Seminar: Dr. Clement Burns

Probing High Temperature Superconductors with X-rays

Friday, April 7 at 3 pm in VW 104

Clement Burns Ph.D., Western Michigan University

Superconducting materials display a variety of unusual phenomenon, including the ability to carry electrical currents without resistance and the expulsion of magnetic fields from their volume.  Many of these systems are well understood, but over the last couple of decades several new classes of exotic superconductors have been discovered which cannot be explained with current theory.  In this talk I will discuss recent work using a free electron laser x-ray source at the SLAC accelerator laboratory to study the high temperature superconductor YBa2Cu4O7-x. Electrons in these systems show a new type of charge order which competes with the superconductivity, and this charge ordering may play an important role in the properties of these materials.

Seminar: If I ran the (quantum) zoo

“If I ran the (quantum) zoo” by Matt Eiles ’13, physics graduate student -Purdue

Friday, February 24

3pm

VanderWerf 104

The highly excited valence electron of an alkali Rydberg atom ranges over incredible distances relative to typical atomic scales. In the cold, dense environment of a Bose-Einstein Condensate this electron can interact with one, two, or many other atoms. This leads to the formation of ultra-long- range Rydberg molecules, which are weakly bound states with dipole moments exceeding those of traditional molecules by several orders of magnitude. In this talk I will discuss the theory of Rydberg molecules and highlight some recent experimental observations of these exotic creatures, and discuss several recent efforts to extend the theory to atoms with two valence electrons and to polyatomic systems. I will conclude with some enthusiastic speculation about how the the long-range anisotropic interactions between Rydberg molecules could explore many-body physics.

Some members of Matt’s zoo include: