Colloquium
Spring 2022 Colloquia will be held in Room 307 of the Science and Engineering Research Facility (unless slated as virtual in the schedule below) on Mondays at 3:30 PM, EST.
Spring Colloquium Chair, Tova Holmes (tholmes@utk.edu)
Lawrence Weinstein, Professor and Eminent Scholar
Old Dominion University
Why don't we all drive electric cars? Does it really matter if you don't recycle that plastic water bottle? If the Sun were made of gerbils, would the Earth be incinerated? How can we answer these questions without relying on experts? This talk will cover the principles of estimating, introduce the "Goldilocks" categories of answers, and then look at some of the big (and small) questions of our time, including: Paper or plastic? Gasoline or electric cars? Should we pee before flying?
David A. Patterson, Cooper-Herron Endowed Professor of Mental Health Research and Practice
UT College of Social Work
Adjunct Professor in the UT Graduate School of Medicine
It is often said, no one gets out of life alive. Equally true is the fact that no one gets out of graduate school without emotion and often physical stress. Since 1980, multiple studies and meta-analyses of mindfulness based clinical interventions have found moderate to strong effect sizes for treatment of anxiety and mood symptoms associated with serious health conditions as well as for individuals experiencing mood-spectrum disorders, stress, and anxiety without co-morbid health conditions. In this conceptual and experiential presentation, we will briefly review the research evidence supporting the health and mental health benefits of mindfulness practices and the neuroscience of mindfulness practices. Session participants will be introduced to a few brief mindfulness practices and given resources for future use. Finally, as this will be an audience of physicists, nonduality and interconnectedness will be touched upon. “Subject and object are only one. The barrier between them cannot be said to have broken down as a result of recent experience in the physical sciences, for this barrier does not exist.” – Erwin Schrodinger.
Christian Ohm
KTH Royal Institute of Technology
After two successful runs of the Large Hadron Collider (LHC), the experimental verification of the particle content of the Standard Model (SM) has been completed with the discovery of the Higgs boson, and so far all searches for beyond-SM physics have resulted in exclusion limits. However, the data collected and analyzed so far is only 5% of the total foreseen until ~2040, and the absolute majority will be delivered by the upgraded High-Luminosity LHC which will explore the energy frontier during the 2030s. I will present an overview of the substantial upgrades of the ATLAS and CMS experiments for the HL-LHC that are currently underway, and the expected sensitivities for selected physics topics. As collider facilities like the LHC used by the global particle physics community take decades to design, construct, and commission, large community planning efforts (like Snowmass in the US) are currently evaluating several options for future colliders as well, and I will also discuss the main options under consideration.
David Matthews
UT College of Architecture and Design
Design Thinking is a human-centered (empathy-based) method of creative inquiry used to transform current conditions into preferred ones. Focus is on developing novel or innovative outcomes when conventional solutions are no longer relevant. Design thinking can be used in an array of disciplines and applications such as developing curricula and new courses, medical equipment, software, policies, and institutional structures. This introductory presentation is for all people interested in the learning processes of creative inquiry from a human-centered perspective.
Dipangkar Dutta
Mississippi State University
One of the motivations for the recent upgrade of Jefferson Lab was to precisely explore the connection between the fundamental quarks and gluons of Quantum Chromodynamics (QCD)- the accepted theory of the strong force - and the effective hadron descriptions of the strong interaction. The ultimate goal being an accurate understanding of the emergence of nuclei from QCD. The key experiments of this program typically aim to study fundamental QCD prediction in nuclei, in search of the onset of these phenomena. Many of the early experiments that have been completed at the upgraded JLab are part of this program designed to address the connection between quarks and nuclei. We will discuss some puzzling new results from the search for squeezed protons and the onset color transparency, a rigorous prediction of QCD. We will also highlight some upcoming experiments.
