Events During the Week of June 22nd through June 29th, 2025
Monday, June 23rd, 2025
- Physics Department Colloquium
- Vera Rubin "First Look" watch party
- Time: 10:00 am - 11:30 am
- Place: 2241 Chamberlin
- Speaker: Keith Bechtol, Miranda Gorsuch, Nicholas Stone, Dean Wilcots, UW–Madison Physics, Astronomy, and College of Letters & Science
- Abstract: Join Keith Bechtol and his group as they celebrate the release of the first images from the Vera C. Rubin Observatory! We'll livestream the official press conference with image release from 10-11am, then Keith and others will hold a Q&A session moderated by Dean Wilcots at 11am. Join us for cake and coffee after the event. Learn more about the international event at
- Host: Keith Bechtol
Tuesday, June 24th, 2025
- No events scheduled
Wednesday, June 25th, 2025
- Social Gathering
- Summer Recess
- Time: 12:30 pm - 1:00 pm
- Place: Bascom Hall 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, June 26th, 2025
- No events scheduled
Friday, June 27th, 2025
- Preliminary Exam
- Fast, high fidelity, on demand qubit initialization out of a latched state using baseband pulses
- Time: 10:00 am - 12:00 pm
- Place: 5310 CH
- Speaker: Piotr Marciniec, Physics PhD Graduate Student
- Abstract: Latched schemes provide high-fidelity readout of quantum dot qubits by exploiting long-lived, nonequilibrium states with easily measured charge occupations. While long-lived latches simplify readout, fast re-initialization is also desirable and cannot be accomplished by relying on the natural decay process of the latched state. In this work, we demonstrate fast, high-fidelity reset of a latched quantum dot hybrid qubit that can be deployed on demand, using only baseband pulses. Our protocol circumnavigates the slow decay process of the latched state by pulsing to a region in gate-voltage space in which the latched state resets in a fast, two-step process. With this pulse, we achieve reset fidelities as high as 98% with reload times as short as 2μs. Our work provides a steppingstone to robust quantum error correction in quantum dot qubits, where the readout and initialization times should be comparable to gate times.
- Host: Mark Eriksson
- Preliminary Exam
- High-fidelity gates in a disordered Si/SiGe wiggle well with strong spin-orbit coupling
- Time: 1:00 pm - 3:00 pm
- Place: 5310 CH
- Speaker: Hudaiba Soomro, Physics PhD Graduate Student
- Abstract: Silicon-based single-electron spin qubits commonly use micromagnets to create an artificial spin orbit coupling (SOC) for Electric Dipole Spin Resonance (EDSR); however, this approach faces scalability challenges. Previously, it has been shown that the Wiggle Well may sufficiently enhance the otherwise weak SOC in the conduction band of Si, allowing for implementation of a strong EDSR protocol; previous calculations indicate that Rabi frequencies exceeding 500MHz/T may be possible [1]. However, SiGe random-alloy disorder causes spatial variations that have not been fully accounted for in these calculations. In this work, we show that alloy disorder gives rise to two main effects relevant for EDSR: the generation of a strong valley dipole (providing an additional EDSR mechanism), and randomization of valley parameters (providing a position-dependent Rabi frequency). We find that the valley-dipole contribution to the Rabi frequency is particularly pronounced in the low-valley-splitting regime. Additionally, we incorporate charge noise effects and compute the position-dependent T2,Rabi time, the dephasing rate, and the quality factor, finding quality factors of the order of 103 . Finally, we identify dephasing-protected ‘sweet spots’ where the qubit is resilient to charge noise.” [1] B. D. Woods, et al., Phys. Rev. B 107, 035418 (2023)
- Host: Mark Friesen
- Theory Seminar (High Energy/Cosmology)
- Neutrinoless double beta decay VS. two neutrino beta decay
- Time: 4:00 pm - 5:30 pm
- Place: Chamberlin 5280
- Speaker: C.S. Kim, Yonsei University
- Abstract: I will first explain 0nuBB decay, and then related practical Dirac-Majorana Confusion Theorem (pDMCT), and issues concerning pDMCT. I will also introduce possible alternatives to 0nuBB, and the quantum statistical approach to overcome pDMCT. Finally, I will compare 0nuBB with 2nuBB to find out which one would be better to discover Majorana property of sub-eV active neutrino.
- Host: Lisa L Everett