot at which the spectral efficiency (transmitted bits per second and hertz) is maximal is determined. It is shown that soliton fiber-optical communication lines can ensure data transmission at a higher spectral efficiency as compared to traditional communication lines and at a high signal-to-noise ratio.
Coherent control of metamaterials
NASA Astrophysics Data System (ADS)
Chakrabarti, Sangeeta; Ramakrishna, S. Anantha; Wanare, Harshawardhan
2009-08-01
We theoretically demonstrate the possibility of dynamically controlling the response of metamaterials at optical frequencies using the well known phenomenon of coherent control. Our results predict a variety of effects ranging from dramatic reduction of losses associated with the resonant response of metamaterials to switchable ultraslow to superluminal propagation of pulses governed by the magnetic field of the incident wave. These effects, generic to all metamaterials having a resonant response, involve embedding the metamaterial in resonant dispersive coherent atomic/molecular media. These effects may be utilized for narrow band switching applications and detectors for radiation below predetermined cut-off frequencies.
Quantum memory with millisecond coherence in circuit QED
NASA Astrophysics Data System (ADS)
Reagor, Matthew; Pfaff, Wolfgang; Axline, Christopher; Heeres, Reinier W.; Ofek, Nissim; Sliwa, Katrina; Holland, Eric; Wang, Chen; Blumoff, Jacob; Chou, Kevin; Hatridge, Michael J.; Frunzio, Luigi; Devoret, Michel H.; Jiang, Liang; Schoelkopf, Robert J.
2016-07-01
Significant advances in coherence render superconducting quantum circuits a viable platform for fault-tolerant quantum computing. To further extend capabilities, highly coherent quantum systems could act as quantum memories for these circuits. A useful quantum memory must be rapidly addressable by Josephson-junction-based artificial atoms, while maintaining superior coherence. We demonstrate a superconducting microwave cavity architecture that is highly robust against major sources of loss that are encountered in the engineering of circuit QED systems. The architecture allows for storage of quantum superpositions in a resonator on the millisecond scale, while strong coupling between the resonator and a transmon qubit enables control, encoding, and readout at MHz rates. This extends the maximum available coherence time attainable in superconducting circuits by almost an order of magnitude compared to earlier hardware. Our design is an ideal platform for studying coherent quantum optics and marks an important step towards hardware-efficient quantum computing in Josephson-junction-based quantum circuits.
Apparatus for generating partially coherent radiation
Naulleau, Patrick P.
2005-02-22
Techniques for generating partially coherent radiation and particularly for converting effectively coherent radiation from a synchrotron to partially coherent EUV radiation suitable for projection lithography.
Studies on nonequilibrium phenomena in supersonic chemically reacting flows
NASA Technical Reports Server (NTRS)
Tiwari, S. N.; Chandrasekhar, Rajnish
1993-01-01
This study deals with a systematic investigation of nonequilibrium processes in supersonic combustion. The two-dimensional, elliptic Navier-Stokes equations are used to investigate supersonic flows with nonequilibrium chemistry and thermodynamics, coupled with radiation, for hydrogen-air systems. The explicit, unsplit MacCormack finite-difference scheme is used to advance the governing equations in time, until convergence is achieved. For a basic understanding of the flow physics, premixed flows undergoing finite rate chemical reactions are investigated. Results obtained for specific conditions indicate that the radiative interactions vary substantially, depending on reactions involving HO2 and NO species, and that this can have a noticeable influence on the flowfield. The second part of this study deals with premixed reacting flows under thermal nonequilibrium conditions. Here, the critical problem is coupling of the vibrational relaxation process with the radiative heat transfer. The specific problem considered is a premixed expanding flow in a supersonic nozzle. Results indicate the presence of nonequilibrium conditions in the expansion region of the nozzle. This results in reduction of the radiative interactions in the flowfield. Next, the present study focuses on investigation of non-premixed flows under chemical nonequilibrium conditions. In this case, the main problem is the coupled turbulence-chemistry interaction. The resulting formulation is validated by comparison with experimental data on reacting supersonic coflowing jets. Results indicate that the effect of heat release is to lower the turbulent shear stress and the mean density. The last part of this study proposes a new theoretical formulation for the coupled turbulence-radiation interactions. Results obtained for the coflowing jets experiment indicate that the effect of turbulence is to enhance the radiative interactions.
Coherence and measurement in quantum thermodynamics
NASA Astrophysics Data System (ADS)
Kammerlander, P.; Anders, J.
2016-02-01
Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed.
Coherence and measurement in quantum thermodynamics.
Kammerlander, P; Anders, J
2016-02-26
Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed.
Coherence and measurement in quantum thermodynamics.
Kammerlander, P; Anders, J
2016-01-01
Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed. PMID:26916503
Coherence and measurement in quantum thermodynamics
Kammerlander, P.; Anders, J.
2016-01-01
Thermodynamics is a highly successful macroscopic theory widely used across the natural sciences and for the construction of everyday devices, from car engines to solar cells. With thermodynamics predating quantum theory, research now aims to uncover the thermodynamic laws that govern finite size systems which may in addition host quantum effects. Recent theoretical breakthroughs include the characterisation of the efficiency of quantum thermal engines, the extension of classical non-equilibrium fluctuation theorems to the quantum regime and a new thermodynamic resource theory has led to the discovery of a set of second laws for finite size systems. These results have substantially advanced our understanding of nanoscale thermodynamics, however putting a finger on what is genuinely quantum in quantum thermodynamics has remained a challenge. Here we identify information processing tasks, the so-called projections, that can only be formulated within the framework of quantum mechanics. We show that the physical realisation of such projections can come with a non-trivial thermodynamic work only for quantum states with coherences. This contrasts with information erasure, first investigated by Landauer, for which a thermodynamic work cost applies for classical and quantum erasure alike. Repercussions on quantum work fluctuation relations and thermodynamic single-shot approaches are also discussed. PMID:26916503
Coherence Constraints and the Last Hidden Optical Coherence
NASA Astrophysics Data System (ADS)
Qian, Xiao-Feng; Malhotra, Tanya; Vamivakas, A. Nick; Eberly, Joseph H.
2016-10-01
We have discovered a new domain of optical coherence, and show that it is the third and last member of a previously unreported fundamental triad of coherences. These are unified by our derivation of a parallel triad of coherence constraints that take the form of complementarity relations. We have been able to enter this new coherence domain experimentally and we describe the novel tomographic approach devised for that purpose.
ERIC Educational Resources Information Center
Lear, Rick
2007-01-01
This article describes how the Coalition of Essential Schools Northwest/Small Schools Project (CESNW/SSP) works with schools and districts to help them shape and then implement a coherent strategy that will lead to a redesigned high school system. The author highlights efforts taking place in two multiple high school districts: (1) Cascades School…
ERIC Educational Resources Information Center
Hobson, R. Peter
2014-01-01
There is a growing body of opinion that we should view autism as fractionable into different, largely independent sets of clinical features. The alternative view is that autism is a coherent syndrome in which principal features of the disorder stand in intimate developmental relationship with each other. Studies of congenitally blind children…
NASA Technical Reports Server (NTRS)
Dybdal, Robert B. (Inventor); Curry, Samuel J. (Inventor)
2009-01-01
An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.
Coherent Raman Umklappscattering
NASA Astrophysics Data System (ADS)
Yuan, L.; Lanin, A. A.; Jha, P. K.; Traverso, A. J.; Voronine, D. V.; Dorfman, K. E.; Fedotov, A. B.; Welch, G. R.; Sokolov, A. V.; Zheltikov, A. M.; Scully, M. O.
2011-10-01
We identify the conditions for coherent Raman scattering to enable the generation of phase-matched, highly directional, nearly-backward-propagating light beams. Our analysis indicates a unique possibility for standoff detection of trace gases using their rotational and vibrational spectroscopic signals. We demonstrate spatial selectivity of Raman transitions and variability of possible Umklappscattering implementation schemes and laser sources.
Dental Optical Coherence Tomography
Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Chuang, Ching-Cheng; Tsai, Jui-che; Lin, Kun-Feng; Sun, Chia-Wei
2013-01-01
This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed. PMID:23857261
Extracting quantum coherence via steering
Hu, Xueyuan; Fan, Heng
2016-01-01
As the precious resource for quantum information processing, quantum coherence can be created remotely if the involved two sites are quantum correlated. It can be expected that the amount of coherence created should depend on the quantity of the shared quantum correlation, which is also a resource. Here, we establish an operational connection between coherence induced by steering and the quantum correlation. We find that the steering-induced coherence quantified by such as relative entropy of coherence and trace-norm of coherence is bounded from above by a known quantum correlation measure defined as the one-side measurement-induced disturbance. The condition that the upper bound saturated by the induced coherence varies for different measures of coherence. The tripartite scenario is also studied and similar conclusion can be obtained. Our results provide the operational connections between local and non-local resources in quantum information processing. PMID:27682450
Shimony-Wolf states and hidden coherences in classical light
NASA Astrophysics Data System (ADS)
Eberly, J. H.
