Efficient, ever-ready quantum memory at room temperature for single photons

TL;DR

This paper demonstrates a room-temperature, hot atomic vapor quantum memory with record 84% efficiency for single photons, enabling scalable quantum networks without complex cooling systems.

Contribution

It introduces a high-efficiency, room-temperature quantum memory using rubidium vapor and a narrowband photon source, surpassing previous efficiency records in simple, maintenance-free systems.

Findings

Achieved 84% recall efficiency for single photons.

Operates at room temperature without vacuum systems.

Uses ultralow spectral bandwidth photon source with rubidium vapor.

Abstract

Efficient quantum memories will be an essential building block of large scale networked quantum systems and provide a link between flying photonic qubits and atomic or quasi-atomic local quantum processors. To provide a path to scalability avoidance of bulky, difficult to maintain systems such as high vacuum and low temperature cryogenics is imperative. Memory efficiencies above 50% are required to be operating above the quantum no-cloning limit. Such high efficiencies have only been achieved in systems with photon sources tailored to the memory bandwidth. In this paper we explore the combination of an ultralow spectral bandwidth source of single photons from cavity-enhanced spontaneous parametric down-conversion with a gas-ensemble atomic memory. Our rubidium vapour gradient echo memory achieves 84$\pm$3% recall efficiency of single photons: a record for an always-ready, hot, and vacuum system free optical memory.