Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 61: Quantum Dots and Wires: Transport Properties
HL 61.1: Vortrag
Mittwoch, 9. März 2016, 14:45–15:00, H16
Spin-triplet relaxation times of different shells in self-assembled quantum dots — •Kevin Eltrudis1, Amran Al-Ashouri1, Andreas Beckel1, Arne Ludwig2, Andreas D. Wieck2, Axel Lorke1, and Martin Geller1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany — 2Chair for Applied Solid State Physics, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
Self-assembled quantum dots (QDs) are among the promising candidates for quantum computation devices, which involve a two level quantum system. A possibility is the two-electron excited spin triplet and its singlet ground state. We demonstrate an all-electrical initialization of the spin triplet state and measure - by electrical means - the spin relaxation time in absence of a magnetic field after the injection of the second electron into the p- and the d-shell. We find a similar spin relaxation time of 25 µs (p-shell) and 23 µs (d-shell). The measurement technique we use is based on the time-resolved transconductance spectroscopy [1]. The InAs QDs are embedded in a GaAs/AlGaAs heterostructure (FET), where an electron reservoir (2DEG) coupled to the QDs serves as charge reservoir as well as sensitive detector for the electron states. By charging the QDs resonantly into the triplet states and observing the electron emission during discharge, we are able to record the relaxation of the triplet states. In future measurements in the presence of a magnetic field even longer spin-relaxation times are expected. [1] B. Marquardt. et al., Nature Commun. 2, 209 (2011)