High-Efficiency Quantum Memory of Full-Bandwidth Squeezed Light

TL;DR

This paper demonstrates a high-efficiency, broadband quantum memory for squeezed light with a 24 MHz bandwidth, achieving high fidelity and low noise, advancing quantum information processing capabilities.

Contribution

The authors develop a quantum memory with significantly increased bandwidth and efficiency for squeezed light using a far-off resonant Raman process, surpassing previous narrowband systems.

Findings

Achieved 80% memory efficiency and 1.0 dB output squeezing.

Bandwidth of 24 MHz, at least 12 times larger than prior systems.

Lowest excess noise of 0.025 shot-noise-units.

Abstract

In continuous-variable quantum information processing, it is crucial to develop high-efficiency and broadband quantum memory of squeezed light, which enables the storage of full-bandwidth information. Here, we present a quantum memory of squeezed light with up to 24 MHz bandwidth, which is at least 12 times that of previous narrowband resonant memory systems, via a far-off resonant Raman process. We achieve output squeezing of as high as 1.0 dB with fidelity above 92% and a memory efficiency of 80%, corresponding to an end-to-end efficiency of 64.2%, when input squeezing is 1.6 dB. The lowest excess noise of 0.025 shot-noise-unit in the memory system is estimated by the noisy channel model which is benefited from optimizing quantum memory performance with a backward retrieval strategy. Our results represent a breakthrough in high-performance memory for squeezed states within tens of MHz-level bandwidth, which has potential applications in high-speed quantum information processing.