The Experts below are selected from a list of 13767 Experts worldwide ranked by ideXlab platform

Jin Wang - One of the best experts on this subject based on the ideXlab platform.

  • Generalized Fluctuation-Dissipation Theorem for Non-equilibrium Spatially Extended Systems
    Frontiers in Physics, 2020
    Co-Authors: Jin Wang
    Abstract:

    The Fluctuation-Dissipation Theorem (FDT) connecting the response of the system to external perturbations with the fluctuations at thermodynamic equilibrium is a central result in statistical physics. There has been effort devoted to extending the FDT in several different directions since its original formulation. In this work we establish a generalized form of the FDT for spatially extended nonequilibrium stochastic systems described by continuous fields. The generalized FDT is formulated with the aid of the nonequilibrium force decomposition in the potential landscape and flux field theoretical framework. The general results are substantiated in the setting of the Ornstein-Uhlenbeck (OU) process and further illustrated by a more specific example worked out in detail. The key feature of this generalized FDT for nonequilibrium spatially extended systems is that it represents a ternary relation rather than a binary relation as the FDT for equilibrium systems does. In addition to the response function and the time derivative of the field-field correlation function that are present in the equilibrium FDT, the field-flux correlation function also enters the generalized FDT. This additional contribution originates from detailed balance breaking that signifies the nonequilibrium irreversible nature of the steady state. In the special case when the steady state is an equilibrium state obeying detailed balance, the field-flux correlation function vanishes and the ternary relation in the generalized FDT reduces to the binary relation in the equilibrium FDT.

  • fluctuation dissipation Theorem for nonequilibrium quantum systems
    EPL, 2016
    Co-Authors: Zhedong Zhang, Jin Wang
    Abstract:

    We present a Fluctuation-Dissipation Theorem (FDT) for nonequilibrium quantum systems with detailed-balance breaking, which deviates from the conventional form of the FDT for equilibrium systems preserving detailed balance. Using the phase space formulation of quantum mechanics and the potential-flux landscape framework, we find that the response function of nonequilibrium quantum systems to external perturbations contains a nontrivial contribution from the quantum curl flux quantifying detailed-balance breaking in the steady state, in addition to the correlation function of observables in the steady state representing the contribution of spontaneous fluctuations which is also present in the equilibrium FDT. We illustrate our general formalism with a harmonic oscillator coupled to two heat baths, and show that the nonequilibrium FDT reduces to the conventional expression at the equilibrium condition when the flux contribution vanishes.

  • potential and flux decomposition for dynamical systems and non equilibrium thermodynamics curvature gauge field and generalized fluctuation dissipation Theorem
    Journal of Chemical Physics, 2011
    Co-Authors: Haidong Feng, Jin Wang
    Abstract:

    The driving force of the dynamical system can be decomposed into the gradient of a potential landscape and curl flux (current). The Fluctuation-Dissipation Theorem (FDT) is often applied to near equilibrium systems with detailed balance. The response due to a small perturbation can be expressed by a spontaneous fluctuation. For non-equilibrium systems, we derived a generalized FDT that the response function is composed of two parts: (1) a spontaneous correlation representing the relaxation which is present in the near equilibrium systems with detailed balance and (2) a correlation related to the persistence of the curl flux in steady state, which is also in part linked to a internal curvature of a gauge field. The generalized FDT is also related to the fluctuation Theorem. In the equal time limit, the generalized FDT naturally leads to non-equilibrium thermodynamics where the entropy production rate can be decomposed into spontaneous relaxation driven by gradient force and house keeping contribution driven by the non-zero flux that sustains the non-equilibrium environment and breaks the detailed balance. On any particular path, the medium heat dissipation due to the non-zero curl flux is analogous to the Wilson lines of an Abelian gauge theory.

