Zusammenfassung
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). ...
Zusammenfassung
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.
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