The theory of topological order was developed largely to describe the fractional quantum Hall states. However, they were not the first topologically ordered phases discovered experimentally. Over 70 years before, Kamerlingh Onnes discovered superconductivity, which is often classified as a symmetry-breaking state. As I will discuss, conventional s-wave superconductors with dynamical electromagnetism are more appropriately characterized by topological order. I will explain how superconductors possess the hallmark characteristics of topological order, including the non-existence of a local order parameter, fractionalization of excitations, non-trivial “braiding” of excitations, a topological quantum field theory description at long wavelengths, ground state degeneracy, and boundary degrees of freedom. From these topological properties, we will observe that conventional superconductors lie in the same “topological universality class” as the deconfined phase of Z2 lattice gauge theory, also known as Kitaev’s toric code.
Note: The room and time has been changed to accommodate the number of courses on Tuesday afternoons this semester. This event will be hybrid. The live talk occurring in Loomis 464 at 10:00 am will be simultaneously broadcast via Zoom. Coffee and snacks will be available outside after the talk for attendees, weather permitting.
The Zoom link will be sent to the Graduate Student and PDRA mailing lists. If you are not on one of those lists and are interested in attending, please email Caitlin at ckengle2@illinois.edu for the link.
