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Events on Wednesday, February 21st, 2024

Physics ∩ ML Seminar
Diffusion Models - A Thermodynamic Perspective
Time: 12:00 pm - 1:00 pm
Place: Chamberlin 2104
Speaker: Akhil Premkumar, KICP Chicago, University of Chicago
Abstract: Diffusion models have found immense success in modeling complex, high dimensional data distributions. Most recently, the text-to-video generation tool, Sora by OpenAI, uses such models to produce extremely high fidelity videos from simple text prompts. In this talk I will introduce a physicist-friendly intuition for diffusion models. Starting with first principles I will demonstrate how diffusion models can be understood as a variational problem, like the ones we come across in physics. I will give a thermodynamic interpretation to the these models, connecting them back to the fluctuation theorems that originally inspired their invention. Based on: arXiv:2310.04490
Host: Moritz Muenchmeyer
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Atomic Physics Seminar
Cavity-enabled measurements and interactions in neutral atoms
Time: 12:00 pm - 1:00 pm
Place: 5310 Chamberlin Hall
Speaker: Zhenjie Yan, UC Berkeley
Abstract: Control over interactions and measurements in quantum systems is crucial for applications such as quantum simulation and computation. In this talk, I will highlight our recent progress in realizing nondestructive readout and long-range interactions in atomic tweezer arrays using a strongly coupled optical cavity. Through selectively coupling a single atom with the cavity mode, we achieve a rapid mid-circuit measurement without perturbing the quantum coherence of the other atoms. Conversely, the collective emission from multiple atoms into the cavity can be coherently enhanced or suppressed. By controlling the atom-cavity interaction at the single-atom level, we observe both super- and subradiant cavity emissions from the constructed atomic ensembles. I will then discuss how we engineer long-range mechanical interactions via photon exchange and present our recent observation of a self-organization phase transition in a mesoscopic system. Finally, I will discuss how the cavity can be used to monitor and manipulate strongly interacting quantum gases, opening new avenues for experimental research in quantum many-body physics.
Host: Thad Walker
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Theory Seminar (High Energy/Cosmology)
Axion Dark Matter: From the Laboratory to the Cosmos
Time: 4:00 pm - 5:00 pm
Place: 5280 Chamberlin Hall
Speaker: Joshua Foster, MIT
Abstract: The quantum chromodynamics (QCD) axion, a possible solution to the Strong CP Problem, and more general axion-like particles, with their intrinsic connection to high-scale theories like Grand Unification and String Theory, represent uniquely well-motivated dark matter candidates. As an ultralight particle, the phenomenology of the axion is fundamentally wave-like, requiring paradigmatically different approaches in the search for dark matter. In this talk, I will describe an ongoing multi-pronged search effort targeting the discovery of the axion through precision measurement with the ABRACADABRA and DMRadio detectors in conjunction with observation of extreme astrophysical systems that may generate smoking-gun signals of their interactions with axions. I will then show how state-of-the-art techniques in high-performance computing can be applied to simulate the nonlinear processes that generate axions in the early universe, leading to sharp predictions of the QCD axion mass and shedding light on the dynamics and observable signals associated with networks of topological defects.
Host: Lisa Everett
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