Description:

"Polarized Signatures of Expanding Synchrotron Hotspots in Sgr A*’s Accretion Flow"

Joe Michail, PhD Student, Zadeh Group, Northwestern University

Sagittarius A* (Sgr A*) is the four million solar mass supermassive black hole residing at the dynamical center of our Galaxy and the latest imaging target for the Event Horizon Telescope (EHT). Despite being the closest supermassive black hole, fewer physical constraints were placed on its accretion flow compared to M87*, the first black hole to be imaged. Sgr A*’s inherent variability, present across the electromagnetic spectrum, contaminated the shadow’s final appearance. Several models are degenerate in describing the variable emission's total intensity variations, but only full-polarization observations can confirm their true nature. I present our full-polarization modeling of an expanding hotspot at 230 GHz observed with ALMA. We find the fitted accretion flow properties are consistent with independent radio/infrared analyses of Sgr A*. This result is the most robust test of the model yet attempted and is a precursor to our multi-wavelength observations simultaneous with the EHT in April 2023.

"Quantization of Superconducting Circuits"

Sai Pavan Chitta, Graduate Student, Koch Group, Northwestern University

Superconducting circuits have been one of the popular devices to make quantum computing processors with. Some of the largest quantum processors, including the one that IBM recently announced, are based on this architecture. In this talk I will briefly introduce the models which are behind such implementations. Starting with a brief introduction to superconducting Josephson junctions, I will talk about how lumped element models of superconducting circuits can be constructed and quantized. I will then describe how this process is arduous and is simplified significantly using the module I added to scqubits, the python package maintained by our group. I will conclude by mentioning my current research on the lumped element model for quantum phase slip junction circuits.