Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 60: Quantum dots: Transport

HL 60.4: Talk

Wednesday, March 18, 2015, 18:00–18:15, EW 203

Stochastic resonance in electron counting — •Timo Wagner, Johannes Bayer, Eddy P. Rugeramigabo, and Rolf J. Haug — Institut für Festkörperphysik - Abteilung Nanostrukturen, Leibniz Universität Hannover, 30167 Hannover, Germany

We performed electron counting experiments on a double quantum dot (QD) as well as on a more advanced serial triple quantum dot structure. For both systems an adjacent quantum point contact (QPC) serves as sensitive charge detector to resolve time dependent single electron tunneling events. From the recorded time trace we extracted the waiting times for tunneling into and out of a quantum dot.

The two waiting time distributions reveal phase correlated oscillations. We identify those characteristic oscillations as stochastic resonance due to the superposition of a small harmonic signal and the bistable stochastic quantum dot signal. Further we studied and simulated the dependency of different system parameters on the resonance.

The quantum dots structures were defined by metallic topgates on a two dimensional electron gas on GaAs/AlGas. The measurements on the double quantum dot were performed in a He3 system at temperatures around 300mK and for the triple dot measurements we used a dilution refrigerator with base temperature around 20mK. Time resolved charge was archieved with a low noise DC setup.