Solid-state photon storage

Richard J. Fitzgerald

Mustafa Gündoğan, Patrick M. Ledingham, Attaallah Almasi +2 more

We report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science.

Mehmet Fatih Yanik, Shanhui Fan

M. Nilsson, Lars Rippe, Stefan Kröll

A scheme for highly efficient storage and recall of single- and few-photon wave-packets in solid state materials (here inorganic crystals doped with rare-earth ions) is presented. The scheme is supported by experimental data showing that single-photon absorption effects can be observed in these materials and also how the materials can be tailored for the quantum state storage and reconstruction operation using suitably selected excitation pulses.

Igor Aharonovich, Dirk Englund, Milos Toth

Yisheng Lei, Haechan An, Zongfeng Li +1 more

Quantum memory devices with high storage efficiency and bandwidth are essential elements for future quantum networks. Solid-state quantum memories can provide broadband storage, but they primarily suffer from low storage efficiency. We use passive optimization and machine learning techniques to demonstrate nearly a 6-fold enhancement in quantum memory efficiency. In this regime, we demonstrate coherent and single-photon-level storage with a high signal-to-noise ratio. The optimization technique presented here can be applied to most solid-state quantum memories to significantly improve the storage efficiency without compromising the memory bandwidth.