Events at Physics

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Events During the Week of October 24th through October 31st, 2021

Sunday, October 24th, 2021

Wonders of Physics
Lab Escape
Time: 10:00 am - 4:00 pm
Place: Ingersoll Physics Museum
Abstract: World-renowned quantum physicist Professor Alberta Pauline Schrödenberg desperately needs your help — the fate and security of the entire world (and more importantly, her funding!) hang in the balance. You’ll have to search her lab, solve mind-blowing puzzles to reveal clues, and hopefully find a way to complete your mission!

For more information, see our listing on the Wisconsin Science Festival website:
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Monday, October 25th, 2021

Plasma Physics (Physics/ECE/NE 922) Seminar
Using magnetic fields and microgravity to explore the physics of dusty plasmas
Time: 12:00 pm
Place: 2241 Chamberlin
Speaker: Ed Thomas, Jr. (Auburn)
Abstract: Over the last three decades, plasma scientists have learned how to control a new type of plasma
system known as a “complex” or “dusty” plasma. These are four-component plasma systems that
consist of electrons, ions, neutral atoms, and charged, solid, nanometer- to micrometer-sized
particles. The presence of these microparticles allow us to “tune” the plasma to have solid-like,
fluid-like, or gas-like properties. This means that dusty plasmas are not just a fourth state of matter
– they can take on the properties of all four states of matter.

From star-forming regions to planetary rings to fusion experiments, charged microparticles can be
found in many naturally occurring and man-made plasma systems. Therefore, understanding the
physics of dusty plasmas can provide new insights into a broad range of astrophysical and
technological problems. This presentation introduces the physical properties of dusty plasmas –
focusing on how the small charge-to-mass ratio of the charged microparticles gives rise to many
of the characteristics of the system. In particular, dusty plasmas can be used to study a variety of
processes in non-equilibrium or dissipative systems such as self-organization and energy cascade
as well as a variety of transport and instability mechanisms. This presentation will discuss results
from our studies of dusty plasmas in high (B ≥ 1 T) magnetic fields using the Magnetized Dusty
Plasma Experiment (MDPX) device at Auburn University and in microgravity experiments using
the Plasmakristall-4 (PK-4) laboratory on the International Space Station.
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Tuesday, October 26th, 2021

Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Comparing Supernova Models Using Past and Future Neutrino Data
Time: 2:00 pm - 3:00 pm
Speaker: Jackson Olsen , University of Minnesota
Abstract: Recent advances in state-of-the-art core-collapse supernova (CCSN) simulations have led to detailed predictions for the neutrino signal. These model predictions can be directly compared using observations. In this talk, I describe a Bayesian comparison of three CCSN neutrino emission models using the Kamiokande II data on SN 1987A. I then present an analysis of the capabilities of a water Cherenkov detector such as Super-Kamiokande to distinguish between these models in the event of a future Galactic CCSN.
Host: Baha Balantekin
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Theory Seminar (High Energy/Cosmology)
Muon g-2 Experiments as Dark Matter Detectors
Time: 4:00 pm - 5:00 pm
Place: Chamberlin 5280
Speaker: Ryan Janish, Fermilab
Abstract: We propose extending the search for dark matter (DM) by using muon spin targets. An ultralight DM background may apply an oscillating torque to muon spins, resulting in novel precession trajectories. A time-resolved reanalysis of muon precession data from the ongoing Fermilab g-2 experiment and from future g-2 and EDM measurements is sensitive to this signal. We place constraints on DM-muon interactions using existing data, and outline the detection reach of a dedicated re-analysis. In addition, some DM candidates alter precession primarily through a shifted precession frequency, i.e. they provide an apparent contribution to the muon magnetic dipole moment which depends on the local DM density. We find that the current muon g-2 anomaly can be explained by pseudoscalar DM which induces an oscillating electric dipole moment for the muon. This explanation may be verified with a time-resolved analysis. Note: This is a hybrid event. A zoom link will be distributed via the seminar mailing list. To join, email the organizer.
Host: Lars Aalsma
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Astronaut Scholarship Foundation presentation
Time: 5:00 pm - 6:00 pm
Place: 1003 Engineering Centers Building
Speaker: Brewster Shaw, NASA
Abstract: Astronaut Brewster Shaw will visit the University of Wisconsin to
share his experiences as a NASA astronaut and the impact of STEM
education during a lecture and scholarship presentation. UW–Madison mathematics and physics major Gage Siebert, one of the recipients of the Foundation's awards, will be recognized as well. This event
is open to the public.
Host: Tim Jensen, Engineering Physics
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Wednesday, October 27th, 2021