Hanno Weitering and ECC Members
| 3:00-3:30PM | Coffee, Cookies, and more! |
|---|---|
| 3:30-3:45 PM | State of the Department Hanno Weitering |
| 3:45-3:55 PM | Tasks and Activities of the ECC (Equity and Community Committee) Adriana Moreo |
| 3:55-4:05 PM | Outcomes of the Undergraduate and Graduate Surveys and proposed Actions Tova Holmes |
| 4:05-4:20 PM | Curriculum Development Anthony Mezzacappa |
| 4:20-5:00 PM | Floor open to Q&A from the audience |
Moderator: Adriana Moreo
Hitesh Changlani
Florida State University
We know from everyday life that depending on the external conditions, a large collection of atoms organizes itself into a solid, liquid, or gas phase. But how does a large number of interacting electrons (a situation frequently encountered in solid state systems) collectively behave? How does electronic matter respond to external electric and magnetic fields? Systems where these questions are difficult to answer are those where the correlations between electrons are strong, which is the case for unconventional high temperature superconductors and quantum magnets. Using examples of real materials and toy models, I show that such strongly correlated systems harbor a rich panoply of phases, which include "valence-bond solids," "quantum spin liquids," and "Fermi gases," and require us to embrace concepts such as "fractionalization" and "topological order." In the second part of the talk, I will focus on our investigations of frustrated magnetic materials (such as those on the kagome and pyrochlore geometries) that are fertile hunting grounds for novel phases of quantum matter. Frustration arises when multiple spatial arrangements of electron spin orientations each have similar collective energy, so there is no clear winner. I will discuss recent exciting experimental and theoretical developments in equilibrium and nonequilibrium dynamics that are enabling a comprehension of how such magnetic systems thermalize or act glassy (in the absence of disorder) in different situations. I conclude with stating some theoretical challenges that need to be addressed to achieve a more complete understanding of strongly correlated electronic matter.
Albert Young
North Carolina State University/TUNL
In the past year, several projects probing for particle physics beyond the "Standard Model" with low energy neutrons have made important progress. In these experiments, neutrons with average energies ranging from room temperature to only a few milli-Kelvin are used to perform high precision measurements sensitive to new physics. This colloquium will concentrate on two experiments: a measurement of the neutron lifetime called UCNtau and an interferometry project measuring waves diffracted from a thick, "perfect" Si crystal. UCNtau, an experiment at the Los Alamos Neutron Science Center, recently reported the most precise measurement of the neutron lifetime to date. Although the neutron lifetime has been measured with increasing precision many times over the past 70 years, it remains the focus of considerable interest both for its impact in probes for new physics and for the role it plays in defining our knowledge of the weak nuclear force. UCNtau determines the neutron lifetime by storing very low energy (ultracold) neutrons in a roughly 1 meter diameter bowl lined with permanent magnets, where they bounce off the magnetic fields in the bowl, and are prevented from escaping through the top of the trap by gravity. The motivation (which includes an ongoing experimental puzzle), recent progress and plans for an upgrade of UCNtau will be presented. The second project measures an interference pattern resulting from "pendellosung," where a neutron beam undergoing diffraction in a (vey nearly ideal) Si crystal produces an observable oscillatory signal in the intensity of the transmitted beam. This oscillatory provides a remarkably precise measurement of the potential experienced by the neutron, permitting a high precision test of the expected interactions of the neutron with the Si lattice. Results from an experimental campaign to measure neutron pendellosung in Si at the Neutron Interferometry and Optics Facility at the National Institute of Standards and Technology will be presented, providing new limits for gravity-like short-ranged forces and insight into the properties of the neutron and the properties of Si crystals.
Taylor Hughes
University of Illinois at Urbana-Champaign
In this talk I will introduce the recently developed concept of higher order topology and discuss realizations of higher order topological insulator phases in quantum materials and in analog engineered materials such as photonic crystals, microwave resonator arrays, and circuit resonator arrays. I will first present a broad overview of condensed matter physics and the role topology plays in this context, which I hope will appeal to a diverse, non-expert audience. For the second half of the talk I will move on to more recent theoretical and experimental developments which include the prediction and experimental discovery of higher order topological insulators. Finally, I will highlight the interplay between topology and geometry by illustrating the sensitivity of higher order topological insulators to crystalline defects such as disclinations, and partial dislocations.
