Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 60: Quantum Dots: Transport

HL 60.2: Vortrag

Mittwoch, 16. März 2011, 15:15–15:30, POT 251

All-electrical measurement of the relaxation time of a two-electron spin-triplet state in InAs quantum dots — Bastian Marquardt¹, •Martin Geller¹, Andreas Beckel¹, Benjamin Baxevanis², Daniela Pfannkuche², Andreas D. Wieck³, Dirk Reuter³, and Axel Lorke¹ — ¹Faculty of Physics and CeNIDE, University of Duisburg-Essen, Germany — ²I. Institut für Theoretische Physik, University Hamburg, Hamburg, Germany — ³Chair of Applied Solid State Physics, Ruhr University, Bochum, Germany

Many-particle spin states in self-assembled quantum dots (QDs) could serve as qubits in quantum information processing devices [1]. However, in optical experiments always the excitonic states are measured, hence, electrical preparation and detection of pure excited many-particle states without electron-hole interaction are still missing. We demonstrate an all-electrical spectroscopy technique on an ensemble of InAs QDs [2]. It allows us to prepare and detect the pure many-particle electron states with their spin-singlet and -triplet configurations, using a time-resolved measurement detection scheme via a 2DEG [3]. This all-electrical measurement scheme enables us to determine the electron spin-relaxation time without an applied magnetic field and without optical excitation to 5 ms at 4 K. The spin relaxation time is independent on the applied magnetic field (up to 2 T) and slightly decreases down to 3 ms at 50 K.

[1] T. D. Ladd et al., Nature 464, 45 (2010). [2] B. Marquardt et al., submitted (2010), Preprint: arXiv: 1007.0392v1. [3] B. Marquardt et al., Appl. Phys. Lett. 95, 22113, (2009).