Quantum Phase Transition in Ultracold 87Rb Atom Gas with Radiant Field

TL;DR

This paper investigates a second-order quantum phase transition in a two-species Bose-Einstein condensate of 87Rb atoms coupled to a quantized radiation field, revealing critical behavior and experimental detectability.

Contribution

It explicitly characterizes the quantum phase transition in the atom-field system and links its universality class to the Dicke model, providing insights into controllable quantum critical phenomena.

Findings

Energy spectrum shows a second-order phase transition controlled by atom-field coupling.

Scaling behavior of collective excitations matches the Dicke model universality class.

Quantum phase transition can be experimentally observed via atom population imbalance.

Abstract

A second-order quantum phase transition in two-species Bose-Einstein condensates of 87Rb atoms coupled by a quantized radiant field is revealed explicitly in terms of the energy spectrum which is obtained in the thermodynamic limit and is controllable by the coupling parameter between the atom and field. The scaling behavior of the collective excitation modes at the critical transition point is seen to be in the same universality class as that of the Dicke model. It is also demonstrated that the quantum phase transition is realizable below the critical temperature of BEC and can be detected experimentally by measuring the abrupt change of atom population imbalance.