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Events During the Week of January 19th through January 26th, 2025

Monday, January 20th, 2025

Academic Calendar
Martin Luther King Jr. Day
Abstract: *Note: actual end time may vary.* No classes\; university offices are closed..
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Academic Calendar
Graduate School Spring 2025: Spring Degree Window Period deadline for doctoral students
Time: 11:55 pm - 12:55 am
Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu
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Tuesday, January 21st, 2025

Academic Calendar
Spring semester instruction begins
Abstract: *Note: actual end time may vary.*
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Wednesday, January 22nd, 2025

Department Meeting
Time: 12:15 pm - 1:00 pm
Place: B343 Sterling Hall
Speaker: Kevin Black, UW - Madison
Host: Kevin Black
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Thursday, January 23rd, 2025

No events scheduled

Friday, January 24th, 2025

Thesis Defense
High-spectral resolution study of the galactic soft X-ray bulge with the X-ray Quantum Calorimeter
Time: 10:00 am - 12:00 pm
Place: 5310 Chamberlin
Speaker: Conjeepuram V Ambarish, Physics PhD Graduate Student
Abstract: The galactic center soft X-ray bulge, clearly seen in the ROSAT R45 map, is one of the brightest diffuse X-ray sources in the night sky. The extended nature of the emission suggests that the source is likely hot gas shock heated by supernovae. Deep shadows from molecular clouds at 2-4 kpc show that the soft X-ray bulge is not a local feature and is likely associated with either the galactic center or one of the inner spiral arms. The spatial extent and the spectral signature of the bulge can be fit rather well to an adiabatic polytrope filling the gravitational potential of the Galaxy supported against collapse by its own pressure. Other theories for the origin of the hot gas include outflows from star-forming regions in the galactic disk, which has a similar extent. Both the models mentioned above predict the presence of multiple components at different temperatures, which is confirmed by Suzaku and XMM-Newton observations. Disentangling these observations to determine the physical state and relative abundances in the different components requires better spectral resolution than exists in current CCD detectors. X-ray quantum calorimeter (XQC) is a sounding rocket payload with silicon thermistor microcalorimeters operated at 50 mK. With a detector area of 1.44 cm2 mechanically collimated to a 60 degree field of view, XQC has a high throughput (~ 1 cm2 sr) along with an energy resolution of ~ 8 eV FWHM below 1 keV. Since the galactic center is too far south to observe from NASA’s standard launch site at White Sands Missile Range (WSMR), XQC was part of NASA’s long-awaited campaign to Australia. We had a successful flight observing the galactic center soft X-ray bulge. I present here the high resolution spectrum with clearly resolved lines from multiple ionization states of carbon, nitrogen, oxygen, neon and iron. Furthermore, I show that the soft X-ray bulge is consistent with either an adiabatic polytrope or an isothermal disk-like model with scale heights of several kiloparsecs, along with contribution from unresolved stars. Additionally, leveraging the high spectral resolution, I present a model-independent framework to get an estimate of the different temperature components in the line of sight as well as decoupling the contributions from thermal emission and solar wind charge exchange.
Host: Dan McCammon
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Physics Department Colloquium
Solid-state spin-photon interfaces for quantum information processing
Time: 3:30 pm - 5:00 pm
Place: Discovery Building, DeLuca Forum
Speaker: Peter Lodahl, Niels Bohr Institute, University of Copenhagen
Abstract:

Semiconductor quantum dots embedded in photonic nanostructures offer a highly efficient and coherent deterministic photon-emitter interface enabling on-demand single-photon sources and multi-photon entanglement sources. We discuss the fundamental operational principles of these devices and introduce a protocol of deterministic entanglement generation by controlling a single spin in the quantum dot. We will present the experimental state-of-the-art of multi-photon entanglement generation including the realization of photon fusion, which is a primitive for fusion-based quantum computing. Finally, we discuss potential applications of this novel hardware for quantum communication and photonic quantum computing.

This event starts at 3:30pm with refreshments. The invited presentation starts at 4pm.

Host: Mark Saffman
Attachments: Abstract-Lodahl-Wisconsin2025.pdf
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