Events at Physics |
Events During the Week of October 20th through October 27th, 2024
Monday, October 21st, 2024
- Wisconsin Quantum Institute
- Chicago Quantum Summit
- Time: 8:45 am - 5:00 pm
- Place: David Rubenstein Forum at the University of Chicago, 1201 E. 60th St., Chicago, IL 60637
- Speaker: Various, Various
- Abstract: The seventh annual Chicago Quantum Summit is a two-day program that will feature dialogue about the growing quantum technology economy, new research initiatives in the field, and efforts to build the quantum workforce. The event will also include the Boeing Quantum Creators Prize Symposium, which promotes early-career researchers whose work moves quantum science in new directions.
- Host: Chicago Quantum Exchange
- Climate & Diversity
- Climate and Diversity Committee Open Hours
- Time: 12:00 pm - 2:00 pm
- Place: Chamberlin 5310
- Speaker: Rachel Zizmann, UW-Madison Physics
- Abstract: Open Hours are welcome for everyone in the department! During these sessions, we have the option to discuss the topic listed, that is not required or necessary for attending
- Host: Rachel Zizmann
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Thermonuclear Fusion in a Stabilized Z Pinch and Integration into a Technology Demonstrator
- Time: 12:05 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Prof. Uri Shumlak, University of Washington-Seattle and ZAP Energy
- Abstract: Many confinement configurations use large magnetic field coils to stabilize plasma, resulting in lower plasma beta – a measure of confinement efficiency defined as the ratio of plasma pressure to magnetic pressure. In contrast, the Z pinch achieves an ideal unity beta without the need for magnetic field coils. An axial plasma current generates the confining magnetic field, which balances the radial plasma pressure gradient. Increasing this current compresses the plasma adiabatically, raising its density and temperature. Despite its potential, the Z pinch is prone to MHD instabilities that destroy confinement. The sheared-flow-stabilized (SFS) Z pinch mitigates these instabilities using axial flows and has shown the ability to confine plasma at fusion conditions without magnetic field coils, promising a more compact fusion device. This presentation will discuss experimental results from the FuZE (Fusion Z-pinch Experiment) device, demonstrating high-performance plasmas and sustained fusion reactions. Neutron energy measurements indicate a thermonuclear fusion process, with reaction rates consistent with adiabatic compression scaling. High-fidelity numerical simulations suggest that sheared-flow stabilization remains effective at reactor-grade plasma conditions. Additionally, scaling studies show the potential of the SFS Z pinch as a high-gain fusion energy source. Finally, we will present an integrated reactor technology demonstrator combining key subsystems including Z-pinch plasma confinement, liquid metal electrodes, and repetitive operation, highlighting its viability as a carbon-free terrestrial power source.
- Host: John Sarff
- Preliminary Exam
- Instrumentation Development & Multi-Messenger Astrophysics with the Cherenkov Telescope Array Observatory
- Time: 3:00 pm - 5:00 pm
- Place: B343 Sterling Hall
- Speaker: Zach Curtis-Ginsberg, Physics PhD Graduate Student
- Host: Justin Vandenbroucke
Tuesday, October 22nd, 2024
- Wisconsin Quantum Institute
- Chicago Quantum Summit
- Time: 8:45 am - 5:00 pm
- Place: David Rubenstein Forum at the University of Chicago, 1201 E. 60th St., Chicago, IL 60637
- Speaker: Various, Various
- Abstract: The seventh annual Chicago Quantum Summit is a two-day program that will feature dialogue about the growing quantum technology economy, new research initiatives in the field, and efforts to build the quantum workforce. The event will also include the Boeing Quantum Creators Prize Symposium, which promotes early-career researchers whose work moves quantum science in new directions.
- Host: Chicago Quantum Exchange
- Graduate Program Event
- Virtual Open House for Physics Graduate Applicants
- Time: 10:00 am - 11:00 am
- Place: Zoom:
- Abstract: Applicants to the UW-Madison Physics PhD and MSPQC programs are invited to join faculty, staff and current students for a virtual open house to learn about admissions, program requirements and life in Madison. We'll have plenty of time for Q&A.
- Host: Sharon Kahn and Elizabeth Baldridge
- Wisconsin Quantum Institute
- Quantum Coffee Hour
- Time: 3:00 pm - 4:00 pm
- Place: Rm.5294, Chamberlin Hall
- Abstract: Please join us for the WQI Quantum Coffee today at 3PM in the Physics Faculty Lounge (Rm.5294 in Chamberlin Hall). This series, which takes place approximately every other Tuesday, aims to foster a casual and collaborative atmosphere where faculty, post-docs, students, and anyone with an interest in quantum information sciences can come together. There will be coffee and treats.
