Chekhovich, Evgeny
Date: Friday May 9, 2014
Time: 14:00
Place: ETH Science City, HPF G 6
Host: Atac Imamoglu
Nuclear magnetic resonance (NMR) in self-assembled quantum dots: structural analysis and quantum computing applications
Evgeny Chekhovich
Department of Physics and Astronomy, University of Sheffield, U.K.
Quantum dots in III-V semiconductors have various favourable properties for applications in quantum information technologies, including strong coupling with light offering excellent optical interfacing, ultrafast coherent manipulation and advanced manufacturing technologies. However, all group III and V atoms have nonzero nuclear spins. Thus instead of a two-level qubit system, the spin of a single electron in a quantum dot is described by the so called ''central spin'' problem [1,2], where the electron (central) spin is strongly coupled to magnetic interaction with an ensemble of few thousand nuclear spins. This electron-nuclear (hyperfine) interaction causes electron spin decoherence and presents a serious challenge on the way towards practical applications of quantum dots.
In this talk, I will show how nuclear magnetic resonance (NMR) techniques can be used to study and manipulate the nuclear spin system of individual quantum dots. In particular I will focus on self-assembled quantum dots, where strain-induced quadrupolar effects have a dramatic impact on nuclear spin physics. Two aspects of NMR techniques will be discussed: Firstly, NMR can be used for non-invasive structural analysis of individual quantum dots. Secondly, pulsed NMR can be employed to probe coherent dynamics of the nuclear spin bath. Our recent pulsed NMR measurements revealed that quadrupolar effects lead to enhanced nuclear spin coherence and strong suppression of nuclear spin bath fluctuations, making strained III-V nanostructures particularly attractive for quantum computation applications.
[1] B. Urbaszek, et al, "Nuclear spin physics in quantum dots: An optical investigation", Rev. Mod. Phys. 85, 79 (2013)
[2] E. A. Chekhovich, et al, "Nuclear spin effects in semiconductor quantum dots" (Review), Nature Materials 12, 494 (2013)