Sensitive Radio-Frequency Measurements of a Quantum Dot by Tuning to Perfect Impedance Matching
Sensitive Radio-Frequency Measurements of a Quantum Dot by Tuning to Perfect Impedance Matching
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DOI：
10.1103/physrevapplied.5.034011
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发表时间：
2016-03-24
影响因子：
4.6
通讯作者：
Laird, E. A.
中科院分区：
文献类型：
--
作者：
Ares, N.;Schupp, F. J.;Laird, E. A.
自旋量子位的电读出需要快速和灵敏的测量，这受到与设备的阻抗匹配不良的阻碍。我们展示了完美的阻抗匹配的射频读出电路，使用电压可调变容二极管，以消除寄生电容。在170 μ V均方根的最大源漏偏置和18 MHz的带宽下，实现了1.6 aF/根Hz的优化电容灵敏度。在量子点的库仑阻塞测量电导和电容，这两个贡献被发现是成比例的预期从准静态隧穿模型。我们将我们的结果与使用量子电容的单次量子位读出的要求进行基准测试，这是一个迄今为止难以捉摸的目标。
Electrical readout of spin qubits requires fast and sensitive measurements, which are hindered by poor impedance matching to the device. We demonstrate perfect impedance matching in a radio-frequency readout circuit, using voltage-tunable varactors to cancel out parasitic capacitances. An optimized capacitance sensitivity of 1.6 aF/root Hz is achieved at a maximum source-drain bias of 170-mu V root-mean-square and with a bandwidth of 18 MHz. Coulomb blockade in a quantum-dot is measured in both conductance and capacitance, and the two contributions are found to be proportional as expected from a quasistatic tunneling model. We benchmark our results against the requirements for single-shot qubit readout using quantum capacitance, a goal that has so far been elusive.