Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 33: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 2
TT 33.12: Vortrag
Donnerstag, 25. März 2010, 17:00–17:15, H19
Anisotropic exchange coupling in double quantum dots — •Fabio Baruffa1, Peter Stano2, and Jaroslav Fabian1 — 1Institute of Theoretical Physics, University of Regensburg, Germany — 2Institute of Physics, Slovak Academy of Science, Bratislava, Slovak Republic
The electron spins in quantum dots are one of the candidates as a qubit for quantum computation [1]. In coupled quantum dots, the two-qubit quantum gate is realized by manipulating the exchange coupling which is due to the Coulomb interaction and the Pauli principle. The presence of the spin-orbit couplings change the magnitude of the exchange and lead to new term due to the lack of the spin-rotational symmetry, the anisotropic exchange [2]. We propose an accurate effective spin Hamiltonian for modeling spin-orbit-induced spin dynamics in the presence of the magnetic field [3]. We have also performed numerically exact calculations of the isotropic and anisotropic exchange coupling in realistic two-electron GaAs coupled quantum dots in the presence of both Dresselhaus and Bychkov-Rashba spin-orbit interactions [4]. The numerics allow us to establish the goodness of our model and to see the limits of previous statements. Furthermore we find that in zero magnetic field the second-order spin-orbit effects are absent at all interdot couplings. This work was supported by the DFG GRK 638.
[1] D. Loss and D. P. DiVincenzo, Phys. Rev. A 57, 120 (1998)
[2] K. V. Kavokin, Phys. Rev. B 64, 075305 (2001)
[3] F. Baruffa, P. Stano and J. Fabian, cond-mat/0908.2961
[4] J. Fabian et al., Acta Phys. Slov. 57, 565 (2007)