Squeezed-light spin noise spectroscopy

TL;DR

This paper demonstrates quantum-enhanced spin noise spectroscopy using polarization-squeezed light, achieving improved signal-to-noise ratio and better sensitivity-broadening trade-offs in atomic vapor measurements.

Contribution

It introduces the use of polarization squeezing to enhance spin noise spectroscopy, showing quantum improvements in sensitivity and noise reduction.

Findings

Squeezing improves signal-to-noise ratio by up to 2.6 dB.

Quantum squeezing enhances the trade-off between sensitivity and broadening.

Experiment with Rb vapor and buffer gas confirms quantum advantage in measurements.

Abstract

We report quantum enhancement of Faraday rotation spin noise spectroscopy by polarization squeezing of the probe beam. Using natural abundance Rb in 100 Torr of N_2 buffer gas, and squeezed light from a sub-threshold optical parametric oscillator stabilized 20 GHz to the blue of the D_1 resonance, we observe that an input squeezing of 3.0 dB improves the signal-to-noise ratio by 1.5 dB to 2.6 dB over the combined (power)$\otimes$(number density) ranges (0.5 mW to 4.0 mW )$\otimes$(1.5 x 10^{12} cm^{-3} to 1.3 x 10^{13} cm^{-3}), covering the ranges used in optimized spin noise spectroscopy experiments. We also show that squeezing improves the trade-off between statistical sensitivity and broadening effects, a previously unobserved quantum advantage.