  • potential and flux decomposition for dynamical systems and non equilibrium thermodynamics curvature gauge field and generalized fluctuation dissipation Theorem
    arXiv: Statistical Mechanics, 2011
    Co-Authors: Haidong Feng, Jin Wang
    Abstract:

    The driving force of the dynamical system can be decomposed into the gradient of a potential landscape and curl flux (current). The Fluctuation-Dissipation Theorem (FDT) is often applied to near equilibrium systems with detailed balance. The response due to a small perturbation can be expressed by a spontaneous fluctuation. For non-equilibrium systems, we derived a generalized FDT that the response function is composed of two parts: (1) a spontaneous correlation representing the relaxation which is present in the near equilibrium systems with detailed balance; (2) a correlation related to the persistence of the curl flux in steady state, which is also in part linked to a internal curvature of a gauge field. The generalized FDT is also related to the fluctuation Theorem. In the equal time limit, the generalized FDT naturally leads to non-equilibrium thermodynamics where the entropy production rate can be decomposed into spontaneous relaxation driven by gradient force and house keeping contribution driven by the non-zero flux that sustains the non-equilibrium environment and breaks the detailed balance.

Diego Porras - One of the best experts on this subject based on the ideXlab platform.

  • Quantum chaotic Fluctuation-Dissipation Theorem: Effective Brownian motion in closed quantum systems.
    Physical review. E, 2019
    Co-Authors: Charlie Nation, Diego Porras
    Abstract:

    We analytically describe the decay to equilibrium of generic observables of a nonintegrable system after a perturbation in the form of a random matrix. We further obtain an analytic form for the time-averaged fluctuations of an observable in terms of the rate of decay to equilibrium. Our result shows the emergence of a Fluctuation-Dissipation Theorem corresponding to a classical Brownian process, specifically, the Ornstein-Uhlenbeck process. Our predictions can be tested in quantum simulation experiments, thus helping to bridge the gap between theoretical and experimental research in quantum thermalization. We test our analytic results by exact numerical experiments in a spin chain. We argue that our Fluctuation-Dissipation relation can be used to measure the density of states involved in the nonequilibrium dynamics of an isolated quantum system.

Thomas Speck - One of the best experts on this subject based on the ideXlab platform.

  • fluctuation dissipation Theorem in nonequilibrium steady states
    EPL, 2010
    Co-Authors: Udo Seifert, Thomas Speck
    Abstract:

    In equilibrium, the Fluctuation-Dissipation Theorem (FDT) expresses the response of an observable to a small perturbation by a correlation function of this variable with another one that is conjugate to the perturbation with respect to energy. For a nonequilibrium steady state (NESS), the corresponding FDT is shown to involve in the correlation function a variable that is conjugate with respect to entropy. By splitting up entropy production into one of the system and one of the medium, it is shown that for systems with a genuine equilibrium state the FDT of the NESS differs from its equilibrium form by an additive term involving total entropy production. A related variant of the FDT not requiring explicit knowledge of the stationary state is particularly useful for coupled Langevin systems. The a priori surprising freedom apparently involved in different forms of the FDT in a NESS is clarified.

  • Extended Fluctuation-Dissipation Theorem for soft matter in stationary flow
    Physical Review E, 2009
    Co-Authors: Thomas Speck, Udo Seifert
    Abstract:

    For soft matter systems strongly driven by stationary flow, we discuss an extended Fluctuation-Dissipation Theorem (FDT). Beyond the linear-response regime, the FDT for the stress acquires an additional contribution involving the observable that is conjugate to the strain rate with respect to the dissipation function. This extended FDT is evaluated both analytically for Rouse polymers and in numerical simulations for colloidal suspensions. More generally, our results suggest an extension of Onsager's regression principle to nonequilibrium steady states.

  • Restoring a Fluctuation-Dissipation Theorem in a nonequilibrium steady state
    Europhysics Letters (EPL), 2006
    Co-Authors: Thomas Speck, Udo Seifert
    Abstract:

    In a nonequilibrium steady state, the violation of the Fluctuation-Dissipation Theorem (FDT) is connected to breaking detailed balance. For the velocity correlations of a driven colloidal particle we calculate an explicit expression of the FDT violation. The equilibrium form of the FDT can be restored by measuring the velocity with respect to the local mean velocity.

David Lacoste - One of the best experts on this subject based on the ideXlab platform.