No events scheduled

Thursday, October 28th, 2021

Astronomy Colloquium
Probing Dynamic Intracluster Medium: Insights from X-ray Surface Brightness Fluctuations
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and Cookies at 3:30 pm, Talk starts at 3:45 pm
Speaker: Irina Zhuravleva , University of Chicago
Abstract: Clusters of galaxies are mainly filled with dark matter and hot, X-ray emitting gas. They evolve through matter accretion along cosmic filaments, violent mergers, feedback from active galactic nuclei (AGN). Despite being very dynamic environments, the processes that drive gas motions in the intracluster medium (ICM), the properties of turbulence and relevant plasma physics remain poorly explored. In this talk, I will mainly focus on observational efforts to probe these physics. A recent analysis of X-ray surface brightness fluctuations in the central regions of bright, nearby galaxy clusters provided constraints on velocity power spectra, effective equation of state of small-scale perturbations produced by AGN feedback, and directly probed how magnetic fields modify small-scale density perturbations of the gas, affecting its transport properties. At the end of the talk, exciting possibilities to probe gas motions and plasma physics in the ICM with near-future XRISM observatory will be discussed.
We strongly encourage you to attend the colloquium in person. If that is impossible, it is available over zoom at the following link:
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Friday, October 29th, 2021

Graduate Introductory Seminar (Physics 701)
Condensed Matter and Quantum Science
Time: 12:05 pm - 12:55 pm
Place: 2241 Chamberlin
Speaker: Mark Eriksson, UW Madison Department of Physics
Host: Sridhara Dasu
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Physics Department Colloquium
Correlating materials analysis with qubit measurements to systematically eliminate sources of noise
Time: 3:30 pm - 4:30 pm
Place: 2103 Chamberlin Hall
Speaker: Nathalie de Leon, Princeton
Abstract: The nitrogen vacancy (NV) center in diamond exhibits spin-dependent fluorescence and long spin coherence times under ambient conditions, enabling applications in quantum information processing and sensing. NV centers near the surface can have strong interactions with external materials and spins, enabling new forms of nanoscale spectroscopy. However, NV spin coherence degrades within 100 nanometers of the surface, suggesting that diamond surfaces are plagued with ubiquitous defects. I will describe our recent efforts to correlate direct materials characterization with single spin measurements to devise methods to stabilize highly coherent NV centers within nanometers of the surface. We also deploy these shallow NV centers as a probe to study the dynamics of a disordered spin ensemble at the diamond surface. Our approach for correlating surface spectroscopy techniques with single qubit measurements to realize directed improvements is generally applicable to many systems. Separately, I will describe our recent efforts to tackle noise and microwave losses in superconducting qubits. Building large, useful quantum systems based on transmon qubits will require significant improvements in qubit relaxation and coherence times, which are orders of magnitude shorter than limits imposed by bulk properties of the constituent materials. This indicates that relaxation likely originates from uncontrolled surfaces, interfaces, and contaminants. Previous efforts to improve qubit lifetimes have focused primarily on designs that minimize contributions from surfaces. However, significant improvements in the lifetime of planar transmon qubits have remained elusive for several years. We have fabricated planar transmon qubits that have both lifetimes and coherence times exceeding 0.3 milliseconds by replacing niobium with tantalum in the device. Following this discovery, we have parametrized the remaining sources of loss in state-of-the-art devices using systematic measurements of the dependence of loss on temperature, power, and geometry. This parametrization, complemented by direct materials characterization, allows for rational, directed improvement of superconducting qubits.
Host: Shimon Kolkowitz
Presentation: abstract_UW Madison.docx
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