Dresden 2003 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Halbleiterphysik
HL 37: Hauptvortrag Beham
HL 37.1: Hauptvortrag
Donnerstag, 27. März 2003, 10:15–11:00, POT/81
Single quantum dot photodiode - a two-level system with electric contacts — •Evelin Beham1, Artur Zrenner2, Stefan Stufler2, Frank Findeis1, Max Bichler1, and Gerhard Abstreiter1 — 1Walter Schottky Institut, Technische Universität München, Am Coulombwall, 85748 Garching, Germany — 2Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany
Semiconductor quantum dots (QDs) can be described as quantum mechanical two-level systems. Under strong electromagnetic driving and in absence of decoherence, such systems exhibit Rabi flopping corresponding to a qubit rotation in the context of quantum computing.
Based on a single QD incorporated in a photodiode we have prepared a two-level system with electric contacts. By means of this single QD photodiode we demonstrate the transfer of coherent optical excitations into a deterministic photocurrent [1]. Coherent photocurrent spectroscopy on a single QD was performed by resonant ps-excitation. With increasing excitation power we observe an oscillating photocurrent due to coherent excitation of the QD-exciton. The QD photocurrent directly reflects Rabi flopping of the exciton state. Under π-pulse-excitation the exciton occupation is inverted from 0 to 1 leading ideally to the creation of exactly one exciton per laser pulse. For this condition, the photocurrent I is determined by the repetition rate of the experiment f and the elementary charge e, resulting quantitatively in I = f · e .
[1] A. Zrenner, E. Beham, S. Stufler, F. Findeis, M. Bichler, G. Abstreiter, Nature 418, 612 (2002)