2015-10-01
The classical theory of polarisation coherence is briefly summarised and then extended. The extension is motivated by the recognition that the traditional theory of two-point coherence provides only what we identify as 'diagonal' correlation functions and their associated two-point coherence matrices. It is pointed out that a wider focus is possible when taking account of the three-sector vector space underlying all two-point coherences in classical optics. This reveals the possibility of observing a new type of 'off-diagonal' correlations that arise when the correlation functions under investigation are associated with points in two distinct vector spaces, pairs of points that are not analogous to the pairs of space points or time points that underlie traditional measures of spatial and temporal coherence. Quantum theory has experience with correlations engaging such 'cross-sector' coherences, for example in tests of Bell inequalities, and the quantum formulations are shown to be easily adopted by classical theory without incorporating quantum features in the optical signals. The familiar theory of classical coherence that is associated with the pioneering work of Emil Wolf is extended in conformance with three criteria advanced by Abner Shimony to obtain formulas for correlation functions and for the Bell measure ? of coherence. Values of ? greater than the standard upper limit ? are predicted for certain classical Shimony-Wolf fields, indicating strong cross-sector coherence, but only when standard measures of coherence such as degree of polarisation ? are minimised. Experimental results confirming the predictions for cross-sector coherence are exhibited.
Non-linear optical diagnostic studies of high pressure non-equilibrium plasmas
NASA Astrophysics Data System (ADS)
Lempert, Walter
2012-10-01
Picosecond Coherent Anti-Stokes Raman Spectroscopy (CARS) is used for study of vibrational energy loading and relaxation kinetics in high pressure nitrogen and air nsec pulsed non-equilibrium plasmas in a pin-to-pin geometry. It is found that ˜33% of total discharge energy in a single pulse in air at 100 torr couples directly to nitrogen vibration by electron impact, in good agreement with master equation modeling predictions. However in the afterglow the total quanta in vibrational levels 0 -- 9 is found to increase by a factor of approximately 2 and 4 in nitrogen and air, respectively, a result in direct contrast to modeling results which predict the total number of quanta to be essentially constant. More detailed comparison between experiment and model show that the VDF predicted by the model during, and directly after, the discharge pulse is in good agreement with that determined experimentally, however for time delays exceeding ˜10 μsec the experimental and predicted VDFs diverge rapidly, particularly for levels v = 2 and greater. Specifically modeling predicts a rapid drop in population of high levels due to net downward V-V energy transfer whereas the experiment shows an increase in population in levels 2 and 3 and approximately constant population for higher levels. It is concluded that a collisional process is feeding high vibrational levels at a rate which is comparable to the rate at which population of the high levels is lost due to net downward V-V. A likely candidate for the source of additional vibrational quanta is the quenching of metastable electronic states of nitrogen to highly excited vibrational levels of the ground electronic state. Recent progress in the development and application of psec coherent Raman electric field and spontaneous Thomson scattering diagnostics for study of high pressure nsec pulsed plasmas will also be presented.
Spatially correlated fluctuations and coherence dynamics in photosynthesis.
Yu, Z G; Berding, M A; Wang, Haobin
2008-11-01
Recent multicolor photon-echo experiments revealed a long-lasting quantum coherence between excitations on the donor and acceptor in photosynthetic systems. Identifying the origin of the quantum coherence is essential to fully understand photosynthesis. Here we present a generic model in which a strong intermolecular steric restoring force in densely packed pigment-protein complexes results in a spatial correlation in conformational (static) variations of chromophores, which in turn induces an effective coupling between high-frequency (dynamic) fluctuations in donor and acceptor. The spatially correlated static and dynamic fluctuations provide a favorable environment to maintain quantum coherence, which can consistently explain the photon-echo measurements.
Coherent hybrid electromagnetic field imaging
Cooke, Bradly J.; Guenther, David C.
2008-08-26
An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.
Operational Resource Theory of Coherence.
Winter, Andreas; Yang, Dong
2016-03-25
We establish an operational theory of coherence (or of superposition) in quantum systems, by focusing on the optimal rate of performance of certain tasks. Namely, we introduce the two basic concepts-"coherence distillation" and "coherence cost"-in the processing quantum states under so-called incoherent operations [Baumgratz, Cramer, and Plenio, Phys. Rev. Lett. 113, 140401 (2014)]. We, then, show that, in the asymptotic limit of many copies of a state, both are given by simple single-letter formulas: the distillable coherence is given by the relative entropy of coherence (in other words, we give the relative entropy of coherence its operational interpretation), and the coherence cost by the coherence of formation, which is an optimization over convex decompositions of the state. An immediate corollary is that there exists no bound coherent state in the sense that one would need to consume coherence to create the state, but no coherence could be distilled from it. Further, we demonstrate that the coherence theory is generically an irreversible theory by a simple criterion that completely characterizes all reversible states. PMID:27058063
Operational Resource Theory of Coherence.
Winter, Andreas; Yang, Dong
2016-03-25
We establish an operational theory of coherence (or of superposition) in quantum systems, by focusing on the optimal rate of performance of certain tasks. Namely, we introduce the two basic concepts-"coherence distillation" and "coherence cost"-in the processing quantum states under so-called incoherent operations [Baumgratz, Cramer, and Plenio, Phys. Rev. Lett. 113, 140401 (2014)]. We, then, show that, in the asymptotic limit of many copies of a state, both are given by simple single-letter formulas: the distillable coherence is given by the relative entropy of coherence (in other words, we give the relative entropy of coherence its operational interpretation), and the coherence cost by the coherence of formation, which is an optimization over convex decompositions of the state. An immediate corollary is that there exists no bound coherent state in the sense that one would need to consume coherence to create the state, but no coherence could be distilled from it. Further, we demonstrate that the coherence theory is generically an irreversible theory by a simple criterion that completely characterizes all reversible states.
Operational Resource Theory of Coherence
NASA Astrophysics Data System (ADS)
Winter, Andreas; Yang, Dong
2016-03-01
We establish an operational theory of coherence (or of superposition) in quantum systems, by focusing on the optimal rate of performance of certain tasks. Namely, we introduce the two basic concepts—"coherence distillation" and "coherence cost"—in the processing quantum states under so-called incoherent operations [Baumgratz, Cramer, and Plenio, Phys. Rev. Lett. 113, 140401 (2014)]. We, then, show that, in the asymptotic limit of many copies of a state, both are given by simple single-letter formulas: the distillable coherence is given by the relative entropy of coherence (in other words, we give the relative entropy of coherence its operational interpretation), and the coherence cost by the coherence of formation, which is an optimization over convex decompositions of the state. An immediate corollary is that there exists no bound coherent state in the sense that one would need to consume coherence to create the state, but no coherence could be distilled from it. Further, we demonstrate that the coherence theory is generically an irreversible theory by a simple criterion that completely characterizes all reversible states.
Investigation of Non-Equilibrium Radiation for Earth Entry
NASA Technical Reports Server (NTRS)
Brandis, Aaron; Johnston, Chris; Cruden, Brett
2016-01-01
This paper presents measurements and simulations of non-equilibrium shock layer radiation relevant to high-speed Earth entry data obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility. The experiments were aimed at measuring the spatially and spectrally resolved radiance at relevant entry conditions for both an approximate Earth atmosphere (79 N2 : 21 O2) as well as a more accurate composition featuring the trace species Ar and CO2 (78.08 N2 : 20.95 O2 : 0.04 CO2 : 0.93 Ar). The experiments were configured to target a wide range of conditions, of which shots from 8 to 11.5 km/s at 0.2 Torr (26.7 Pa) are examined in this paper. The non-equilibrium component was chosen to be the focus of this study as it can account for a significant percentage of the emitted radiation for Earth entry, and more importantly, non-equilibrium has traditionally been assigned a large uncertainty for vehicle design. The main goals of this study are to present the shock tube data in the form of a non-equilibrium metric, evaluate the level of agreement between the experiment and simulations, identify key discrepancies and to promote discussion about various aspects of modeling non-equilibrium radiating flows. Radiance profiles integrated over discreet wavelength regions, ranging from the VUV through to the NIR, were compared in order to maximize both the spectral coverage and the number of experiments that could be used in the analysis. A previously defined non-equilibrium metric has been used to allow comparisons with several shots and reveal trends in the data. Overall, LAURAHARA is shown to under-predict EAST by as much as 50 and over-predict by as much as 20 depending on the shock speed. DPLRNEQAIR is shown to under-predict EAST by as much as 40 and over-predict by as much as 12 depending on the shock speed. In terms of an upper bound estimate for the absolute error in wall-directed heat flux, at the lower speeds investigated in this paper, 8 to 9 km/s, even
Nonequilibrium properties of trapped ions under sudden application of a laser
NASA Astrophysics Data System (ADS)
Cifuentes, A. A.; Nicacio, F.; Paternostro, M.; Semião, F. L.
