# Raman Quantum Memory with Built-In Suppression of Four-wave Mixing Noise

## TL;DR

This paper presents a simple quantum interference scheme to suppress four-wave mixing noise in Raman quantum memories, significantly improving noise performance and advancing scalable quantum photonic networks.

## Contribution

The authors develop and experimentally implement a novel interference-based noise suppression method for Raman quantum memories in warm vapor.

## Key findings

- Over an order of magnitude noise reduction achieved.
- Method to quantify residual noise contributions.
- Route proposed for further noise suppression.

## Abstract

Quantum memories are essential for large-scale quantum information networks. Along with high efficiency, storage lifetime and optical bandwidth, it is critical that the memory add negligible noise to the recalled signal. A common source of noise in optical quantum memories is spontaneous four-wave mixing. We develop and implement a technically simple scheme to suppress this noise mechanism by means of quantum interference. Using this scheme with a Raman memory in warm atomic vapour we demonstrate over an order of magnitude improvement in noise performance. Furthermore we demonstrate a method to quantify the remaining noise contributions and present a route to enable further noise suppression. Our scheme opens the way to quantum demonstrations using a broadband memory, significantly advancing the search for scalable quantum photonic networks.