Upcoming Colloquia

Monday, February 25

4:00 PM, C215 ESC

Simon Billinge

Columbia University, Applied Physics and Applied Mathematics

When hard materials act soft:

Local symmetry breaking in materials, how to find it, and why you should care about it

Modern materials under study for next generation technologies, such as for energy conversion and storage, environmental remediation and health, are highly complex, often heterogeneous and nano structured. A full understanding of the structure requires us to go beyond crystallography and to study the local structure, which is a major experimental challenge. There are recently emerging powerful experimental developments, for example, using the atomic pair distribution function technique (PDF), among others. In this talk I will focus on bulk materials that have distorted local structures, a potentially large class of materials where, nonetheless this property has been largely overlooked. In particular, I will focus on materials where atomic or bonding orbitals are electronically active, driving the local atomic distortions. I will describe a new language we are developing for classifying these materials, and new modeling tools that are under development to reveal the local structures. I will also mention areas that need addressing in this endeavor.

Prof. Billinge earned his Ph.D in Materials Science and Engineering from University of Pennsylvania in 1992, following a BA at Oxford University. He spent 2 years at Los Alamos National Laboratory as a post-doctoral researcher before joining the Physics & Astronomy faculty at Michigan State University in 1994.  In 2008 he took up his current positions as Professor of Applied Physics, Applied Mathematics and Materials Science at Columbia University and Scientist at Brookhaven National Laboratory. He has published more than 200 papers in scholarly journals, and is currently a Section Editor of Acta Crystallographica A: Advances and Foundations.  Honors and awards include being a fellow of both the American Physical Society and the Neutron Scattering Society of America, a former Fulbright Scholar and Sloane fellow, the recipient of the J. D. Hanawalt Award of the International Center for Diffraction Data in 2010, and recognition by the Carnegie Corporation of New York in 2011 for contributions to the nation as an immigrant. As an outstanding academic citizen, teacher, and scholar, he received the University Distinguished Faculty and the Thomas H. Osgood Undergraduate Teaching awards at Michigan State.  Prof. Billinge's research focuses on the study of local-structure property relationships of disordered crystals and nanocrystals using advanced x-ray and neutron diffraction techniques. In particular he is a leader in the development of the atomic pair distribution function (PDF) method applied to complex materials. These methods are applied to the study of nanoscale structure and its role in the properties of diverse materials of interest, for example, in energy, catalysis, environmental remediation and pharmaceuticals.

Monday, March 4

4:00 PM, C215 ESC

James Wells

University of Michigan, Physics

Testing origin-of-matter explanations through precision neutron studies

One of the most intriguing mysteries of nature is why there is more matter in the universe than anti-matter given that the basic laws of particle physics do not appear to allow for it. One promising direction of explanation attacks the conservation of baryon number, which I will argue is one of the most vulnerable principles in fundamental physics. Forthcoming neutron oscillation and transition experiments may reveal much about just how the universe managed to make us and not anti-us.

Professor Wells is a theoretical physicist whose research explores ideas designed to solve outstanding "origins" problems in fundamental physics: the origin of gauge symmetries, dark matter, flavor violations, CP violation, and mass.  After BS and MS degrees in Physics at BYU, he earned a PhD in particle physics at the University of Michigan in 1995, and then did post-doctoral research at SLAC-Stanford and CERN.  He joined the Physics faculty at UC Davis and Lawrence Berkeley Laboratory for several years before moving to the University of Michigan in 2002, where he is currently the PI of the High Energy Theory group.  He was also a Staff Scientist in Theory Division at CERN in Geneva (2007-2013).  Professor Wells is a Fellow of the American Physical Society, a recipient of an Outstanding Junior Investigator (OJI) Award from the U.S. Department of Energy, a recipient of the Sloan Fellowship from the Alfred P. Sloan Foundation, and a Humboldt Fellow.

Monday, March 11

4:00 PM, C215 ESC

Benjamin Pratt-Ferguson

Raytheon

Physics in Industry

Did you know that fewer than 20% of PhD physicists work in academia, with only 5% unemployment? Where are the rest of the physicists? Would you be interested in directed research with near-term realization of your work? Come learn about working in Industry! Often, Physicists enter the industrial workforce without much exposure or information on what to expect. Yes, they know how to solve problems and accomplish research into detailed subject areas, but what should they expect when joining a company where Engineering discipline is paramount?  This talk will discuss the requirements placed on new employees at an engineering based company, and the role of the physicist in the organization, along with statistical background information on physics in industry.

Monday, March 25

4:00 PM, C215 ESC

Tom Killian

Rice University, Physics and Astronomy

Laser Cooled Neutral Plasmas: A Laboratory for the Study of Strongly Coupled Systems

Through laser-cooling we have created plasmas with ion temperatures as low as 50 mK and achieved a factor of 4 enhancement in the coupling strength, placing the laser-cooled UNP in the same coupling regime as white dwarf stars and allowing for experimental benchmarking of new models and molecular dynamics simulations of transport.  Although the technique we use, optical molasses, is well established, the high collision rates and rapid hydrodynamic expansion of the plasma create a unique environment for laser cooling.  Ultracold neutral plasmas (UNPs), generated by photoionization of a laser-cooled gas, are a powerful platform for studying strong coupling in classical systems, and serve as an ideal laboratory model for other strongly coupled plasmas. In this talk, I will present experimental studies of self-diffusion and thermal equilibration, and describe the role of strong coupling in these phenomena. I will also present results from the first application of laser-cooling to a neutral plasma, which increases the achievable coupling strength.  Strong coupling arises when interaction energies are comparable to, or exceed, kinetic energies, and this occurs in diverse systems such as dense white dwarf stars, strongly correlated electron systems, and cold quantum gases. In all environments, strong coupling complicates theoretical description and gives rise to new, emergent phenomena.

