Events During the Week of November 10th through November 16th, 2024
Monday, November 11th, 2024
- Informal String Theory Seminar
- Curvature-induced moduli stabilization
- Time: 10:30 am - 11:30 am
- Place: Chamberlin 5280
- Speaker: Flavio Tonioni, KU Leuven
- Abstract: We discuss FLRW-cosmologies with negatively-curved spatial slices that induce a late-time stabilization of all the moduli of an effective field theory through Hubble friction, independently of the moduli-space curvature. This holds for pure moduli, which appear ubiquitously in string compactifications. Crucially, the cosmological solutions approach a Milne universe. Hence, the mechanism we describe in fact corresponds to late-time moduli stabilization in Minkowski spacetime.
- Host: Gary Shiu
- 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
- Plasma Physics (Physics/ECE/NE 922) Seminar
- The Physics of SPARC and ARC: Predictive Results and Open Questions
- Time: 12:05 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Alex Creely, Common Wealth Fusion Systems
- Abstract: Commonwealth Fusion Systems and its partners are in the late stages of building the SPARC tokamak, aiming for operation by the end of 2026, and are in the early stages of designing the ARC fusion power plant, aiming for operation in the early 2030s. As part of designing SPARC and preparing for operations, a large body of computational and empirical predictive work has been completed. This work, combined with SPARC’s new parameter space and robust early diagnostic set mean that early operation of SPARC will provide a wellspring of opportunity to validate predictions, both computational and empirical, ranging from gyrokinetic predictions of core performance, to H-mode power thresholds, to alpha particle dynamics, and many more. This talk will present some of the most impactful predictive work for SPARC and summarize the unique opportunities for validation. Simultaneously, CFS and its partners have begun predictive physics work as part of the ARC power plant design process, with the understanding that there remain significant uncertainties in these predictions. This talk will summarize a number of early results of the physics analysis of ARC, including core turbulence, vertical stability, and heat exhaust. In addition, the strategy for incorporating both confirmatory and exploratory physics results from SPARC into the ARC design will be presented.
- Host: John Sarff
Tuesday, November 12th, 2024
- Council Meeting
- Physics Council Meeting
- Time: 12:00 pm - 1:00 pm
- Place: 2314 Chamberlin Hall
- Speaker: Kevin Black, UW - Madison
- Host: Kevin Black
- Physics Education Innovation Seminar
- Adapting Summer Term Physics 103 to an Online Format
- Time: 1:00 pm - 2:00 pm
- Place: B343 Sterling Hall
- Speaker: Benjamin Spike, University of Wisconsin - Madison
- Abstract:
Zoom Meeting ID: 302 365 8376
Zoom recording available. Please contact Josh Weber for access.
For the past two summers, Physics 103 has been taught in a semi-synchronous online format utilizing pre-recorded lectures and live discussions led by Teaching Assistants. The increased flexibility afforded by this format has resulted in a substantial increase in enrollment compared to previous summers, allowing greater access to the course for students who would otherwise have not been able to participate. In this talk I will describe the process of bringing Physics 103 online, highlight the innovative use of iOLab for remote laboratory activities, and discuss future directions for further enhancing the online course experience.
Speaker bio:
Ben received his Ph.D in physics from the University of Colorado-Boulder in 2014, having previously earned a B.S. in physics and mathematics from UW-Madison in 2007. He served as Academic Coordinator & Lecturer at the University of California-Berkeley before joining the UW-Madison physics department in 2017. Since then, he has overseen the implementation of active learning techniques in large-enrollment service courses including Physics 103 and 104. - Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
- Cosmology of Dark Energy Radiation
- Time: 2:00 pm
- Place: Join Zoom Meeting Meeting ID: 989 8774 9464 Passcode: 986897
- Speaker: Dr. Kim Berghaus , Caltech
- Abstract: If dark energy evolves in time its dynamical component could be dominated by a bath of dark radiation. Since dark energy was subdominant in the early universe, the dark energy radiation evades the usual stringent constraints on extra relativistic species from the cosmic microwave background, allowing for up to 9% of the energy density today to be dark radiation. In this talk, I will discuss how dark energy radiation can emerge from a fundamental theory, its predictions for cosmological observables, as well as discovery potential and constraints with existing and future precision cosmological datasets including measurements of the cosmic microwave background, baryon acoustic oscillations, and supernova data. Considering extensions that allow the dark radiation to populate neutrinos, axions, and dark photons, I will discuss the direct detection prospects of a thermal background comprised of these candidates consistent with cosmological constraints on dark energy radiation. A dark photon background is the most promising prospect for direct detection, and experimental programs such as the late dark energy radiation experiment (LADERA) will probe new parameter space.
NOTE: All participants and hosts are now required to sign into a Zoom account prior to joining meetings hosted by UC Berkeley.
- Host: Baha Balantekin
- Worlds in the Making: Origins of Stars, Planets, and Life
- Aging Worlds: Tracing the Evolution of Planetary Systems
- Time: 7:00 pm - 8:00 pm
- Place: Space Place
- Speaker: Melinda Soares-Furtado, UW-Madison
- Abstract: A series of talks by UW-Madison scientists from the Wisconsin Center for Origins Research (WiCOR), hosted by UW Space Place.
