Efficient integrated quantum memory for light

TL;DR

This paper presents highly efficient integrated quantum memories using rare-earth-ion doped crystals with record efficiencies up to 80%, enabling scalable quantum networks and photonic processors.

Contribution

The authors demonstrate two novel architectures achieving high efficiency, multimode capacity, and tunability in integrated quantum memories, surpassing previous efficiency limits.

Findings

Achieved 80.3% storage efficiency for weak coherent pulses.

Stored 20 temporal modes with 51.3% average efficiency.

Enabled spectrally tunable storage via variable strain.

Abstract

Scalable implementation of quantum networks and photonic processors require integrated photonic memories with high efficiency, yet current integrated systems have been limited to storage efficiencies below 27.8%. Here, we demonstrate highly efficient integrated quantum memories based on rare-earth-iondoped crystals coupled with impedance-matched microcavities, realized in two novel architectures: 200-micrometer-thin membranes of Eu3+:Y2SiO5 integrated with fiber-based microcavities, and waveguide-based cavities fabricated using femtosecond lasers. Our approach achieves reliable integrated quantum storage with record efficiencies of 80.3(7)% for weak coherent pulses and 69.8(1.6)% for telecom-heralded single photons, alongside the storage of 20 temporal modes with an average efficiency of 51.3(2)%. Moreover, the thin-membrane Eu3+:Y2SiO5 architecture enables spectrally tunable efficient quantum storage via variable strain, providing a flexible interface for quantum networks. By combining high efficiency, large multimode capacity, and tunability, our devices establish a versatile hardware foundation for scalable quantum repeaters and chip-scale photonic processors.