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arXiv · 1301.7461

Quantum interference and phonon-mediated back-action in lateral quantum dot circuits

G. Granger·D. Taubert·C. E. Young·L. Gaudreau·A. Kam·S. A. Studenikin·P. Zawadzki·D. Harbusch·D. Schuh·W. Wegscheider·Z. R. Wasilewski·A. A. Clerk·S. Ludwig·A. S. Sachrajda
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Abstract

Spin qubits have been successfully realized in electrostatically defined, lateral few-electron quantum dot circuits. Qubit readout typically involves spin to charge information conversion, followed by a charge measurement made using a nearby biased quantum point contact. It is critical to understand the back-action disturbances resulting from such a measurement approach. Previous studies have indicated that quantum point contact detectors emit phonons which are then absorbed by nearby qubits. 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 quantum point contact 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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G. Granger, D. Taubert, C. E. Young, L. Gaudreau, A. Kam, S. A. Studenikin, P. Zawadzki, D. Harbusch, D. Schuh, W. Wegscheider, Z. R. Wasilewski, A. A. Clerk, S. Ludwig, A. S. Sachrajda. 2013-01-30. Quantum interference and phonon-mediated back-action in lateral quantum dot circuits. https://doi.org/10.1038/nphys2326

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