Events at Physics |
Events During the Week of August 22nd through August 29th, 2021
Sunday, August 22nd, 2021
- Academic Calendar
- Official degree conferral date on diploma for students graduating at the end of Summer term 2021
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Academic Calendar
- Graduate School Summer 2021: Doctoral Degree Deadline
- Time: 11:55 pm - 12:55 am
- Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu URL:
Monday, August 23rd, 2021
- Academic Calendar
- Graduate School Fall 2021: Fall degree window period begins
- Abstract: *Important Note: The “Window Period” is the time between the end of one degree period and the beginning of the next. You must have been registered for the previous semester (Fall, Spring, or Summer). If all degree requirements are met by the end of the window period, your degree will be granted for the following semester. However, you will not have to register or pay fees for the next semester. CONTACT: 262-2433, gsacserv@grad.wisc.edu
- Thesis Defense
- Coherent and cavity-based measurement of two-particle states
- Time: 4:00 pm
- Place: Zoom link below
- Speaker: Joelle Corrigan, Physics PhD Graduate Student
- Abstract: With their small footprint and compatibility with industry fabrication techniques, semiconducting quantum dots have shown great potential as a platform for quantum computing.Though one of the most basic qubit implementations requires only a single electron within one quantum dot, many other platforms or readout schemes involve coupling between multiple quantum dots and differentiating between two-particle, singlet-triplet states. In silicon or Si/SiGe systems, the most basic singlet-triplet splitting depends on the valley state, which is much lower than the quantum dot’s potential-defined orbital state and can vary widely based on dot confinement and position (typically 5-40GHz). In this talk I first introduce a tunable latched readout scheme and demonstrate its use in charge-mapped readout of the quantum dot hybrid qubit. This scheme is then used to characterize a series of two-particle states using both Rabi and Ramsey pulsing, revealing 8 different transitions below 10GHz. The presence of these low energy levels is explained by considering electron-electron interactions within the system, and the data are fit using a six-level Hamiltonian. The last part of the talk will focus on a 3D integrated resonator-dot system. Driving the double-quantum-dot detuning at the cavity frequency reveals an enhanced coupling response of the cavity to the double-quantum-dot tunneling transition. This response is fit to using theory for a modulated longitudinal coupling between the dots and the cavity to good agreement. Finally, fast dc pulses are used to probe the singlet-triplet splitting in the system by populating excited states in the quantum dot. Join Zoom Meeting Meeting ID: 408 330 5280 Passcode: qubit
- Host: Mark Eriksson, Faculty Advisor
Tuesday, August 24th, 2021
- No events scheduled
Wednesday, August 25th, 2021
- Physics ∩ ML Seminar
- Towards Flow-based MCMC for Lattice Gauge Theory with Fermions
- Time: 11:00 am - 12:15 pm
- Place: Online Seminar: Please sign up for our mailing list at www.physicsmeetsml.org for zoom link
- Speaker: Danilo Rezende, Deepmind
- Abstract: In this talk, we’ll review some of the recent developments in Gauge equivariant normalizing flows and discuss their application to sampling field configurations in a lattice. We’ll start by looking at flows for scalar fields and their extension to include fermions in the Yukawa model; we’ll then move on to our work on sampling pure Gauge fields for U(N) and SU(N) Gauge theories. Finally, we’ll discuss how we could extend the pure-Gauge flows to include fermions in the Schwinger model.
- Host: Gary Shiu
Thursday, August 26th, 2021
- R. G. Herb Condensed Matter Seminar
- Imaging work and dissipation in the quantum Hall state of graphene
- Time: 10:00 am
- Place: Chamberlin 2103
- Speaker: Arthur
- Abstract: Dissipationless topologically protected states are of major interest as well as of practical importance in metrology and quantum information technology. Although topological protection can be robust theoretically, in realistic devices it is often fragile against various dissipative mechanisms, which are difficult to probe directly because of their microscopic origins. By utilizing scanning nanothermometry [1], we visualized and investigated microscopic mechanisms undermining the topological protection in the quantum Hall state in graphene. Our simultaneous nanoscale thermal and scanning gate microscopy enables to identify two distinct and spatially separated scattering processes. I will show how these observations reveal that the dissipation is governed by a crosstalk between counter-propagating pairs of channels that appear at graphene boundaries because of edge reconstruction due to charge accumulation at the edges[2]. Time permitting, I will present a semi-classical transport model quantifying the effect of edge accumulation under moderate magnetic fields and in particular the strikingly high non-local voltages it generates[3]. I will discuss its implication for Hall measurements in particular in the case of charge-neutral graphene. References : [1] D. Halbertal,et al., Nature 539, 407-410(2016) [2] A. Marguerite, et al., Nature 575, 628-633 (2019) [3] A. Aharon-Steinberg, et al., Nature 593, 528-534 (2021) ***************************** Seminar can also be viewed virtually at:
- Host: Victor Brar
Friday, August 27th, 2021
- No events scheduled