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TT: Fachverband Tiefe Temperaturen

TT 93: Quantum Coherence and Quantum Information Systems (joint session TT/MA)

TT 93.1: Invited Talk

Thursday, March 15, 2018, 15:00–15:30, H 2053

Non-Markovian Quantum Thermodynamics: Second Law and Fluctuation Theorems — •Robert S Whitney — Laboratoire de Physique et Modélisation des Milieux Condensés, Université Grenoble Alpes & CNRS, 25 avenue des Martyrs, BP166 38042 Grenoble, France

The thermodynamics of quantum systems which are strongly coupled to reservoirs is fraught with difficulties, such as non-factorizable initial conditions and non-Markovian system dynamics. However, there is huge practical interest in machines (heat engines, refrigerators, etc) in this strong coupling regime, because weak-coupling implies very small currents, and hence very small power outputs.

This work shows that a real-time diagrammatic technique is an equivalent of stochastic thermodynamics for strongly-coupled non-Markovian quantum machines. Symmetries are found between quantum trajectories and their time-reverses on the Keldysh contour, for any interacting quantum system coupled to ideal reservoirs of electrons, phonons or photons. These lead to quantum fluctuation theorems the same as the well-known classical ones (Jarzynski and Crooks equalities, non-equilibrium partition identity, etc), whether the system’s dynamics are Markovian or not. Some of these also hold for non-factorized initial states. We identify a family of approximations, suitable for concrete calculations of a machine’s power and efficiency, which respect the symmetries that ensure fluctuation theorems. In all cases, including non-factorized initial states, the second law of thermodynamics is proven to hold on average, with fluctuations violating it.
arXiv:1611.00670