Cavity-aided non-demolition measurements for atom counting and spin squeezing

TL;DR

This paper explores cavity-aided non-demolition measurements for atom counting and spin squeezing, aiming to enhance spectroscopic sensitivity and generate entangled states with minimal heating.

Contribution

It provides analytical expressions for measurement resolution and spectroscopic enhancement in cavity-aided non-demolition measurements, including fundamental limits for $^{87}$Rb.

Findings

Derived formulas for measurement resolution and enhancement

Analyzed fundamental limits on spectroscopic improvements

Applicable to scalable quantum sensing with atomic ensembles

Abstract

Probing the collective spin state of an ensemble of atoms may provide a means to reduce heating via the photon recoil associated with the measurement and provide a robust, scalable route for preparing highly entangled states with spectroscopic sensitivity below the standard quantum limit for coherent spin states. The collective probing relies on obtaining a very large optical depth that can be effectively increased by placing the ensemble within an optical cavity such that the probe light passes many times through the ensemble. Here we provide expressions for measurement resolution and spectroscopic enhancement in such cavity-aided non-demolition measurements as a function of cavity detuning. In particular, fundamental limits on spectroscopic enhancements in $^{87}$Rb are considered.