Each week during the semester, the Department of Physics invites faculty, students and the local community to hear prominent scientists discuss intriguing physics research. Unless otherwise noted, colloquia are held Tuesdays in room 1410 of the John S. Toll Physics Building at 3:30 p.m. (preceded by light refreshments at 3:00 p.m.).
UMD Physics Colloquium Series on YouTube: https://www.youtube.com/channel/UCNs64N_dGAjxWMIzG0wgDZA
For further information, please contact the Physics Department at 301-405-5946 or email .
September 8
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John Mather, NASAHosted by Steve Rolston New Technology for New Astrophysics
How is it possible that 1/4 of the Nobel Prizes in Physics since 2006 have been for astrophysics? All 5 of them came from new technologies, and two required space observatories. I’ll review the breakthrough ideas that grew into discoveries, and suggest where future technologies might go.
The JWST is working brilliantly, and has found Little Red Dots, the current mystery object. But there’s still no Earth 2.0. The DKIST solar telescope with adaptive optics is working beautifully. The Vera Rubin Telescope is online, the Nancy Grace Roman Space Telescope will be launched just before this colloquium to study dark matter, dark energy, and exoplanets, and the 39 m diameter Extremely Large Telescope will be doing science around 2030. Among the new possibilities: the Habitable Worlds Observatory, a workhorse UV-near IR observatory with a coronagraph for exoplanets, and X-ray and far IR observatories from Probe class ($1B) to flagships. New detector and mirror technologies are making both exciting. The NAUTILUS concept will use molded glass lenses up to 8 m in diameter in space to collect light for spectroscopy. We’re also developing hybrid observatories combining telescopes and interferometers on the ground with satellites. The Landolt absolute photometric calibrator beacon will fly in 2029, and the CELESTE mission is a proposed Small Explorer to offer a laser beacon for adaptive optics to the ELT, giving it diffraction-limited image quality at visible wavelengths where the sky is darkest. An orbiting starshade could cast a star shadow on the ELT and enable imaging of another Earth in one minute. The Black Hole Explorer would extend the Event Horizon Telescope with an orbiting antenna could measure the spin of a black hole. If you can imagine it, you can build it. |
September 15 |
Chris Palmer, University of MarylandThe Shape of the Higgs Potential, and Why It Matters
The Higgs mechanism explains how fundamental particles acquire mass, but the shape of the Higgs potential, the energy function that sets this mechanism in motion, remains poorly constrained. Its self-coupling terms are connected both to the stability of the electroweak vacuum and to whether the conditions for a first-order phase transition, relevant to the universe's matter-antimatter asymmetry, were present in the early universe. Measurements of single Higgs boson production are most directly sensitive to the potential's curvature near its minimum (the Higgs mass) with a loop-level handle on the self-coupling. The classic direct probe requires the exceedingly rare production of pairs of Higgs bosons. I will present my measurements of Higgs boson couplings and searches for Higgs pair production at the CMS experiment, the precision luminosity and machine-learning techniques that enable them, and prospects for constraining the Higgs self-coupling with the High-Luminosity LHC and future collider facilities.
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September 22 |
Juan Maldacena, IASHosted by Raman SundrumThe entropy of Hawking Radiation
Black holes are fascinating spacetime configurations predicted by general relativity. When quantum mechanics is taken into account, black holes are found to emit thermal radiation, called "Hawking radiation". Recently, an interesting area formula for the quantum entropy of black holes was derived. This also leads to a surprising new way to compute the entropy of Hawking radiation. This result indicates that black hole formation and evaporation are consistent with standard quantum-mechanical laws.
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September 29 |
TBA |
October 6
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Wes Campbell, UCLAHosted by Steve RolstonTBA |
October 13 |
Fall break
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October 20 |
Zohreh Davoudi, University of MarylandQuantum-computing frontiers in nuclear and particle physics
How does matter evolve after the Big Bang or in particle colliders? What does the phase diagram of strongly interacting matter look like? What is the dynamical response of a large nucleus to probes of new physics? A large, reliable quantum computer holds the promise of addressing these questions by enabling first-principles simulations of matter. In this talk, I will motivate the need for a quantum-computational nuclear- and particle-physics program, describe a journey toward quantum simulation of systems governed by the fundamental interactions of the Standard Model or their effective descriptions, and present current resource estimates for solving various problems of interest. I will also showcase examples that demonstrate remarkable progress in quantum-hardware implementations and theory-algorithm-experiment codesign efforts. Altogether, these advances will help position the field to take advantage of increasingly capable quantum computers as they become available.
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October 27 |
Anson Hook, University of MarylandTBA |
November 3 |
Shivaji Sondhi, Oxford UniversityHosted by Alicia Kollár TBA |
November 10 at 4 p.m. in AJC 1101Paint Branch
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Kerry Vahala, CaltechRings of Light: Nonlinear Optics in the Age of Integration
Light can be trapped and stored in microscopic rings of transparent materials, circulating millions of times at a discrete set of resonant frequencies. In these tiny structures, photons linger far longer than intuition would suggest, turning simple rings into extraordinary reservoirs of optical energy. Over the past several decades, advances in fabrication and design have pushed this photon recycling to unprecedented extremes. What began as a curiosity in resonant optics has evolved into a powerful new platform for nonlinear optics, ultra-stable lasers, and precision measurement. After a brief look back at the origins of these devices and the earliest nonlinear demonstrations, this talk will survey recent breakthroughs in ring-resonator technology and systems. A central theme will be the miniaturization of precision metrology to the chip scale: frequency synthesis, optical clocks, and microwave signal generation built from optical frequency microcombs. Integrated routes to highly coherent visible and near-visible light sources will also be highlighted. Finally, we look ahead to the transformative measurement and sensing systems enabled by these tiny rings of light.
Please note: this talk will be held in Clark Hall, room 1101 at 4 p.m. Refreshments will be served at 3:30 p.m. |
November 17Shih-I Pai
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Bill Bialek, Princeton UniversityHosted by Chris Jarzynski TBA |
December 1 |
TBATBA |
December 8 |
Roni Harnik, Fermi National Accelerator LaboratoryHosted by the Graduate Student Colloquium Committee TBA |