Fractionalization in Josephson junction arrays hinged by quantum spin Hall edges

Cenke Xu, Liang Fu
2010 Physical Review B  
In this paper we study a novel superconductor-ferromagnet-superconductor (SC-FM-SC) Josephson junction array deposited on top of a two-dimensional quantum spin Hall (QSH) insulator. The existence of Majorana bound states at the interface between SC and FM gives rise to charge-e tunneling, in addition to the usual charge-2e Cooper pair tunneling, between neighboring superconductor islands. Moreover, because Majorana fermions encode the information of charge number parity, an exact Z_2 gauge
more » ... ture naturally emerges and leads to many new insulating phases, including a deconfined phase where electrons fractionalize into charge-e bosons and topological defects. A new superconductor-insulator transition has also been found.
doi:10.1103/physrevb.81.134435 fatcat:np3lilkambhqzmbdbgvov7mpka