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

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.

25 pages, 8 figures

References in corpus (6)

• An electrostatically defined serial triple quantum dot charged with few electrons
• A double-dot quantum ratchet driven by an independently biased quantum point contact
• Two path transport measurements on a triple quantum dot
• The 3D transport diagram of a triple quantum dot
• Telegraph Noise in Coupled Quantum Dot Circuits Induced by a Quantum Point Contact
• Statistical electron excitation in a double quantum dot induced by two independent quantum point contacts

Cited by in corpus (2)

• Coherent quantum ratchets driven by tunnel oscillations: Fluctuations and correlations
• Ultra-narrow ionization resonances in a quantum dot under broadband excitation