2016-07-01
Coherent quantum-state manipulation of trapped ions using classical laser fields is a trademark of modern quantum technologies. In this work, we study aspects of work statistics and irreversibility in a single trapped ion due to sudden interaction with the impinging laser. This is clearly an out-of-equilibrium process where work is performed through illumination of an ion by the laser. Starting with the explicit evaluation of the first moments of the work distribution, we proceed to a careful analysis of irreversibility as quantified by the nonequilibrium lag. The treatment employed here is not restricted to the Lamb-Dicke limit, which allows us to investigate the interplay between nonlinearities and irreversibility. We show that in these multiquantum or sideband regimes, variation of the Lamb-Dicke parameter causes a nonmonotonic behavior of the irreversibility indicator. Counterintuitively, we find a working point where nonlinearity helps reversibility, making the sudden quench of the Hamiltonian closer to what would have been obtained quasistatically and isothermally.
Coherent structure formation in turbulent thermal superfluids.
Kivotides, Demosthenes
2006-05-01
By means of numerical calculations, we show that in turbulent thermal superfluids the normal fluid induces coherent bundles of quantized line vortices in the superfluid. These filamentary structures are formed in between the normal fluid vortices, acquiring eventually comparable circulation. They are self-stretched and evolve according to self-regulating dynamics. Their spectrum mimics the normal fluid spectrum with the mutual friction force exciting the large scales and damping the small scales. Strongly interacting triads of them merge sporadically into stronger, braided vortex filaments, inducing strong fluctuations in the system's energetics. A theoretical account of the system's statistical mechanics is proposed. PMID:16712309
Muscatello, Jordan; Jaeger, Frederike; Matar, Omar K; Müller, Erich A
2016-05-18
Recent experimental results suggest that stacked layers of graphene oxide exhibit strong selective permeability to water. To construe this observation, the transport mechanism of water permeating through a membrane consisting of layered graphene sheets is investigated via nonequilibrium and equilibrium molecular dynamics simulations. The effect of sheet geometry is studied by changing the offset between the entrance and exit slits of the membrane. The simulation results reveal that the permeability is not solely dominated by entrance effects; the path traversed by water molecules has a considerable impact on the permeability. We show that contrary to speculation in the literature, water molecules do not pass through the membrane as a hydrogen-bonded chain; instead, they form well-mixed fluid regions confined between the graphene sheets. The results of the present work are used to provide guidelines for the development of graphene and graphene oxide membranes for desalination and solvent separation.
NASA Astrophysics Data System (ADS)
Mo, M. Y.; Kantorovich, L.
2001-02-01
We apply the non-equilibrium statistical operator method to non-contact atomic force microscopy, considering explicitly the statistical effects of (classical) vibrations of surface atoms and associated energy transfer from the tip to the surface. We derive several, physically and mathematically equivalent, forms of the equation of motion for the tip, each containing a friction term due to the so-called intrinsic mechanism of energy dissipation first suggested by Gauthier and Tsukada. Our exact treatment supports the results of some earlier work which were all approximate. We also demonstrate, using the same theory, that the distribution function of the tip in the coordinate-momentum phase subspace is governed by the Fokker-Planck equation and should be considered as strongly peaked around the exact values t and t of the momentum and the position of the tip, respectively.
Nonequilibrium dynamics of vortex arrest in a finite-temperature Bose-Einstein condensate
Wright, T. M.; Bradley, A. S.; Ballagh, R. J.
2010-01-15
We perform finite-temperature dynamical simulations of the arrest of a rotating Bose-Einstein condensate by a fixed trap anisotropy, using a Hamiltonian classical-field method. We consider a quasi-two-dimensional condensate containing a single vortex in equilibrium with a rotating thermal cloud. Introducing an elliptical deformation of the trapping potential leads to the loss of angular momentum from the system. We identify the condensate and the complementary thermal component of the nonequilibrium field and compare the evolution of their angular momenta and angular velocities. By varying the trap anisotropy we alter the relative efficiencies of the vortex-cloud and cloud-trap coupling. For strong trap anisotropies the angular momentum of the thermal cloud may be entirely depleted before the vortex begins to decay. For weak trap anisotropies, the thermal cloud exhibits a long-lived steady state in which it rotates at an intermediate angular velocity.
Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study
NASA Astrophysics Data System (ADS)
Hoang Viet, Man; Derreumaux, Philippe; Li, Mai Suan; Roland, Christopher; Sagui, Celeste; Nguyen, Phuong H.
2015-10-01
Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.
A time-accurate algorithm for chemical non-equilibrium viscous flows at all speeds
NASA Technical Reports Server (NTRS)
Shuen, J.-S.; Chen, K.-H.; Choi, Y.
1992-01-01
A time-accurate, coupled solution procedure is described for the chemical nonequilibrium Navier-Stokes equations over a wide range of Mach numbers. This method employs the strong conservation form of the governing equations, but uses primitive variables as unknowns. Real gas properties and equilibrium chemistry are considered. Numerical tests include steady convergent-divergent nozzle flows with air dissociation/recombination chemistry, dump combustor flows with n-pentane-air chemistry, nonreacting flow in a model double annular combustor, and nonreacting unsteady driven cavity flows. Numerical results for both the steady and unsteady flows demonstrate the efficiency and robustness of the present algorithm for Mach numbers ranging from the incompressible limit to supersonic speeds.
Picosecond dissociation of amyloid fibrils with infrared laser: A nonequilibrium simulation study
Hoang Viet, Man; Roland, Christopher Sagui, Celeste; Derreumaux, Philippe; Nguyen, Phuong H.; Li, Mai Suan
2015-10-21
Recently, mid-infrared free-electron laser technology has been developed to dissociate amyloid fibrils. Here, we present a theoretical framework for this type of experiment based on laser-induced nonequilibrium all-atom molecular dynamics simulations. We show that the fibril is destroyed due to the strong resonance between its amide I vibrational modes and the laser field. The effects of laser irradiation are determined by a balance between fibril formation and dissociation. While the overall rearrangements of the fibril finish over short time scales, the interaction between the peptides and the solvent continues over much longer times indicating that the waters play an important role in the dissociation process. Our results thus provide new insights into amyloid fibril dissociation by laser techniques and open up new venues to investigate the complex phenomena associated with amyloidogenesis.
Calculation of H2-He Flow with Nonequilibrium Ionization and Radiation: an Interim Report
NASA Technical Reports Server (NTRS)
Furudate, Michiko; Chang, Keun-Shik
2005-01-01
The nonequilibrium ionization process in hydrogen-helium mixture behind a strong shock wave is studied numerically using the detailed ionization rate model developed recently by Park which accounts for emission and absorption of Lyman lines. The study finds that, once the avalanche ionization is started, the Lyman line is self-absorbed. The intensity variation of the radiation at 5145 Angstroms found by Leibowitz in a shock tube experiment can be numerically reproduced by assuming that ionization behind the shock wave prior to the onset of avalanche ionization is 1.3%. Because 1.3% initial ionization is highly unlikely, Leibowitz s experimental data is deemed questionable. By varying the initial electron density value in the calculation, the calculated ionization equilibration time is shown to increase approximately as inverse square-root of the initial electron density value. The true ionization equilibration time is most likely much longer than the value found by Leibowitz.
Muscatello, Jordan; Jaeger, Frederike; Matar, Omar K; Müller, Erich A
2016-05-18
Recent experimental results suggest that stacked layers of graphene oxide exhibit strong selective permeability to water. To construe this observation, the transport mechanism of water permeating through a membrane consisting of layered graphene sheets is investigated via nonequilibrium and equilibrium molecular dynamics simulations. The effect of sheet geometry is studied by changing the offset between the entrance and exit slits of the membrane. The simulation results reveal that the permeability is not solely dominated by entrance effects; the path traversed by water molecules has a considerable impact on the permeability. We show that contrary to speculation in the literature, water molecules do not pass through the membrane as a hydrogen-bonded chain; instead, they form well-mixed fluid regions confined between the graphene sheets. The results of the present work are used to provide guidelines for the development of graphene and graphene oxide membranes for desalination and solvent separation. PMID:27121070
Modes of storage ring coherent instabilities
Wang, J.M.
