Graduate Program Events |
Events During the Week of May 11th through May 18th, 2025
Sunday, May 11th, 2025
- Academic Calendar
- Graduate School Spring 2025: Doctoral degree deadline
- Time: 11:55 pm - 12:55 am
- Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu
Monday, May 12th, 2025
- Academic Calendar
- Spring Semester Grading deadline
- Abstract: *Note: actual end time may vary.*
- Preliminary Exam
- The Magellanic System: The Clouds and their circumgalactic medium within a cosmological context
- Time: 1:00 pm - 3:00 pm
- Place: B343 Sterling or
- Speaker: Robin Chisholm, Physics PhD student
- Abstract: Despite tremendous strides in our understanding of the Magellanic Clouds -the closest and most massive dwarf galaxies to the Milky Way (MW)- many questions, especially regarding their circumgalactic medium (CGM), remain open. We characterize the warm CGM of an isolated dwarf galaxy pair with properties similar to the Magellanic Clouds prior to their infall into a MW-mass halo, in the HESTIA cosmological simulations. The massive dwarf hosts a warm coronal gas envelope with a temperature of T ~ 3 x 10^5 K, consistent with expectations for virialized CGM in dwarf halos. Tidal interactions produce a neutral gas stream that extends over ~ 150 kpc, with an HI mass of ~ 10^8 M⊙, similar to the Magellanic Stream. Furthermore, in the Hestia simulation suite, we find that coronal gas is ubiquitous in all halos with M > 10^11 M⊙, implying that massive dwarfs generically develop extended gaseous envelopes prior to accretion. This result has significant implications for the survival of neutral tidal structures, and suggests that current and future high-ion UV absorption-line observations are indicative of warm coronae surrounding LMC-mass dwarfs, independent of their environment. We conclude by discussing future plans to further our understanding of the Magellanic System by running a suite of isolated simulations to constrain the Small Magellanic Cloud's orbital histories.
- Host: Elena D'Onghia
Tuesday, May 13th, 2025
- No events scheduled
Wednesday, May 14th, 2025
- No events scheduled
Thursday, May 15th, 2025
- No events scheduled
Friday, May 16th, 2025
- Thesis Defense
- Noise characterization for Spin and Charge qubits
- Time: 10:00 am - 12:00 pm
- Place: 5280 CH
- Speaker: Deepak Mallubhotla, Physics PhD student
- Abstract: Quantum computing offers substantial advantages over classical computers for certain problems, but a fundamental challenge persists: qubits suffer from environmental noise causing decoherence. To achieve scales required for practical applications, error correction techniques must overcome these noise limitations. Studying various noise types is essential for developing effective mitigation strategies.
This dissertation first analyzes evanescent-wave Johnson noise (EWJN) near small metallic devices. Caused by thermal and quantum charge motion in conductors, this noise creates field fluctuations beyond the conductor's surface. Noise correlations B(x, t) B(x', t') are calculated when device size is smaller than material skin depth, yielding closed-form solutions via multipole expansion.
Next, EWJN is examined near BCS superconductors using a half-space geometry where superconductor dimensions exceed qubit distance. Superconductors generate less noise than normal conductors at temperatures well below critical temperature, for both magnetic and electric fields. A Hebel-Slichter peak with enhanced noise appears just below critical temperature, dependent on qubit orientation.
Finally, this dissertation discusses 1/f charge noise.
It has been hypothesized that this noise is caused by fluctuating two-level systems (TLSs). We show that measurements of noise power spectral density do not fully determine TLS parameters exactly, and present a Bayesian technique of assigning likelihoods to different parameter ranges instead. This allows for partial, statistical information to be extracted, giving predictions of TLS size and density. Two recent measurements are analyzed, giving predictions consistent with both each other and with measurements in the literature obtained through other techniques. - Host: Maxim Vavilov/Bob Joynt
Saturday, May 17th, 2025
- No events scheduled
Sunday, May 18th, 2025
- Academic Calendar
- Faculty contract year ends
- Abstract: *Note: actual end time may vary.*