Quantum phase transition and critical fluctuations of an attractive Bose gas in a double well potential

TL;DR

This paper investigates the quantum phase transition and critical fluctuations in an attractive Bose gas confined in a double well potential, linking spontaneous symmetry breaking with Landau-Ginzburg theory.

Contribution

It demonstrates how a second order phase transition and spontaneous symmetry breaking emerge from a quantum model of an attractive Bose gas in a double well.

Findings

Identification of the order parameter and critical point.

Analysis of quantum fluctuations around the critical point.

Connection between quantum model and Landau-Ginzburg scheme.

Abstract

We consider a Bose gas with an attractive interaction in a symmetric double well potential. In the Hartree approximation, the ground state solution spontaneously breaks the symmetry of the trapping potential above certain value of the interaction strength. We demonstrate how the Landau-Ginzburg scheme of the second order phase transition emerges from the quantum model and show its link to the spontaneous symmetry breaking mentioned above. We identify the order parameter, the critical point and analyze quantum fluctuations around it.