Post-Ehrenfest many-body quantum interferences in ultracold atoms far-out-of-equilibrium

TL;DR

This paper develops a semiclassical theory that accurately captures quantum interference effects in many-body bosonic systems, especially in ultracold atoms far from equilibrium, surpassing traditional approximations like the truncated Wigner method.

Contribution

The authors introduce a new semiclassical approach that includes quantum interferences beyond Ehrenfest time, improving the understanding of quantum dynamics in many-body systems.

Findings

The theory accurately reproduces post-Ehrenfest quantum interference phenomena.

It enables high-precision many-body spectroscopy.

It bridges classical and quantum descriptions in ultracold atomic systems.

Abstract

Far out-of-equilibrium many-body quantum dynamics in isolated systems necessarily generate interferences beyond an Ehrenfest time scale, where quantum and classical expectation values diverge. Of great recent interest is the role these interferences play in the spreading of quantum information across the many degrees of freedom, i.e.~scrambling. Ultracold atomic gases provide a promising setting to explore these phenomena. Theoretically speaking, the heavily-relied-upon truncated Wigner approximation leaves out these interferences. We develop a semiclassical theory which bridges classical and quantum concepts in many-body bosonic systems and properly incorporates such missing quantum effects. For mesoscopically populated Bose-Hubbard systems, it is shown that this theory captures post-Ehrenfest quantum interference phenomena very accurately, and contains relevant phase information to perform many-body spectroscopy with high precision.