Wayne State University

Aim Higher

Colloquia are presented on Thursdays at 3:45 pm in Room 245 of the Physics Building, unless otherwise noted.

Refreshments are served at 3:30 pm.

2016-2017 Schedule

Thursday, September 8th, 2016

     Speaker: Dr. Chris Polly, Fermilab

      Title: Muon g-2 and the quest for new physics

      Abstract: One of the most imperative questions in particle physics today is whether or not new physics will emerge at the few TeV scale. Observational hints for new physics have arisen from several sectors with exciting theoretical implications that can potentially be explained by supersymmetry, dark matter, or other exotic models.  One of the most persistent hints comes from the Brookhaven muon g-2 experiment, where an ultra-precise measurement of the muon anomalous magnetic moment differs by >3 sigma from the theoretical expectation.  The anomalous magnetic moment of the muon provides a unique window into the TeV scale, and a new effort is underway at Fermilab to improve the experimental precision.  A review of the physics, the principles behind the experiment, and the incredible journey to bring the experiment to the point it is at today will be discussed.

Thursday, September 15th, 2016 

      Speaker: Prof. Sambandamurthy Ganapathy, SUNY Buffalo

      Title: Nanoscale investigation of strongly correlated oxide materials

      Abstract: Strongly correlated materials display a rich variety of phenomena, including superconductivity, giant magnetoresistance and metal-insulator transitions, as strong interactions lead to competing ground states. Vanadium oxide is a prototypical correlated electron material that exhibits a large metal-insulator transition (MIT) close to room temperature. The scientific interest in this material lies in understanding the fundamental mechanisms that are responsible for driving the transition. The large resistive switching and the convenient MIT temperature make this a potential material in electrical and electro-optic applications as switches and memory elements.

In this talk, I will present results from our studies on transport properties of single nanobeam devices of vanadium dioxide and epitaxial thin films of nickelates. We seek to control and understand the MIT using several tuning parameters such as temperature, metal doping and electric field. Probing these materials in the nanoscale and the application of noise spectroscopy allow us to distinguish between possible physical mechanisms that are responsible for the transition and to explore the nonequilibrium physics of correlated materials.

Thursday, September 22nd, 2016 

      Speaker: Prof. Adam Smith, University of Akron

      Title: Resolving molecular interfaces in biological membranes

      Abstract: The plasma membrane is the boundary between a cell and its surroundings. Protein receptors are embedded in the membrane to create a sensory device that processes environmental cues. The spatial and temporal arrangement of these receptors is critical to function, but the physical and chemical driving forces are not well understood. Membrane protein dimerization, for example, is a key regulator of many receptor pathways, but its role in others is still controversial or completely unknown. Hierarchical assembly of receptor complexes upon ligand stimulation is central to many signaling pathways, but the kinetics and thermodynamics of the assembly process are still poorly understood. Lipids in the membrane play many structural and regulatory roles in receptor activation, but the details of the lipid-protein interface are still largely unexplored because of experimental difficulties. In this seminar I will describe two ongoing projects in my group. In the first project we investigate membrane protein interactions in live cells using PIE-FCCS and related methods. These efforts have led to several key insights into the organization and activation mechanism of receptors like plexins, growth factor receptors, and visual photoreceptors. The second project is to resolve the details of lipid-protein coupling in model membranes to build a more complete picture of the chemical landscape that governs cell communication.

Thursday, September 29th, 2016

      Speaker: Prof. Peter Lepage, Cornell University

      Title: 40 Years of Lattice QCD

      Abstract: Lattice QCD was invented in 1973-74 by Ken Wilson, who passed away in 2013. This talk will describe the evolution of lattice QCD through the past 40 years with particular emphasis on its first years, and on the past decade, when lattice QCD simulations finally came of age. Thanks to theoretical breakthroughs in the late 1990s and early 2000s, lattice QCD simulations now produce the most accurate theoretical calculations in the history of strong-interaction physics. They play an essential role in high-precision experimental studies of physics within and beyond the Standard Model of Particle Physics. The talk will include a non-technical review of the conceptual ideas behind this revolutionary development in (highly) nonlinear quantum physics, together with a survey of its current impact on theoretical and experimental particle physics, and prospects for the future.

