Highly multimode memory in a crystal

TL;DR

This paper demonstrates the experimental storage of over a thousand temporal modes in a thulium-doped crystal using a novel frequency modulation technique for atomic frequency comb preparation, achieving high bandwidth and multimode capacity.

Contribution

It introduces a new frequency modulation method for AFC preparation that improves spectral selectivity and is applicable to various rare-earth doped materials for quantum memory.

Findings

Stored 1060 temporal modes in a crystal

Achieved a 0.93 GHz storage bandwidth

Used frequency modulation for AFC preparation

Abstract

We experimentally demonstrate the storage of 1060 temporal modes onto a thulium-doped crystal using an atomic frequency comb (AFC). The comb covers 0.93 GHz defining the storage bandwidth. As compared to previous AFC preparation methods (pulse sequences i.e. amplitude modulation), we only use frequency modulation to produce the desired optical pumping spectrum. To ensure an accurate spectrally selective optical pumping, the frequency modulated laser is self-locked on the atomic comb. Our approach is general and should be applicable to a wide range of rare-earth doped material in the context of multimode quantum memory.