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Events on Friday, April 15th, 2022

Wisconsin Quantum Institute
HQAN Quantum Research Colloquium
Time: 9:00 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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