|Title||8 pi-periodic dissipationless ac Josephson effect on a quantum spin Hall edge via a quantum magnetic impurity|
|Publication Type||Journal Article|
|Year of Publication||2017|
|Authors||H-Y. Hui, and J. D. Sau|
|Journal||PHYSICAL REVIEW B|
|Date Published||JAN 9|
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.