Generation of squeezed optical states via stored classical pulses in a Bose gas

TL;DR

This paper proposes a method to generate squeezed light by storing classical pulses in a Bose-Einstein condensate and using atom-atom collisions to produce spin squeezing, which is then transferred to light.

Contribution

It introduces a novel scheme combining optical storage in a BEC with collisional dynamics to produce and transfer optical squeezing.

Findings

Several dB of squeezing can be transferred to the retrieved light.

The scheme accounts for realistic losses and efficiencies.

Optimal storage times are identified for maximum squeezing.

Abstract

We propose and analyze a scheme to generate squeezed light by storing a classical probe pulse in a Bose--Einstein condensate (BEC) and exploiting the nonlinear evolution caused by atom--atom collisions during the storage time. A $\Lambda$-type optical memory interface maps a chosen temporal probe mode onto a single phase-matched collective spin wave; for a coherent input this prepares a tunable coherent spin state of a two-component BEC, with its initial spin orientation set by the stored mean excitation number and the phase relation between the probe and control fields. Collisional interactions during storage then implement one-axis-twisting dynamics and generate spin squeezing in the atomic ensemble. We account for realistic loss and finite memory and retrieval efficiencies, and model readout as a single-mode beam-splitter mapping that transfers the atomic quadrature squeezing onto a propagating optical mode. We identify optimal storage times and predict that, under realistic conditions, several dB of squeezing can be transferred to the retrieved light.