Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 30: Quantum dots and wires: Transport properties II

HL 30.11: Vortrag

Dienstag, 26. Februar 2008, 17:00–17:15, ER 164

Noise measurements of a quantized charge pump — •Frank Hohls¹, Niels Maire¹, Bernd Kaestner², Hans Werner Schumacher², and Rolf J. Haug¹ — ¹Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, 30167 — ²Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig

Delivering a quantized number of electrons per cycle reliable and with very high repetition would allow to define a quantum standard for the ampere. Recently a new promising way was demonstrated to achieve quantized charge pumping of a current I=Nef_p at very high pumping frequencies f_p [1].

We performed low frequency (f<20 kHz) current noise measurements of such a pump. We observe a strong suppression of the noise power S_I when the pumped current is quantized. This agrees well with the prediction for an ideal pump: S_I is expected to vanish if exactly N electrons are transferred in each cycle of the driving frequency. Furthermore we study also the current dependence of the noise power in between quantized current plateaus and find good agreement with a theoretical model.

[1] Blumenthal et al., Nat. Phys. 3, 343 (2007); Kaestner et al., cond-mat-0707.0993.