Emergent gauge theories in Quantum spin Hall superconductor Josephson arrays and cold atom system

          @misc{ scivideos_PIRSA:10050081,
            doi = {10.48660/10050081},
            url = {https://pirsa.org/10050081},
            author = {Xu, Cenke},
            keywords = {},
            language = {en},
            title = {Emergent gauge theories in Quantum spin Hall superconductor Josephson arrays and cold atom system},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2010},
            month = {may},
            note = {PIRSA:10050081 see, \url{https://scivideos.org/index.php/pirsa/10050081}}
          }
          

Abstract

We study a 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 structure naturally emerges and leads to many new insulating phases, including a deconfined phase where electrons fractionalize into charge-e bosons and topological defects. We will also discuss the ultracold alkaline earth atoms trapped in optical lattice, which naturally has a SU(N) spin symmetry with N as large as 10. An SU(2)xU(1) gauge theory emerges in a large part of the phase diagram of this system.