Fast, noise-free memory for photon synchronization at room temperature

TL;DR

This paper introduces a fast, low-noise optical memory using rubidium vapor that operates at room temperature, significantly improving photon synchronization for quantum networks.

Contribution

The authors demonstrate a novel ladder memory (FLAME) that achieves high bandwidth, low noise, and long storage times at room temperature, enabling better quantum photonic synchronization.

Findings

Stored and retrieved 1.7-ns pulses with 0.5 photons on average

Achieved a memory lifetime of 86 ns and efficiency of 25%

Reduced added noise to below 10^-4 photons

Abstract

Future quantum photonic networks require coherent optical memories for synchronizing quantum sources and gates of probabilistic nature. We demonstrate a fast ladder memory (FLAME) mapping the optical field onto the superposition between electronic orbitals of rubidium vapor. Employing a ladder level-system of orbital transitions with nearly degenerate frequencies simultaneously enables high bandwidth, low noise, and long memory lifetime. We store and retrieve 1.7-ns-long pulses, containing 0.5 photons on average, and observe short-time external efficiency of 25%, memory lifetime (${1/e}$) of 86 ns, and below ${10^{-4}}$ added noise photons. Consequently, coupling this memory to a probabilistic source would enhance the on-demand photon generation probability by a factor of 12, the highest number yet reported for a noise-free, room-temperature memory. This paves the way towards the controlled production of large quantum states of light from probabilistic photon sources.