Berlin 2012 – wissenschaftliches Programm

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SYSD: Symposium SKM Dissertationspreis

SYSD 1: SKM Dissertation Prize

SYSD 1.4: Hauptvortrag

Montag, 26. März 2012, 13:00–13:20, EW 201

All-electrical preparation and detection of excited many-particle states in self-assembled quantum dots — •Bastian Marquardt — Faculty of Physics and CeNIDE, University of Duisburg-Essen, Germany — Cavendish Laboratory, University of Cambridge, United Kingdom

Self-assembled quantum dots (QDs) with their strong confinement are promising candidates for qubit operations above liquid helium temperatures. The ambitious realization of qubits by using artificial atoms requires the preparation and control of excited charge or spin states. Here, I introduce an all-electrical preparation and read-out scheme for (excited) charge/spin states in self-assembled InAs QDs at 4 K [1]. A two-dimensional electron gas placed nearby to the dots acts as a non-invasive charge detector [2,3]. Using a novel time-resolved transport spectroscopy allows us to generate and to detect excited many-particle states with a defined number of charge carriers. The excitation spectra of the first three "QD elements" with their non-equilibrium charge/spin configurations are resolved, i. e. the spectrum of single-charged (QD-Hydrogen), double-charged (QD-Helium) and triple-charged QDs (QD-Lithium). Comparison with many-particle calculations make it possible to identify the different configurations and in particular to verify the detection of the first excited triplet state in QD-Helium, which could serve as a spin qubit at B=0.

[1] Marquardt et al., Nature Commun. 2, 209 (2011); [2] Marquardt et al., Appl. Phys. Lett 95, 022113 (2009); [3] Marquardt et al., Appl. Phys. Lett 99, 223510 (2011)