Wednesday, October 23rd, 2024
- Theory Seminar (High Energy/Cosmology)
- A Twist on Heterotic Little String Dualities
- Time: 4:00 pm - 5:00 pm
- Place: Chamberlin 5280
- Speaker: Hamza Ahmed, Northeastern University
- Abstract: 6D Little String Theories (LSTs) are an interesting class of UV complete theories which possess both QFT-like properties, such as higher-form global symmetries, and gravity-like properties, such as T-duality. In particular, this talk will focus on Heterotic LSTs and explore the T-duality landscape of such theories when discrete symmetry twists are allowed along the compactification circle. Starting from charge conjugation twists, we construct duality chains with (un)twisted LSTs by utilizing the duality invariant data and carefully considering the massive spectrum. This significantly extends the known T-duality landscape. To fully prove the duality, we realize dual theories as arising from inequivalent fibrations in F-theory on the same non-compact genus-one fibered Calabi-Yau (CY) manifold, and then use M/F-theory duality. Furthermore, we also consider discrete symmetries corresponding to the permutation of tensor multiplets and — based on the invariant data — construct a new class of duals (CHL-like twisted LSTs) with no known geometric construction.
- Host: Gary Shiu
Thursday, October 24th, 2024
- R. G. Herb Condensed Matter Seminar
- In-situ twisting and imaging of moiré superlattices
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Monica Allen, UCSD
- Abstract: Moiré superlattices, which form in twisted stacks of 2D materials, constitute a versatile platform for the exploration of topological and correlated phenomena. Here we present a route to mechanically tune the twist angle of individual atomic layers with a precision of a fraction of a degree inside a scanning probe microscope, which enables continuous control of the electronic band structure in-situ. In twisted bilayer graphene, we demonstrate nanoscale control of the moiré wavelength via mechanical rotation, as revealed using piezoresponse force microscopy. We also extend this methodology to create twistable boron nitride devices, enabling dynamic control of the ferroelectric domain structure. This approach provides a route for real-time manipulation of moiré materials, which may allow for systematic investigation of the phase diagrams at multiple angles in a single device. Looking forward, we will also discuss progress on the construction of a new milliKelvin microwave impedance microscope in a dilution refrigerator, which supports spatially-resolved detection of topological states in the GHz regime. As an application, I will briefly discuss the imaging of edge modes in a Chern insulator.
- Host: Alex Levchenko
- Preliminary Exam
- Characterizing the Diffuse Astrophysical Neutrino Flux with Contained and Uncontained Cascades in IceCube
- Time: 2:00 pm - 4:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Zoe Rechav, Physics PhD Graduate Student
- Abstract: Recently, the IceCube Neutrino Observatory has reported a deviation from a single power law in the extragalactic diffuse neutrino flux. This deviation is primarily driven by the hardening of the low-energy flux below 30 TeV. However, uncertainties remain in many features of the neutrino flux across the energy spectrum, including but not limited to the characterization of the neutrino flux below 30 TeV, the flux bump at ~30 TeV, the flux dip at ~500 TeV, and the characterization of the neutrino flux above 10 PeV. A stronger constraint on the energy spectrum is needed to resolve these uncertainties.
The DNNCascades event selection is a neural network based, high statistics cascade-like dataset that was first used to detect high energy neutrinos in the Galactic plane. As well as contained cascades, the selection includes ~30% uncontained cascades – neutrinos with interaction vertices at the edge or outside of the detector instrumentation volume. The high statistics, contained and uncontained cascades event selection could be key to more tightly constraining the diffuse flux across the energy spectrum.
My work involves optimizing this unique event selection to bring into the diffuse neutrino physics space. Extensive work on updated atmospheric neutrino background modeling, systematics updates, and data/MC improvement will be discussed, as well as my intention to perform an astrophysical diffuse flux measurement that could resolve uncertain features of the astrophysical spectrum. - Host: Lu Lu
- Astronomy Colloquium
- The X-ray Sky in High Definition: Twenty-five Years of Astrophysics with the Chandra X-ray Observatory
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Patrick Slane, Harvard Center for Astrophysics
- Abstract: X-ray astronomy is a product of the space age. Possible only from viewing platforms above the atmosphere, the first celestial X-ray source other than the Sun was discovered just over sixty years ago. Following fresh on the heels of this discovery, with X-ray astronomy just barely in its infancy, an almost unimaginably-bold proposal was put forth to build a visionary space-borne observatory based on X-ray optics whose resolution and sheer size represented leaps by orders of magnitude over any such mirrors ever built. Following a series of smaller, but ever-improving X-ray observatories, this vision was fully realized in July of 1999 with the launch and deployment of NASA's Chandra X-ray Observatory.
