Skip to main content

P&A Colloquium

Physics & Astronomy Colloquium

Dr. Elise Novitski, University of Washington

Title: A new approach to measuring neutrino mass

Abstract: Of all the fundamental fermion masses, those of the neutrinos alone remain unmeasured. From their unknown origin to their effects on the evolution of the universe, neutrino masses are of interest across cosmology, nuclear physics, and particle physics. Neutrino oscillation experiments have set a non-zero lower limit on the mass scale, in contradiction to the original Standard Model prediction. To measure neutrino mass precisely and directly one must turn to beta decay and search for a telltale distortion in the spectrum. I will describe a new technique called Cyclotron Radiation Emission Spectroscopy (CRES), in which beta decay of tritium occurs in a magnetic field and each electron's ~1 fW of cyclotron radiation is directly detected. Electron energies are then determined via a relativistic relationship between energy and frequency. I will present the first CRES-based mass limits from the Project 8 experiment, which demonstrate the promise of this technique for surmounting the systematic and statistical barriers that currently limit the precision of direct neutrino mass measurements. I will also describe the next steps on the path to sensitivity to a mass of 40 meV/c^2, covering the entire inverted ordering of neutrino masses

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Paul Torrey, University of Virginia

Title: Simulating the Universe: From Illustris to DREAMS

Abstract: Over the past few decades, cosmological simulations have revolutionized how we study galaxy formation and the large-scale structure of the universe. By combining advances in computational methods, physical modeling and high-performance computing, these simulations now allow us to trace the evolution of cosmic structure from the earliest moments after the Big Bang to the richly structured galaxies we observe today. 

Projects such as Illustris and IllustrisTNG have provided detailed, physically grounded predictions for how galaxies form and evolve, capturing the interplay among dark matter, gas dynamics, star formation and feedback from supermassive black holes. The publicly released data from these simulations have become a cornerstone of modern extragalactic astrophysics, powering thousands of scientific studies worldwide and shaping how we interpret observations across wavelengths and cosmic time. 

In this talk, I will highlight some of the key insights these simulations have revealed, emphasizing both their predictive successes and the limits of our current physical understanding. I will also discuss how new approaches, specifically the DREAMS simulation framework, are enabling us to quantify uncertainty across large, high-resolved cosmological ensembles, transforming simulations from single “best guess” models into powerful statistical laboratories for testing theories of galaxy formation.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Hendrik Schatz, Michigan State University

Title: Rare Isotopes in the Cosmos

Abstract: Atomic nuclei with short lifetimes of fractions of seconds, so called rare isotopes, play an important role in the universe despite their fleeting existence. They serve as stepping stones for the synthesis of chemical elements, they shape the nature of stellar explosions, and they are the major constituents of neutron stars. I will give an overview of the role of rare isotopes in the cosmos and recent efforts to study astrophysical reactions involving rare isotopes at the Facility for Rare Isotope Beams at Michigan State University. As an example, I will discuss accreting neutron stars. These systems are among the brightest X-ray sources in the sky and exhibit an extraordinay range of rare isotope physics. By combining observations, astrophysical modeling, and nuclear physics experiments they can provide new insights into the behavior of matter under extreme temperatures and densities. 

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Ambrose Seo, University of Kentucky

Title: Shaping Light and Charge in Two-Dimensional Materials with Plasmonic Nanostructures

Abstract: Two-dimensional materials such as MoS2 are just one atom thick, which gives them remarkable optical and electronic properties, but also makes them challenging to use efficiently in devices, since their ultrathin nature limits how strongly they interact with light. During my sabbatical in Seoul, I explored new ways to overcome this challenge by combining MoS2 with carefully designed metallic nanostructures that can trap and guide light at the nanoscale. By embedding gold or silver nanowires and nanogrooves beneath or alongside MoS2, we found that we could significantly boost its light emission, collect photo-generated charges more effectively, and improve the efficiency of heterostructures that pair MoS2 with oxide semiconductors. These studies show how "plasmonic" effects, i.e., collective oscillations of electrons in metals, can be harnessed to control light–matter interactions in atomically thin materials. I will present the key outcomes of these projects and discuss how they point toward future opportunities for next-generation devices.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Daniel Tataru, University of California, Berkeley

Title: Free boundary problems for Euler flows

Abstract: Free boundary problems are very interesting but also very challenging problems in fluid dynamics, where the boundary of the fluid is also freely moving along with the fluid flow. 

I will discuss two such models, governed by the compressible, respectively the incompressible Euler equations, including also MHD flows.  This is joint work with Mihaela Ifrim, and in part with Benjamin Pineau and Mitchell Taylor.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Erik Henriksen, Washington University

Title: Thermal transport in atomically thin materials

Abstract: Inspired by the potential to study quantum spin liquid-related phenomena in unusual magnetic materials, we are developing methods to measure thermal properties of single- and few-layer atomically thin materials as well as thicker flakes. We will briefly introduce the Kitaev-type quantum spin liquid and the most promising material candidate at the moment, a-RuCl3, and then review some recent experimental progress including a surprisingly large and useful charge transfer when a-RuCl3 is placed in proximity to other materials. The remainder of the talk will cover our latest work on a technique to simultaneously measure the thermal conductivity and specific heat in suspended quasi-2D systems starting with SiN membranes and moving on to flakes of a-RuCl3, hexagonal boron nitride and also the antiferromagnet FePS3.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Roger Pynn, Indiana University Bloomington

Title: What are Entangled Neutrons, Anyway?

