The fine structure of quantum spin ice
Abstract: Quantum spin liquids are low temperature phases of magnetic materials in which quantum fluctuations prevent the establishment of long-range magnetic order. These phases support fractionalized spin excitations (spinons) coupled to emergent photons. In this talk, I will review the basic picture of how quantum electrodynamics emerges in 3D spin ice and then turn to several results regarding its `fine structure'. I will argue that the fine structure constant α-- the dimensionless coupling which controls the interactions between light and matter -- generically takes values ~0.1 in quantum spin ice, much larger than the α ~ 1/137 of our universe . The large fine structure constant modifies the spinon dynamics considerably. The consequent qualitative features in inelastic neutron scattering could help identify these phases . Time permitting, I will also discuss how axions can appear in the system .