Thursday, October 6th, 2016 

      Speaker: Prof. Chenggang Tao, Virginia Tech

      Title: Interfaces in Atomically Thin 2D Materials

       Abstract: Emerging two-dimensional (2D) materials, such as atomically thin transition metal dichalcogenides and graphene, have been the subject of intense research efforts for their fascinating properties and potential applications in future electronic and optical devices. The interfaces in these 2D materials, including domain boundaries, edges and heterojunctions, strongly govern the electronic and magnetic behavior and may also potentially host new quantum states. On the other hand, these interfaces are more susceptible to thermal fluctuation and external stimuli. In this talk I will present our scanning tunneling microscopy (STM) and spectroscopy (STS) explorations of edges of mono- and few-layer molybdenum disulfide (MoS 2 ) nanostructures and will show how step edges on titanium diselenide (TiSe 2 ) surfaces change dynamically due to electrical fields. I will also discuss temperature evolution of novel quasi-1D fullerene nanostructures on graphene.

Thursday, October 13th, 2016

      Speaker: Prof. Xiang Qiang (Rosie) Chu, Wayne State University

      Title: Protein Dynamics on Multiple Timescales Studied by Neutron Scattering

      Abstract: Proteins undergo sophisticated changes in space and time, in order to keep the cells functioning. These motions are believed to ultimately govern the biological function and activities of the protein. Neutron scattering provide exceptional tools for studying the structures and dynamics of protein in real time at the molecular level. In our recent research, we use quasi-elastic neutron scattering (QENS) technique to study the dynamic behavior of a hyperthermophilic protein, IPPase, that is found in the deep-sea, in the time range of 10ps to 1ns. Our results indicate that under a pressure of 100 MPa, close to that of the native environment deep under the sea, IPPase displays much faster relaxation dynamics than a mesophilic model protein, hen egg white lysozyme (HEWL) at all measured temperatures, opposite to what we observed previously under ambient pressure. This contradictory observation provides evidence that the protein energy landscape (EL) is distorted by high pressure, which is significantly different for hyperthermophilic (IPPase) and mesophilic (HEWL) proteins. We further derive from our observations a schematic denaturation phase diagram together with ELs for the two very different proteins, which can be used as a general picture to understand the dynamical properties of thermophilic proteins under pressure. In addition, using a direct time-of-flight Fermi chopper neutron spectrometer (SEQUOIA) at ORNL, we obtained a full map of the milli-eV phonon-like excitations in the fully deuterated protein. The Q range of the observed excitations corresponds to the length scale of about 2.5 to 3 Å, which is close to the length scales of the secondary structures of proteins (4-5 Å) and reflects the collective intra-protein motions. These observations and further investigation using neutron scattering can reveal important macromolecular dynamic behaviors that cannot be otherwise measured by other techniques.

Thursday, October 20th, 2016 - no colloquium

      Fall Get Together

Thursday, October 27th, 2016

     Speaker: Prof. Gil Paz, Wayne State University

      Title: How Big is the Proton?

      Abstract: In 2010 the proton charge radius was extracted for the first time from muonic hydrogen, a bound state of a muon and a proton. The value obtained was five standard deviations away from the regular hydrogen extraction. Taken at face value, this might be an indication of a new force in nature coupling to muons, but not electrons. It also forces to reexamine our understanding of the structure of the proton.

In this talk I will describe an ongoing research effort that seeks to address and resolve this "proton radius puzzle". In particular I will discuss:  1) A modern approach to controlling nucleon form factors leading  to new model-independent extractions of the proton and neutron magnetic radii. 2) How to separate and control nucleon and nuclear effects  in neutrino-nucleus interaction, crucial for the USA and worldwide neutrino program. 3) Reevaluation of proton structure effects in the theory behind the muonic hydrogen result, correcting 40 years of such theoretical calculations. 4) Developing new theoretical tools that would allow to directly connect muonic hydrogen to a new muon-proton scattering experiment. 

