High-flux sub-Poissonian twin-beam generation from warm atomic vapor

TL;DR

This paper reports the generation of high-flux, sub-Poissonian twin beams via four-wave mixing in warm rubidium vapor, demonstrating strong intensity and photon-number squeezing suitable for quantum sensing.

Contribution

It introduces a fiber-compatible, near-resonance twin-photon source with high flux and sub-Poissonian statistics, advancing scalable quantum technologies.

Findings

Achieved 5.5 dB intensity-difference squeezing in free space

Observed -0.7 Mandel Q parameter indicating photon-number squeezing

Temporal correlations match theoretical predictions with flat-topped profiles

Abstract

We demonstrate sub-Poissonian twin-beam generation via near-degenerate spontaneous four-wave mixing in warm $^{85}\mathrm{Rb}$ at 795 nm. The twin beams exhibit approximately $5.5~\mathrm{dB}$ of intensity-difference squeezing in free space and about $3~\mathrm{dB}$ after coupling into polarization-maintaining fibers. Time-resolved photon counting yields Mandel parameters of $Q \approx -0.7$ for each beam, revealing strong photon-number squeezing in each beam individually. The temporal correlation between the twin photons exhibits a distinctive flat-topped profile, reflecting multiple $\chi^{(3)}$ processes in the atomic medium and showing excellent agreement with theory. This fiber-compatible, near atomic-resonance, high-flux sub-Poissonian twin-photon source is well suited for integration into scalable quantum-enhanced sensing and information processing applications.