Spin interactions and switching in vertically tunnel-coupled quantum dots

Burkard, G. and Seelig, G. and Loss, D.. (2000) Spin interactions and switching in vertically tunnel-coupled quantum dots. Physical Review B, Vol. 62, H. 4. pp. 2581-2592.

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Official URL: http://edoc.unibas.ch/dok/A5254745

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We determine the spin-exchange coupling J between two electrons located in two vertically tunnel-coupled quantum dots, and its variation when magnetic (B) and electric (E) fields (both in-plane and perpendicular) are applied. We predict a strong decrease of J as the in-plane B field is increased, mainly due to orbital compression. Combined with the Zeeman splitting, this leads to a singlet-triplet crossing, which can be observed as a pronounced jump in the magnetization at in-plane fields of a few T, and perpendicular fields of the order of 10 T for typical self-assembled dots. We use harmonic potentials to model the confining of electrons, and calculate the exchange J using the Heitler-London and Hund-Mulliken techniques, including the long-range Coulomb interaction With our results we provide experimental criteria for the distinction of singlet and triplet states, and therefore for microscopic spin measurements. In the case where dots of different sizes are coupled, we present a simple method to switch the spin coupling on and off with exponential sensitivity using an in-plane electric field. Switching the spin coupling is essential for quantum computation using electronic spins as qubits.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Mesoscopics (Loss)
UniBasel Contributors:Loss, Daniel
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Institute of Physics
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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