1986-12-01
Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)
Coherent Radiation Effects in the LCLS Undulator
Reiche, S.; Huang, Z.; /SLAC
2010-12-14
For X-ray Free-Electron Lasers such as LCLS and TESLA FEL, a change in the electron energy while amplifying the FEL radiation can shift the resonance condition out of the bandwidth of the FEL. The largest sources of energy loss is the emission of incoherent undulator radiation. Because the loss per electron depends only on the undulator parameters and the beam energy, which are fixed for a given resonant wavelength, the average energy loss can be compensated for by a fixed taper of the undulator. Coherent radiation has a strong enhancement proportional to the number of electrons in the bunch for frequencies comparable to or longer than the bunch dimension. If the emitted coherent energy becomes comparable to that of the incoherent emission, it has to be included in the taper as well. However, the coherent loss depends on the bunch charge and the applied compression scheme and a change of these parameters would require a change of the taper. This imposes a limitation on the practical operation of Free-Electron Lasers, where the taper can only be adjusted manually. In this presentation we analyze the coherent emission of undulator radiation and transition undulator radiation for LCLS, and estimate whether the resulting energy losses are significant for the operation of LCLS.
Characterization of partially coherent ultrashort XUV pulses
NASA Astrophysics Data System (ADS)
Bourassin-Bouchet, Charles; Couprie, Marie-Emmanuelle
2015-05-01
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, i.e. that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. As an example, the lack of longitudinal coherence, that is shot-to-shot fluctuations, of Free-Electron Lasers (FEL) has prevented so far their full amplitude and phase temporal characterization. To sort out this issue, we have adapted Frequency-Resolved Optical Gating (FROG), the first and one of the most widespread techniques for pulse characterization, to enable the measurement of partially coherent XUV pulses even down to the attosecond timescale. Especially, this technique allows one to overcome the sources of decoherence that normally prevent a pulse measurement, such as the spectrometer resolution or the presence of XUV/laser arrival time jitter.
Nonequilibrium quantum chains under multisite Lindblad baths
NASA Astrophysics Data System (ADS)
Guimarães, Pedro H.; Landi, Gabriel T.; de Oliveira, Mario J.
2016-09-01
We study a quantum XX chain coupled to two heat reservoirs that act on multiple sites and are kept at different temperatures and chemical potentials. The baths are described by Lindblad dissipators, which are constructed by direct coupling to the fermionic normal modes of the chain. Using a perturbative method, we are able to find analytical formulas for all steady-state properties of the system. We compute both the particle or magnetization current and the energy current, both of which are found to have the structure of Landauer's formula. We also obtain exact formulas for the Onsager coefficients. All properties are found to differ substantially from those of a single-site bath. In particular, we find a strong dependence on the intensity of the bath couplings. In the weak-coupling regime, we show that the Onsager reciprocal relations are satisfied.
Nonequilibrium dynamics of an ultracold dipolar gas
NASA Astrophysics Data System (ADS)
Sykes, A. G.; Bohn, J. L.
2015-01-01
We study the relaxation and damping dynamics of an ultracold, but not quantum degenerate, gas consisting of dipolar particles. These simulations are performed using a direct simulation Monte Carlo method and employing the highly anisotropic differential cross section of dipoles in the Wigner threshold regime. We find that both cross-dimensional relaxation and damping of breathing modes occur at rates that are strongly dependent on the orientation of the dipole moments relative to the trap axis. The relaxation simulations are in excellent agreement with recent experimental results in erbium. The results direct our interest toward a less explored regime in dipolar gases where interactions are dominated by collision processes rather than mean-field interactions.
Boltzmann equation solver adapted to emergent chemical non-equilibrium
Birrell, Jeremiah; Wilkening, Jon; Rafelski, Johann
2015-01-15
We present a novel method to solve the spatially homogeneous and isotropic relativistic Boltzmann equation. We employ a basis set of orthogonal polynomials dynamically adapted to allow for emergence of chemical non-equilibrium. Two time dependent parameters characterize the set of orthogonal polynomials, the effective temperature T(t) and phase space occupation factor ϒ(t). In this first paper we address (effectively) massless fermions and derive dynamical equations for T(t) and ϒ(t) such that the zeroth order term of the basis alone captures the particle number density and energy density of each particle distribution. We validate our method and illustrate the reduced computational cost and the ability to easily represent final state chemical non-equilibrium by studying a model problem that is motivated by the physics of the neutrino freeze-out processes in the early Universe, where the essential physical characteristics include reheating from another disappearing particle component (e{sup ±}-annihilation)
Nonequilibrium dynamics of spin-orbit-coupled lattice bosons
NASA Astrophysics Data System (ADS)
Ng, H. T.
2015-10-01
We study the nonequilibrium dynamics of two-component bosonic atoms in a one-dimensional optical lattice in the presence of spin-orbit coupling. In the Mott-insulating regime, the two-component bosonic system at unity filling can be described by the quantum spin X X Z model. The atoms are initially prepared in their lower spin states. The system becomes out of equilibrium by suddenly introducing spin-orbit coupling to the atoms. The system shows the relaxation and nonstationary dynamics, respectively, in the different interaction regimes. We find that the time average of magnetization is useful to characterize the many-body dynamics. The effects of even and odd numbers of sites are discussed. Our result sheds light on nonequilibrium dynamics due to the interplay between spin-orbit coupling and atomic interactions.
The Avogadro Challenge ---Nanodynamics Study on Nonequilibrium Problems---
NASA Astrophysics Data System (ADS)
Yukawa, S.; Ito, N.
Computer performance is now reaching to realize 1 mol operations, that is, 6 × 10(23) arithmetic operations. Such Avogadro-scale computer will open a new era of sciences and technologies via renovations of fields in material sciences, which had been assuming that the Avogadro number be a synonym of infinity. Since the first milestone was placed by B. J. Alder half-a-century ago, a road to thermal equilibrium properties was well paved and linear transport phenomena have also been tamed with nonequilibrium simulations. Now the front lines confront nonlinear nonequilibrium problems. As an example, molecular-dynamics simulation of a shock tube which is an analogue of volcanic eruption is given.
Imaging Nonequilibrium Atomic Vibrations with X-ray Diffuse Scattering
Trigo, M.; Chen, J.; Vishwanath, V.H.; Sheu, Y.M.; Graber, T.; Henning, R.; Reis, D; /SLAC /Stanford U., Appl. Phys. Dept.
2011-03-03
We use picosecond x-ray diffuse scattering to image the nonequilibrium vibrations of the lattice following ultrafast laser excitation. We present images of nonequilibrium phonons in InP and InSb throughout the Brillouin-zone which remain out of equilibrium up to nanoseconds. The results are analyzed using a Born model that helps identify the phonon branches contributing to the observed features in the time-resolved diffuse scattering. In InP this analysis shows a delayed increase in the transverse acoustic (TA) phonon population along high-symmetry directions accompanied by a decrease in the longitudinal acoustic (LA) phonons. In InSb the increase in TA phonon population is less directional.
Maximum work extraction and implementation costs for nonequilibrium Maxwell's demons
NASA Astrophysics Data System (ADS)
Sandberg, Henrik; Delvenne, Jean-Charles; Newton, Nigel J.; Mitter, Sanjoy K.
2014-10-01
We determine the maximum amount of work extractable in finite time by a demon performing continuous measurements on a quadratic Hamiltonian system subjected to thermal fluctuations, in terms of the information extracted from the system. The maximum work demon is found to apply a high-gain continuous feedback involving a Kalman-Bucy estimate of the system state and operates in nonequilibrium. A simple and concrete electrical implementation of the feedback protocol is proposed, which allows for analytic expressions of the flows of energy, entropy, and information inside the demon. This let us show that any implementation of the demon must necessarily include an external power source, which we prove both from classical thermodynamics arguments and from a version of Landauer's memory erasure argument extended to nonequilibrium linear systems.
Evolution of specialization under non-equilibrium population dynamics.
Nurmi, Tuomas; Parvinen, Kalle
2013-03-21
We analyze the evolution of specialization in resource utilization in a mechanistically underpinned discrete-time model using the adaptive dynamics approach. We assume two nutritionally equivalent resources that in the absence of consumers grow sigmoidally towards a resource-specific carrying capacity. The consumers use resources according to the law of mass-action with rates involving trade-off. The resulting discrete-time model for the consumer population has over-compensatory dynamics. We illuminate the way non-equilibrium population dynamics affect the evolutionary dynamics of the resource consumption rates, and show that evolution to the trimorphic coexistence of a generalist and two specialists is possible due to asynchronous non-equilibrium population dynamics of the specialists. In addition, various forms of cyclic evolutionary dynamics are possible. Furthermore, evolutionary suicide may occur even without Allee effects and demographic stochasticity.
The nonequilibrium Ehrenfest gas: a chaotic model with flat obstacles?
