326 research outputs found
Dark State Adiabatic Passage with spin-one particles
Adiabatic transport of information is a widely invoked resource in connection
with quantum information processing and distribution. The study of adiabatic
transport via spin-half chains or clusters is standard in the literature, while
in practice the true realisation of a completely isolated two-level quantum
system is not achievable. We explore here, theoretically, the extension of
spin-half chain models to higher spins. Considering arrangements of three
spin-one particles, we show that adiabatic transport, specifically a
generalisation of the Dark State Adiabatic Passage procedure, is applicable to
spin-one systems. We thus demonstrate a qutrit state transfer protocol. We
discuss possible ways to physically implement this protocol, considering
quantum dot and nitrogen-vacancy implementations.Comment: 8 pages, 6 figures (some in colour), comments welcom
Conduction band tight-binding description for silicon applied to phosphorous donors
A tight-binding parametrization for silicon, optimized to correctly reproduce
effective masses as well as the reciprocal space positions of the
conduction-band minima, is presented. The reliability of the proposed
parametrization is assessed by performing systematic comparisons between the
descriptions of donor impurities in Si using this parametrization and
previously reported ones. The spectral decomposition of the donor wavefunction
demonstrates the importance of incorporating full band effects for a reliable
representation, and that an incomplete real space description results from a
truncated reciprocal space expansion as proposed within the effective mass
theory.Comment: 4 pages, 3 figure
Extended interface states enhance valley splitting in Si/SiO2
Interface disorder and its effect on the valley degeneracy of the conduction
band edge remains among the greatest theoretical challenges for understanding
the operation of spin qubits in silicon. Here, we investigate a
counterintuitive effect occurring at Si/SiO2 interfaces. By applying tight
binding methods, we show that intrinsic interface states can hybridize with
conventional valley states, leading to a large ground state energy gap. The
effects of hybridization have not previously been explored in details for
valley splitting. We find that valley splitting is enhanced in the presence of
disordered chemical bonds, in agreement with recent experiments.Comment: 4 pages, 4 figure
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