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 [1]. The large fine structure constant modifies the spinon dynamics considerably. The consequent qualitative features in inelastic neutron scattering could help identify these phases [2]. Time permitting, I will also discuss how axions can appear in the system [3].
[1] Pace, Morampudi, Moessner, Laumann. Phys. Rev. Lett. 127, 117205 (2021).
[2] Morampudi, Wilczek, Laumann. Phys. Rev. Lett. 124, 097204 (2020).
[3] Pace, Castelnovo, Laumann. arXiv:2109.06890.
Joint Quantum Institute Seminars take place live each Monday during Fall and Spring Semesters, 11:00 a.m. - 12:00 p.m. Eastern Time, in Room 2400 of the Atlantic Building. University of Maryland affiliates may participate using Zoom. The Seminars are also simulcast world-wide on the Joint Quantum Institute YouTube channel, https://www.youtube.com/user/JQInews(link is external) , which supports audience participation in the chat interface.