Theory of noise suppression in {\Lambda}-type quantum memories by means of a cavity

TL;DR

This paper demonstrates how placing a b1b3;-type quantum memory inside an optical cavity can suppress noise from four-wave mixing, enabling more effective room-temperature quantum memory for single photons.

Contribution

It introduces a cavity-based method to suppress four-wave mixing noise in b1b3;-type quantum memories at room temperature, improving their viability.

Findings

Cavity placement reduces four-wave mixing noise.

Enhanced quantum memory performance at room temperature.

Potential for scalable quantum information processing.

Abstract

Quantum memories, capable of storing single photons or other quantum states of light, to be retrieved on-demand, offer a route to large-scale quantum information processing with light. A promising class of memories is based on far-off-resonant Raman absorption in ensembles of $\Lambda$-type atoms. However at room temperature these systems exhibit unwanted four-wave mixing, which is prohibitive for applications at the single-photon level. Here we show how this noise can be suppressed by placing the storage medium inside a moderate-finesse optical cavity, thereby removing the main roadblock hindering this approach to quantum memory.