Dr. Stephen Taylor, Vanderbilt University

Title: Charting the Gravitational-wave Universe At Light-year Wavelengths

Abstract: The Universe is thrumming with gravitational waves. June 2023 brought the first evidence for an all-sky background of nanohertz-frequency gravitational waves, discovered by collaborations including the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and groups in Europe, Australia, India, and China. This was an endeavor decades in the making, requiring painstakingly precise timing observations of scores of millisecond pulsars across the Milky Way using flagship radio telescopes. While the results from separate groups are consistent with one another—and the leading interpretation of a population of supermassive black-hole binaries as the source—the observations provoke many new questions. Do the results imply a population of binaries more massive than expected? What are the observational milestones as the first individually resolvable binary signals come into focus? Can we link these signals to their host galaxies or electromagnetic counterparts? In this talk, I will chart the path to discovery, reflect on what we have learned since our announcement, and explore the exciting opportunities and synergies ahead—including the role of next-generation radio instruments and space-borne gravitational-wave missions.

Dr. Zhoudunming (Kong) Tu, Brookhaven National Laboratory

Title: Exciting the Entangled Vacuum - A New Era in Understanding Visible Matter

Abstract: Not until quite recently was the vacuum recognized as anything more than empty space. Today, we understand it as a dynamic medium, filled with fluctuating fields and virtual particle pairs that shape the very structure of our universe. These invisible pairs break a fundamental symmetry of nature—chiral symmetry—and are thought to generate more than 99% of the mass of the visible universe. Yet, how this hidden mechanism connects to the confinement of quarks inside protons, neutrons, and other particles remains one of the deepest unsolved problems in physics.

In this talk, I will present new insights into this question using high-energy particle collisions at the Relativistic Heavy Ion Collider (RHIC). Such collisions can briefly liberate the virtual quark–antiquark pairs of the vacuum, which then bind together into hadrons such as Λ hyperons. Recent results from these studies open an experimental window into the quantum structure of the vacuum, with far-reaching implications for our understanding of mass, matter, and the strong force described by Quantum Chromodynamics.

Dr. Kyle Leach

Associate Professor

Department of Physics

Colorado School of Mines

Host: Korsch

Title: Hunting for Ghosts using Rare-Isotope Doped Superconducting and Optomechanical Sensors

Abstract: Nuclear beta and electron capture (EC) decay serve as sensitive probes of the structure and symmetries at the microscopic scale of our Universe. As such, precision measurements of the final-state products in these processes can be used as powerful laboratories to search for new physics from the meV to TeV scale. Significant advances in “rare isotope” availability and quality, coupled with decades of sensing technique development from the AMO community have led us into a new era of fundamental tests of nature using unstable nuclei. For the past few years, we have taken the approach of embedding radioisotopes in thin-film superconducting tunnel junctions (STJs) to precisely measure the recoiling atom that gets an eV-scale “kick” from the neutrino following EC decay. These recoils are encoded with the fundamental quantum information of the neutrino and decay process, as well as carrying unique signatures of weakly coupled beyond standard model (BSM) physics; including neutrino mass, exotic weak currents, and potential “dark” particles created within the energy-window of the decay. These measurements provide a complimentary and (crucially) model-independent portal to the dark sector with sensitivities that push towards synergy between laboratory and cosmological probes. In this talk, I will discuss the broad program we have developed to provide leading limits in these areas as well as the technological advances across several sub-disciplines of science required to enable this work, including subatomic physics, quantum engineering, atomic theory, and materials science. Finally, I will discuss future prospects of extending this work using macroscopic amounts of harvested exotic atoms from the Facility for Rare Isotope Beams (FRIB) in optically levitated nanospheres for direct momentum measurements of the decay recoils.

Neutrinos have come a long way in the human endeavor from their days as a ``desperate remedy.''  Their study now forms the cornerstone of the high energy physics program in the United States.  The U.S. will play host to an international project called DUNE which will explore many of the most important open questions in neutrino physics.  We discovered neutrino mass by doing long-distance quantum phase interferometry with large detectors that were both sensitive scientific instruments and exquisitely beautiful devices.  DUNE will employ an enormous liquid argon time-projection chamber to make the most thorough measurements of neutrino oscillation phenomena ever undertaken.  The large far detector will enable the exploration of a plethora of physical phenomena including nucleon decay and dark matter.  After briefly discussing the history of neutrinos, I will describe the measurements we will make with DUNE and some physics opportunities we will have along the way.