Physics Department Colloquium

Abstract: Words of Richard Feynman “What I cannot create, I do not understand” inspire r

Abstract: The guided transmission of optical waves is essential for modern applications in communication, information processing, and energy systems. Traditionally, light guiding in structures like optical fibers has been predominantly achieved through total internal reflection. In periodic structures, a range of other physical mechanisms can also facilitate optical wave transport.

 Perhaps "The quark model for an AMO audience'' would be a better title? Anyway, I will tell you a bit about the spectroscopy of strongly interacting particles, a bit about the quark model, a bit about how people calculate the masses of bound states of quarks and gluons, and a bit about some states that I think are particularly interesting.

Abstract: We are all physicists, and have at least some acquaintance with mathematics. And we all have a fear of nuclear war. There are currently nine nations with these dreadful weapons. Can you name them? This colloquium will criticize the current meaning of deterrence, and offer an alternative, with evidence.

Abstract: The Dark Energy Spectroscopic Instrument (DESI) collaboration is conducting a 5 year redshift survey of 40 million extra-galactic sources over 14,000 square degrees of the northern sky. One of its primary goals is to measure the cosmic expansion history with baryon acoustic oscillations (BAO). I will present the measurement of BAO in galaxy, quasar and Lyman-alpha forest tracers from the first year of observation.

Abstract: The ability to measure what students are learning (or not) is a crucial component of crafting effective learning environments. In particular, low-stakes, standardized diagnostic assessments can provide a valuable tool for tracking student learning over time and between instructional approaches to identify effective strategies that improve students' understanding of core physics content.

When can isolated many body quantum systems fail to go to equilibrium under their own dynamics, and how robust can this 'ergodicity breaking’ be? This question has been a central theme of research in quantum dynamics and statistical mechanics over the past decade, and I will share with you some highlights, focusing on three key developments: many body localization, dynamics with multipolar symmetries, and dynamics with higher form symmetries. I will present the rich and exotic phenomena that arise in these three regimes, and how they may be realized experimentally.

Abstract: Laser-based measurement and control of atomic and molecular states form the foundation of modern quantum technology and provide deep insights to fundamental physics. The recent breakthrough of quantum-state-resolved thorium-229 nuclear laser spectroscopy marks the beginning of precision metrology for nuclear transitions. Using a state-of-the-art frequency comb in the vacuum-ultraviolet, we coherently excite the thorium nuclear clock transition and link its frequency directly to today’s most precise atomic clock based on strontium-87.

Abstract: I will review some modern applications of effective field theories outside their traditional particle physics domain. In particular, I will focus on spontaneous symmetry breaking for spacetime symmetries. The effective theories for the associated Goldstone excitations capture the low-energy/long-distance dynamics of a number of physical systems, from ordinary macroscopic media (solids, fluids, superfluids, supersolids) to more exotic cosmological ones.

Abstract: The emergence of quasiparticles with fractional charge and fractional statistics is an essential feature of fractional quantum Hall states, which occur in two-dimensional electron gas under a strong magnetic field. An interesting question is whether fractional electron states can form spontaneously in quantum materials without the external magnetic field.