Dr. Robert S. Whitney – 13 Décembre

Fluctuation theorems show us that the second law of thermodynamics is only valid on average, with fluctuations violating it on short time-scales. I will give a gentle introduction to fluctuation theorems; explaining why they are interesting, and deriving one for a simple quantum system. I will then discuss our recent work which brings together Keldysh theory and quantum thermodynamics, by showing that a real-time diagramatic technique can provide a quantum equivalent of stochastic thermodynamics for non-Markovian quantum machines (heat engines, refrigerators, etc). We identify symmetries between quantum trajectories and their time-reverses on the Keldysh contour. These lead to quantum fluctuations theorems the same as the well-known classical ones (Jarzynski and Crooks equalities, non-equilibrium partition identity, etc), but which hold whether the system’s dynamics are Markovian or not. Our proof applies to systems with Kondo effects or other strong correlations, and to systems in superposition states or with time-dependent driving.
[Preprint: R.S. Whitney arXiv:1611.00670]