Ma You-Zhi, Jin Ming, Chen Duo-Lun, Zhou Zong-Quan, Li Chuan-Feng, Guo Guang-Can
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, China.
CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China.
Nat Commun. 2021 Jul 19;12(1):4378. doi: 10.1038/s41467-021-24679-4.
Photon echo is a fundamental tool for the manipulation of electromagnetic fields. Unavoidable spontaneous emission noise is generated in this process due to the strong rephasing pulse, which limits the achievable signal-to-noise ratio and represents a fundamental obstacle towards their applications in the quantum regime. Here we propose a noiseless photon-echo protocol based on a four-level atomic system. We implement this protocol in a Eu:YSiO crystal to serve as an optical quantum memory. A storage fidelity of 0.952 ± 0.018 is obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity achievable using the classical measure-and-prepare strategy. In this work, the demonstrated noiseless photon-echo quantum memory features spin-wave storage, easy operation and high storage fidelity, which should be easily extended to other physical systems.
光子回波是操纵电磁场的一种基本工具。由于强重相位脉冲，在此过程中会不可避免地产生自发辐射噪声，这限制了可实现的信噪比，并成为其在量子领域应用的一个基本障碍。在此，我们提出一种基于四能级原子系统的无噪声光子回波协议。我们在铕掺杂钇硅氧晶体（Eu:YSiO）中实现此协议，将其用作光量子存储器。对于用单光子级相干脉冲编码的时间槽量子比特，获得了0.952±0.018的存储保真度，这远远超过了使用经典测量与制备策略可实现的最大保真度。在这项工作中，所展示的无噪声光子回波量子存储器具有自旋波存储、操作简便和存储保真度高的特点，应能轻松扩展到其他物理系统。
