Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: TR: Quantum Coherence and Quantum Information Systems 1

TT 18.3: Talk

Tuesday, March 23, 2010, 14:30–14:45, H21

Spin and entanglement dynamics in Double Quantum Dots due to hyperfine interaction: A homogenous coupling approach — •Bjoern Erbe and John Schliemann — Institute of Theoretical Physics, University of Regensburg

Quantum dot spin qubits are among the most promising and most intensively investigated building blocks of possible future solid state quantum computation systems [1]. One of the major limitations of the decoherence time of the confined electron spin is its interaction with surrounding nuclear spins by means of hyperfine interaction [2]. Apart from this adverse aspect, hyperfine interaction can act as a ressource of quantum information processing [3]. For the above reasons it is of key interest to understand the hyperfine induced spin dynamics.

We consider the hyperfine interaction in a double quantum dot in zero magnetic field. We give an exact solution of the model for homogenous hyperfine coupling constants and derive the dynamics therefrom. By a detailed investigation of the short time spin dynamics we calculate the decoherence time, which turns out to be in very good agreement with experimental data.

[1] D. Loss and D.P. DiVincenco, Phys. Rev. A 57, 120 (1998)

[2] J. Schliemann, A. Khaetskii, and D.Loss, J. Phys.: Condens Matter 15, R1809-R1833 (2003)

[3] see e.g.: J.M. Taylor, A. Imamoglu, and M.D. Lukin, Phys. Rev. Lett.91, 246802 (2003