Relative intensity squeezing by four-wave mixing with loss: an analytic model and experimental diagnostic

TL;DR

This paper develops an analytic model for four-wave mixing in atomic vapor that accounts for gain and loss, providing closed-form expressions for relative intensity squeezing and validating the model with experimental data.

Contribution

It introduces a novel matrix calculus-based analytic model for predicting relative intensity squeezing in four-wave mixing with loss, validated by experiments.

Findings

Analytic expressions accurately predict squeezing levels.

Model effectively diagnoses experimental conditions.

Experimental results confirm theoretical predictions.

Abstract

Four-wave mixing near resonance in an atomic vapor can produce relative intensity squeezed light suitable for precision measurements beyond the shot-noise limit. We develop an analytic distributed gain/loss model to describe the competition of mixing and absorption through the non-linear medium. Using a novel matrix calculus, we present closed-form expressions for the degree of relative intensity squeezing produced by this system. We use these theoretical results to analyze experimentally measured squeezing from a $^{85}$Rb vapor and demonstrate the analytic model's utility as an experimental diagnostic.