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Events at Physics

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Events During the Week of April 10th through April 17th, 2022

Sunday, April 10th, 2022

Wonders of Physics
The Wonders of Physics annual show
Time: 1:00 pm - 2:15 pm
Place: 2103 Chamberlin Hall or watch virtually at
Abstract: The Wonders of Physics 39th annual show! We're excited to welcome you back to 2103 Chamberlin for our presentation. It's filled with exciting demonstrations, lasts a bit over an hour, and is suitable for all ages. On Sunday, April 10, the annual shows will be livestreamed at
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Wonders of Physics
The Wonders of Physics annual show
Time: 4:00 pm - 5:15 pm
Place: 2103 Chamberlin Hall or virtually at
Abstract: The Wonders of Physics 39th annual show! We're excited to welcome you back to 2103 Chamberlin for our presentation. It's filled with exciting demonstrations, lasts a bit over an hour, and is suitable for all ages. On Sunday, April 10, the annual shows will be livestreamed at
Host: Haddie McLean
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Monday, April 11th, 2022

APS Chapters
APS Chapters Coffee Hour
Time: 1:00 pm - 2:00 pm
Place: Chamberlin 4274
Abstract: The UW Madison APS Chapter will be hosting a coffee hour and discussion of the APS webinar "Student to Student: Advocacy and Peer Initiatives to Strengthen Graduate Student Mental Health". Stop in to socialize over coffee and stay for the discussion!
Zoom link:
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Tuesday, April 12th, 2022

Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Black hole archeology with gravitational waves
Time: 2:00 pm - 3:00 pm
Place: virtual -
Speaker: Djuna Croom, IPPP Durham University
Abstract: The growing gravitational wave dataset makes black hole population studies possible. In this talk I will demonstrate how such studies can be used to study particle and nuclear physics. The key insight is that a wide range of initial stellar masses leave no compact remnant, due to the physics of pair-instability; the unpopulated space in the stellar graveyard is known as the black hole mass gap (BHMG). New physics can dramatically alter the late stages of stellar evolution and shift the BHMG, when it acts as an additional source of energy (loss) or modifies the equation of state. The latter will be the focus of this talk, in which I will show some new results with axions in the so-called cosmic triangle. I will also demonstrate how these predictions can be tested with the gravitational wave observations by the LIGO/Virgo/Kagra collaboration, and what we can already infer from GWTC-2 and 3. Join Zoom Meeting
Host: Baha Balantekin
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Council Meeting
Physics Council Meeting
Time: 4:00 pm - 5:00 pm
Place: 2314 Chamberlin
Speaker: Eriksson, UW-Madison, Department of Physics
Host: Eriksson
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Wednesday, April 13th, 2022

Physics ∩ ML Seminar
A duality connecting neural network and cosmological dynamics
Time: 11:00 am - 12:15 pm
Place: Chamberlin 5280 (Zoom link also available for online participants who signed up on our mailing list)
Speaker: Sven Krippendorf, Ludwig Maximilian University
Abstract: We demonstrate that the dynamics of neural networks trained with gradient descent and the dynamics of scalar fields in a flat, vacuum energy dominated Universe are structurally profoundly related. This duality provides the framework for synergies between these systems, to understand and explain neural network dynamics and new ways of simulating and describing early Universe models. Working in the continuous-time limit of neural networks, we analytically match the dynamics of the mean background and the dynamics of small perturbations around the mean field, highlighting potential differences in separate limits. We perform empirical tests of this analytic description and quantitatively show the dependence of the effective field theory parameters on hyperparameters of the neural network. As a result of this duality, the cosmological constant is matched inversely to the learning rate in the gradient descent update.
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Department Meeting
Time: 12:15 pm - 1:15 pm
Place: B343 Sterling
Speaker: Mark Eriksson, UW-Madison, Department of Physics
Host: Mark Eriksson
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Thursday, April 14th, 2022

ECE Distinguished Seminar Series
Geospatial Sensor Networks for Water and Agriculture
Time: 1:00 pm - 2:00 pm
Place: 1153 Mechanical Engineering
Speaker: Supratik Guha, Pritzker School of Molecular Engineering, The University of Chicago, Argonne National Labs
Host: ECE
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Friday, April 15th, 2022

Wisconsin Quantum Institute
HQAN Quantum Research Colloquium
Time: 9:00 am - 10:00 am
Place: 4274 Chamberlin
Speaker: Angela Kou (UIUC), Smitha Vishveshwara (UIUC)
Abstract: Join us for updates on the latest research from the NSF Quantum Leap Challenge Institute HQAN.
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Theory Seminar (High Energy/Cosmology)
A Cosmological Lithium Solution from Discrete Gauged Baryon Minus Lepton Number
Time: 1:00 pm
Place: Chamberlin 5280
Speaker: Seth Koren, University of Chicago
Abstract: We propose the infrared gauge symmetry of our sector includes an unbroken discrete gauged subgroup of baryon minus lepton number of order 2 x 3 colors x 3 generations = 18, the inclusion of which does not modify local physics. We UV complete this at Λ as the familiar U(1)_{B-NcL} Abelian Higgs theory, and the early universe phase transition forms cosmic strings which are charged under an emergent higher-form gauge symmetry. These topological defects catalyze interactions which turn 3 baryons into 3 leptons at strong scale rates in an analogue of the Callan-Rubakov effect.

The cosmological lithium problem---that the observed primordial abundance is lower than theoretical expectations by a factor of a few---is perhaps the most statistically significant anomaly of SM+ΛCDM, and has resisted decades of attempts by cosmologists, nuclear physicists, and astronomers alike to root out systematics. We write down a model in which B-NcL strings superconduct bosonic global baryon plus lepton currents and catalyze solely 3p+ → 3e+. We suggest that such cosmic strings have disintegrated O(1) of the lithium nuclei formed during Big Bang Nucleosynthesis and estimate the rate, with our benchmark model finding Λ∼108 GeV gives the right number density of strings.
Host: George Wojcik
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Physics Department Colloquium
Atoms Interlinked by Light: Programmable Interactions and Emergent Geometry
Time: 3:30 pm
Place: 2103 Chamberlin Hall
Speaker: Monika Schleier-Smith, Stanford University
Abstract: The graph of interactions in a quantum many-body system is crucial for governing the flow of information and the structure of correlations. We engineer programmable nonlocal interactions in an array of atomic ensembles within an optical resonator, where photons convey information between distant atomic spins. In our system of spin-1 atoms, the photon-mediated interactions manifest in the formation of correlated atom pairs. For all-to-all interactions, we verify the resulting entanglement by observing spin-nematic squeezing. We furthermore achieve versatile control of the graph of interactions by programming the spectrum of an optical drive field, thereby realizing effective geometries entirely distinct from the physical geometry of the array. We apply this toolbox to explore frustrated interactions, non-trivial topologies, and an emergent treelike geometry inspired by concepts of quantum gravity.
Host: Shimon Kolkowitz
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