Events at Physics |
Events During the Week of August 2nd through August 9th, 2026
Monday, August 3rd, 2026
- No events scheduled
Tuesday, August 4th, 2026
- Thesis Defense
- Applications of Statistical Data Assimilation to Neutrino Flavor Oscillations in Solar and CCSN Environments
- Time: 11:00 am - 1:00 pm
- Place: 5280 Chamberlin or
- Speaker: Caroline Laber-Smith, Physics PhD Graduate Student
- Abstract: Neutrinos can be a powerful avenue for exploring astrophysical environments, as their low rate of interaction makes them reliable carriers of information. However, this same trait makes it difficult to observe neutrinos, leading to a lack of data. We explore applications within neutrino physics of statistical data assimilation (SDA), a technique well-suited to problems with sparse data. Specifically, we focus on neutrino flavor evolution inside of matter.
First, we take an SDA-based approach to modeling flavor evolution of solar neutrinos undergoing dynamics described by the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We incorporate measurements of solar neutrino flavor composition from the Borexino and Sudbury Neutrino Observatory experiments as a constraint for our model. This serves as a test case to establish the efficacy of SDA for neutrino oscillations. We find that this approach can reproduce the expected behavior from a typical forward integration method when the MSW effect is included in model dynamics. After verifying SDA can match established results, we use SDA to derive estimates of the solar neutrino mixing angle. Additionally, we constrain electron density inside the Sun and find a result consistent with the standard solar model.
We then turn to neutrinos in a core-collapse supernova (CCSN), where high neutrino density allows for complex behavior from neutrino-neutrino interactions. Despite their important role in CCSN dynamics, this complex nonlinear behavior makes collective CCSN neutrino oscillations difficult to model. We apply SDA to the task of modeling flavor evolution within the CCSN envelope, using a matter density profile and simulated measurements of neutrino flavor external to the CCSN. We demonstrate that SDA could be used with neutrino measurements to distinguish between multiple possible matter profiles, and to place a limit on fluctuations in matter density. - Host: A. Baha Balantekin
Wednesday, August 5th, 2026
- Social Gathering
- Summer Recess
- Time: 12:30 pm - 1:00 pm
- Place: Lawn in front of Birge Hall
- Speaker: Everyone is welcome
- Abstract: If the weather is nice, we'll meet on Bascom Hill (in front of Birge Hall). Feel free to bring your lunch. We will borrow cornhole and ladder toss from the L&S Dean's Office and play outside for 30 minutes. Some of us will probably walk up together, meeting in the courtyard between Chamberlin and Sterling ~12:25. Feel free to walk with us! No need to sign up. Just come join us!
- Host: Sharon Kahn
Thursday, August 6th, 2026
- No events scheduled
Friday, August 7th, 2026
- Preliminary Exam
- Qubit control in Si/SiGe: Hopping based single qubit gates
- Time: 10:30 am - 12:30 pm
- Place: 5310 Chamberlin
- Speaker: Minyoung Kim, Physics PhD Graduate Student
- Abstract: Control of spin qubits in Si/SiGe is conventionally achieved through electric dipole spin resonance (EDSR), which requires a high-frequency driving field and the accompanying heating that limits gate performance. An alternative is the hopping gate, in which an electron is shuttled between two quantum dots whose quantization axes are non-parallel, so that a universal gate is assembled from a sequence of wait times rather than by resonant driving. In this talk, I will present a systematic analysis of hopping-based universal single-qubit gates and their implementation in the Wiggle Well, a Si/SiGe heterostructure with oscillating Ge concentration which enhances intrinsic spin orbit coupling and couples the tilt angle between quantization axes to the valley phase of each dot. Because a physical ramp between charge configurations takes finite time, the evolution is decomposed into an idealized rotation and a residual "kick" operator, whose components can be extracted experimentally from hopping oscillations and then compensated. Simulations including Landau-Zener leakage, hyperfine fields from residual Si, Ge isotopes, and charge noise map the resulting infidelity landscape as a function of magnetic field and ramp time, identifying the regime in which high fidelity hopping gates are achievable. Related work on tunnl-and valley-coupling measurment in double quantum dots and ongoing noise correlation spectroscopy with excahnge-only qubits will also be discussed.
- Host: Benjamin Woods
Saturday, August 8th, 2026
- No events scheduled
Sunday, August 9th, 2026
- Academic Calendar
- 8-week Summer Session Ends
- Abstract: *Note: actual end time may vary.* CONTACT: admin@secfac.wisc.edu