Events on Thursday, October 16th, 2025
- Preliminary Exam
- Dielectric Loss in Superconducting Qubits
- Time: 12:30 pm - 2:30 pm
- Place: B343 Sterling
- Speaker: Spencer Weeden, Physics PhD Graduate Student
- Abstract: Superconducting circuits are leading candidates for realizing quantum bits ("qubits"). To build a useful quantum computer, it is necessary to understand and mitigate energy relaxation in these qubits. Currently, energy relaxation is dominated by amorphous oxide layers residing at circuit interfaces. Here we study energy relaxation as a function of qubit frequency and time for various qubit geometries. We compare our experimental results with Monte Carlo simulations, and develop a model that describes energy relaxation due to defects residing at the substrate-air interface and along the Josephson junction leads.
- Host: Robert McDermott
- Astronomy Colloquium
- Witnessing the End of Star Formation in Galaxies, a Post-Starburst Story
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Prof. Ann Zabludoff, University of Arizona
- Abstract: While astronomers are now detecting very early galaxy formation and tracing galaxy evolution over a Hubble time, we remain baffled by the present-day dichotomy between disky galaxies that are forming stars and spheroidal galaxies that are not. The key is to find galaxies in transition from one class to the other, preferably in the nearby universe where we have access to an abundance of spatially resolved and multi-wavelength data. We have now identified thousands of such "post-starburst galaxies" whose dynamics, stellar populations, star clusters, and morphologies are consistent with recent, dramatic evolution. This evolution often arises from galaxy-galaxy interactions and is connected in complex ways to the galaxy's central, supermassive black hole and newly formed stars. For reasons that we are working to explain, these galaxies are the preferred sites for stellar tidal disruptions by supermassive black holes, a surprising link between sub-pc and kpc scales reminiscent of the black hole-galaxy bulge mass relation. Regardless of the physical mechanism that drives it, the preference for certain host galaxies is a valuable tool for rapidly classifying these rare astrophysical transients, especially in the era of advancing AI and the Vera Rubin Observatory's Legacy Survey of Space and Time.
- Host: Nicholas Stone