Radio-Frequency-Detected Fast Charge Sensing in Undoped Silicon Quantum Dots.,Nano Letters

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Radio-Frequency-Detected Fast Charge Sensing in Undoped Silicon Quantum Dots.
Nano Letters ( IF 9.6 ) Pub Date : 2020-01-23 , DOI: 10.1021/acs.nanolett.9b03847
Akito Noiri ₁ , Kenta Takeda ₁ , Jun Yoneda ₁ , Takashi Nakajima ₁ , Tetsuo Kodera ₂ , Seigo Tarucha ₁

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Spin qubits in silicon quantum dots offer a promising platform for a quantum computer as they have a long coherence time and scalability. The charge sensing technique plays an essential role in reading out the spin qubit as well as tuning the device parameters, and therefore, its performance in terms of measurement bandwidth and sensitivity is an important factor in spin qubit experiments. Here we demonstrate fast and sensitive charge sensing by radio frequency reflectometry of an undoped, accumulation-mode Si/SiGe double quantum dot. We show that the large parasitic capacitance in typical accumulation-mode gate geometries impedes reflectometry measurements. We present a gate geometry that significantly reduces the parasitic capacitance and enables fast single-shot readout. The technique allows us to distinguish between the singly- and doubly occupied two-electron states under the Pauli spin blockade condition in an integration time of 0.8 μs, the shortest value ever reported in silicon, by the signal-to-noise ratio of 6. These results provide a guideline for designing silicon spin qubit devices suitable for the fast and high-fidelity readout.

中文翻译：

未掺杂的硅量子点中的射频检测快速电荷感测。

硅量子点中的自旋量子位具有长的相干时间和可扩展性，因此为量子计算机提供了一个有希望的平台。电荷感测技术在读取自旋量子位以及调整器件参数方面起着至关重要的作用，因此，其在测量带宽和灵敏度方面的性能是自旋量子位实验的重要因素。在这里，我们演示了通过射频反射法对未掺杂的累积模式Si / SiGe双量子点进行快速灵敏的电荷感测。我们表明，典型的累积模式栅极几何形状中的大寄生电容会阻碍反射测量。我们提出了一种栅极几何形状，该几何形状可大大降低寄生电容并实现快速单次读出。

更新日期：2020-01-24

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