- Host: Jim Lattis
Wednesday, November 13th, 2024
- Department Meeting
- Time: 12:15 pm - 1:15 pm
- Place: B343 Sterling Hall -
- Speaker: Kevin Black, UW-Madison
- Host: Kevin Black
Thursday, November 14th, 2024
- R. G. Herb Condensed Matter Seminar
- Extrinsic and intrinsic superconducting diode effects
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Jukka Vayrynen, Purdue University
- Abstract: The critical current of a superconducting wire can be non-reciprocal, i.e., dependent on current direction, when inversion and time-reversal symmetry are broken. This so-called superconducting diode effect has gained renewed attention in recent years, due to the possibility that the effect may arise from the interplay of spin-orbit coupling and Zeeman effect in a uniform superconductor. I will discuss the superconducting diode effect originating from two different mechanisms, studied in recent preprints [1-2]. The first one is an extrinsic one arising from the geometry of the setup rather than intrinsic properties. It is however relevant for uniform superconducting heterostructures due to the formation of interfacial diamagnetic currents and Josephson vortices [1]. In the second part of the talk, I will discuss an intrinsic mechanism that is relevant for generic quasi-one-dimensional superconducting system where the critical current is determined by Cooper pair depairing. By introducing a minimal model, we find the key ingredients to obtain intrinsic superconducting diode effect. The model can be microscopically derived as a low-energy limit of a Rashba spin-orbit coupled superconductor in a Zeeman field [2] or of an edge state of a two-dimensional topological insulator [3]. The results quantify how system parameters such as spin-orbit coupling and quantum confinement affect the strength of the diode effect and provide a complementary description to previous Ginzburg-Landau theories of the effect. [1] Diamagnetic mechanism of critical current non-reciprocity in multilayered superconductors, Sundaresh, Vayrynen, Lyanda-Geller, Rokhinson, arXiv:2207.03633. [2] Superconducting diode effect in quasi-one-dimensional systems, de Picoli, Blood, Lyanda-Geller, Vayrynen, arXiv:2302.04277 [3] Superconducting Diode Effect in Two-dimensional Topological Insulator Edges and Josephson Junctions, Huang, de Picoli, Vayrynen, arXiv:2404.14566
- Host: Elio König
- Wisconsin Quantum Institute Colloquium
- Engineering a topological quantum computer
- Time: 3:30 pm - 5:00 pm
- Place: Discovery Building, DeLuca Forum
- Speaker: Brad Lackey, Microsoft
- Abstract:
I will provide a high-level introduction to Majorana qubits and show some recent experimental results at Microsoft that realize these in nanowire devices. I will then present a potential computing stack for a topological quantum computer based on Majorana qubits and provide some estimates about the capabilities of such a machine on some applications of scientific and industrial value.
This event starts at 3:30pm with refreshments, followed at 3:45pm by a short presentation titled "Efficient implementation of qLDPC codes with neutral atom qubits", by Cody Poole (Saffman group). The invited presentation starts at 4pm.
- Host: Mark Saffman
- Astronomy Colloquium
- An Equity-Minded Approach to Graduate Education: The Wisconsin Sloan Center for Systemic Change
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Erika Marín-Spiotta, UW-Madison
- Abstract: The Wisconsin Sloan Center for Systemic Change, or WiSC2, is a hub for innovating and leading transformative work for excellence in graduate education at UW. Supported by the Alfred P. Sloan Foundation, the aim of Systemic Change centers is to remove entrenched barriers to student success, improve student outcomes, and create educational environments that are more equitable and effective for all. Research at UW–Madison and elsewhere has shown that student success is influenced by students’ academic preparation and self-efficacy and their sense of community and their feelings of belonging. This is especially true for students from backgrounds historically excluded from higher education and from science.
- Host: Melinda Soares-Furtado
Friday, November 15th, 2024
- Physics Department Colloquium
- Attoseconds: faster than a New York minute!
- Time: 3:30 pm - 4:30 pm
- Place: Chamberlin 2241
- Speaker: Louis F. DiMauro, The Ohio State University
- Abstract: The genesis of light pulses with attosecond (10-18 seconds) durations signifies a new frontier in time-domain physics. This achievement was recognized by the 2023 Nobel prize in Physics for Agostini, Krausz and L’Huillier. The scientific importance is obvious: the time-scale necessary for probing the motion of an electron(s) in the ground state is attoseconds (atomic unit of time 24 as). The availability of attosecond pulses has allowed, for the first time, the study of the time-dependent dynamics of correlated electron systems by freezing the electronic motion, in essence exploring the structure with ultra-fast snapshots, then following the subsequent evolution using interferometry techniques. This talk will examine the fundamental principles, the underlying physics and the prescription for forming and measuring attosecond light pulses in the laboratory.
- Host: Uwe Bergmann