Bianca, Carlo; Rondoni, Lamberto
2009-03-01
It is known that the nonequilibrium version of the Lorentz gas (a billiard with dispersing obstacles [Ya. G. Sinai, Russ. Math. Surv. 25, 137 (1970)], electric field, and Gaussian thermostat) is hyperbolic if the field is small [N. I. Chernov, Ann. Henri Poincare 2, 197 (2001)]. Differently the hyperbolicity of the nonequilibrium Ehrenfest gas constitutes an open problem since its obstacles are rhombi and the techniques so far developed rely on the dispersing nature of the obstacles [M. P. Wojtkowski, J. Math. Pures Appl. 79, 953 (2000)]. We have developed analytical and numerical investigations that support the idea that this model of transport of matter has both chaotic (positive Lyapunov exponent) and nonchaotic steady states with a quite peculiar sensitive dependence on the field and on the geometry, not observed before. The associated transport behavior is correspondingly highly irregular, with features whose understanding is of both theoretical and technological interests.
Nonequilibrium multiphase mixture modeling of energetic material response
Baer, M.R.; Hertel, E.; Bell, R.
1995-12-31
To model the shock-induced behavior of porous or damaged energetic materials, a nonequilibrium mixture theory has been developed and incorporated into the shock physics code, CTH. Foundation for this multiphase model is based on a continuum mixture formulation given by Baer and Nunziato. In this nonequilibrium approach, multiple thermodynamic and mechanics fields are resolved including the effects of material relative motion, rate-dependent compaction, drag and heat transfer interphase effects and multiple-step combustion. Benchmark calculations are presented which simulate low-velocity piston impact on a propellant porous bed and experimentally-measured wave features are well replicated with this model. This mixture model introduces micromechanical models for the initiation and growth of reactive multicomponent flow which are key features to describe shock initiation and self-accelerated deflagration-to-detonation combustion behavior. To complement one-dimensional simulation, two dimensional numerical simulations are presented which indicate wave curvature effects due to the loss of wall confinement.
Non-equilibrium Flows of Reacting Air Components in Nozzles
NASA Astrophysics Data System (ADS)
Bazilevich, S. S.; Sinitsyn, K. A.; Nagnibeda, E. A.
2008-12-01
The paper presents the results of the investigation of non-equilibrium flows of reacting air mixtures in nozzles. State-to-state approach based on the solution of the equations for vibrational level populations of molecules and atomic concentrations coupled to the gas dynamics equations is used. For the 5-component air mixture (N2, O2, NO, N, O) non-equilibrium distributions and gasdynamical parameters are calculated for different conditions in a nozzle throat. The influence of various kinetic processes on distributions and gas dynamics parameters is studied. The paper presents the comparison of the results with ones obtained for binary mixtures of molecules and atoms and various models of elementary processes.
Infinite-noise criticality: Nonequilibrium phase transitions in fluctuating environments
NASA Astrophysics Data System (ADS)
Vojta, Thomas; Hoyos, Jose
We study the effects of time-varying environmental noise on nonequilibrium phase transitions in spreading and growth processes. Using the examples of the logistic evolution equation as well as the contact process, we show that such temporal disorder gives rise to a distinct type of critical points at which the effective noise amplitude diverges on long time scales. This leads to enormous density fluctuations characterized by an infinitely broad probability distribution at criticality. We develop a real-time renormalization-group theory that provides a general framework for the effects of temporal disorder on nonequilibrium processes. We also discuss how general this exotic critical behavior is, we illustrate the results by computer simulations, and we touch upon experimental applications of our theory. Supported by the NSF under Grant No. DMR-1205803, by Simons Foundation, by FAPESP under Grant No. 2013/09850-7, and by CNPq under Grant Nos. 590093/2011-8 and 305261/2012-6.
Entropy Production and Non-Equilibrium Steady States
NASA Astrophysics Data System (ADS)
Suzuki, Masuo
2013-01-01
The long-term issue of entropy production in transport phenomena is solved by separating the symmetry of the non-equilibrium density matrix ρ(t) in the von Neumann equation, as ρ(t) = ρs(t) + ρa(t) with the symmetric part ρs(t) and antisymmetric part ρa(t). The irreversible entropy production (dS/dt)irr is given in M. Suzuki, Physica A 390(2011)1904 by (dS/dt)irr = Tr( {H}(dρ s{(t)/dt))}/T for the Hamiltonian {H} of the relevant system. The general formulation of the extended von Neumann equation with energy supply and heat extraction is reviewed from the author's paper (M. S.,Physica A391(2012)1074). irreversibility; entropy production; transport phenomena; electric conduction; thermal conduction; linear response; Kubo formula; steady state; non-equilibrium density matrix; energy supply; symmetry-separated von Neumann equation; unboundedness.
Nonequilibrium viscous flow over Jovian entry probes at high altitudes
NASA Technical Reports Server (NTRS)
Kumar, A.; Szema, K. Y.; Tiwari, S. N.
1979-01-01
The viscous chemical nonequilibrium flow around a Jovian entry body is investigated at high altitudes using two different methods. First method is only for the stagnation region and integrates the full Navier-Stokes equations from the body surface to the freestream. The second method uses viscous shock layer equations between the body surface and the shock. Due to low Reynolds numbers, both methods use surface slip boundary conditions and the second method also uses shock slip boundary conditions. The results of the two methods are compared at the stagnation point. It is found that the entire shock layer is under chemical nonequilibrium at higher altitudes and that the slip boundary conditions are important at these altitudes.
Maximum work extraction and implementation costs for nonequilibrium Maxwell's demons.
Sandberg, Henrik; Delvenne, Jean-Charles; Newton, Nigel J; Mitter, Sanjoy K
2014-10-01
We determine the maximum amount of work extractable in finite time by a demon performing continuous measurements on a quadratic Hamiltonian system subjected to thermal fluctuations, in terms of the information extracted from the system. The maximum work demon is found to apply a high-gain continuous feedback involving a Kalman-Bucy estimate of the system state and operates in nonequilibrium. A simple and concrete electrical implementation of the feedback protocol is proposed, which allows for analytic expressions of the flows of energy, entropy, and information inside the demon. This let us show that any implementation of the demon must necessarily include an external power source, which we prove both from classical thermodynamics arguments and from a version of Landauer's memory erasure argument extended to nonequilibrium linear systems. PMID:25375450
Nonequilibrium phase transitions in cuprates observed by ultrafast electron crystallography.
Gedik, Nuh; Yang, Ding-Shyue; Logvenov, Gennady; Bozovic, Ivan; Zewail, Ahmed H
2007-04-20
Nonequilibrium phase transitions, which are defined by the formation of macroscopic transient domains, are optically dark and cannot be observed through conventional temperature- or pressure-change studies. We have directly determined the structural dynamics of such a nonequilibrium phase transition in a cuprate superconductor. Ultrafast electron crystallography with the use of a tilted optical geometry technique afforded the necessary atomic-scale spatial and temporal resolutions. The observed transient behavior displays a notable "structural isosbestic" point and a threshold effect for the dependence of c-axis expansion (Deltac) on fluence (F), with Deltac/F = 0.02 angstrom/(millijoule per square centimeter). This threshold for photon doping occurs at approximately 0.12 photons per copper site, which is unexpectedly close to the density (per site) of chemically doped carriers needed to induce superconductivity. PMID:17446397
Towards Non-Equilibrium Dynamics with Trapped Ions
NASA Astrophysics Data System (ADS)
Silbert, Ariel; Jubin, Sierra; Doret, Charlie
2016-05-01
Atomic systems are superbly suited to the study of non-equilibrium dynamics. These systems' exquisite isolation from environmental perturbations leads to long relaxation times that enable exploration of far-from-equilibrium phenomena. One example of particular relevance to experiments in trapped ion quantum information processing, metrology, and precision spectroscopy is the approach to thermal equilibrium of sympathetically cooled linear ion chains. Suitable manipulation of experimental parameters permits exploration of the quantum-to-classical crossover between ballistic transport and diffusive, Fourier's Law conduction, a topic of interest not only to the trapped ion community but also for the development of microelectronic devices and other nanoscale structures. We present progress towards trapping chains of multiple co-trapped calcium isotopes geared towards measuring thermal equilibration and discuss plans for future experiments in non-equilibrium statistical mechanics. This work is supported by Cottrell College Science Award from the Research Corporation for Science Advancement and by Williams College.
Investigation of Non-Equilibrium Radiation for Earth Entry
NASA Technical Reports Server (NTRS)
Brandis, A. M.; Johnston, C. O.; Cruden, B. A.
