Burchesky Sean, Anderegg Loïc, Bao Yicheng, Yu Scarlett S, Chae Eunmi, Ketterle Wolfgang, Ni Kang-Kuen, Doyle John M
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2021 Sep 17;127(12):123202. doi: 10.1103/PhysRevLett.127.123202.
Qubit coherence times are critical to the performance of any robust quantum computing platform. For quantum information processing using arrays of polar molecules, a key performance parameter is the molecular rotational coherence time. We report a 93(7) ms coherence time for rotational state qubits of laser cooled CaF molecules in optical tweezer traps, over an order of magnitude longer than previous systems. Inhomogeneous broadening due to the differential polarizability between the qubit states is suppressed by tuning the tweezer polarization and applied magnetic field to a "magic" angle. The coherence time is limited by the residual differential polarizability, implying improvement with further cooling. A single spin-echo pulse is able to extend the coherence time to nearly half a second. The measured coherence times demonstrate the potential of polar molecules as high fidelity qubits.
量子比特相干时间对于任何稳健的量子计算平台的性能都至关重要。对于使用极性分子阵列进行的量子信息处理，一个关键性能参数是分子旋转相干时间。我们报告了在光镊阱中激光冷却的CaF分子的旋转态量子比特的相干时间为93(7)毫秒，比之前的系统长一个数量级以上。通过将光镊偏振和外加磁场调整到“魔角”，可以抑制量子比特态之间由于差分极化率引起的非均匀展宽。相干时间受残余差分极化率的限制，这意味着进一步冷却会有所改善。单个自旋回波脉冲能够将相干时间延长至近半秒。所测量的相干时间证明了极性分子作为高保真量子比特的潜力。
