Quantum interference and phonon-mediated back-action in lateral quantum-dot circuits
Quantum interference and phonon-mediated back-action in lateral quantum-dot circuits
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DOI：
10.1038/nphys2326
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发表时间：
2012-07-01
期刊：
影响因子：
19.6
通讯作者：
Sachrajda, A. S.
中科院分区：
文献类型：
--
作者：
Granger, G.;Taubert, D.;Sachrajda, A. S.
自旋量子比特已成功地在静电定义的横向少电子量子点电路(1-4)中实现。量子比特读出通常涉及自旋到电荷信息的转换，随后使用附近的偏置量子点接触(1，5，6)(QPC)进行电荷测量。理解这种测量方法产生的反作用干扰是至关重要的(7，8)。以前的研究表明，QPC探测器发射声子，然后被附近的量子比特吸收(9-13)。我们在这里报道了在多点电路中观察到的显著的反作用效应，其中探测器产生的声子的吸收被量子干涉效应强烈地修正，并表明这一现象可以用结合了QPC和相干声子吸收的理论来很好地描述。我们的实验和理论相结合的结果提出了在量子比特读出过程中抑制反作用的策略。
Spin qubits have been successfully realized in electrostatically defined, lateral few-electron quantum-dot circuits(1-4). Qubit readout typically involves spin to charge information conversion, followed by a charge measurement made using a nearby biased quantum point contact(1,5,6) (QPC). It is critical to understand the back-action disturbances resulting from such a measurement approach(7,8). Previous studies have indicated that QPC detectors emit phonons which are then absorbed by nearby qubits(9-13). We report here the observation of a pronounced back-action effect in multiple dot circuits, where the absorption of detector-generated phonons is strongly modified by a quantum interference effect, and show that the phenomenon is well described by a theory incorporating both the QPC and coherent phonon absorption. Our combined experimental and theoretical results suggest strategies to suppress back-action during the qubit readout procedure.