Hans Christen
Oak Ridge National Laboratory
Neutrons, photons, and electrons are the three most common probes used to determine the structure and dynamics of materials. So, what is the advantage of using neutrons? In this presentation, I will describe how and why neutrons are used to understand topics as diverse as Li-ion conductivity in battery materials, strain evolution in 3D-printed structures, the binding between drug molecules and proteins, heat transport in thermoelectrics, and magnetic excitations in quantum materials. I’ll show examples from the two neutron sources at Oak Ridge National Laboratory: the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS), and I’ll describe the different characteristics of each source.
Stephen Wilson
UC Santa Barbara
Kagome metals are compelling materials platforms for hosting electronic states that feature an interplay between topologically nontrivial electronic states and correlated electron phenomena. These two features can, for instance, arise from the Dirac points, flatbands, and saddle-points endemic to the band structures of kagome networks. States featuring orbital magnetism and unconventional superconductivity are predicted to arise at select fillings, in particular within systems where the saddle-points are located close to the Fermi level. In this talk I will present some of our recent work exploring the electronic properties of two new classes of kagome metals, each with Z2 topology and saddle points close to Fermi energy. Specifically, our work studying the compounds AV3Sb5 (A=K, Cs, Rb) and RV6Sn6 (R=rare earth ion) will be presented. The former family of compounds exhibit an unusual charge density that shows hints of time-reversal symmetry breaking intertwined with a low temperature superconducting ground state. The latter family provide a tunable platform for interfacing magnetic order and frustrated magnetic interactions with a topologically nontrivial kagome band structure. Unconventional electronic properties observed in each class of these new kagome compounds and open questions will be discussed.
Michele Kotiuga
EPFL
Since the Bronze Age, humans have been manipulating, designing and optimizing materials to fit our needs. The advent of quantum mechanics in the early 1900s gave us the foundation to understand how a material’s properties stem from its constituent fundamental particles and how these properties can be manipulated. After nearly a century, computational tools based on quantum mechanics possess the accuracy to characterize materials in silico, in effect running virtual experiments, before they are ever synthesized. In order to direct the search for novel functional materials, insights from these calculations can be used to develop design rules. In this talk I will present results on a variety of perovskites, an extremely versatile class of materials exhibiting a wide range of function properties with the chemical formula ABX . First, I will discuss properties that stem from the crystal structure, focusing on ferroelectricity, along with a recent method we have developed to identify stable structures and its application in barium titanate (BaTiO ) — the prototypical ferroelectric perovskite. Second, I will discuss the ability of the rare-earth nickelates (RNiO ) to localize charge when doped at high concentrations leading to a reversible metal- or semiconductor-to-insulator transition. I will discuss experimental and computational results that demonstrate how these materials can be tailored for a number of potential applications from solid-state electrolytes to ferroelectrics.
Isobel Ojalvo
Princeton University
The LHC collider and its experiments have been successful in their effort to complete the Standard Model of particle physics through the discovery of the Higgs Boson. Measurements have been made in a variety of Standard Model production and decay modes. However, the currently funded colliders and experiments still leave a number of important measurements out of reach. Several attractive future collider concepts, which are potentially feasible to be constructed in the US or abroad in the next 10-30 years, are being considered during the Snowmass planning study. These are intermediate-scale and compact collider projects that could prove to be cost-effective and timely, and help advance particle physics beyond the HL-LHC goals. We discuss these collider proposals and the prospect of Higgs measurements at the future experiments.
Kelly Holley-Bockelmann
Vanderbilt University
Astronomers now know that supermassive black holes are in nearly every galaxy. Though these black holes are an observational certainty, nearly every aspect of their evolution -- from their birth, to their fuel source, to their basic dynamics -- is a matter of lively debate. Fortunately, LISA, a space-based gravitational wave observatory set to launch in 2034, will revolutionize this field by providing data that is complementary to electromagnetic observations as well as data in regimes that are electromagnetically dark. This talk will touch on our current understanding of how SMBHs form, evolve, and alter their galaxy host, and will outline the theoretical, computational and observational work needed to make the most of LISA observations.