Events on Thursday, October 23rd, 2025
- R. G. Herb Condensed Matter Seminar
- Multi-Partite Entanglement and Spectral Witness in Quantum Materials
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Yao Wang, Emory University
- Abstract: The rapidly advancing field of quantum materials demands increasingly precise methods for characterizing and controlling entanglement. While early progress was made in quantum optics, extending these approaches to complex many-body systems in quantum materials remains a major challenge. In this talk, I will introduce the entanglement witness framework for characterizing the bounds of entanglement depth using solid-state spectroscopies. In the first half of the talk, I will begin with the detection of spin entanglement in quantum magnets through the quantum metrology and spin quantum Fisher information (QFI). These metrics can be accessed via inelastic neutron scattering and resonant inelastic x-ray scattering (RIXS). Importantly, RIXS provides a route to extend such probes far out of equilibrium, enabling the control of entanglement with light. In the second half of the talk, I will move beyond entanglement among distinguishable local modes to explore entanglement in systems of indistinguishable fermions. I will present a generalized framework for multi-particle entanglement among electrons, based on the cumulant reduced density matrix and the nonlinear response characteristics of RIXS.
- Host: Ilya Esterlis
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Multimessenger Probes of High-Energy Neutrino Production in AGN and Microquasars
- Time: 2:30 pm - 3:30 pm
- Place: Chamberlin 5280
- Speaker: Jose Carpio, University of Nevada
- Abstract: The discovery of astrophysical neutrinos by the IceCube Neutrino Observatory established neutrinos as a new messenger, opening a window to the most extreme particle accelerators in the Universe. Created in hadronic interactions, high-energy neutrinos are necessarily co-produced with γ-rays. The detection of neutrinos from NGC 1068, without accompanying γ-rays, thus reveals production in γ-ray–opaque environments, pointing to dense AGN cores as powerful accelerators. Meanwhile, IceCube's observation of Galactic neutrinos has opened a new front in understanding the sources of cosmic rays. Recent HAWC and LHAASO detections of >100 TeV γ-rays from microquasars such as SS 433 and V4641 Sgr show that compact binaries can also accelerate particles to high energies. This observation motivates targeted neutrino searches to determine whether the γ-rays are leptonic or hadronic in nature. In this talk, I will use the measured AGN neutrino spectra and γ-ray data to constrain source models and their contribution to the isotropic neutrino flux. In addition, I will use the γ-ray and X-ray data from SS 433 and V4641 Sgr to predict their neutrino fluxes from a hadronic component and assess their detection prospects with current and next-generation neutrino detectors.
- Host: Lu Lu
- Astronomy Colloquium
- Precise Stellar Properties via Bayesian Analysis of Stellar Evolution
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Prof. Ted von Hippel, Embry-Riddle Aeronautical University
- Abstract: While it is well known that astronomers can use stellar models to infer the ages of open and globular clusters, as well as populations of white dwarfs, what is often not appreciated is that with precision astrometry and photometry, we can frequently infer the ages of individual stars. Individual stellar ages are themselves valuable, for instance for exoplanet host stars, and these individual stellar ages can be aggregated for stellar population studies. I will discuss our Bayesian approach to comparing stellar evolution models to data to infer stellar ages, and also speak briefly about how this approach can be used to derive highly precise stellar cluster properties, infer binary mass ratios, and even study multi-component globular clusters. My group’s BASE-9 code, upon which this work is based, is open-source and available on GitHub, and for those interested in incorporating it into their research, we are happy to provide training and support.
- Host: Nicholas Stone