Regensburg 2019 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 17: Statistical Physics (General) I

DY 17.4: Talk

Tuesday, April 2, 2019, 10:45–11:00, H19

Strong Coupling and non-Markovian Effects in the Statistical Notion of Temperature — •Camilo Alfonso Moreno and Juan Diego Urbina — Institut für Theoretische Physik, Universität Regensburg, Germany

We investigate the emergence of temperature T in the system-plus-reservoir paradigm starting from the fundamental microcanonical scenario at total fixed energy E. As shown by Schwinger [1] for the regime of weak coupling γ between system and environment, T(E) emerges from the saddle-point analysis that leads to the usual ensemble equivalence in the thermodynamic limit [2]. By extending these ideas for finite γ, in [3] we provide a consistent generalization of temperature T(E,γ) in strongly coupled systems and we illustrate its main features for the specific model of Quantum Brownian Motion where it leads to consistent microcanonical thermodynamics. Interestingly, we show that while this T(E,γ) is a monotonically increasing function of the total energy E, its dependence with γ is a purely quantum effect drastically different for Markovian and non-Markovian regimes. We also derive a generalization of the idea of equivalence of ensembles for systems with finite coupling and discuss possible issues when the observables are not smooth and must be taking into account in the saddle-point analysis.

P. C. Martin, J. Schwinger, Phys. Rev 6, 115 (1959).
N. J. Morgenstern, Quantum Statistical Field Theory (2017)
C. A. Moreno, J. D. Urbina, arXiv:1811.12110, (2018).