2016-01-01
For Earth re-entry at velocities between 8 and 11.5 km/s, the accuracy of NASA's computational uid dynamic and radiative simulations of non-equilibrium shock layer radiation is assessed through comparisons with measurements. These measurements were obtained in the NASA Ames Research Center's Electric Arc Shock Tube (EAST) facility. The experiments were aimed at measuring the spatially and spectrally resolved radiance at relevant entry conditions for both an approximate Earth atmosphere (79% N2 : 21% O2 by mole) as well as a more accurate composition featuring the trace species Ar and CO2 (78.08% N2 : 20.95% O2 : 0.04% CO2 : 0.93% Ar by mole). The experiments were configured to target a wide range of conditions, of which shots from 8 to 11.5 km/s at 0.2 Torr (26.7 Pa) are examined in this paper. The non-equilibrium component was chosen to be the focus of this study as it can account for a significant percentage of the emitted radiation for Earth re-entry, and more importantly, non-equilibrium has traditionally been assigned a large uncertainty for vehicle design. The main goals of this study are to present the shock tube data in the form of a non-equilibrium metric, evaluate the level of agreement between the experiment and simulations, identify key discrepancies and to examine critical aspects of modeling non-equilibrium radiating flows. Radiance pro les integrated over discreet wavelength regions, ranging from the Vacuum Ultra Violet (VUV) through to the Near Infra-Red (NIR), were compared in order to maximize both the spectral coverage and the number of experiments that could be used in the analysis. A previously defined non-equilibrium metric has been used to allow comparisons with several shots and reveal trends in the data. Overall, LAURA/HARA is shown to under-predict EAST by as much as 40% and over-predict by as much as 12% depending on the shock speed. DPLR/NEQAIR is shown to under-predict EAST by as much as 50% and over-predict by as much as 20% depending
The nonequilibrium Ehrenfest gas: A chaotic model with flat obstacles?
NASA Astrophysics Data System (ADS)
Bianca, Carlo; Rondoni, Lamberto
2009-03-01
It is known that the nonequilibrium version of the Lorentz gas (a billiard with dispersing obstacles [Ya. G. Sinai, Russ. Math. Surv. 25, 137 (1970)], electric field, and Gaussian thermostat) is hyperbolic if the field is small [N. I. Chernov, Ann. Henri Poincare 2, 197 (2001)]. Differently the hyperbolicity of the nonequilibrium Ehrenfest gas constitutes an open problem since its obstacles are rhombi and the techniques so far developed rely on the dispersing nature of the obstacles [M. P. Wojtkowski, J. Math. Pures Appl. 79, 953 (2000)]. We have developed analytical and numerical investigations that support the idea that this model of transport of matter has both chaotic (positive Lyapunov exponent) and nonchaotic steady states with a quite peculiar sensitive dependence on the field and on the geometry, not observed before. The associated transport behavior is correspondingly highly irregular, with features whose understanding is of both theoretical and technological interests.
Three-dimensional thermochemical nonequilibrium flow modeling for hypersonic flows
NASA Technical Reports Server (NTRS)
Tam, L. T.; Li, C. P.
1989-01-01
A three-dimensional thermochemical nonequilibrium model has been developed and applied to the study of entry flows surrounding space vehicles. The model accounts for both chemical and vibrational nonequilibrium phenomena behind the bow shock. The thermodynamic state of a real gas is modeled with a translational-rotational temperature and a electron-vibrational temperature. Their internal energies are averaged to determine the temperature used in the reaction rates calculation. In order to establish the validity of the selected models, both one- and two-temperature models with seven and/or eleven species were investigated. Several numerical experiments that include a sphere, the RAMC vehicle and 3D AFE forebody flows were performed. Preliminary results were compared with RAMC-II experimental data. Good agreement was obtained after a two-temperature model with eleven species and thirty reactions was incorporated into the study.
Detailed and simplified nonequilibrium helium ionization in the solar atmosphere
Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit E-mail: mats.carlsson@astro.uio.no
2014-03-20
Helium ionization plays an important role in the energy balance of the upper chromosphere and transition region. Helium spectral lines are also often used as diagnostics of these regions. We carry out one-dimensional radiation-hydrodynamics simulations of the solar atmosphere and find that the helium ionization is set mostly by photoionization and direct collisional ionization, counteracted by radiative recombination cascades. By introducing an additional recombination rate mimicking the recombination cascades, we construct a simplified three-level helium model atom consisting of only the ground states. This model atom is suitable for modeling nonequilibrium helium ionization in three-dimensional numerical models. We perform a brief investigation of the formation of the He I 10830 and He II 304 spectral lines. Both lines show nonequilibrium features that are not recovered with statistical equilibrium models, and caution should therefore be exercised when such models are used as a basis for interpretating observations.
Nonequilibrium Thermodynamics and Nonlinear Kinetics in a Cellular Signaling Switch
NASA Astrophysics Data System (ADS)
Qian, Hong; Reluga, Timothy C.
2005-01-01
We develop a rigorous nonequilibrium thermodynamics for an open system of nonlinear biochemical reactions responsible for cell signal processing. We show that the quality of the biological switch consisting of a phosphorylation-dephosphorylation cycle, such as those in protein kinase cascade, is controlled by the available intracellular free energy from the adenosine triphosphate (ATP) hydrolysis invivo: ΔG=kBTln(([ATP]/Keq[ADP]), where Keq is the equilibrium constant. The model reveals the correlation between the performance of the switch and the level of ΔG. The result demonstrates the importance of nonequilibrium thermodynamics in analyzing biological information processing, provides its energetic cost, establishes an interplay between signal transduction and energy metabolism in cells, and suggests a biological function for phosphoenergetics in the ubiquitous phosphorylation signaling.
Sum rule for response function in nonequilibrium Langevin systems
NASA Astrophysics Data System (ADS)
Yuge, Tatsuro
2010-11-01
We derive general properties of the linear-response functions of nonequilibrium steady states in Langevin systems. These correspond to extension of the results which were recently found in Hamiltonian systems [A. Shimizu and T. Yuge, J. Phys. Soc. Jpn. 79, 013002 (2010)10.1143/JPSJ.79.013002]. We discuss one of the properties, the sum rule for the response function, in particular detail. We show that the sum rule for the response function of the velocity holds in the underdamped case, whereas it is violated in the overdamped case. This implies that the overdamped Langevin models should be used with great care. We also investigate the relation of the sum rule to an equality on the energy dissipation in nonequilibrium Langevin systems, which was derived by Harada and Sasa.
Approach to non-equilibrium behaviour in quantum field theory
Kripfganz, J.; Perlt, H.
1989-05-01
We study the real-time evolution of quantum field theoretic systems in non-equilibrium situations. Results are presented for the example of scalar /lambda//phi//sup 4/ theory. The degrees of freedom are discretized by studying the system on a torus. Short-wavelength modes are integrated out to one-loop order. The long-wavelength modes considered to be the relevant degrees of freedom are treated by semiclassical phase-space methods. /copyright/ 1989 Academic Press, Inc.
Smoothed-particle hydrodynamics and nonequilibrium molecular dynamics
Hoover, W. G.; Hoover, C. G.
1993-08-01
Gingold, Lucy, and Monaghan invented a grid-free version of continuum mechanics ``smoothed-particle hydrodynamics,`` in 1977. It is a likely contributor to ``hybrid`` simulations combining atomistic and continuum simulations. We describe applications of this particle-based continuum technique from the closely-related standpoint of nonequilibrium molecular dynamics. We compare chaotic Lyapunov spectra for atomistic solids and fluids with those which characterize a two-dimensional smoothed-particle fluid system.
Calculations of heavy ion charge state distributions for nonequilibrium conditions
NASA Technical Reports Server (NTRS)
Luhn, A.; Hovestadt, D.
1985-01-01
Numerical calculations of the charge state distributions of test ions in a hot plasma under nonequilibrium conditions are presented. The mean ionic charges of heavy ions for finite residence times in an instantaneously heated plasma and for a non-Maxwellian electron distribution function are derived. The results are compared with measurements of the charge states of solar energetic particles, and it is found that neither of the two simple cases considered can explain the observations.
Nonequilibrium molecular motion in a hypersonic shock wave.
Pham-Van-Diep, G; Erwin, D; Muntz, E P
1989-08-11
Molecular velocities have been measured inside a hypersonic, normal shock wave, where the gas experiences rapid changes in its macroscopic properties. As first hypothesized by Mott-Smith, but never directly observed, the molecular velocity distribution exhibits a qualitatively bimodal character that is derived from the distribution functions on either side of the shock. Quantitatively correct forms of the molecular velocity distribution function in highly nonequilibrium flows can be calculated, by means of the Direct Simulation Monte Carlo technique.
Diffusive mass transfer by nonequilibrium fluctuations: Fick's law revisited.
Brogioli, D; Vailati, A
2001-01-01
Recent experimental and theoretical works have shown that giant fluctuations are present during diffusion in liquid systems. We use linearized fluctuating hydrodynamics to calculate the net mass transfer due to these nonequilibrium fluctuations. Remarkably, the mass flow turns out to coincide with the usual Fick's one. The renormalization of the hydrodynamic equations allows us to quantify the gravitational modifications of the diffusion coefficient induced by the gravitational stabilization of long wavelength fluctuations.
