Physics (Internal)

Undephasing the generalized Gibbs ensemble

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: Understanding the long time limit of closed quantum many-body systems prepared in some initial non-equilibrium pure state has attracted a lot of interest in recent years. One central question is whether such a system will thermalize or not. In integrable systems the long time limit leads generically to a generalized Gibbs ensemble (GGE) description. For example for the one dimensional transverse field Ising model one can prove that asymptotically all local observables can be calculated in the GGE. In my talk I will show how one can approximately reverse the time arrow of this dynamics using a spin echo-like local Hamiltonian. In this sense the time evolved system never forgets that it is in a pure state and remembers the initial values of local observables like the longitudinal and transverse magnetization. The time evolution can be thought of as dephasing leading to a GGE, which can be undone with this spin echo-like setup.