Non-stationary coherent quantum many-body dynamics through dissipation

TL;DR

This paper demonstrates conditions under which quantum many-body systems avoid reaching equilibrium due to dissipation, leading to persistent, non-stationary dynamics akin to a quantum time-crystal, with potential implementations in ultracold atoms.

Contribution

It identifies generic conditions for dissipation to prevent stationarity in quantum many-body systems, extending the concept of quantum time-crystals to dissipative environments.

Findings

Dissipation can sustain non-stationary quantum dynamics.

Conditions for non-stationarity are simple and generic.

Potential realization with ultracold atoms in optical lattices.

Abstract

The assumption that quantum systems relax to a stationary state in the long-time limit underpins statistical physics and much of our intuitive understanding of scientific phenomena. For isolated systems this follows from the eigenstate thermalization hypothesis. When an environment is present the expectation is that all of phase space is explored, eventually leading to stationarity. Notable exceptions are decoherence-free subspaces that have important implications for quantum technologies and have so far only been studied for systems with a few degrees of freedom. Here we identify simple and generic conditions for dissipation to prevent a quantum many-body system from ever reaching a stationary state. We go beyond dissipative quantum state engineering approaches towards controllable long-time non-stationarity typically associated with macroscopic complex systems. This coherent and oscillatory evolution constitutes a dissipative version of a quantum time-crystal. We discuss the possibility of engineering such complex dynamics with fermionic ultracold atoms in optical lattices.