Quantum quenches from an excited state

Gesualdo Delfino, Marianna Sorba

Published 2023-04-05Version 1

Determining the role of initial conditions in the late time evolution is a key issue for the theory of nonequilibrium dynamics of isolated quantum systems. Here we extend the theory of quantum quenches to the case in which before the quench the system is in an excited state. In particular, we show analytically that lack of relaxation at large times requires the presence of a one-quasiparticle contribution to the nonequilibrium state, as originally shown in [J. Phys. A 47 (2014) 402001] for the quenches from the ground state.