(Non) equilibrium dynamics: a (broken) symmetry of the Keldysh generating functional
Camille Aron, Giulio Biroli, Leticia F. Cugliandolo
SciPost Phys. 4, 008 (2018) · published 31 January 2018
- doi: 10.21468/SciPostPhys.4.1.008
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Abstract
We unveil the universal (model-independent) symmetry satisfied by Schwinger-Keldysh quantum field theories whenever they describe equilibrium dynamics. This is made possible by a generalization of the Schwinger-Keldysh path-integral formalism in which the physical time can be re-parametrized to arbitrary contours in the complex plane. Strong relations between correlation functions, such as the fluctuation-dissipation theorems, are derived as immediate consequences of this symmetry of equilibrium. In this view, quantum non-equilibrium dynamics -- e.g. when driving with a time-dependent potential -- are seen as symmetry-breaking processes. The symmetry-breaking terms of the action are identified as a measure of irreversibility, or entropy creation, defined at the level of a single quantum trajectory. Moreover, they are shown to obey quantum fluctuation theorems. These results extend stochastic thermodynamics to the quantum realm.
Cited by 21
Authors / Affiliations: mappings to Contributors and Organizations
See all Organizations.- 1 2 Camille Aron,
- 1 3 Giulio Biroli,
- 4 Leticia F. Cugliandolo