@article {ISI:000391848000004,
title = {8 pi-periodic dissipationless ac Josephson effect on a quantum spin Hall edge via a quantum magnetic impurity},
journal = {PHYSICAL REVIEW B},
volume = {95},
number = {1},
year = {2017},
month = {JAN 9},
pages = {014505},
abstract = {Time-reversal invariance places strong constraints on the properties of the quantum spin Hall edge. One such restriction is the inevitability of dissipation in a Josephson junction between two superconductors formed on such an edge without the presence of interaction. Interactions and spin-conservation breaking are key ingredients for the realization of the dissipationless ac Josephson effect on such quantum spin Hall edges. We present a simple quantum impurity model that allows us to create a dissipationless fractional Josephson effect on a quantum spin Hall edge. We then use this model to substantiate a general argument that shows that any such nondissipative Josephson effect must necessarily be 8 pi periodic.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.95.014505},
author = {Hui, Hoi-Yin and Sau, Jay D.}
}