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Events During the Week of October 25th through November 1st, 2020

Monday, October 26th, 2020

Plasma Physics (Physics/ECE/NE 922) Seminar
Zonal Flow Generation by Convectively Excited Waves
Time: 12:00 pm
Place: Zoom meeting
Speaker: Prof. Daniel Lecoanet, Northwestern University
Abstract: Many natural systems have turbulent, convective regions adjacent to stably-stratified regions. This occurs in most stars, the Earth’s atmosphere, and planetary cores. In all these systems, the turbulent convection can excite waves in the stably stratified region. Although these waves carry nearly zero net momentum, they can still spontaneously generate zonal flows in the stable layers. In this talk, I will describe recent work to characterize the wave excitation process, as well as the zonal-flow evolution induced by the waves. These studies can help interpret recent zonal-flow measurements in the Earth’s atmosphere as well as in red giant stars.

Connection information:

Join Zoom Meeting

Meeting ID: 991 5610 7574
Passcode: 883688
Host: Paul Terry
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Tuesday, October 27th, 2020

PGSC phenomeNal Open Graduate Seminar
Time: 2:30 pm
Speaker: Trevor Oxholm, Physics PhD Graduate Student
Abstract: You're Gonna Go Far, KID: cosmology with superconducting Kinetic Inductance Detectors on balloon- and space-based missions
Sub-millimeter astronomy is entering a new frontier. Earth’s atmosphere plagues ground-based sub-mm telescopes with high levels of background radiation, so astronomers are relocating their instruments to high-altitude balloons, and in the near future, onto satellites. This new era of low-background sub-mm astronomy requires highly sensitive detector technologies, for which we turn to superconductivity. The Kinetic Inductance Detector (KID), a superconducting microresonator technology that has only recently seen its first light, is being commissioned for this new generation of instruments. The EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM), led by NASA-Goddard Space Flight Center scientists, is among the first in this class of instruments. I will describe the technology behind KIDs designed for EXCLAIM, and the science we plan to accomplish. I will also describe the potential for the use of KIDs in future space missions, along with the science that can be accomplished with such a low-background, highly sensitive survey of the cosmos.
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Thesis Defense
Circuit Quantum Electrodynamics with Si/SiGe Quantum Dots
Time: 3:00 pm
Speaker: Nathan Holman, Physics PhD Graduate Student
Abstract: In this talk I present an approach to engineering quantum mechanical circuits utilizing superconducting resonators and Si/SiGe quantum dots in a cQED framework as a basis for quantum computing technology. I will discuss the microwave engineering principles for the quantum dot wiring to nearly eliminate unintended resonator photon leakage out the dot leads without the use of on chip lumped element LC filters. Using this approach, quality factors as high as 30k have been achieved and are limited by the intentional coupling of the resonator to the readout lead. Next, I discuss the development and characterization of a novel growth technique for an ultrathin (< 2 nm) and high quality SiO2 gate dielectric aimed at reducing charge noise. As a demonstration of improved charge coherence, I will show low frequency (< 500 MHz) Landau-Zener-Stückelberg-Majorana interferometry experiments of a dressed valley-orbit state. Lastly, I will present ongoing efforts to further improve device performance and reproducibility by decoupling the fabrication of the quantum dots and resonators using a multi-chip module architecture. Preliminary measurements of a double and triple quantum dots coupled to an off chip, high impedance TiN resonator will be shown.
Host: Mark Eriksson, Faculty Advisor
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Council Meeting
Time: 4:00 pm - 5:00 pm
Place: Virtual
Speaker: Sridhara Dasu, UW-Madison
Host: Sridhara Dasu, Department Chair
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Wednesday, October 28th, 2020

Department Meeting
Department Meeting - CANCELLED
Time: 12:15 pm - 1:30 pm
Place: Virtual see "abstract" for connection info
Speaker: Sridhara Dasu, Department Chair, UW-Madison
Host: Sridhara Dasu, Department Chair
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Thursday, October 29th, 2020

Astronomy Colloquium
Illuminating the Chemistry of Planet Formation with X-ray Flares
Time: 3:30 pm - 5:00 pm
Place: Zoom meeting(see Abstract ) Coffee and tea 3:30pm, Talk 3:45pm
Speaker: isle Cleeves, University of Virginia
Abstract: The chemistry of protoplanetary disks sets the initial composition of newly formed planets and may also regulate the efficiency by which planets form. Disk chemical abundances typically evolve over timescales spanning thousands if not millions of years. Consequently, it was a surprise when ALMA observations taken over the course of a single year showed significantly variable molecular emission in H13CO+ relative to the otherwise constant thermal dust emission in the IM Lup protoplanetary disk. HCO+ is a known X-ray sensitive molecule, and one possible explanation is that stellar activity is perturbing the chemical "steady state" of the disk. If confirmed, simultaneous observations may provide a new tool to measure (and potentially map) fundamental disk parameters, such as electron density, as the light from X-ray flares propagates across the disk.

Meeting ID: 885 1389 6776 Passcode: 713070
Host: Professor Stanimirovic and Coco Zhang
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Friday, October 30th, 2020

Graduate Introductory Seminar (Physics 701)
Using physics to understand and save coral reefs from climate change
Time: 12:05 pm - 12:55 pm
Place: BBCollaborate
Speaker: Pupa Gilbert, UW Madison Department of Physics
Host: Sridhara Dasu
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Theory Seminar (High Energy/Cosmology)
Quantum Penrose Inequality
Time: 2:00 pm - 3:00 pm
Place: For zoom link, sign up at:
Speaker: Marija Tomašević, Universitat de Barcelona
Abstract: According to the classical Penrose inequality, the mass at spatial infinity is bounded from below by a function of the area of certain trapped surfaces. We exhibit quantum field theory states that violate this relation at the semiclassical level. We formulate a Quantum Penrose Inequality by replacing the area with the generalized entropy of the light-sheet of an appropriate quantum trapped surface. We perform a number of nontrivial tests of our proposal, and we consider and rule out alternative formulations. We also discuss the relation to weak cosmic censorship.
Host: Lars Aalsma
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Department Coffee Hour
Time: 3:30 pm - 4:30 pm
Abstract: Join us weekly for an informal virtual coffee hour! Catch up with others in the department, tell us how things are going, and impress everyone with your Zoom background skills. Coffee Hour is open to any and all faculty, staff, and students in the department. Sometimes we have a topic, and we'll try to get that topic posted here in advance or sent out by email before each coffee hour.
Host: Department
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