Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: Poster: Quantum Dots and Optics
HL 63.68: Poster
Mittwoch, 22. März 2017, 15:00–19:00, P1A
Microsecond two-electron spin relaxation 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 — 2Chair for Applied Solid State Physics, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
Self-assembled quantum dots (QDs) are promising candidates for quantum computation devices that require a two level system. One possibility is the two-electron excited spin triplet and its singlet ground state. The self-assembled 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 temporal decay of the triplet states by time-resolved transconductance spectroscopy [1]. This allows us to determine - by electrical means - the spin relaxation time after the injection of the second electron into the p- or d-shell. We find spin relaxation times of 25 µs (p-shell) and 23 µs (d-shell), orders of magnitude longer compared to optical experiments where an additional hole is present [2]. Future measurements in presence of a magnetic field are expected to demonstrate even longer spin-relaxation times in such an electrical device. [1] B. Marquardt. et al., Nature Commun. 2, 209 (2011) [2] F. Sotier et al., Nature Physics 5, 352 - 356 (2009)