Revival of Silenced Echo and Quantum Memory for Light

TL;DR

This paper introduces a novel quantum memory protocol that uses spatial phase mismatching to silence primary echoes, enabling noise-free secondary echoes for reliable quantum information storage.

Contribution

It presents an innovative quantum memory method that leverages phase mismatching to suppress primary echoes, improving quantum memory fidelity.

Findings

Experimental demonstration of echo silencing via phase mismatching

Successful retrieval of secondary echo without noise contamination

Enhanced quantum memory performance demonstrated

Abstract

We propose an original quantum memory protocol. It belongs to the class of rephasing processes and is closely related to two-pulse photon echo. It is known that the strong population inversion produced by the rephasing pulse prevents the plain two-pulse photon echo from serving as a quantum memory scheme. Indeed gain and spontaneous emission generate prohibitive noise. A second $\pi$-pulse can be used to simultaneously reverse the atomic phase and bring the atoms back into the ground state. Then a secondary echo is radiated from a non-inverted medium, avoiding contamination by gain and spontaneous emission noise. However, one must kill the primary echo, in order to preserve all the information for the secondary signal. In the present work, spatial phase mismatching is used to silence the standard two-pulse echo. An experimental demonstration is presented.