IQIM Postdoctoral and Graduate Student Seminar

Note: IQIM seminar will be held in the Ginsburg seminar room.

Abstract: We introduce the (spin or boson) quantum breakdown model in a 1D lattice, which has an exponential U(1) symmetry defined by a unit of charge decaying exponentially in space. For spins larger than a threshold, we show that the model exhibits a quantum breakdown condensate phase that spontaneously breaks the exponential U(1) symmetry. Surprisingly, this spontaneous symmetry breaking (SSB) phase has no gapless Goldstone modes and no off-diagonal long-range order. It has an exponentially large number of SSB ground states, which resembles a quantum spin glass requiring no disorder. For small spins, the model can exhibit a symmetry-protected topological phase (SPT), or a more exotic phase which has half of the properties of the usual SPT. This challenges the existing classification schemes of quantum phases of matter.

Lunch will be provided on the lawn north of Bridge, following the talk.