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Singlet-triplet decoherence due to nuclear spins in a double quantum dot

Coish, W. A. and Loss, D.. (2005) Singlet-triplet decoherence due to nuclear spins in a double quantum dot. Physical Review B, Vol. 72, H. 12 , 125337, 12 S..

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Official URL: http://edoc.unibas.ch/dok/A5254657

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Abstract

We have evaluated hyperfine-induced electron spin dynamics for two electrons confined to a double quantum dot. Our quantum solution accounts for decay of a singlet-triplet correlator even in the presence of a fully static nuclear spin system, with no ensemble averaging over initial conditions. In contrast to an earlier semiclassical calculation, which neglects the exchange interaction, we find that the singlet-triplet correlator shows a long-time saturation value that differs from 1/2, even in the presence of a strong magnetic field. Furthermore, we find that the form of the long-time decay undergoes a transition from a rapid Gaussian to a slow power law (similar to 1/t(3/2)) when the exchange interaction becomes nonzero and the singlet-triplet correlator acquires a phase shift given by a universal (parameter independent) value of 3 pi/4 at long times. The oscillation frequency and time-dependent phase shift of the singlet-triplet correlator can be used to perform a precision measurement of the exchange interaction and Overhauser field fluctuations in an experimentally accessible system. We also address the effect of orbital dephasing on singlet-triplet decoherence and find that there is an optimal operating point where orbital dephasing becomes negligible.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Mesoscopics (Loss)
UniBasel Contributors:Loss, Daniel
Item Type:Article, refereed
Bibsysno:Link to catalogue
Publisher:American Institute of Physics
ISSN:0163-1829
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:25
Deposited On:22 Mar 2012 13:48

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