Double-lambda microscopic model for entangled light generation by four-wave-mixing

TL;DR

This paper models four-wave mixing in a double-{ extLambda} atomic system to predict quantum correlations and entanglement in generated light beams, providing theoretical insights aligned with recent experimental capabilities.

Contribution

It introduces a microscopic Heisenberg-Langevin model for four-wave mixing in a double-{ extLambda} system, predicting quantum correlations and entanglement in cold atomic media.

Findings

Quantum-correlated beams with noise below -6 dB of the standard quantum limit.

Entanglement between seed and conjugate beams with inseparability down to 0.25.

Theoretical framework aligns with and guides experimental realization of entangled light.

Abstract

Motivated by recent experiments, we study four-wave-mixing in an atomic double-{\Lambda} system driven by a far-detuned pump. Using the Heisenberg-Langevin formalism, and based on the microscopic properties of the medium, we calculate the classical and quantum properties of seed and conju- gate beams beyond the linear amplifier approximation. A continuous variable approach gives us access to relative-intensity noise spectra that can be directly compared to experiments. Restricting ourselves to the cold-atom regime, we predict the generation of quantum-correlated beams with a relative-intensity noise spectrum well below the standard quantum limit (down to -6 dB). Moreover entanglement between seed and conjugate beams measured by an inseparability down to 0.25 is expected. This work opens the way to the generation of entangled beams by four-wave mixing in a cold atomic sample.