A quarter century later, Chandra remains the world's premier X-ray astrophysics facility - the crucial high energy component of NASA's fleet of flagship observatories. From resolving the hazy X-ray background into a speckled array dominated primarily by black holes to peering through a gravitational lens to peek at supermassive black hole formation at the edge of time, Chandra has continued to do things that no other X-ray observatory can. It is unique, it is powerful, and it is healthy - poised to help continue framing the future of high energy astrophysics for years to come. As we celebrate its ongoing success, I will provide a summary of some of the most exciting results from Chandra's ever-increasing scientific legacy, along with a look forward to its continued role as both a unique stand-alone facility and a core element for panchromatic investigations of the Universe. - Host: Melinda Soares-Furtado
Friday, October 25th, 2024
- Thesis Defense
- Alloy disorder, valley splitting, and shuttling for spin qubits in Si/SiGe heterostructures
- Time: 1:00 pm - 3:00 pm
- Place: 5310 Chamberlin Hall;
- Speaker: Merritt Losert, Physics PhD Graduate Student
- Abstract: Spin qubits in Si/SiGe heterostructures have several advantages as scalable qubit platforms, including their small size, their long coherence times, and their reliance upon conventional semiconductor fabrication methods. However, microscopic disorder in the semiconductor structure impact these qubits in a variety of ways, reducing qubit yield. In particular, the valley energy splitting (the energy gap between the two low-lying conduction band valley states) is widely variable, and highly sensitive to microscopic disorder. In this dissertation, we study the effects of disorder on spin qubits formed from quantum dots in Si/SiGe heterostructures, focusing particularly on the valley energy splitting. We demonstrate that alloy disorder (disorder due to the random arrangement of Si and Ge atoms in the SiGe alloy) has a profound impact on these qubits. We develop a theory to explain the impact of alloy disorder on the valley splitting, and we compare the results of this theory to a variety of experiments, finding good quantitative agreement. We demonstrate that alloy disorder determines the valley splitting in most realistic devices, and we propose a high-Ge heterostructure that enhances alloy disorder in order to increase average valley splittings. We also examine the impact of alloy disorder on long-distance qubit connectivity via conveyor-mode electron shuttling. We demonstrate that alloy disorder leads to valley excitations, causing quantum information to leak out of the qubit subspace. We develop a variety of schemes to mitigate these excitations, by either avoiding valley excitations or mitigating their impact, providing recipes for high-fidelity spin shuttling in several device regimes.
- Host: Mark Friesen; Susan Coppersmith
- Physics Department Colloquium
- No nus is good news
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall
- Speaker: Daniel Green, UC San Diego
- Abstract: Cosmic surveys offer a unique window into fundamental physics, particularly the physics of light particles such as neutrinos. The recent results from DESI have placed surprisingly stringent constraints on the sum of neutrino masses, nearly excluding the entire range of masses consistent with neutrino oscillation measurements. In this colloquium, I will review what we have learned about cosmic neutrinos from maps of the universe. I will the discuss this confusing situation, the status possible explanations for the current data, and the implications for Beyond the Standard Model physics.
- Host: Moritz Münchmeyer, Gary Shiu
- Black and Brown in Physics
- Gender Minorities and Women in Physics
- BBiP & GMaWiP LGBTQ+ Heritage Month Movie Night
- Time: 5:30 pm - 7:30 pm
- Place: Chamberlain 2241
- Abstract: The Black and Brown in Physics (BBiP), and Gender Minorities and Women in Physics (GMaWiP) student orgs would like to invite you to our combined LGBTQ+ Heritage Month movie night happening Friday Oct. 25 at 5:30 PM in Chamberlain 2241. In honor of it also being October, we plan on showing the movie “I Saw the TV Glow”, a psychological horror film. We will also be providing popcorn and drinks! We hope that you will be able to join us! Important Note: This movie has a trigger warning for suicide ideation / imagery. Official Trailer: Synopsis: A classmate introduces teenage Owen to a mysterious late-night TV show -- a vision of a supernatural world beneath their own. In the pale glow of the television, Owen's view of reality begins to crack.
- Host: Faizah Siddique
