Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 72: Quantum dots: Transport properties

HL 72.4: Vortrag

Mittwoch, 2. April 2014, 15:45–16:00, POT 251

Two-path Transport Measurements with Bias Dependence on a Triple Quantum Dot — •Monika Kotzian, Maximilian C. Rogge, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany

We present transport measurements on a lateral triple quantum dot with a star-like geometry and one lead attached to each dot. [1] The research on triple quantum dots is motivated by fundamental physics and by the fact that it can work as a single qubit. [2] The structure is made with local anodic oxidation by AFM on a GaAs/AlGaAs heterostructure, the design allowing to simultaneously measure the conductance along two different paths with two quantum dots in each path. Two of the leads are used as source contacts and one lead as a drain contact. Thus the setup provides the possibility of applying two different bias voltages to the system to study the interaction between the paths. By controlling the potentials via the four gates of the device resonances of two and all three dots can be generated. [3,4] Signatures of three dots can be detected in both transport paths. In the region of the triple dot resonance we observe a sharp suppression of the dc current depending on bias voltage, which we attribute to current blocking due to the presence of an interference phenomenon - a dark state.

[1] M. C. Rogge, R. J. Haug, Phys. Rev. B 77, 193306 (2008). [2] P. Hawrylak, M. Korkusinski, Solid State Comm. 136 (2005), pp. 508-512. [3] L. Gaudreau, et al., PRL 97, 036807 (2006). [4] M. C. Rogge, R. J. Haug, New Journal of Physics 11, 113037 (2009).