High-performance Raman quantum memory with optimal control

TL;DR

This paper demonstrates a high-efficiency, high-fidelity atomic Raman quantum memory using optimal control in Rb87 vapour, achieving record efficiency and fidelity for practical quantum information applications.

Contribution

The authors develop an optimal control technique that significantly improves efficiency and fidelity in atomic Raman memories, surpassing previous limitations.

Findings

Memory efficiency of 82.6% for 10-ns pulses

Unconditional fidelity of 98.0%, exceeding no-cloning limit

Achieved highest efficiency in atomic Raman memories to date

Abstract

Quantum memories with high efficiency and fidelity are essential for long-distance quantum communication and information processing. Techniques have been developed for quantum memories based on atomic ensembles. The atomic memories relying on the atom-light resonant interaction usually suffer from the limitations of narrow bandwidth. The far-off-resonant Raman process has been considered a potential candidate for use in atomic memories with large bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in Rb87 vapour with the development of an optimal control technique. A memory efficiency of 82.6% for 10-ns optical pulses is achieved and is the highest realized to date in atomic Raman memories. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic Raman memory towards practical applications in quantum information processing.