Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 60: Quantum dots: Transport
HL 60.3: Vortrag
Mittwoch, 18. März 2015, 17:45–18:00, EW 203
All-electrical measurement of the spin-triplet relaxation time in self-assembled quantum dots — •A. Al-Ashouri1, K. Eltrudis1, A. Beckel1, A. Ludwig2, A. D. Wieck2, A. Lorke1, and M. Geller1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany — 2Chair for Applied Solid State Physics, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany
Devices for quantum computation require coherent access to qubits, which can be realized by a two level quantum system in quantum dots (QDs). Promising candidates for a suitable system include the excited spin triplet and its singlet ground state. A long lifetime is expected for an excited spin state, however, a desirable all-electrical read-out scheme for the qubit state has yet to be realized.
Here we use time-resolved transconductance spectroscopy1 to electrically prepare and detect the triplet state in self-assembled InAs QDs and find a long spin relaxation time in the order of µ s. The investigated QDs are embedded in a GaAs\AlGaAs matrix using a heterostructure FET. They are coupled to a two dimensional electron gas (2DEG) via a tunneling barrier. The 2DEG is used as a charge reservoir as well as a sensitive detector for the electron states in the QDs. After initialization of the spin-triplet state we observe the electron emission during read-out and in this way are able to record the temporal decay of the triplet state. The long timescale for the decay promises future coherent manipulation of such a spin-qubit.
[1] A. Beckel et al., Phys. Rev. B 89, 155430 (2014).