Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 21: Transport: Quantum Dots, Quantum Wires, Point Contacts II (TT jointly with O)
O 21.1: Vortrag
Montag, 31. März 2014, 16:00–16:15, HSZ 204
A two-atom electron pump — Benoit Roche1, Roman-Pascal Riwar1, Benoit Voisin1, Eva Dupont-Ferrier1, Romain Waquez3, Maud Vinet3, Marc Sanquer1, •Janine Splettstoesser2, and Xavier Jehl1 — 1SPSMS, UMR-E, CEA Grenoble, INAC, Grenoble, France — 2MC2, Chalmers University of Technology, Göteborg, Sweden — 3CEA, LETI, MINATEC, Grenoble, France
In recent years there has been a lot of interest in time-dependently driven quantum systems, such as quantum-dot pumps, both in the adiabatic regime of slow driving as well as in the high-frequency regime. However, all experiments so far were carried out in either one of these regimes, but were not subsequently tuned to both.
I will present an experimental realization [1] of electron pumping through two phosphorus donors in series implanted in a silicon nanowire. While quantized pumping is achieved in the low-frequency adiabatic regime, remarkable features are observed at higher frequency, when the charge transfer is limited either by the tunnelling rates to the electrodes or between the two donors. We model the transitions between quantum states involving a Landau-Zener transition, allowing to reproduce in detail the characteristic signatures observed in the non-adiabatic regime. Interestingly, the breakdown of the adiabatic limit can thus accurately be associated to the relation of the respective time-scales of tunneling to the electrodes or between the donors, compared to the time-scales of the driving. Consequently, information on the time-scales can be extracted from a detailed inspection of the pumping signal.
B. Roche, et al., Nat. Commun. 4, 1581 (2013)