Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 16: Electron spin qubits in semiconductor quantum dots (Focus session with TT)
HL 16.10: Vortrag
Montag, 31. März 2014, 18:15–18:30, POT 051
Spin-orbit effects on nuclear state preparation at the S−T+ anti-crossing in double quantum dots — •Marko J. Rančić and Guido Burkard — University of Konstanz
We explore the interplay of spin-orbit and hyperfine effects on the nuclear preparation schemes in two-electron double quantum dots, e.g. in GaAs. The quantity of utmost interest is the electron spin decoherence time T2* in dependence of the number of sweeps through the electron spin singlet S triplet T+ anti-crossing. Decoherence of the electron spin is caused by the difference field induced by the nuclear spins. We study the case where a singlet S(2,0) is initialized, in which both electrons are in the left dot. Subsequently, the system is driven repeatedly through the anti-crossing and back using linear electrical bias sweeps. Our model describes the passage through the anti-crossing with a large number of equally spaced, step-like parameter increments. We develop a numerical method describing the nuclear spins fully quantum mechanically, which allows us to track their dynamics. Both Rashba and Dresselhaus spin-orbit terms do depend on the angle θ between the [110] crystallographic and the inter-dot axis. Our results show that the suppression of decoherence (and therefore the enhancement of T2*) is inversely proportional to the strength of the spin-orbit interaction, which is tuned by varying the angle θ.