Quantum phase transition in an atomic Bose gas with a Feshbach resonance

TL;DR

This paper investigates a quantum phase transition in an atomic Bose gas near a Feshbach resonance, revealing a transition between pure molecular and mixed atomic-molecular condensates, characterized by an Ising order parameter.

Contribution

It identifies the nature of the quantum phase transition and maps the phase diagram, extending the quantum critical point into finite temperature transitions.

Findings

Quantum phase transition between molecular and atomic-molecular condensates.

Transition characterized by an Ising order parameter.

Phase diagram includes a line of finite temperature Ising transitions.

Abstract

We show that in an atomic Bose gas near a Feshbach resonance a quantum phase transition occurs between a phase with only a molecular Bose-Einstein condensate and a phase with both an atomic and a molecular Bose-Einstein condensate. We show that the transition is characterized by an Ising order parameter. We also determine the phase diagram of the gas as a function of magnetic field and temperature: the quantum critical point extends into a line of finite temperature Ising transitions.