Mimicking Nonequilibrium Steady States with Time-Periodic Driving
NASA Astrophysics Data System (ADS)
Raz, O.; Subaşı, Y.; Jarzynski, C.
2016-04-01
Under static conditions, a system satisfying detailed balance generically relaxes to an equilibrium state in which there are no currents. To generate persistent currents, either detailed balance must be broken or the system must be driven in a time-dependent manner. A stationary system that violates detailed balance evolves to a nonequilibrium steady state (NESS) characterized by fixed currents. Conversely, a system that satisfies instantaneous detailed balance but is driven by the time-periodic variation of external parameters—also known as a stochastic pump (SP)—reaches a periodic state with nonvanishing currents. In both cases, these currents are maintained at the cost of entropy production. Are these two paradigmatic scenarios effectively equivalent? For discrete-state systems, we establish a mapping between nonequilibrium stationary states and stochastic pumps. Given a NESS characterized by a particular set of stationary probabilities, currents, and entropy production rates, we show how to construct a SP with exactly the same (time-averaged) values. The mapping works in the opposite direction as well. These results establish a proof of principle: They show that stochastic pumps are able to mimic the behavior of nonequilibrium steady states, and vice versa, within the theoretical framework of discrete-state stochastic thermodynamics. Nonequilibrium steady states and stochastic pumps are often used to model, respectively, biomolecular motors driven by chemical reactions and artificial molecular machines steered by the variation of external, macroscopic parameters. Our results loosely suggest that anything a biomolecular machine can do, an artificial molecular machine can do equally well. We illustrate this principle by showing that kinetic proofreading, a NESS mechanism that explains the low error rates in biochemical reactions, can be effectively mimicked by a constrained periodic driving.
Tunneling Measurements of Charge Imbalance of Non-Equilibrium Superconductors
NASA Astrophysics Data System (ADS)
Yagi, R.; Utsunomiya, K.; Tsuboi, K.; Kubota, T.; Terao, Y.; Ikebuchi, Y.
2008-10-01
We have observed excess current due to charge imbalance in the voltage-current characteristics of a superconductor-insulator-normal (SIN) tunnel junction connected to a non-equilibrium superconductor. It was found that that the excess current was unchanged against the bias voltage as expected from the theory of charge imbalance. The estimated excess current approximately agreed with the estimation from one-dimensional diffusion model of charge imbalance transport.
Complementarity relations for quantum coherence
NASA Astrophysics Data System (ADS)
Cheng, Shuming; Hall, Michael J. W.
2015-10-01
Various measures have been suggested recently for quantifying the coherence of a quantum state with respect to a given basis. We first use two of these, the l1-norm and relative entropy measures, to investigate tradeoffs between the coherences of mutually unbiased bases. Results include relations between coherence, uncertainty, and purity; tight general bounds restricting the coherences of mutually unbiased bases; and an exact complementarity relation for qubit coherences. We further define the average coherence of a quantum state. For the l1-norm measure this is related to a natural "coherence radius" for the state and leads to a conjecture for an l2-norm measure of coherence. For relative entropy the average coherence is determined by the difference between the von Neumann entropy and the quantum subentropy of the state and leads to upper bounds for the latter quantity. Finally, we point out that the relative entropy of coherence is a special case of G-asymmetry, which immediately yields several operational interpretations in contexts as diverse as frame alignment, quantum communication, and metrology, and suggests generalizing the property of quantum coherence to arbitrary groups of physical transformations.
Unexpected coherence and conservation.
Cazelles, B.; Bottani, S.; Stone, L.
2001-01-01
The effects of migration in a network of patch populations, or metapopulation, are extremely important for predicting the possibility of extinctions both at a local and a global scale. Migration between patches synchronizes local populations and bestows upon them identical dynamics (coherent or synchronous oscillations), a feature that is understood to enhance the risk of global extinctions. This is one of the central theoretical arguments in the literature associated with conservation ecology. Here, rather than restricting ourselves to the study of coherent oscillations, we examine other types of synchronization phenomena that we consider to be equally important. Intermittent and out-of-phase synchronization are but two examples that force us to reinterpret some classical results of the metapopulation theory. In addition, we discuss how asynchronous processes (for example, random timing of dispersal) can paradoxically generate metapopulation synchronization, another non-intuitive result that cannot easily be explained by the standard theory. PMID:11749716
Correlation, coherence and context
NASA Astrophysics Data System (ADS)
Eberly, J. H.
2016-08-01
The modern theory of coherence is based on correlation functions. A generic example could be written < {{V}\\ast}≤ft({{t}1}\\right)V≤ft({{t}2}\\right)> , denoting an average of products of the values of a signal V(t) at two specified times. Here we infer that t is a degree of freedom that the signal depends on. Typically, physical variables depend on more than one degree of freedom, and recognition of this has prompted attention to some interesting questions for the correlation functions and the several coherences that can be attributed to the same optical field. We examine some of the questions arising from the standpoint of experimental contexts. Degree of polarizability and degree of entanglement (classical non-separability) can serve as starting points for quantitative assignments.
Spectroscopic Low Coherence Interferometry
NASA Astrophysics Data System (ADS)
Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.
Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.
Strongly correlated quantum transport out-of-equilibrium
NASA Astrophysics Data System (ADS)
Dutt, Prasenjit
The revolutionary advances in nanotechnology and nanofabrication have facilitated the precise control and manipulation of mesoscopic systems where quantum effects are pronounced. Quantum devices with tunable gates have made it possible to access regimes far beyond the purview of linear response theory. In particular, the influence of strong voltage and thermal biases has led to the observation of novel phenomena where the non-equilibrium characteristics of the system are of paramount importance. We study transport through quantum-impurity systems in the regime of strong correlations and determine the effects of large temperature and potential gradients on its many-body physics. In Part I of this thesis we focus on the steady-state dynamics of the system, a commonly encountered experimental scenario. For a system consisting of several leads composed of non-interacting electrons, each individually coupled to a quantum impurity with interactions and maintained at different chemical potentials, we reformulate the system in terms of an effective-equilibrium density matrix. This density matrix has a simple Boltzmann-like form in terms of the system's Lippmann-Schwinger (scattering) operators. We elaborate the conditions for this description to be valid based on the microscopic Hamiltonian of the system. We then prove the equivalence of physical observables computed using this formulation with corresponding expressions in the Schwinger-Keldysh approach and provide a dictionary between Green's functions in either scheme. An imaginary-time functional integral framework to compute finite temperature Green's functions is proposed and used to develop a novel perturbative expansion in the interaction strength which is exact in all other system parameters. We use these tools to study the fate of the Abrikosov-Suhl regime on the Kondo-correlated quantum dot due to the effects of bias and external magnetic fields. Next, we expand the domain of this formalism to additionally
Aeroacoustic and aerodynamic applications of the theory of nonequilibrium thermodynamics
NASA Technical Reports Server (NTRS)
Horne, W. Clifton; Smith, Charles A.; Karamcheti, Krishnamurty
1991-01-01
Recent developments in the field of nonequilibrium thermodynamics associated with viscous flows are examined and related to developments to the understanding of specific phenomena in aerodynamics and aeroacoustics. A key element of the nonequilibrium theory is the principle of minimum entropy production rate for steady dissipative processes near equilibrium, and variational calculus is used to apply this principle to several examples of viscous flow. A review of nonequilibrium thermodynamics and its role in fluid motion are presented. Several formulations are presented of the local entropy production rate and the local energy dissipation rate, two quantities that are of central importance to the theory. These expressions and the principle of minimum entropy production rate for steady viscous flows are used to identify parallel-wall channel flow and irrotational flow as having minimally dissipative velocity distributions. Features of irrotational, steady, viscous flow near an airfoil, such as the effect of trailing-edge radius on circulation, are also found to be compatible with the minimum principle. Finally, the minimum principle is used to interpret the stability of infinitesimal and finite amplitude disturbances in an initially laminar, parallel shear flow, with results that are consistent with experiment and linearized hydrodynamic stability theory. These results suggest that a thermodynamic approach may be useful in unifying the understanding of many diverse phenomena in aerodynamics and aeroacoustics.
Nonequilibrium Steady State Thermodynamics and Fluctuations for Stochastic Systems
NASA Astrophysics Data System (ADS)
Taniguchi, Tooru; Cohen, E. G. D.
