Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session: Quantum Dots and Wires - Transport & Optical Properties

HL 44.1: Poster

Tuesday, March 27, 2012, 09:30–12:30, Poster D

Two-path Transport Measurements 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] Technical and scientific improvement allow the fabrication of triple quantum dots and their analysis.[2] Research on them is motivated by fundamental physics and by the fact that they can work as a single qubit.[3] It also is the smallest system with quantum dots being part of a qubit chain needed for quantum computers. Our sample design allows to simultaneously measure the conductance along two different paths with two quantum dots in each path. The structure is made with local anodic oxidation by AFM on a GaAs/AlGaAs heterostructure. By controlling the potentials via the four gates triple points with two dots and quadruple points with all three dots in resonance can be established.[4,5] Using two of the leads as source contacts and one lead as a drain contact, signatures of three dots can be detected in both transport paths. The setup provides the possibility of applying different bias voltages to the two sources and detecting excited states of the dots.

[1] M. C. Rogge, R. J. Haug, Phys. Rev. B 77, 193306 (2008). [2] D. Schröer, et al., Phys. Rev. B 76, 075306 (2007). [3] P. Hawrylak, M. Korkusinski, Solid State Comm. 136 (2005), pp. 508-512. [4] L. Gaudreau, et al., PRL 97, 036807 (2008). [5] M. C. Rogge, R. J. Haug, NJP 11, 113037 (2009).