A long-lived multi-mode qubit register is an enabling technology for modular quantum computing architectures. For interfacing with superconducting qubits, such a quantum memory should be able to store incoming quantum microwave fields at the single-photon level for long periods of time, and retrieve them on-demand. Here, we demonstrate the partial absorption of a train of weak microwave fields in an ensemble of bismuth donor spins in silicon, their storage for 100 ms, and their retrieval, using a Hahn-echo-like protocol. The long storage time is obtained by biasing the bismuth donors at a clock transition. Phase coherence and quantum statistics are preserved in the storage.
@article{arxiv.2005.09275,
title = {Multimode storage of quantum microwave fields in electron spins over 100 ms},
author = {V. Ranjan and J. O'Sullivan and E. Albertinale and B. Albanese and T. Chanelière and T. Schenkel and D. Vion and D. Esteve and E. Flurin and J. J. L. Morton and P. Bertet},
journal= {arXiv preprint arXiv:2005.09275},
year = {2020}
}