On-demand control of photon echoes far exceeding the spin coherence constraint via coherence swapping between optical and spin transitions

TL;DR

This paper demonstrates a method for on-demand photon echo control that significantly extends storage time and efficiency, enabling advances in long-distance quantum communication through coherence swapping between optical and spin states.

Contribution

It introduces a novel optical locking technique in stimulated photon echoes that surpasses previous coherence constraints, achieving ultralong storage and high efficiency.

Findings

Photon storage time extended by several orders of magnitude.

Retrieval efficiency increased by fifty times.

Phase-independent coherence conversion achieved.

Abstract

Using on-demand coherence conversion via optical locking in conventional stimulated (three-pulse) photon echoes, ultralong, ultraefficient photon storage has been observed in a rare-earth Pr3+ doped Y2SiO5, where storage time is several orders of magnitude longer and retrieval efficiency is enhanced by fifty times. Compared with the same method applied to two-pulse photon echoes for a rephasing halt, use of spectral grating in the stimulated photon echoes offers a phase-independent coherence conversion between optical and spin states. Eventually an ultralong spin population decay-dependent photon storage protocol is achieved by applying optical locking to a spectral grating in conventional stimulated photon echoes. The present breakthrough in both photon storage time and retrieval efficiency opens a door to long-distance quantum communications utilizing quantum repeaters.