Towards high-speed optical quantum memories

TL;DR

This paper demonstrates a high-bandwidth quantum memory in cesium vapor capable of storing and retrieving sub-nanosecond light pulses with over 1 GHz spectral bandwidth, significantly increasing data rates for quantum information processing.

Contribution

It introduces a novel off-resonant two-photon transition method that enables GHz bandwidth quantum memory with high efficiency and coherence in hot atomic vapor.

Findings

Memory bandwidth exceeds 1 GHz

Data rate increases by nearly 1000 times

Memory efficiency is 15%

Abstract

Quantum memories, capable of controllably storing and releasing a photon, are a crucial component for quantum computers and quantum communications. So far, quantum memories have operated with bandwidths that limit data rates to MHz. Here we report the coherent storage and retrieval of sub-nanosecond low intensity light pulses with spectral bandwidths exceeding 1 GHz in cesium vapor. The novel memory interaction takes place via a far off-resonant two-photon transition in which the memory bandwidth is dynamically generated by a strong control field. This allows for an increase in data rates by a factor of almost 1000 compared to existing quantum memories. The memory works with a total efficiency of 15% and its coherence is demonstrated by directly interfering the stored and retrieved pulses. Coherence times in hot atomic vapors are on the order of microsecond - the expected storage time limit for this memory.