Thursday, November 3rd, 2016

     Speaker: Prof. Eva Halkiadakis, Rutgers University

     Title: Exploring the Energy Frontier at the Large Hadron Collider

      Abstract: The Large Hadron Collider (LHC) at the CERN laboratory is the world’s most powerful particle accelerator.  The start of the proton collider program at the LHC brought the dawn of the exploration of a new energy frontier.  The LHC has had a successful and highly productive Run 1 (2010-2012), colliding protons with a center-of-mass energy up to 8 TeV, and in 2012 the observation of a new Higgs-like boson was announced to the world by the CMS and ATLAS collaborations. The year 2015 marked the beginning of Run 2 of the LHC and we entered a new era of even higher proton collisions at 13 TeV;  in 2016 we have broken data-taking records collecting an unprecedented amount of data at these high energies. The LHC experiments have an extensive program of searches for physics beyond the Standard Model, exploring uncharted territory at the energy frontier. I will present the status of the LHC and highlight experimental results using the latest 13 TeV data in Run 2, with aspecial focus on the CMS experiment.

Thursday, November 10th, 2016

     Speaker: Prof. Steffen Bass, Duke University

      Title: A data-driven approach to quantifying the shear viscosity of nature’s most ideal liquid

      Abstract:  About a microsecond after the Big Bang, the universe was in a state called the Quark Gluon Plasma (QGP), in which quarks and gluons, the basic constituents of the strong nuclear force, roamed freely. Due to its large expansion, this plasma went through a phase transition to form hadrons - most importantly nucleons - which constitute the building blocks of matter as we know it today. Determining the properties of the QGP would not only teach us about the dynamics of the early universe, but also teach us about the properties of its underlying quantum field theory (Quantum Chromo-Dynamics) at high temperatures and densities - domains of the theory that are currently not accessible in first principles calculations.

Only in the last 10-15 years have accelerators been able to create the conditions of temperature and density in the laboratory that are favorable for the QGP to exist. The Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory was built specifically to observe and study this phase of matter and the Large Hadron Collider (LHC) at CERN has devoted a significant research program to this purpose as well.

One of the most surprising discoveries to come out of QGP research is that it behaves like a liquid with the smallest specific viscosity ever observed in nature. This lecture will elucidate how an interdisciplinary collaboration of experimental and theoretical physicists together with computer scientists and statisticians has been able to tease out the remarkable properties of this extreme liquid and how scientific advances in Bayesian statistics and grid computing have come to bear to advance one of the most dynamic areas of Nuclear Physics.

Thursday, November 17th, 2016

     Speaker: Prof. Laura Cadonati, Georgia Tech

     Title: The discovery of gravitational waves in Advanced LIGO

     Abstract: Gravitational waves, ripples in the fabric of space-time produced by catastrophic astrophysical events, are arguably the most elusive prediction of Einstein’s theory of General Relativity, so feeble that Einstein himself thought their detection was impossible. Nevertheless, one hundred years later, the Laser Interferometer Gravitational-wave Observatory (LIGO) has announced the observation of gravitational waves produced by the collision of two black holes. This groundbreaking discovery marks the opening of a new window on the Universe and a new era of gravitational wave astrophysics, where gravitational waves will provide new insights into black holes and neutron stars, and maybe even reveal new objects.  In this talk I will present results from the first observing run of Advanced LIGO, and discuss its implications for a new gravitational wave astronomy.

Thursday, December 1st, 2016 

     Speaker: Prof. Tobias Baumgart, University of Pennsylvania

     Title: Mechanisms of Membrane Curvature Generation

     Abstract: Membrane curvature has developed into a forefront of membrane biophysics. Numerous proteins involved in membrane curvature sensing and membrane curvature generation have recently been discovered, including proteins containing the crescent-shaped BAR domain as membrane binding and shaping module. Accordingly, the structure of these proteins and their multimeric complexes is increasingly well-understood. Substantially less understood, however, are the detailed mechanisms of how these proteins interact with membranes in a curvature-dependent manner. New experimental approaches need to be combined with established techniques to be able to fill in these missing details. Here we use model membrane systems in combination with a variety of biophysical techniques to characterize mechanistic aspects of BAR domain protein function. This includes a characterization of membrane curvature sensing and membrane generation. We present a new approach to investigate membrane shape instabilities introduce membrane shape stability diagrams as a powerful tool to enhance the mechanistic understanding of membrane trafficking phenomena, including endocytosis, with molecular detail.

