Report on 1705.10800v2

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 dynamicse.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, 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.