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Events During the Week of April 14th through April 21st, 2024

Monday, April 15th, 2024

Plasma Physics (Physics/ECE/NE 922) Seminar
“Continuum gyrokinetic study of high-field mirror fusion plasmas”
Time: 12:00 pm - 1:15 pm
Place: 1227 Engineering Hall
Speaker: Manaure Francisquez, PPPL
High-temperature superconducting (HTS) magnetic mirrors exploit strong fields with high mirror ratio to compress loss cones and enhance confinement, and may result in cheaper, more compact fusion power plants. Yet these devices may exhibit interchange instabilities, which can be studied with gyrokinetics given the strong magnetization and prevalence of kinetic effects. In this work [1] we aim to (a) determine if oft-used gyrokinetic models for open field lines produce the electron-confining (Pastukhov) electrostatic potential and (b) examine and address challenges faced by gyrokinetic codes in studying HTS mirrors. We show that a one-dimensional limit of said models self-consistently develops a potential qualitatively approaching the analytical Pastukhov level. Additionally, we describe the computational challenges of studying high mirror ratios with open field line gyrokinetic solvers and offer a method to mitigate small time steps needed for time integration in colossal magnetic field gradients produced by HTS coils, providing a 19X speedup. Additional algorithmic solutions will be discussed.

[1] M. Francisquez, et al. Phys. Plasmas 30, 102504 (2023)
Host: Prof. Cary Forest and Prof. Carl Sovinec
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Tuesday, April 16th, 2024

Council Meeting
CANCELLED: Physics Council Meeting
Time: 3:00 pm - 4:00 pm
Place: 2314 Chamberlin Hall
Speaker: Mark Eriksson, UW-Madison
Host: Mark Eriksson
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Wisconsin Quantum Institute
Quantum Coffee Hour
Time: 3:00 pm - 4:00 pm
Place: Rm.5294, Chamberlin Hall
Abstract: Please join us for the WQI Quantum Coffee today at 3PM in the Physics Faculty Lounge (Rm.5294 in Chamberlin Hall). This series, which takes place approximately every other Tuesday, aims to foster a casual and collaborative atmosphere where faculty, post-docs, students, and anyone with an interest in quantum information sciences can come together. There will be coffee and treats.
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Wednesday, April 17th, 2024

Department Meeting
Time: 12:15 pm - 1:15 pm
Speaker: Mark Eriksson, UW - Madison
will be rescheduled in the near future.
Host: Mark Eriksson
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Careers for Physicists
Career Talk - Inpleo Data Science
Time: 4:00 pm - 5:00 pm
Place: 5280 Chamberlin
Speaker: Orly Olbum, Chief of Data Science, Inpleo, Inc.
Abstract: We’re delighted to welcome Orly Olbum, Chief of Data Science at Inpleo, Inc., to talk about internship and career opportunities. Inpleo has opportunities for people at all levels – undergrad through postdoc.
We’ll gather in person . . .Orly will join us virtually.
Host: Sharon Kahn and Evan Heintz
Presentation: Inpleo.pdf
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Thursday, April 18th, 2024

R. G. Herb Condensed Matter Seminar
New twists on topology in moiré quantum matter
Time: 10:00 am - 11:00 pm
Place: 5310 Chamberlin
Speaker: Matthew Yankowitz, U Washington
Abstract: Moiré patterns formed by stacking atomically thin van der Waals crystals can give rise to dramatic new physical properties, in select cases generating flat bands that host a variety of intertwined correlated and topological states of matter. I will discuss two distinct moiré platforms that each exhibit their own unique topological properties. The first is twisted bilayer-trilayer graphene, in which we observe the formation of generalized anomalous Hall crystals that either triple or quadruple the area of the moiré unit cell. These states exhibit a fully-developed integer quantum anomalous Hall effect, with a Chern number that can be flipped between +1 and -1 by out-of-plane or in-plane magnetic fields or by an electric displacement field. The second system we study is twisted molybdenum ditelluride (tMoTe 2 ), which was recently found to host the fractional quantum anomalous Hall effect. By probing tMoTe2 on the atomic scale using scanning tunneling microscopy and spectroscopy, we are able to detect fingerprints of the layer pseudospin skyrmion lattice responsible for generating the topology of the moiré bands. Our findings showcase the diverse range of novel topological properties that can arise in moiré materials.
Host: Alex Levchenko
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Hunting for Galactic PeVatrons in the X-ray Regime
Time: 2:30 pm - 3:30 pm
Place: CH 5310 /
Speaker: Shuo Zhang, MSU
Abstract: Cosmic rays with energies up to a few PeV are believed to originate from our own galaxy. However, the origin of Galactic cosmic-rays has remained a mystery for over a century since their discovery. The H.E.S.S. observatory discovered a PeVatron within 10 parsecs of the center of our galaxy, which suggests that the supermassive black hole Sgr A* may be responsible. Despite being one of the least active supermassive black holes, Sgr A* may have acted as a potential particle accelerator during its active stage in the past. In this talk, I will describe our attempts to find multi-wavelength observational evidence that Sgr A* used to be a PeVatrons, as well as how we can reconstruct Sgr A* activity history in the past few million years. I will also introduce our ongoing observational efforts to identify other Galactic PeVatron candidates discovered by LHAASO and to test whether they bear a nature of supernova remnants, pulsar wind nebula or else.
Host: Lu Lu
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Wisconsin Quantum Institute Colloquium
Visible-Light Photonic Integration for Atomic and Quantum Sciences and Applications
Time: 3:30 pm - 5:00 pm
Place: Discovery Building, DeLuca Forum
Speaker: Daniel J Blumenthal, University of California Santa Barbara

