Quantum-field dynamics of expanding and contracting Bose-Einstein condensates

TL;DR

This paper studies the quantum field dynamics of Bose-Einstein condensates under controlled interactions, demonstrating Kerr squeezing and proposing a homodyne detection scheme to observe number squeezing.

Contribution

It introduces a method to analyze quantum statistics in BECs with tunable interactions and proposes a practical homodyne scheme for detecting quadrature and number squeezing.

Findings

Quantum field undergoes Kerr squeezing from non-interacting state.

Homodyne scheme converts quadrature squeezing into number squeezing.

Numerical demonstration using Hartree-Fock-Bogoliubov formalism.

Abstract

We analyze the dynamics of quantum statistics in a harmonically trapped Bose-Einstein condensate, whose two-body interaction strength is controlled via a Feshbach resonance. From an initially non-interacting coherent state, the quantum field undergoes Kerr squeezing, which can be qualitatively described with a single mode model. To render the effect experimentally accessible, we propose a homodyne scheme, based on two hyperfine components, which converts the quadrature squeezing into number squeezing. The scheme is numerically demonstrated using a two-component Hartree-Fock-Bogoliubov formalism.