Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 43: Invited Talk: Stefan Ludwig
HL 43.1: Hauptvortrag
Dienstag, 12. März 2013, 15:00–15:30, H2
Single phonon quantum interference and back-action in quantum-dot electrical circuits — Ghislain Granger1, Daniela Taubert2, Carolyn Young3, L. Gaudreau1, A. Kam1, S. Studenikin1, D. Harbusch2, Dieter Schuh4, Werner Wegscheider4,5, Zbigniew Wasilew2, Aashish Clerk3, Andrew Sachrajda1, and •Stefan Ludwig2 — 1NRC Canada — 2Uni München — 3McGill, Canada — 4Uni Regensburg — 5ETH Zürich
Lateral few-electron quantum-dot circuits are promising candidates for metrology and quantum information applications. Qubit readout typically involves a charge measurement made probing the current through a nearby biased quantum point contact (QPC). For quantum applications it is critical to understand the back-action disturbances resulting from such a measurement approach. It is well-established that QPC detectors emit phonons which are possibly reabsorbed by nearby qubits [1]. Here, we present 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 [2]. The reported phenomenon is well described by a theory incorporating both the QPC and coherent phonon absorption in coupled dots. It also promises applications: destructive interference allows strategies to suppress back-action during the qubit readout procedure. Furthermore, our experiments reveal the usability of coupled dots as a single phonon detector and spectrometer.
[1] D. Harbusch, et al., PRL 104, 196801 (2010); [2] G. Granger, et al., Nat. Phys. 8, 522 (2012).