Enhancing Quantum Memories with Light-Matter Interference

TL;DR

This paper introduces a novel light-matter interference technique to significantly improve quantum memory efficiency, bandwidth, and noise performance, advancing scalable quantum information processing.

Contribution

We demonstrate a new interference-based protocol that enhances quantum memory efficiency without increasing atomic density or laser power, applicable across various architectures.

Findings

Achieved over 34% efficiency in warm Cesium vapor quantum memory.

Predicted efficiencies exceeding 96% in cold atomic ensembles.

Reduced laser intensity requirements by over an order-of-magnitude.

Abstract

Future optical quantum technologies, such as quantum networks, distributed quantum computing and sensing, demand efficient, broadband quantum memories. However, achieving high efficiency without introducing noise, reducing bandwidth, or limiting scalability remains a challenge. Here, we present a new approach to enhance quantum memory protocols by leveraging constructive light-matter interference, leading to an increase in memory efficiency without increasing atomic density or laser intensity. We implement this method in a Raman quantum memory in warm Cesium vapor, and achieve more than a three-fold improvement in total efficiency reaching $(34.3\pm8.4)\%$, while retaining GHz-bandwidth operation and low noise levels. Numerical simulations predict that this approach can boost efficiencies in systems limited by atomic density, such as cold atomic ensembles, from $65\%$ to beyond $96\%$, while in warm atomic vapors it could reduce the laser intensity needed to reach a given efficiency by over an order-of-magnitude, exceeding $95\%$ total efficiency. Furthermore, our method preserves the single-mode nature of the memory at high efficiencies. This new protocol is applicable to various memory architectures, paving the way toward scalable, efficient, low-noise, and high-bandwidth quantum memories.