Fast Incomplete Decoherence of Nuclear Spins in Quantum Hall Ferromagnet

Technion - Israel Institute of Technology, H̱efa, Haifa, Israel
Physical Review B (Impact Factor: 3.74). 11/2000; 64(19). DOI: 10.1103/PhysRevB.64.193306
Source: arXiv


A scenario of the quantum computing process based on the manipulation of a large number of nuclear spins in quantum Hall (QH) ferromagnets is presented. It is found that vacuum quantum fluctuations in the QH ferromagnetic ground state at filling factor nu =1, associated with the virtual excitations of spin waves, lead to fast incomplete decoherence of the nuclear spins. A fundamental constraint on the level of decoherence is set by this fluctuation effect. For GaAs multiple-quantum-well structures we find a coherence level not smaller than 1-10(-9), which is safely above the danger level of quantum error correction methods.

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Available from: Tsofar Maniv, Jan 31, 2013
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    • "The processes of relaxation and decoherence considered here [21] [22] [23] [24] [25] [26] [27] [28] are associated with the dynamics of a small, few-qubit quantum system as it interacts with the environment. Ultimately, for a large, multi-qubit system, many-body quantum chaos-like behavior must also be accounted for, and some advances in model system studies have been reported recently [5] [58]. "
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    ABSTRACT: We survey recent work on designing and evaluating quantum computing implementations based on nuclear or bound-electron spins in semiconductor heterostructures at low temperatures and in high magnetic fields. General overview is followed by a summary of results of our theoretical calculations of decoherence time scales and spin–spin interactions. The latter were carried out for systems for which the two-dimensional electron gas provides the dominant carrier for spin dynamics via exchange of spin-excitons in the integer quantum Hall regime.
    Computer Physics Communications 07/2002; 146(3-146):331-338. DOI:10.1016/S0010-4655(02)00424-1 · 3.11 Impact Factor
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    ABSTRACT: Decoherence of a shallow donor electron spin in silicon caused by electron-lattice interaction is studied. We find that there are two time scales associated with the evolution of the electron spin density matrix: the fast but incomplete decay due to the interaction with non-resonant phonons followed by slow relaxation resulting from spin flips accompanied by resonant phonon emission. We estimate both time scales as well as the magnitude of the initial drop of coherence for P donor in Si and argue that the approach used is suitable for evaluation of phonon induced decoherence for a general class of localized spin states in semiconductors. Comment: in Plain Tex, 10 pages, 1 figure, submitted to Phys. Rev. B
    Physical Review B 12/2001; 65(24). DOI:10.1103/PhysRevB.65.245213 · 3.74 Impact Factor
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