Spin decay in a quantum dot coupled to a quantum point contact

Massoud Borhani, Vitaly N. Golovach, and Daniel Loss
Phys. Rev. B 73, 155311 – Published 12 April 2006

Abstract

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 a6 where a 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 readout schemes.

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  • Received 27 October 2005

DOI:https://doi.org/10.1103/PhysRevB.73.155311

©2006 American Physical Society

Authors & Affiliations

Massoud Borhani, Vitaly N. Golovach, and Daniel Loss

  • Department of Physics and Astronomy, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland

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Issue

Vol. 73, Iss. 15 — 15 April 2006

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