Thomas Killian is a Professor of Physics and Astronomy and the Associate Dean for Strategic Planning in the Wiess School of Natural Sciences at Rice University. He joined the Physics and Astronomy Department at Rice in 2001, and his research focuses on the behavior of atomic gases and plasmas at extremely low temperatures, as low as a few billionths of a degree above absolute zero. Dr. Killian is a recipient of the Marshall Scholarship, the David and Lucille Packard Foundation Science and Engineering Fellowship, and the Alfred P. Sloan Research Fellowship. In 2010, he was elected a Fellow of the American Physical Society, and from 2012-2016, he was Chair of the Department of Physics and Astronomy at Rice.

Monday, April 1

4:00 PM, C215 ESC

Michael Griffin

BYU Mathematics

Monstrous Moonshine

Symmetries in nature are encoded by mathematical “groups.” In the 1970’s, during efforts to completely classify the finite simple groups, several striking apparent coincidences emerged connecting the then-conjectural “Monster group” to the theory of modular functions. Conway and Norton turned these observed ‘coincidences’ into a precise conjecture known as “Monstrous Moonshine.” Borcherds proved the conjecture in 1992, embedding Monstrous Moonshine in a deeper theory of vertex operator algebras which have important physical interpretations. Fifteen years after Borcherds’ proof, Witten conjectured an important role of Monstrous Moonshine in his search for a theory of pure quantum gravity in three dimensions. Under Witten’s theory, the irreducible components of the Monster module represent energy states of black holes. The distribution of these energy states can be found using tools from number theory.Moonshine-phenomena have also been observed for other groups besides the Monster. Notably the Umbral Moonshine conjectures of Cheng, Duncan, and Harvey arise from the symmetry groups of each of the 24-dimensional Niemeier lattices. In each case, we anticipate physical interpretations to gravity theories analogous to Wittens’ conjecture for Monstrous Moonshine.

Michael Griffin is an assistant professor at Brigham Young University. He recently finished a couple years as a postdoc at the Universität zu Köln and Princeton University. He researches number theory—particularly automorphic forms, Moonshine, and elliptic curves. He also enjoys hiking mountains and climbing rocks, and has a minor obsession with all things Indian.

Monday, April 8

4:00 PM, C215 ESC

Matthew Memmott

BYU Chemical Engineering

The Future of Nuclear Power in the US

Nuclear Power currently produces 20% of the US electricity, and has done so for several decades.  However, the current power generation markets and environments are leading to increased talk of nuclear reactor shutdowns.   What then is the future of nuclear power?   There is a clear path for nuclear technology and nuclear energy to move forward, though it will require adaptation, evolution, and vision.   This presentation will discuss the advantages, difficulties, and costs of advanced nuclear energy, and will discuss details of how such advanced nuclear energy might be made possible.

Dr. Memmott received a B.S. in chemical engineering from BYU in 2005, and a M.S. and PhD in Nuclear Science and Engineering from the Massachusetts Institute of Technology in 2007 and 2009, respectively. His research focuses on advanced nuclear reactor design, nuclear safety, and system modeling. Dr. Memmott currently teaches courses in fluid mechanics and introductory nuclear engineering. Dr. Memmott's graduate work focused on the development of innovative fuel configurations for sodium fast reactors. Following his graduation from MIT, Dr. Memmott worked as a senior engineer in the advanced reactor group at Westinghouse Electric Company. Dr. Memmott's research at BYU focuses on enhancing the passive safety of both current and advanced nuclear reactor technology while improving the economics, fuel utilization, and grid adaptability of current plants.

Monday, April 15

4:00 PM, C215 ESC

Shanti Deemyad

University of Utah

Physics of Light Dense Matter: Quantum and Classical Effects

Restricting the volume of material through application of pressure, changes the dominance of interactions within the material and exposes unnatural states of matter not found in our predominantly adiabatic universe. These new basic interactions include inner electron core chemistry, interstitial electron localizations, quantum criticality and quantum ground states. Such interactions do not play a significant role in the elegant organization of the periodic table at ambient pressure, however they play a role in a denser periodic table which to date remains mostly unexplored. One of the most exotic phenomena in condensed matter is the phase transitions purely driven by quantum effects. While quantum fluctuations in electronic states are always relevant, it is also possible to observe quantum effects in lattice of very light elements. At ambient conditions, the lightest metal of the periodic system is lithium. Similar to hydrogen and helium even at zero temperature lattice of lithium remains far from static. However, while the fascinating quantum nature of condensed helium is suppressed at high densities, due to its metallic nature, lithium is expected to adapt more quantum solid behavior under compression. In this talk I will review some of the major goals of research in high pressure physics and discuss the physics of ultra-light materials under extreme pressures. I will also present some of our studies on quantum contributions to the structural phase transitions of lithium at low temperature, the structure of its low temperature structure and will present our results on the resolving the long lasting mystery of lithium ground state 1,2.

We welcome anyone who wish to attend, and typically serve refreshments ten minutes before the colloquium begins. Speakers generally keep their presentation accessible to undergraduate physics students.