Unitary Cavity Spin Squeezing by Quantum Erasure

TL;DR

This paper proposes methods to enhance cavity spin squeezing by erasing light-atom entanglement, significantly improving squeezing performance and scaling in atomic gases.

Contribution

It introduces theoretical techniques for quantum erasure to improve cavity spin squeezing beyond previous limits.

Findings

Quantum erasure enhances squeezing scaling from S^(-1/2) to S^(-2/3).

Methods for erasing light-atom entanglement are proposed.

Performance improvements are robust even with light scattering considered.

Abstract

Deterministic light-induced spin squeezing in an atomic gas is limited by photon shot noise or, equivalently, by atomic state information escaping with the light field mediating the effective atom-atom interaction. We show theoretically that the performance of cavity spin squeezing [M.H. Schleier-Smith, I.D. Leroux, and V. Vuleti\'{c}, Phys. Rev. A 81, 021804(R) (2010)] can be substantially improved by erasing the light-atom entanglement, and propose several methods for doing so. Accounting for light scattering into free space, quantum erasure improves the scaling of cavity squeezing from S^(-1/2) to S^(-2/3), where S is the total atomic spin.