Macroscopic self trapping in BECs: analysis of a dynamical quantum phase transition

TL;DR

This paper investigates a dynamical quantum phase transition in Bose-Einstein condensates within a double-well potential, highlighting the limitations of mean-field theory and emphasizing the role of quantum fluctuations and symmetry breaking.

Contribution

It reveals that the transition from Josephson oscillations to self-trapping involves strongly correlated states beyond mean-field approximation, providing new insights into quantum phase transitions in BECs.

Findings

Transition involves strongly correlated delocalized states

Mean-field theory cannot describe the transition

Quantum fluctuations and symmetry breaking are key

Abstract

We consider a Bose-Einstein condensate in a double-well potential undergoing a dynamical transition from the regime of Josephson oscillations to the regime of self-trapping. We analyze the statistical properties of the ground state (or the highest excited state) of the Hamiltonian in these two regimes for attractive (repulsive) interactions. We demonstrate that it is impossible to describe the transition within the mean-field theory. In contrast, the transition proceeds through a strongly correlated delocalized state, with large quantum fluctuations, and spontaneous breaking of the symmetry.