On-demand storing time-bin qubit states with optical quantum memory

TL;DR

This paper demonstrates a low-cost optical quantum memory with high efficiency and fidelity using a butterfly-shaped cavity, suitable for quantum communication networks.

Contribution

The authors experimentally realize a simple, cost-effective optical quantum memory with high storage efficiency and fidelity, advancing practical quantum communication.

Findings

Storage efficiency per round up to 95.0%

Overall state fidelity exceeds 99.1%

Potential for practical quantum communication applications

Abstract

Quantum memory, serving as a crucial device for storing and releasing quantum states, holds significant importance in long-distance quantum communications. Up to date, quantum memories have been realized in many different systems. However, most of them have complex structures and high costs. Besides, it is not easy to simultaneously achieve both high storage efficiency and fidelity. In this paper, we experimentally demonstrate a low-cost optical quantum memory with high efficiency and high fidelity, by utilizing a butterfly shaped cavity consisting of one polarization beam splitter, two reflecting mirrors and one pockels cell crystal. In order to quantify the quality of the quantum memory, we carry out tomography measurements on the time-bin qubits encoded with weak coherent states after storage for N rounds. The storage efficiency per round can reach up to 95.0\%, and the overall state fidelity can exceed 99.1\%. It thus seems very promising for practical implementation in quantum communication and networks.