Events at Physics |
Events During the Week of October 13th through October 20th, 2024
Monday, October 14th, 2024
- 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
- Improved NBI and diagnostics on the Lithium Tokamak Experiment-β
- Time: 12:05 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Bill Capecchi, University of Wisconsin-Madison
- Abstract: Neutral beam injection (NBI) can fulfill a crucial role in sustaining, fueling, and heating low recycling plasmas in the Lithium Tokamak Experiment-β (LTX-β). Initial results and modeling showed limited heating and low coupling of the beam due to a strong dependence on variations in beam and plasma parameters throughout a discharge, and were only successful at a modest beam energy of 13 keV, well below the maximum beam energy of 20 keV. Modeling of these discharges suggested heating above that observed, indicating the need for improved determination of the injected beam power and profile shape. A 2D tungsten wire calorimeter has been designed and installed at the outlet of the neutral beam neutralizer which will give shot specific beam profile data and allow improved constraints on future beam modeling. A neutral particle analyzer (NPA) from UW-Madison is being installed to provide direct measurement of the confined fast ion population energy distribution. LTX-β is completing a vented maintenance phase during which the neutral beam was realigned to a more optimal injection geometry. Previous modeling has predicted peak beam coupling occurs at a tangency radius around 35 cm; the actual shift from 19 to 33 cm (limited by scrape-off on the injection port) is predicted to improve beam coupling by 30% at a beam energy of 13 keV. Improvements to coupling increase with beam energy; at the max beam energy of 20 keV the coupled fraction is expected to double. The status and plans for the upcoming run campaign will be discussed.
- Host: John Sarff
Tuesday, October 15th, 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
- Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
- Leptogenesis with testable right-handed neutrinos
- Time: 2:00 pm
- Place: Join Zoom Meeting ID: 989 8774 9464 Passcode: 986897
- Speaker: Stefan Sandner , LANL
- Abstract: The talk will focus on the testability prospects of the minimal type-I seesaw model to generate the light neutrino masses and the associated mechanism generating the observed baryon asymmetry.
We will see how CP invariants emerge in the analytical solutions of the quantum kinetic equations, which will, in turn, reveal previously undiscovered correlations among various observables.
For non-degenerate right-handed neutrinos, a significant modification of the neutrinoless double-beta decay rate is anticipated compared to that of active neutrinos, at reach of current and future experiments, and a highly constrained flavor structure for the mixing with the active neutrinos. On the other hand, for degenerate right-handed neutrinos, we will see how light neutrino oscillations and collider experiments are sufficient to fully predict both the baryon asymmetry and the amplitude of neutrinoless double-beta decay.
- Host: Baha Balantekin
Wednesday, October 16th, 2024
- Department Meeting
- Time: 12:15 pm - 1:15 pm
- Place: B343 Sterling Hall -
- Speaker: Kevin Black, UW-Madison
- Host: Kevin Black
Thursday, October 17th, 2024
- R. G. Herb Condensed Matter Seminar
- An Electron Linear Accelerator for On-Demand Qubit Irradiation
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Thomas McJunkin, Johns Hopkins University
- Abstract: Superconducting transmon qubits are known to be susceptible to errors due to ionizing radiation from ambient radioactive decay and cosmic ray sources (muons). In this talk, I'll present an electron linear accelerator (linac) as an on-demand high-energy particle source to study deleterious effects on a multi-qubit transmon system. The linac provides a pulsed, microsecond burst of ~20 MeV electrons that are redirected at a modified dilution refrigerator. I'll show how single electron collisions with the quantum chip mimic the energy deposition from a typical cosmic ray muon and cause correlated qubit errors. The error dynamics of individual qubits and the system as a whole can be easily and quickly extracted due to the on-demand nature of our radiation source. Though radiation-induced quasiparticle tunneling primarily results in transient relaxation errors, this experimental scheme also reveals excitation and frequency detuning errors. I'll also present differences in error behavior due to qubit design and state preparation. This new facility provides a testbed for novel qubit design and packaging techniques for radiation-induced error mitigation.
- Host: Mark Friesen
- Climate & Diversity
- L & S Lunch and Learn
- Time: 12:00 pm - 1:00 pm
- Place: Zoom
- Speaker: L&S DEI Leadership
- Abstract: How to be culturally responsive to mentoring graduate students
- Department Meeting
- Closed Department Meeting
- Time: 12:15 pm - 1:00 pm
- Place: VIRTUAL, link will be sent later.
