Dephasing and the steady state in quantum many-particle systems

TL;DR

This paper investigates how dephasing leads to steady states in quantum many-particle systems, exploring conditions for relaxation, effects of dimensionality, and implications for entanglement growth after parameter quenches.

Contribution

It provides explicit derivations of steady states in integrable systems and identifies conditions under which dephasing occurs or fails, linking to entanglement dynamics.

Findings

Dephasing causes finite subsystems to reach steady states in integrable systems.

Certain scenarios show dephasing is ineffective, depending on system parameters.

Post-quench entanglement entropy becomes extensive, enabling controlled entanglement generation.

Abstract

We discuss relaxation in bosonic and fermionic many-particle systems. For integrable systems, the time evolution can cause a dephasing effect, leading for finite subsystems to certain steady states. We give an explicit derivation of those steady subsystem states and devise sufficient prerequisites for the dephasing to take place. We also find simple scenarios, in which dephasing is ineffective and discuss the dependence on dimensionality and criticality. It follows further that, after a quench of system parameters, bipartite entanglement entropy will become extensive. This provides a way of creating strong entanglement in a controlled fashion.