Experimental superradiance and slow light effects for quantum memories

TL;DR

This paper investigates high optical depth phenomena like superradiance and slow light in quantum memory materials, demonstrating their effects on decay rates, slow light, and retrieval efficiency, with implications for improving quantum storage schemes.

Contribution

It provides experimental insights into superradiance and slow light effects at moderate to high optical depths, relevant for enhancing quantum memory protocols.

Findings

Superradiance occurs at alphaL < 5 with decay rates > 1/T2*

Off-resonant slow light effects are demonstrated at high alphaL

Maximum retrieval efficiency of ~20% is achieved and analyzed

Abstract

The effects of high optical depth phenomena, such as superradiance, are investigated in potential quantum memory materials. The results may have relevance for several schemes, including CRIB, AFC and EIT-based quantum memories, which are based on using ensembles as storage media. It is shown that strong superradiant effects, manifested as decay rates larger than 1/T2*, are present even for moderate values of alphaL < 5, and increases as a function of alphaL. For even higher alphaL, effects like off-resonant slow light is demonstrated and discussed, and finally, the efficiency of time-reversed optimized input pulses are tested. A maximum retrieval efficiency of ~20% is reached, and agreement with the theoretically expected result is discussed.