- Speaker: Kevin Black, UW-Madison
- Closed meeting to discuss personnel matters—pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law Closed to all but tenured faculty
- Host: Kevin Black
- Astronomy Colloquium
- High Fidelity Spectroscopy of Exoplanet and Protoplanetary Disk Atmospheres
- Time: 2:30 pm - 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Geoffrey A. Blake, California Institute of Technology
- Abstract: The extraordinary range of conditions in protoplanetary disks drives complex patterns of atomic, molecular, and dust abundances - especially for abundant 'volatile' species such as water, carbon monoxide, and small organics that condense at different spatial locations, or 'snowlines' in the disk. The bulk composition of planets can thus vary, compared to that of their host star, depending on their origin and migration history. The latest generation of Adaptive Optics (AO)-fed infrared spectrographs now provide sufficiently high dynamic range capabilities to robustly characterize exoplanetary and protoplanetary disk atmospheres. This talk will present an overview of recent results from Keck Planet Imager and Characterizer (KPIC)-NIRSPEC studies of exoplanet/brown dwarf atmospheres and those from the JWST Infrared Spectroscopic Chemistry Survey (JDISCS) conducted with Mid-InfraRed Instrument (MIRI) IFU.
- Host: Melinda Soares-Furtado
- Wisconsin Quantum Institute Colloquium
- Quantum Computing and Quantum Security for the Financial Industry
- Time: 3:30 pm - 5:00 pm
- Place: Discovery Building, DeLuca Forum
- Speaker: Marco Pistoia, JPMorganChase
- Abstract:
The world of computing is evolving at a groundbreaking rate with quantum computing offering exponential accuracy and processing speed for solving a variety of financial use cases when compared to traditional compute strategies. On the flip side, although quantum computing has the potential to drive transformational changes across digital society, these advances in computational power will also introduce significant risks such as the disruption to widely used encryption standards. This presentation will discuss some recent results obtained by JPMorganChase in the field of quantum computing and quantum cryptography. For quantum computing, we will go over scaling advantage, random circuit sampling, some recent quantum optimization work, and the opportunity to integrate quantum computing and quantum communications for privacy in distributed machine learning. In the area of quantum cryptography and networking, we will discuss the need for building security solutions that encompass both post quantum cryptography and quantum key distribution.
This event starts at 3:30pm with refreshments, followed at 3:45pm by a short presentation titled "Facilitating Variational Quantum Algorithm Design with Reconstructed Landscapes", by Tianyi Hao (Tannu group). The invited presentation starts at 4pm.
- Host: Swamit Tannu
Friday, October 18th, 2024
- Preliminary Exam
- Gate tunable spin splitting of germanium quantum well Josephson junctions
- Time: 1:00 pm - 3:00 pm
- Place: 5310 Chamberlin Hall or
- Speaker: Avani Vivrekar, Physics PhD Graduate Student
- Abstract: In my prelim exam, I will discuss Andreev spin qubits, a novel super-semi hybrid platform for quantum computation. Proximitized germanium (Ge) heterostructures are a promising host platform for Andreev qubits due to their strong spin-orbit coupling, high mobility, and naturally low nuclear spin abundance. A key distinction between Ge and traditional materials used for Andreev qubits, such as indium arsenide (InAs), is the form of their Rashba spin-orbit coupling, which is linear in momentum for InAs but cubic for Ge. In this talk, I will compare the effects of linear versus cubic spin-orbit coupling on the physics of Andreev qubits. I will also discuss the impact of charge defects on Andreev spin qubits in both InAs and Ge and explore the implications of these analyses for implementing Andreev spin qubits using Ge.
- Host: Mark Friesen
- Physics Department Colloquium
- Backlighting the large-scale structure with the cosmic microwave background
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin
- Speaker: Emmanuel Schaan, Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), Stanford
- Abstract: Upcoming large-scale structure (LSS) and cosmic microwave background (CMB) experiments offer a unique opportunity to turn the Universe into a particle physics laboratory and determine the nature of dark matter, dark energy, and the masses of the neutrinos. I will present innovative methods to jointly analyze these datasets and unleash their full constraining power. My group's research explores two powerful ways of using the CMB as a backlight for the LSS: revealing the invisible dark matter (gravitational lensing) and baryons (Sunyaev-Zel'dovich and patchy screening effects) via their shadows on the CMB. These methods will yield percent-precision maps of the dark and baryonic matter on cosmic scales, from combinations of CMB experiments like the Atacama Cosmology Telescope, Simons Observatory and CMB-S4 with LSS experiments like the Dark Energy Spectroscopic Instrument and the Rubin Observatory. These will not only shed light on dark matter, dark energy and the neutrinos, but they will also constrain models of inflation and transform our understanding or galaxy formation.
- Host: Moritz Muenchmeyer