Erickson Stephen D, Wu Jenny J, Hou Pan-Yu, Cole Daniel C, Geller Shawn, Kwiatkowski Alex, Glancy Scott, Knill Emanuel, Slichter Daniel H, Wilson Andrew C, Leibfried Dietrich
National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2022 Apr 22;128(16):160503. doi: 10.1103/PhysRevLett.128.160503.
We propose and demonstrate a protocol for high-fidelity indirect readout of trapped ion hyperfine qubits, where the state of a ^{9}Be^{+} qubit ion is mapped to a ^{25}Mg^{+} readout ion using laser-driven Raman transitions. By partitioning the ^{9}Be^{+} ground-state hyperfine manifold into two subspaces representing the two qubit states and choosing appropriate laser parameters, the protocol can be made robust to spontaneous photon scattering errors on the Raman transitions, enabling repetition for increased readout fidelity. We demonstrate combined readout and back-action errors for the two subspaces of 1.2_{-0.6}^{+1.1}×10^{-4} and 0_{-0}^{+1.9}×10^{-5} with 68% confidence while avoiding decoherence of spectator qubits due to stray resonant light that is inherent to direct fluorescence detection.
我们提出并演示了一种用于囚禁离子超精细量子比特高保真间接读出的方案，其中使用激光驱动的拉曼跃迁将(^{9}Be^{+})量子比特离子的状态映射到(^{25}Mg^{+})读出离子上。通过将(^{9}Be^{+})基态超精细流形划分为代表两个量子比特状态的两个子空间，并选择合适的激光参数，该方案可以对拉曼跃迁上的自发光子散射误差具有鲁棒性，从而能够重复操作以提高读出保真度。我们在68%的置信度下演示了两个子空间的联合读出和反作用误差，分别为(1.2_{-0.6}^{+1.1}×10^{-4})和(0_{-0}^{+1.9}×10^{-5})，同时避免了由于直接荧光检测固有的杂散共振光导致的旁观者量子比特退相干。
