An important field of work of our group is the controlled pumping of single electron in semiconductor nanostructures. Semiconductor single electron pumps in principle allow higher pumping frequencies and thus higher output currents than standard metallic SET pumps. By pumping in the GHz frequency regime output currents up to several nA can be realized which is crucial for most applications like the direct closure of the metrological triangle or clocked single photon sources.
We concentrate on a novel pumping mechanism in semiconductor nanostructures using strongly modulated electrostatic barriers [1]. The present work focuses on pumping by modulation of a single parameter [2] and on parallelization of single charge pump to further increase the current output [3]. Details of the transport mechanism can be found in in Ref. [4].
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| Schematic illustration of pumping of a single electron by modulating a single gate parameter (VAC). | Single electron pump based on GaAs/AlGaAs heterostruktur. The direction of the pumped current can be determiend by choosing the left or right outer gate (colored in violet). The middle gate (colored in yellow) coltrolles the number of pumped electrons per cycle. |
[1] M. D. Blumenthal, B Kaestner, et al. Nature Physics (2007).
[2] B. Kaestner, V. Kashcheyevs, S. Amakawa, M.D. Blumenthal, L. Li, T.J.B.M. Janssen, G. Hein, K. Pierz, T. Weimann, U. Siegner, H.W. Schumacher, Non-adiabatic single-parameter quantized charge pumping, Phys. Rev. B 77, 153301 (2008).
[3] P. Mirovsky, B. Kaestner, C. Leicht, A. C. Welker, T. Weimann, K. Pierz, and H. W. Schumacher, to be published in Appl. Phys. Lett. (arXiv:1011.2705v1 [cond-mat.mes-hall]).
[4] V. Kashcheyevs and B. Kaestner, Universal decay cascade model for dynamical quantum dot initialization, Phys. Rev. Lett. 104, 186805 (2010).