Feshbach-Einstein condensates

TL;DR

This paper explores the phase diagram of a two-species Bose-Hubbard model with Feshbach resonance, revealing an exotic super-Mott phase and atomic/molecular condensates, using advanced quantum Monte Carlo methods.

Contribution

It introduces a quantum Monte Carlo approach to study the phase diagram, discovering new phases not predicted by mean-field theories.

Findings

Identification of an exotic super-Mott phase.

Discovery of a phase with atomic but no molecular condensate.

Confirmation and disagreement with mean-field predictions.

Abstract

We investigate the phase diagram of a two-species Bose-Hubbard model describing atoms and molecules on a lattice, interacting via a Feshbach resonance. We identify a region where the system exhibits an exotic super-Mott phase and regions with phases characterized by atomic and/or molecular condensates. Our approach is based on a recently developed exact quantum Monte Carlo algorithm: the Stochastic Green Function algorithm with tunable directionality. We confirm some of the results predicted by mean-field studies, but we also find disagreement with these studies. In particular, we find a phase with an atomic but no molecular condensate, which is missing in all mean-field phase diagrams.