Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Transport: Quantum Coherence and Quantum Information Systems

TT 9.10: Talk

Monday, February 25, 2008, 16:45–17:00, H 2053

Exponential Decay in a Spin Bath — William Anthony Coish^1,2, •Jan Fischer², and Daniel Loss² — ¹Institute for Quantum Computing and Department of Physics and Astronomy, Waterloo, Ontario, Canada — ²Department of Physics, University of Basel, Switzerland

We show that the coherence of an electron spin interacting with a bath of nuclear spins can exhibit a well-defined purely exponential decay for special (’narrowed’) bath initial conditions in the presence of a strong applied magnetic field. This is in contrast to the typical case, where spin-bath dynamics have been investigated in the non-Markovian limit, giving super-exponential or power-law decay of correlation functions. We calculate the relevant decoherence time T₂ explicitly for free-induction decay and find a simple expression with dependence on bath polarization, magnetic field, the shape of the electron wave function, dimensionality, total nuclear spin I, and isotopic concentration for experimentally relevant heteronuclear spin systems.