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Parity anomaly and spin transmutation in quantum spin Hall Josephson junctions

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 نشر من قبل Yang Peng
 تاريخ النشر 2016
  مجال البحث فيزياء
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We study the Josephson effect in a quantum spin Hall system coupled to a localized magnetic impurity. As a consequence of the fermion parity anomaly, the spin of the combined system of impurity and spin-Hall edge alternates between half-integer and integer values when the superconducting phase difference across the junction advances by $2pi$. This leads to characteristic differences in the splittings of the spin multiplets by exchange coupling and single-ion anisotropy at phase differences, for which time-reserval symmetry is preserved. We discuss the resulting $8pi$-periodic (or $mathbb{Z}_4$) fractional Josephson effect in the context of recent experiments.

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