# Optical spin-wave storage in a solid-state hybridized electron-nuclear spin ensemble

## TL;DR

This paper demonstrates optical storage in a rare-earth ion system using hybridized electron-nuclear spins, achieving a balance of long storage time and high bandwidth, advancing quantum memory technology.

## Contribution

First demonstration of optical storage using spin states in a rare-earth ion with electronic spin, combining long storage time and high bandwidth.

## Key findings

- Storage time of 1.2 ms achieved
- Optical bandwidth of 10 MHz demonstrated
- Memory efficiency around 3%

## Abstract

Solid-state impurity spins with optical control are currently investigated for quantum networks and repeaters. Among these, rare-earth-ion doped crystals are promising as quantum memories for light, with potentially long storage time, high multimode capacity, and high bandwidth. However, with spins there is often a tradeoff between bandwidth, which favors electronic spin, and memory time, which favors nuclear spins. Here, we present optical storage experiments using highly hybridized electron-nuclear hyperfine states in $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$, where the hybridization can potentially offer both long storage time and high bandwidth. We reach a storage time of 1.2 ms and an optical storage bandwidth of 10 MHz that is currently only limited by the Rabi frequency of the optical control pulses. The memory efficiency in this proof-of-principle demonstration was about 3%. The experiment constitutes the first optical storage using spin states in any rare-earth ion with electronic spin. These results pave the way for rare-earth based quantum memories with high bandwidth, long storage time and high multimode capacity, a key resource for quantum repeaters.