2008-02-01
We use the work done on and the heat removed from a system to maintain it in a nonequilibrium steady state for a thermodynamic-like description of such a system as well as of its fluctuations. Based on an extended Onsager-Machlup theory for nonequilibrium steady states we indicate two ambiguities, not present in an equilibrium state, in defining such work and heat: one due to a non-uniqueness of time-reversal procedures and another due to multiple possibilities to separate heat into work and an energy difference in nonequilibrium steady states. As a consequence, for such systems, the work and heat satisfy multiple versions of the first and second laws of thermodynamics as well as of their fluctuation theorems. Unique laws and relations appear only to be obtainable for concretely defined systems, using physical arguments to choose the relevant physical quantities. This is illustrated on a number of systems, including a Brownian particle in an electric field, a driven torsion pendulum, electric circuits and an energy transfer driven by a temperature difference.
Zeroth law and nonequilibrium thermodynamics for steady states in contact
NASA Astrophysics Data System (ADS)
Chatterjee, Sayani; Pradhan, Punyabrata; Mohanty, P. K.
2015-06-01
We ask what happens when two nonequilibrium systems in steady state are kept in contact and allowed to exchange a quantity, say mass, which is conserved in the combined system. Will the systems eventually evolve to a new stationary state where a certain intensive thermodynamic variable, like equilibrium chemical potential, equalizes following the zeroth law of thermodynamics and, if so, under what conditions is it possible? We argue that an equilibriumlike thermodynamic structure can be extended to nonequilibrium steady states having short-ranged spatial correlations, provided that the systems interact weakly to exchange mass with rates satisfying a balance condition—reminiscent of a detailed balance condition in equilibrium. The short-ranged correlations would lead to subsystem factorization on a coarse-grained level and the balance condition ensures both equalization of an intensive thermodynamic variable as well as ensemble equivalence, which are crucial for construction of a well-defined nonequilibrium thermodynamics. This proposition is proved and demonstrated in various conserved-mass transport processes having nonzero spatial correlations.
Nonequilibrium ionization effects in asymmetrically heated loops. [in solar corona
NASA Technical Reports Server (NTRS)
Spadaro, D.; Antiochos, Spiro K.; Mariska, J. T.
1991-01-01
The effects of nonequilibrium ionization on magnetic loop models with a steady siphon flow that is driven by a nonuniform heating rate are investigated. The model developed by Mariska (1988) to explain the observed redshifts of transition region emission lines is examined, and the number densities of the ions of carbon and oxygen along the loop are computed, with and without the approximation of ionization equilibrium. Considerable deviations from equilibrium were found. In order to determine the consequences of these nonequilibrium effects on the characteristics of the EUV emission from the loop plasma, the profiles and wavelength positions of all the important emission lines due to carbon and oxygen were calculated. The calculations are in broad agreement with Mariska's conclusions, although they show a significant diminution of the Doppler shifts, as well as modifications to the line widths. It is concluded that the inclusion of nonequilibrium effects make it more difficult to reproduce the observed characteristics of the solar transition region by means of the asymmetric-heating models.
Thermostat for nonequilibrium multiparticle-collision-dynamics simulations.
Huang, Chien-Cheng; Varghese, Anoop; Gompper, Gerhard; Winkler, Roland G
2015-01-01
Multiparticle collision dynamics (MPC), a particle-based mesoscale simulation technique for complex fluid, is widely employed in nonequilibrium simulations of soft matter systems. To maintain a defined thermodynamic state, thermalization of the fluid is often required for certain MPC variants. We investigate the influence of three thermostats on the nonequilibrium properties of a MPC fluid under shear or in Poiseuille flow. In all cases, the local velocities are scaled by a factor, which is either determined via a local simple scaling approach (LSS), a Monte Carlo-like procedure (MCS), or by the Maxwell-Boltzmann distribution of kinetic energy (MBS). We find that the various scaling schemes leave the flow profile unchanged and maintain the local temperature well. The fluid viscosities extracted from the various simulations are in close agreement. Moreover, the numerically determined viscosities are in remarkably good agreement with the respective theoretically predicted values. At equilibrium, the calculation of the dynamic structure factor reveals that the MBS method closely resembles an isothermal ensemble, whereas the MCS procedure exhibits signatures of an adiabatic system at larger collision-time steps. Since the velocity distribution of the LSS approach is non-Gaussian, we recommend to apply the MBS thermostat, which has been shown to produce the correct velocity distribution even under nonequilibrium conditions.
Sebastion, R.L.
1995-10-01
The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system.
Bianchi, Eugenio; Magliaro, Elena; Perini, Claudio
2010-07-15
In this paper we discuss a proposal of coherent states for loop quantum gravity. These states are labeled by a point in the phase space of general relativity as captured by a spin-network graph. They are defined as the gauge-invariant projection of a product over links of Hall's heat kernels for the cotangent bundle of SU(2). The labels of the state are written in terms of two unit vectors, a spin and an angle for each link of the graph. The heat-kernel time is chosen to be a function of the spin. These labels are the ones used in the spin-foam setting and admit a clear geometric interpretation. Moreover, the set of labels per link can be written as an element of SL(2,C). These states coincide with Thiemann's coherent states with the area operator as complexifier. We study the properties of semiclassicality of these states and show that, for large spins, they reproduce a superposition over spins of spin-networks with nodes labeled by Livine-Speziale coherent intertwiners. Moreover, the weight associated to spins on links turns out to be given by a Gaussian times a phase as originally proposed by Rovelli.
Photoacoustics with coherent light
Bossy, Emmanuel; Gigan, Sylvain
2016-01-01
Since its introduction in the mid-nineties, photoacoustic imaging of biological tissue has been one of the fastest growing biomedical imaging modality, and its basic principles are now considered as well established. In particular, light propagation in photoacoustic imaging is generally considered from the perspective of transport theory. However, recent breakthroughs in optics have shown that coherent light propagating through optically scattering medium could be manipulated towards novel imaging approaches. In this article, we first provide an introduction to the relevant concepts in the field, and then review the recent works showing that it is possible to exploit the coherence of light in conjunction with photoacoustics. We illustrate how the photoacoustic effect can be used as a powerful feedback mechanism for optical wavefront shaping in complex media, and conversely show how the coherence of light can be exploited to enhance photoacoustic imaging, for instance in terms of spatial resolution or for designing minimally invasive endoscopic devices. Finally, we discuss the current challenges and perspectives down the road towards practical applications in the field of photoacoustic imaging. PMID:27069874
Quantum speed limits of a qubit system interacting with a nonequilibrium environment
NASA Astrophysics Data System (ADS)
He, Zhi; Yao, Chun-Mei; Li, Li; Wang, Qiong
2016-08-01
The speed of evolution of a qubit undergoing a nonequilibrium environment with spectral density of general ohmic form is investigated. First we reveal non-Markovianity of the model, and find that the non-Markovianity quantified by information backflow of Breuer et al. [Phys. Rev. Lett. 103 210401 (2009)] displays a nonmonotonic behavior for different values of the ohmicity parameter s in fixed other parameters and the maximal non-Markovianity can be achieved at a specified value s. We also find that the non-Markovianity displays a nonmonotonic behavior with the change of a phase control parameter. Then we further discuss the relationship between quantum speed limit (QSL) time and non-Markovianity of the open-qubit system for any initial states including pure and mixed states. By investigation, we find that the QSL time of a qubit with any initial states can be expressed by a simple factorization law: the QSL time of a qubit with any qubit-initial states are equal to the product of the coherence of the initial state and the QSL time of maximally coherent states, where the QSL time of the maximally coherent states are jointly determined by the non-Markovianity, decoherence factor and a given driving time. Moreover, we also find that the speed of quantum evolution can be obviously accelerated in the wide range of the ohmicity parameter, i.e., from sub-Ohmic to Ohmic and super-Ohmic cases, which is different from the thermal equilibrium environment case. Project supported by the National Natural Science Foundation of China (Grants Nos. 61505053 and 61475045), the Natural Science Foundation of Hunan Province, China(Grant No. 2015JJ3092), the School Foundation from the Hunan University of Arts and Science (Grant No. 14ZD01), the Fund from the Key Laboratory of Photoelectric Information Integration and Optical Manufacturing Technology of Hunan Province, China, and the Construction Program of the Key Discipline in Hunan University of Arts and Science (Optics).
Overall coherence and coherent-mode expansion of spectrally partially coherent plane-wave pulses.
Lajunen, Hanna; Tervo, Jani; Vahimaa, Pasi
2004-11-01
The modal theory for spectrally partially coherent nonstationary plane waves is introduced. The theory is first developed in the space-frequency domain and then extended to the space-time domain. Propagation properties of the coherent modes are analyzed. The concept of the overall degree of coherence is extended to the domain of nonstationary fields, and it is shown that the overall degree of coherence of partially coherent plane-wave pulses is the same in the space-frequency and space-time domains. The theory is applied to the recently introduced concept of spectrally Gaussian Schell-model plane-wave pulses.