Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 7: Single Photon Sources and Qbits

HL 7.1: Talk

Monday, March 14, 2011, 11:00–11:15, FOE Anorg

Hyperfine interaction in electron spin qubits in quantum dots coupled via an optical cavity — •Julia Hildmann and Guido Burkard — Fachbereich Physik, Universitaet Konstanz, D-78457 Konstanz, Deutschland

Electron spin states in semiconductor structures represent good candidates for implementing quantum bits (qubits) [1]. Logical gates between distant qubits can be realized using a high finesse cavity and an adjustable laser field [2]. Virtual Raman transitions between an electron in the conduction band and a heavy hole in the valence band provide a controllable mechanism for single and two qubit operations. However there are several processes in semiconductor quantum dots leading to decoherence. In the time scale for the optical control of the qubit states the main source of the decoherence is due to Fermi contact hyperfine interaction with the surrounding nuclear spins (e.g. Overhauser shift of the Zeeman frequency) [3]. Here we calculate the fidelities of the two qubit operations in the presence of the nuclear spins. [1] D. Loss and D. P. DiVincenzo, Phys Rev. A 57, 120 (1998). [2] A. Imamoglu et al, Phys. Rev. Lett. 83, 4204 (1999). [3] W. A. Coish and J. Baugh, Phys. Stat. Solidi (b) 149, 1443 (2009).