Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 63: Poster: Quantum Dots and Optics

HL 63.60: Poster

Wednesday, March 22, 2017, 15:00–19:00, P1A

Energy scales in quantum dots for single electron pumps — •Tobias Wenz¹, Friederike Stein¹, Frank Hohls¹, Hans Werner Schumacher¹, and Vyacheslavs Kashcheyevs² — ¹Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany — ²Faculty of Physics and Mathematics, University of Latvia, LV 1002 Riga, Latvia

Quantum dots with tunable barriers can be used as single electron pumps. By capturing a well-defined number of electrons n from source and emitting them to drain with a high frequency f a quantized current I=nef is produced, where e is the electron charge [1]. This concept is useful for on-demand electron sources for electron quantum optics and for the redefinition of the ampere by fixing the value of e. Several theoretical models, like the decay cascade model [2], describe the performance of tunable-barrier pumps in different regimes of operation. While they yield good fits, the respective energy scales cannot be easily obtained. This work aims at putting a number to these energy scales. One approach is to investigate the performance of single electron pumps at different temperatures and observe the broadening of transition lines in different pumping regimes. Another method is to use custom-tailored waveforms to extract tunneling rates during the loading phase of the quantum dot. Furthermore, this method can be used to study excited states in the quantum dot and reveal two-electron effects.
B. Kaestner & V. Kashcheyevs, Rep. Prog. Phys. 78, 103901 (2015)
V. Kashcheyevs & B. Kaestner, Phys. Rev. Lett. 104, 186805 (2010)