  • Modified Fluctuation-Dissipation Theorem for general non-stationary states and application to the Glauber-Ising chain
    Journal of Statistical Mechanics: Theory and Experiment, 2011
    Co-Authors: Gatien Verley, Raphael Chetrite, David Lacoste
    Abstract:

    In this paper, we present a general derivation of a modified Fluctuation-Dissipation Theorem (MFDT) valid near an arbitrary non-stationary state for a system obeying Markovian dynamics. We show that the method for deriving modified Fluctuation-Dissipation Theorems near non-equilibrium stationary states used by Prost et al (2009 Phys. Rev. Lett. 103 090601) is generalizable to non-stationary states. This result follows from both standard linear response theory and from a transient fluctuation Theorem, analogous to the Hatano-Sasa relation. We show that this modified Fluctuation-Dissipation Theorem can be interpreted at the trajectory level using the notion of stochastic trajectory entropy, in a way which is similar to what has been done recently in the case of the MFDT near non-equilibrium steady states (NESS). We illustrate this framework with two solvable examples: the first example corresponds to a Brownian particle in a harmonic trap subjected to a quench of temperature and to a time-dependent stiffness; the second example is a classic model of coarsening systems, namely the 1D Ising model with Glauber dynamics.

  • modified fluctuation dissipation Theorem near non equilibrium states and applications to the glauber ising chain
    arXiv: Statistical Mechanics, 2011
    Co-Authors: Gatien Verley, Raphael Chetrite, David Lacoste
    Abstract:

    In this paper, we present a general derivation of a modified fluctuation- dissipation Theorem (MFDT) valid near an arbitrary non-stationary state for a system obeying markovian dynamics. We show that the method to derive modified fluctuation- dissipation Theorems near non-equilibrium stationary states used by J. Prost et al., PRL 103, 090601 (2009), is generalizable to non-stationary states. This result follows from both standard linear response theory and from a transient fluctuation Theorem, analogous to the Hatano-Sasa relation. We show that this modified fluctuation- dissipation Theorem can be interpreted at the trajectory level using the notion of stochastic trajectory entropy, in a way which is similar to what has been done recently in the case of MFDT near non-equilibrium steady states (NESS). We illustrate this framework with two solvable examples: the first example corresponds to a system obeying linear Langevin dynamics and submitted to a quentch of temperature. The second example is a classic model of coarsening systems, namely the 1D Ising model with Glauber dynamics.

  • modified fluctuation dissipation Theorem for non equilibrium steady states and applications to molecular motors
    EPL, 2011
    Co-Authors: Gatien Verley, Kirone Mallick, David Lacoste
    Abstract:

    We present a theoretical framework to understand a modified Fluctuation-Dissipation Theorem valid for systems close to non-equilibrium steady states and obeying Markovian dynamics. We discuss the interpretation of this result in terms of trajectory entropy excess. The framework is illustrated on a simple pedagogical example of a molecular motor. We also derive in this context generalized Green-Kubo relations similar to the ones obtained recently in Seifert U., Phys. Rev. Lett., 104 (2010) 138101 for more general networks of biomolecular states.

  • modified fluctuation dissipation Theorem for non equilibrium steady states and applications to molecular motors
    arXiv: Statistical Mechanics, 2010
    Co-Authors: Gatien Verley, Kirone Mallick, David Lacoste
    Abstract:

    We present a theoretical framework to understand a modified Fluctuation-Dissipation Theorem valid for systems close to non-equilibrium steady-states and obeying markovian dynamics. We discuss the interpretation of this result in terms of trajectory entropy excess. The framework is illustrated on a simple pedagogical example of a molecular motor. We also derive in this context generalized Green-Kubo relations similar to the ones derived recently by Seifert., Phys. Rev. Lett., 104, 138101 (2010) for more general networks of biomolecular states.

Charlie Nation - One of the best experts on this subject based on the ideXlab platform.

  • Quantum chaotic Fluctuation-Dissipation Theorem: Effective Brownian motion in closed quantum systems.
    Physical review. E, 2019
    Co-Authors: Charlie Nation, Diego Porras
    Abstract:

    We analytically describe the decay to equilibrium of generic observables of a nonintegrable system after a perturbation in the form of a random matrix. We further obtain an analytic form for the time-averaged fluctuations of an observable in terms of the rate of decay to equilibrium. Our result shows the emergence of a Fluctuation-Dissipation Theorem corresponding to a classical Brownian process, specifically, the Ornstein-Uhlenbeck process. Our predictions can be tested in quantum simulation experiments, thus helping to bridge the gap between theoretical and experimental research in quantum thermalization. We test our analytic results by exact numerical experiments in a spin chain. We argue that our Fluctuation-Dissipation relation can be used to measure the density of states involved in the nonequilibrium dynamics of an isolated quantum system.