Real-Time Charge Initialization of Diamond Nitrogen-Vacancy Centers for Enhanced Spin Readout
Real-Time Charge Initialization of Diamond Nitrogen-Vacancy Centers for Enhanced Spin Readout
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DOI：
10.1103/physrevapplied.13.024016
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发表时间：
2020-02-07
影响因子：
4.6
通讯作者：
Bassett, Lee C.
中科院分区：
文献类型：
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作者：
Hopper, David A.;Lauigan, Joseph D.;Bassett, Lee C.
量子比特性能的一个常见障碍是不完美的状态初始化。在金刚石氮空位（N-V）中心的情况下，初始化保真度受到光泵浦期间缺陷电荷状态的波动的限制。在这里，我们使用实时控制来确定性地初始化N-V中心在室温下的电荷状态。我们证明了一个最大的电荷初始化保真度为（99.4 +/- 0.1）%，并提出了一个定量模型的初始化过程中，允许系统级优化的自旋读出的信噪比。即使当考虑到与初始化序列相关联的开销时，将电荷初始化保真度从75%的稳态值增加到接近100%允许实验中的2倍加速，同时保持相同的信噪比。结合基于自旋-电荷转换的高保真度读出，实时初始化使传统方法的速度提高了20倍，从而使我们的单N-V中心自旋的交流磁灵敏度估计为1.3 nT/Hz（1/2）。实时控制方法对于具有N-V中心的量子传感应用以及探测电荷相关物理立即有益，并且它将促进多量子比特系统的量子反馈控制协议。
A common impediment to qubit performance is imperfect state initialization. In the case of the diamond nitrogen-vacancy (N-V) center, the initialization fidelity is limited by fluctuations in the defect's charge state during optical pumping. Here we use real-time control to deterministically initialize the N-V center's charge state at room temperature. We demonstrate a maximum charge initialization fidelity of (99.4 +/- 0.1)% and present a quantitative model of the initialization process that allows system-level optimization of the spin-readout signal-to-noise ratio. Even when the overhead associated with the initialization sequence is accounted for, increasing the charge initialization fidelity from the steady-state value of 75% to nearly 100% allows a factor-of-2 speedup in experiments while maintaining the same signal-to-noise-ratio. In combination with high-fidelity readout based on spin-to-charge conversion, real-time initialization enables a factor-of-20 speedup over traditional methods, resulting in an estimated ac magnetic sensitivity of 1.3 nT/Hz(1/2) for our single-N-V-center spin. The real-time control method is immediately beneficial for quantum-sensing applications with N-V centers as well as for probing charge-dependent physics, and it will facilitate protocols for quantum feedback control over multiqubit systems.