Abstract: For more than 75 years, neutron scattering has been a powerful tool for probing the positions 
and dynamics of atoms, as well as the magnetic fields that shape material properties. In 
parallel, advances in light optics have increasingly harnessed the quantized nature of photons 
to achieve higher precision and uncover new phenomena. Can similar quantum ideas be 
applied to neutrons? Remarkably, the spin, momentum, and energy of individual neutrons can 
indeed be placed into entangled, Bell-like states. In this talk, I will describe how such 
entanglement has been realized experimentally, and how we validated its existence.
The challenge now is to exploit these mode-entangled neutrons to access new forms of 
information. Recent theoretical work suggests that entangled neutrons could uniquely probe 
electron spin entanglement in specific systems—though experimental confirmation remains to 
be achieved. Still, entanglement has already enabled measurements that would have been 
impossible otherwise. As one example, I will present the first observation of a giant Goos–
Hänchen effect for matter waves and indicate prospects for applying similar techniques to 
materials of scientific and technological relevance. Looking forward, these methods will be 
especially valuable at the next-generation neutron source now being planned at Oak Ridge 
National Laboratory.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Dr. Shahnawaz Rather, The University of Kentucky

Title: From Coherence to Correlation: Electron-Nuclear Dynamics in Photoinduced Processes

Abstract: Researchers have long pondered whether quantum mechanics might be relevant to the functioning of chemical and biological systems. This idea has fascinated scientists and the public alike, yet it has proven difficult to move beyond speculation and address the central question of functionally relevant quantum effects unequivocally. The challenge has been that realistic chemical or biological systems exhibit enormous energetic disorder, preventing quantum coherence effects from surviving over functionally relevant timescales. However, recent work has indicated that coherence phenomena can appear differently from what researchers initially expected. Rather than manifesting or functioning as quantum bits, coherence effects in molecular systems appear to involve electron-nuclear correlations that can be robust and functionally relevant.

I will present the state of recent discoveries that extend beyond the extensively studied photosynthetic systems. I argue that electron transfer reactions occurring on ultrafast timescales provide a profound basis for understanding electron–nuclear correlations and demonstrate how vibrations can dictate reaction outcomes. I will discuss electron-nuclear correlations through the spin-vibronic effect and how it regulates singlet–triplet conversion in binuclear transition-metal complexes. I will also describe how electron-nuclear interactions can drive energy flow in photocatalysts from a light-harvesting site to a reaction site by bridging the two entities via vibronic delocalization. Toward the end, I will share some of our recent results on shifting vibronic resonances in singlet fission. I will conclude with a forecast that order on the quantum-mechanical scale, even in energetically disordered systems, can emerge from robust electron-nuclear correlations. This understanding could ultimately enable the design of structural control elements for enhanced functioning of energy-conversion systems.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Title: Final result from the Fermilab Muon g-2 Experiment

Abstract: On June 3, 2025, the Fermilab Muon g-2 Collaboration released its final determination for the muon's magnetic anomaly, a_μ = (g - 2)/2. Our result, after roughly a decade of design and construction and six years of data taking, was a_μ = 116 592 071(15)×10−11. The anomaly a_mu was determined from the ratio of the muon's anomalous precession frequency and the proton's Lamor precession frequency in the magnetic field of a 15 m diameter, 1.5 Tesla, superconducting muon storage ring. In this talk I'll discuss the science that motivated the  g-2 project and the techniques used to reach the 127-ppb precision. I'll also comment on the future work on the muon anomaly and the June 3, New York Times headline that the 'Muon Experiment was Hugely Successful but Clarifed Little'.

Date:
-
Location:
CP 153
Event Series:

Physics & Astronomy Colloquium

Title: Evidence for Missing Matter in the Inner Solar System: Does the Sun have a Dark Disk?

Abstract: The total mass and distribution of dark matter within the Solar system are poorly known, albeit constraints from measurements of planetary orbits exist. We have discovered, however, that different sorts of determinations of the Sun’s gravitational quadrupole moment can combine to yield new and highly sensitive constraints on the mass distribution close to the Sun. These outcomes provide evidence for a non-luminous disk in this region, nominally coplanar with Mercury’s orbit, and we develop how we can use this finding to limit its mass. The mass estimates associated with its known matter components, although uncertain, point to a prominent dark-matter contribution, which merits further investigation. We describe how existing spacecraft studies of the inner solar system support the existence of a circumsolar dust ring, and we note how continuing observational studies of the inner solar system, including the use of space-based quantum technology, can not only help to refine these constraints but also to identify the nature of and the mass of its dark-matter component.

Date:
-
Location:
CP 153
Event Series: