Dynamical generation of geometric squeezing in interacting Bose-Einstein condensates

TL;DR

This paper explores how to generate geometric squeezing in interacting Bose-Einstein condensates by destabilizing collective excitations, enabling exponential suppression of quantum fluctuations.

Contribution

It identifies superfluid stability as the reason for non-squeezing in interacting BECs and proposes a dynamical method to induce squeezing by breaking stability criteria.

Findings

Non-interacting BECs can be squeezed via a frequency quench.

Interacting BECs exhibit oscillations without squeezing due to stability.

Breaking superfluid stability enables exponential quantum fluctuation suppression.

Abstract

When the rotating frequency of a non-interacting Bose-Einstein condensate (BEC) confined in a weak anisotropic harmonic potential is suddenly quenched to its trapping frequency, the condensate evolves from its ground state to a single-mode squeezed state with exponentially growing quantum fluctuation anisotropy. Such a squeezed state is called the geometrically squeezed state. However, for interacting BECs with two-body collisions, a similar quench only results in quantum fluctuations oscillating periodically without squeezing. In this work, we identify superfluid stability as the key factor behind this non-squeezing phenomenon, with the periodic oscillations arising from collective excitations of a stable collective excitation mode. By strategically breaking the stability criteria, we propose a dynamical approach for generating squeezing that can exponentially suppress quantum fluctuations in a relatively short time, surpassing the efficiency of existing experimental preparation schemes.