We examine the validity of fluctuation-dissipation relations in isolated quantum systems taken out of equilibrium by a sudden quench. We focus on the dynamics of trapped hard-core bosons in one-dimensional lattices with dipolar interactions whose strength is changed during the quench. We find indications that fluctuation-dissipation relations hold if the system is nonintegrable after the quench, as well as if it is integrable after the quench if the initial state is an equilibrium state of a nonintegrable Hamiltonian. On the other hand, we find indications that they fail if the system is integrable both before and after quenching.
Ehsan Khatami, Guido Pupillo, Mark Srednicki, and Marcos Rigol. "Fluctuation-Dissipation Theorem in an Isolated System of Quantum Dipolar Bosons after a Quench" Physical Review Letters (2013): 050403-050408. doi:10.1103/PhysRevLett.111.050403