Squeezing of thermal fluctuations in four-wave mixing in a \Lambda-scheme

TL;DR

This paper theoretically explores how four-wave mixing in a b1-scheme of three-level atoms can produce two-mode quadrature squeezing, highlighting the impact of thermal noise and optimal conditions for maximum squeezing.

Contribution

It introduces a detailed theoretical model of noise transfer in four-wave mixing within a b1-scheme, identifying optimal parameters for squeezing under thermal conditions.

Findings

Thermal photons at low frequency significantly affect squeezing quality.

Inelastic processes influence ground state coherence decay.

Optimal density-length product depends on relaxation and drive parameters.

Abstract

We theoretically investigate the mechanism of two-mode quadrature squeezing in regime of four-wave mixing in a \Lambda-scheme of three-level atoms embedded in a thermal reservoir. We demonstrate that the process of nonlinear transfer of noise from the low frequency of ground state splitting to the optical frequency drastically modifies the condition of effective two-mode squeezing. The damage factor is significant if number of thermal photons at the low frequency is high and the role of inelastic processes in ground state coherence decay is not negligible. We found the optimal conditions for squeezing, in particular optimal density-length product of active medium depending on the relaxation parameters and drive intensity.