Spin-valley lifetimes and tunability in a silicon quantum dot

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• Dr Alessandro Rossi, The University of New South Wales, Sydney
• Tuesday 22 October 2013, 14:30-15:30
• Microelectronics Research Centre, Cavendish Laboratory, JJ Thomson Avenue, Cambridge.

If you have a question about this talk, please contact Dr T. Ferrus.

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A major challenge for the use of silicon towards spin-based quantum computation is represented by the multi-valley nature of its conduction band. The valley splitting typically depends on physics at the atomic scale (e.g. surface roughness and interface disorder) and several experiments to date have revealed a wide variability of splittings among devices with limited control over it. I am going to report on the accurate tunability of the valley separation that we achieved via simple electro-static control of gate electrodes in a metal-oxide-semiconductor quantum dot. We used this control capability to explore the interplay between spin and valley degrees of freedom. In particular, we observed that when spin and valley splittings coincide the spin decay rate exhibits a dramatic enhancement (hot-spot) for a 1-electron system and a minimum (cold-spot) for a 2-electron system. These characteristic features can be explained via a novel relaxation mechanism based on admixing of spin and valley eigenstates.

This talk is part of the Hitachi Cambridge Laboratory series.

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