Wen YANG
Abstract: Utilization of the spin of electron localized in semiconductor quantum dots as carriers of quantum information has been a major direction in solid-state quantum information. A critial obstacle in this development is the rapid loss of the phase coherence (i.e., decoherence) of the electron spin due to its contact hyperfine interaction with the nuclear spins of the host lattice. The electron spin decoherence is essentially determined by the electron-nuclear entanglement established by the many-body evolution of the nuclear spins conditioned on the electron spin states. In this talk, I will describe my recent studies on the electron spin decoherence. In particular, my collaborator and I have developed the cluster-correlation expansion theory for the conditional many-body evolution of the nuclear spins responsible for the electron spin decoherence. We have established the connection between the cluster-correlation expansion theory and three existing quantum many-body theories, including the pair-correlation approximation [W. Yao et al., Phys. Rev. B 74, 195301 (2006)] ,the standard linked cluster expansion, and the cluster expansion [W. M. Witzel and S. Das Sarma, Phys. Rev. B 74, 035322 (2006)]. Comparision between different theories in an exactly solvable spin-chain model shows that the cluster-correlation expansion outperforms other theories in both convergence and accuracy.
Location: 606 conference room
Date and time: Jul 1th, 2011 2:30 P.M.
