Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 29: Transport: Quantum Coherence and Quantum Information Systems - Part 1

TT 29.8: Talk

Thursday, March 30, 2006, 11:45–12:00, HSZ 304

Spin Decay in a Quantum Dot Coupled to a Quantum Point Contact — •Massoud Borhani, Vitaly Golovach, and Daniel Loss — Department of Physics - University of Basel - Basel - Switzerland

We consider a mechanism of spin decay for an electron spin in a quantum dot due to coupling to a nearby quantum point contact (QPC) with and without an applied bias voltage. The coupling of spin to charge is induced by the spin-orbit interaction in the presence of a magnetic field. We perform a microscopic calculation of the effective Hamiltonian coupling constants to obtain the QPC-induced spin relaxation and decoherence rates in a realistic system. This rate is shown to be proportional to the shot noise of the QPC in the regime of large bias voltage and scales as No-dqa^(-6)No-dq where No-dqaNo-dq is the distance between the quantum dot and the QPC. We find that, for some specific orientations of the setup with respect to the crystallographic axes, the QPC-induced spin relaxation and decoherence rates vanish, while the charge sensitivity of the QPC is not changed. This result can be used in experiments to minimize QPC-induced spin decay in read-out schemes.