scholarly journals Theory of Non-Equilibrium Heat Transport in Anharmonic Multiprobe Systems at High Temperatures

Entropy ◽  
2021 ◽  
Vol 23 (12) ◽  
pp. 1630
Author(s):  
Keivan Esfarjani
Keyword(s):  
Heat Transport ◽  
Large Temperature ◽  
Vibrational Modes ◽  
Leading Order ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Quartic Term ◽  
Classical Formalism ◽  
Central Device ◽  
Non Equilibrium

We consider the problem of heat transport by vibrational modes between Langevin thermostats connected by a central device. The latter is anharmonic and can be subject to large temperature difference and thus be out of equilibrium. We develop a classical formalism based on the equation of motion method, the fluctuation–dissipation theorem and the Novikov theorem to describe heat flow in a multi-terminal geometry. We show that it is imperative to include a quartic term in the potential energy to insure stability and to properly describe thermal expansion. The latter also contributes to leading order in the thermal resistance, while the usually adopted cubic term appears in the second order. This formalism paves the way for accurate modeling of thermal transport across interfaces in highly non-equilibrium situations beyond perturbation theory.

Reply to ‘Comment on “Collective effects in bremsstrahlung in plasmas” ’

1998 ◽  
Vol 60 (2) ◽  
pp. 447-448 ◽  
Author(s):  
V. N. TSYTOVICH ◽  
R. BINGHAM ◽  
U. de ANGELIS ◽  
A. FORLANI
Keyword(s):  
Particle Distribution ◽  
Thermal Plasmas ◽  
Solar Interior ◽  
The Other ◽  
Standard Approach ◽  
Collective Effects ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Electron Bremsstrahlung ◽  
Non Equilibrium

We reply here to a criticism of our paper (Tsytovich et al. 1996) by Iglesias (1997).In our paper we present a very general formulation of collective effects in bremsstrahlung that is valid for any non-equilibrium non-Maxwellian particle distribution. This result is given in (2.20) early in the paper. The standard treatments of bremsstrahlung found in books like Bekefi (1966) are only for thermal plasmas, where the fluctuation–dissipation theorem is valid. Note that the fluctuation–dissipation theorem cannot be used for non-thermal or non-dipole fields, and in this respect the method we use is more general. Our method is the more complex of the approaches used, but, as stated, it can handle situations that cannot be treated by the standard approach. Our main result is the formula (2.20), which is valid for any non-equilibrium non-Maxwellian particle distribution, and which cannot be found anywhere else in the literature. Furthermore, we find new qualitative effects indicating that the ion–ion bremsstrahlung (which is always neglected in the literature) is not small in the case where the collective effects are taken into account, and is in fact, for certain frequencies, of the order of the electron–electron bremsstrahlung. The other qualitatively new result is that, where collective effects are important, the electron–electron bremsstrahlung is not of the order v2Te/c2, as it is for the case in the absence of collective effects, but of the order ω2pe/ω2 times less – which, for example in the solar interior, where ω2pe/ω2 is of the order of v2Te/c2, is then of the order of v4Te/c4.

Non-equilibrium Fluctuation-Dissipation Theorem for Stationary Anomalous Diffusion

2015 ◽  
Vol 46 (6) ◽  
pp. 1155
Author(s):  
L.C. Lapas ◽  
R. Morgado ◽  
A.L.A. Penna ◽  
F.A. Oliveira
Keyword(s):  
Anomalous Diffusion ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Non Equilibrium

scholarly journals Fluctuation-dissipation theorem for non-equilibrium quantum systems

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 66 ◽  
Author(s):  
Mohammad Mehboudi ◽  
Anna Sanpera ◽  
Juan M. R. Parrondo
Keyword(s):  
Statistical Physics ◽  
Logarithmic Derivative ◽  
Quantum Systems ◽  
Quantum Metrology ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Time Correlations ◽  
Central Result ◽  
Arbitrary Quantum ◽  
Non Equilibrium

The fluctuation-dissipation theorem (FDT) is a central result in statistical physics, both for classical and quantum systems. It establishes a relationship between the linear response of a system under a time-dependent perturbation and time correlations of certain observables in equilibrium. Here we derive a generalization of the theorem which can be applied to any Markov quantum system and makes use of the symmetric logarithmic derivative (SLD). There are several important benefits from our approach. First, such a formulation clarifies the relation between classical and quantum versions of the equilibrium FDT. Second, and more important, it facilitates the extension of the FDT to arbitrary quantum Markovian evolution, as given by quantum maps. Third, it clarifies the connection between the FDT and quantum metrology in systems with a non-equilibrium steady state.

scholarly journals The Response to Stratospheric Forcing and Its Dependence on the State of the Troposphere

2009 ◽  
Vol 66 (7) ◽  
pp. 2107-2115 ◽  
Author(s):  
Cegeon J. Chan ◽  
R. Alan Plumb
Keyword(s):  
Time Scale ◽  
Equilibrium Temperature ◽  
Intrinsic Variability ◽  
Winter Solstice ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Order Of Magnitude ◽  
Leading Mode ◽  
Set Up ◽  
Hemisphere Winter

Abstract In simple GCMs, the time scale associated with the persistence of one particular phase of the model’s leading mode of variability can often be unrealistically large. In a particularly extreme example, the time scale in the Polvani–Kushner model is about an order of magnitude larger than the observed atmosphere. From the fluctuation–dissipation theorem, one implication of these simple models is that responses are exaggerated, since such setups are overly sensitive to any external forcing. Although the model’s equilibrium temperature is set up to represent perpetual Southern Hemisphere winter solstice, it is found that the tropospheric eddy-driven jet has a preference for two distinct regions: the subtropics and midlatitudes. Because of this bimodality, the jet persists in one region for thousands of days before “switching” to another. As a result, the time scale associated with the intrinsic variability is unrealistic. In this paper, the authors systematically vary the model’s tropospheric equilibrium temperature profile, one configuration being identical to that of Polvani and Kushner. Modest changes to the tropospheric state to either side of the parameter space removed the bimodality in the zonal-mean zonal jet’s spatial distribution and significantly reduced the time scale associated with the model’s internal mode. Consequently, the tropospheric response to the same stratospheric forcing is significantly weaker than in the Polvani and Kushner case.

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