Conditional Spin-Squeezing of a Large Ensemble via the Vacuum Rabi Splitting

TL;DR

This paper demonstrates a method to generate conditionally spin-squeezed states in a large atomic ensemble using vacuum Rabi splitting, enhancing quantum measurement precision.

Contribution

It introduces a novel approach employing vacuum Rabi splitting for QND measurements to produce spin-squeezed states in nearly one million atoms.

Findings

Achieved 3.4 dB improvement in phase estimation over standard quantum limit.

Utilized a low finesse optical cavity with nearly 10^6 Rb-87 atoms.

Potential applications in improving atomic sensor accuracy and fundamental physics tests.

Abstract

We use the vacuum Rabi splitting to perform quantum nondemolition (QND) measurements that prepare a conditionally spin-squeezed state of a collective atomic psuedo-spin. We infer a 3.4(6) dB improvement in quantum phase estimation relative to the standard quantum limit for a coherent spin state composed of uncorrelated atoms. The measured collective spin is composed of the two-level clock states of nearly 10^6 Rb-87 atoms confined inside a low finesse F = 710 optical cavity. This technique may improve atomic sensor precision and/or bandwidth, and may lead to more precise tests of fundamental physics.