1:30 pm VIA ZOOM
Defect and disorder operator in (2+1)d quantum phases.
Defects have been playing an increasingly important role in our understanding of quantum phases of matter and quantum field theories in general. In this talk I will discuss properties of disorder operators associated with a (0-form) global symmetry in (2+1)d, which create symmetry defect lines. The expectation value of the disorder operator defined over a spatial region in a symmetry-preserving ground state generally shows a perimeter scaling, but often with universal sub-leading corrections. I will argue that in a symmetric gapped phase, the sub-leading correction is an invariant related to quantum dimensions of defects, which will be demonstrated assuming conformally invariant entanglement spectra. When the system is gapless described by a conformal field theory (CFT), the sub-leading correction scales logarithmically with the perimeter, whose coefficient is a universal function of opening angles of sharp corners of the region. I will discuss analytically-tractable limits of the universal function, as well as numerical simulations in lattice models of O(n) CFTs and deconfined quantum critical point.