Faithful Solid State Optical Memory with Dynamically Decoupled Spin Wave Storage

TL;DR

This paper demonstrates a long-duration optical quantum memory in a rare earth crystal by transferring optical coherence to nuclear spins and protecting it with dynamical decoupling, achieving 20 ms storage time.

Contribution

The work introduces a method combining optical-to-spin coherence transfer with dynamical decoupling to significantly extend quantum memory storage times in solid-state systems.

Findings

Achieved 20 ms storage time in a rare earth doped crystal.

Demonstrated preservation of phase coherence with high visibility.

Showed that decoupling sequences improve retrieval efficiency.

Abstract

We report an optical memory in a rare earth doped crystal with long storage times, up to 20 ms, together with an optical bandwidth of 1.5 MHz. This is obtained by transferring optical coherences to nuclear spin coherences, which were then protected against environmental noise by dynamical decoupling. With this approach, we achieved a 33 fold increase in spin wave storage time over the intrinsic spin coherence lifetime. Comparison between different decoupling sequences indicates that sequences insensitive to initial spin coherence increase retrieval efficiency. Finally, an interference experiment shows that relative phases of input pulses are preserved through the whole storage process with a visibility close to 1, demonstrating the usefulness of dynamical decoupling for extending the storage time of quantum memories.