Coherent backscattering in the Fock space of ultracold bosonic atoms

TL;DR

This paper provides numerical evidence of coherent backscattering in the Fock space of a small disordered Bose-Hubbard system, highlighting a many-body interference effect observable through time evolution from a Fock state.

Contribution

It demonstrates the occurrence of coherent backscattering in Fock space of a Bose-Hubbard system and proposes experimental measurement methods using ultracold atoms.

Findings

Enhanced detection probability of initial Fock state due to backscattering

Destruction of backscattering with synthetic gauge fields

Relevance in both thermalized and localized regimes

Abstract

We present numerical evidence for the occurrence of coherent backscattering in the Fock space of a small disordered Bose-Hubbard system consisting of four sites and containing five particles. This many-body interference phenomenon can most conveniently be seen in time evolution processes that start from a Fock state of the Bose-Hubbard system. It manifests itself in an enhanced detection probability of this initial state as compared to other Fock states with comparable total energy. We argue that coherent backscattering in Fock space can be experimentally measured with ultracold bosonic atoms in optical lattices using state-of-the-art single-site detection techniques. A synthetic gauge field can be induced in order to break time-reversal symmetry within the lattice and thereby destroy coherent backscattering. While this many-body interference effect is most prominently visible in the presence of eigenstate thermalization, we briefly discuss its significance in the opposite regime of many-body localization.