Add to Calendar 2026-02-02T13:30:00 2026-02-02T16:00:00 Interacting surface topological matter: conformal manifolds and entanglement entropy Event Information: Abstract: Symmetry-protected topological (SPT) phases host gapless surface states that are robust against weak, symmetry-preserving interactions, while strong interactions can drive symmetry-breaking ordered phases. The phase boundary separating the gapless and ordered phases can host exotic conformal field theory states typically not observed in conventional quantum phase transitions, which we refer to as surface topological quantum critical points (sTQCPs) In this dissertation, we study attractive interaction-driven quantum criticality on the surface of three-dimensional topological insulators hosting multiple Dirac cones. In the multi-dimensional interaction parameter space, the phase boundary separating the gapless and the ordered phases forms a continuous manifold. We show that in the limit of suppressed quantum fluctuations, the universality of this phase boundary is governed by conformal manifolds, continuous families of interacting conformal field theories characterized by exactly marginal operators. However, higher-order quantum fluctuations break the conformal manifolds into isolated fixed points of varying infrared stabilities. Remarkably, we find that along the RG flow within the manifold, an EPR-like entanglement entropy in fermion flavor space always increases. Infrared stable conformal field theories correspond to maximally entangled interaction operators, while weakly entangled fixed points are unstable. These results establish the central role of entangled conformal operators and their entropy in shaping the universality classes of sTQCPs."   Event Location: HENN 302