论文标题
忠实的固态自旋波量子记忆，用于极化量子位
A faithful solid-state spin-wave quantum memory for polarization qubits
论文作者
论文摘要
由于在单个空间和时间模式下易于运输，准确的量子操作以及对反谐波的高鲁棒性，因此偏振化编码的量子位在量子信息任务中特别有用。极化量子位的可靠存储对于建造大型量子网络至关重要。在这里，我们使用在稀土离子掺杂晶体中实现的无嘈杂的光子回声协议（151EU3+：Y2SIO5）实现了光子极化量子的忠实量子记忆。基于对Y2SIO5晶体位点2的151EU3+离子的详细光谱研究，使用单个晶体实现了量子记忆，该晶体为两个正交极化状态提供了近乎均匀的吸收。获得了0.919（24）的过程保真度，以存放单光子级相干脉冲携带的Qubits，这超出了使用经典的测量和培训策略可以实现的最大忠诚度。这种紧凑的设备应为构建长寿命可运输的量子存储器和基于内存的量子网络提供有用的解决方案。
Polarization-encoded qubits are particularly useful in quantum information tasks due to the easy transportation in a single spatial and temporal mode, the accurate qubit manipulation and the high robustness against decoherence. Reliable storage of polarization-encoded qubits is essential for the construction of large-scale quantum networks. Here we demonstrate a faithful quantum memory for photonic polarization qubits using the noiseless photon echo protocol implemented in a rare-earth-ion doped crystal (151Eu3+:Y2SiO5). Based on a detailed spectroscopic investigation on the 151Eu3+ ions at the site 2 of Y2SiO5 crystals, the qubit memory is implemented using a single piece of crystal which provides a near-uniform absorption for two orthogonal polarization states. A process fidelity of 0.919(24) is obtained for the storage of qubits carried by single-photon-level coherent pulses, which is beyond the maximal fidelity that can be achieved using the classical measure-and-prepare strategy. This compact device shall provide a useful solution for the construction of a long-lived transportable quantum memory and the memory-based quantum networks.
