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Hole Spin Decoherence in Quantum Dots

Hole Spin Decoherence in Quantum Dots. Denis Bulaev and Daniel Loss Department of Physics University of Basel, Switzerland. Motivation. Quantum computing Qubit with long coherence time. Pros of heavy hole. Weak hyperfine interactions with nuclei ( p -symmetry ). Cons of heavy hole.

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Hole Spin Decoherence in Quantum Dots

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  1. Hole Spin Decoherence in Quantum Dots Denis Bulaev and Daniel Loss Department of Physics University of Basel, Switzerland

  2. Motivation • Quantum computing • Qubit with long coherence time Pros of heavy hole • Weak hyperfine interactions with nuclei (p-symmetry) Cons of heavy hole • Strong spin-orbit interactions with light holes • Difficulties in coherent spin manipulation • ...

  3. Motivation • Quantum computing • Qubit with long coherence time Pros of heavy hole • Weak hyperfine interactions with nuclei (p-symmetry) • Weak spin-orbit interactions with light holes in 2D QDs Cons of heavy hole • Difficulties in coherent spin manipulation • ...

  4. Motivation • Quantum computing • Qubit with long coherence time Pros of heavy hole • Weak hyperfine interactions with nuclei (p-symmetry) • Weak spin-orbit interactions with light holes in 2D QDs • Possibilities for coherent spin manipulation via EDSR Cons of heavy hole • ...

  5. Effective Hamiltonian of Heavy Holes [R. Winkler, PRB 62, 4245 (2000)] [DB & D. Loss, PRL 95, 076805 (2006)] g(GaAs) = 2.5, g(InAs) = -2.2. [H.W. van Kestern, et al., PRB 41, 5283 (1990)] [M.Bayer,et al., PRL 82, 1748 (1999)]

  6. Spin Relaxation Rates GaAs Quantum Dot (g = 2.5) InAs Quantum Dot (g = -2.2) [DB & D. Loss, PRL 95, 076805 (2006)]

  7. B-field Dependence of Rates Electrons phonons Hso Heavy holes Dresselhaus SO coupling Rashba SO coupling

  8. Summary • Anticrossing and spin mixing (GaAs QD) • T2 = 2T1 at low temperatures • Peaks on the spin relaxation decay curve (GaAs QD) • RashbaDresselhaus • Spin relaxation time for heavy holes CAN BE longer than for electrons

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