Decay and fragmentation in an open Bose-Hubbard chain

TL;DR

This paper investigates how dissipation affects the stability and decay of ultracold atoms in an optical lattice, revealing a phase transition and the formation of entangled breather states with potential quantum applications.

Contribution

It demonstrates that controlled dissipation can stabilize a Bose-Einstein condensate and details a phase transition leading to entangled breather states in an open Bose-Hubbard chain.

Findings

Dissipation can stabilize a BEC in an optical lattice.

A dynamical phase transition occurs with initial state instability.

Strong interactions lead to entangled breather formation.

Abstract

We analyze the decay of ultracold atoms from an optical lattice with loss form a single lattice site. If the initial state is dynamically stable a suitable amount of dissipation can stabilize a Bose-Einstein condensate, such that it remains coherent even in the presence of strong interactions. A transition between two different dynamical phases is observed if the initial state is dynamically unstable. This transition is analyzed here in detail. For strong interactions, the system relaxes to an entangled quantum state with remarkable statistical properties: The atoms bunch in a few "breathers" forming at random positions. Breathers at different positions are coherent, such that they can be used in precision quantum interferometry and other applications.