Visible-light integrated photonics will enable compact, reliable quantum and atomic experiments. Integration also has the potential to bring about improved performance and scalability as well as new functionality for sensing, computation, clocks, and metrology. We discuss progress in ultra-low-loss silicon nitride integration for precision lasers, modulators, and other atomic and quantum related photonics. We will also describe progress towards higher-level functionality integration in experiments and applications that involve cold atoms, trapped ions and neutral atoms.

This event starts at 3:30pm with refreshments, followed at 3:45pm by a short presentation by Xuting Yang (Jennifer Choy group), titled "Atomic magnetometry using a metasurface polarizing beamsplitter". The invited presentation starts at 4pm.

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Astronomy Colloquium
NIRWALS: the Near InfraRed Washburn Astronomical Laboratories Spectrograph on SALT
Time: 3:30 pm - 4:30 pm
Place: 4421 Sterling Hall
Speaker: Marsha Wolf, UW-Madison
Abstract: Advances in astronomical instrumentation propel our understanding of the universe. One example is how integral field spectroscopic surveys of thousands of nearby galaxies over the last decade have revealed unprecedented spatially-resolved views into the details of galaxy evolution. The University of Wisconsin Astronomy Department’s Washburn Astronomical Laboratories specializes in integral field instrumentation. We were involved in the SDSS-IV MaNGA survey that observed 10,000 galaxies, recently commissioned the Near InfraRed Washburn Astronomical Laboratories Spectrograph (NIRWALS) on the 11-meter Southern African Large Telescope (shared-risk science observations begin in May 2024), and are currently developing a speckle imaging integral field spectrograph for the Lowell Discovery Telescope. This talk will focus on NIRWALS with descriptions of its development history, capabilities, early performance on SALT, and a preview into new galaxy evolution studies that it will enable. The near infrared spectral band allows access to nebular lines that are tracers of dust-obscured star formation, AGN activity, and shocks, providing a critical probe into galaxy quenching processes. Recent ALMA observations have shown that post-starburst galaxies, in which optical spectra indicate that star formation has been rapidly quenched, still contain significant reservoirs of gas. So, what stopped the star formation? We are launching a new project to observe 50 post-starburst galaxies with NIRWALS, using them as laboratories to investigate whether their star formation is still ongoing, but hidden by dust, or whether feedback from AGN or galactic winds have depressed star formation efficiency by dominating the ISM energetics in these galaxies.
Host: Ke Zhang
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Friday, April 19th, 2024

Physics Department Colloquium
Dual-Species Quantum Processors and Quantum Networks
Time: 3:30 pm - 5:00 pm
Place: 2241 Chamberlin Hall
Speaker: Hannes Bernien, University of Chicago
Abstract: Reconfigurable arrays of neutral atoms are an exciting platform to study quantum many-body phenomena and quantum information protocols. Their excellent coherence combined with programmable Rydberg interactions have led to intriguing observations such as quantum phase transitions, the discovery of quantum many-body scars, and novel quantum computing architectures. Here, I will introduce new methods for controlling and measuring atom arrays that open up compelling directions in quantum state control, quantum feedback and many-body physics. First, I will introduce a dual-species atomic array in which the second atomic species can be used to measure and control the primary species. We use an array of cesium qubits to correct correlated phase errors on an array of rubidium data qubits [1]. Rydberg interactions between the two species lead to novel regimes, including greatly enhanced resonant dipole interactions, that we use to demonstrate a 2-qubit gate and quantum non-demolition readout [2]. An alternative, hybrid approach for engineering interactions and scaling these quantum systems is the coupling of atoms to nanophotonic structures in which photons mediate interactions between atoms. Such a system can function as the building block of a large-scale quantum network. In this context, I will present quantum network node architectures that are capable of long-distance entanglement distribution at telecom wavelengths [3] and show how to combine atom-array capabilities with large photonic chips [4]. [1] Singh, Bradley, Anand, Ramesh, White, Bernien, Science 380, 1265 (2023) [2] Anand, Bradley, White, Ramesh, Singh, Bernien, arXiv:2401.10325 (2024) [3] Menon, Singh, Borregaard, Bernien NJP 22, 073033 (2020) [4] Menon, Glachman, Pompili, Dibos, Bernien, arXiv:2311.02153 (2023)
Host: Mark Saffman
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Academic Calendar
Graduate School Spring 2024: Request for all Master&#39;s and Doctoral Degree Warrants
Time: 4:00 pm - 5:00 pm
Abstract: CONTACT: 262-2433,
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