Thursday, January 19th, 2017 

     Speaker: Prof. Wenjun Zheng, University at Buffalo

     Title: Investigating protein dynamics with coarse-grained physics-based modeling

     Abstract: Membrane curvature has developed into a forefront of membrane biophysics. Numerous proteins involved in membrane curvature sensing and membrane curvature generation have recently been discovered, including proteins containing the crescent-shaped BAR domain as membrane binding and shaping module. Accordingly, the structure of these proteins and their multimeric complexes is increasingly well-understood. Substantially less understood, however, are the detailed mechanisms of how these proteins interact with membranes in a curvature-dependent manner. New experimental approaches need to be combined with established techniques to be able to fill in these missing details. Here we use model membrane systems in combination with a variety of biophysical techniques to characterize mechanistic aspects of BAR domain protein function. This includes a characterization of membrane curvature sensing and membrane generation. We present a new approach to investigate membrane shape instabilities introduce membrane shape stability diagrams as a powerful tool to enhance the mechanistic understanding of membrane trafficking phenomena, including endocytosis, with molecular detail.

Thursday, January 26th, 2017

     Speaker: Prof. Bradford Orr, University of Michigan

     Title: Revamping the teaching of Introductory Mechanics

     Abstract: Eight years ago the Michigan Physics Department began a process to reinvigorate the teaching of its introductory (freshman) mechanics classes.  We had identified a number of issues that were negatively impacting our program and desired a means to address them.  This talk will describe the problematic issues and the manner in which they have been addressed. I will discuss specific examples of the introduction of numerical computation in the revamped classes that have excited our faculty and students.  One positive outcome is the doubling of majors graduating from our department.

Thursday, February 2nd, 2017 

     Speaker: Dr. Alex Matos-Abiague, University at Buffalo

     Title: Spintronics: Novel Materials and Opportunities

     Abstract: Spintronics (or spin electronics), an alternative to conventional electronics recognized by the 2010 Nobel Prize in Physics, is driven by the need for faster, more powerful and  yet more  efficient  devices. Spintronic devices  use  electron  spins,  which  are  ignored  in conventional  electronics, for nonvolatile  information  storage,  sensing,  and  logic. While spins are typically manipulated by external magnetic fields, solid-state materials also offer a great potential for spin manipulation using effective, momentum-dependent “magnetic” fields,  the  so-called  spin-orbit  fields arising  from relativistic  effects. Those  fields accounting for spin-orbit interactions can be exceptionally large in some materials, leading to exotic  topological  properties and  solid-state  realizations of particles predicted in relativistic quantum field theories, such as Weyl, Dirac, and Majorana fermions [1]. This talk will focus on the physical origin of interfacial and synthetic spin-orbit fields [2] as well as their  effects  on  emergent  phenomena  in  hybrid  heterostructures, initially  studied in high-energy  physics. Key  implications  of  spin-orbit-mediated  phenomena in  topological materials  [3] as  well  as  present theoretical challenges and opportunities for  novel  two-dimensional crystals exhibiting strong spin-orbit coupling will also be addressed.

1. G. L. Fatin, A. Matos-Abiague, B. Scharf, and I. Žutić, Phys. Rev. Lett. 117, 077002 (2016).
2. T.  Hupfauer,  A.  Matos-Abiague,  M.  Gmitra,  F.  Schiller, J.  Loher,  D.  Bougeard,  Ch.  Back, J. Fabian, and D. Weiss, Nature Comm. 6, 7374 (2015)
3. B. Scharf, A. Matos-Abiague, J. E. Han, E. Hankiewicz, and I. Žutić, Phys. Rev. Lett. 117, 166806 (2016).

Thursday, February 9th, 2017

     Speaker: Prof. Sang-Hyun Oh, University of Minnesota

      Title: New approaches to nanofabrication for plasmonics and biosensing

     Abstract: I will present our recent work based on two unconventional nanofabrication techniques, namely, template stripping for making ultra-smooth patterned metals and atomic layer lithography for mass-producing sub-10 nm gaps. With template stripping, instead of directly patterning noble metal films, which are difficult to plasma-etch, we engineer inverse patterns in crystalline silicon templates using mature IC processing techniques. After metal deposition and peeling, ultra-smooth patterns in the silicon template are faithfully replicated onto a deposited metal film. We have used template stripping to create high-performance plasmonic gratings, waveguides, resonators, nanohole arrays, and ultra-sharp pyramidal tips for various biosensing and spectroscopy applications.  I will also present surface modification techniques to combine these metal nanostructures with biomembranes for real-time kinetic biosensing and spectroscopy. Recently our group has demonstrated another technique called atomic layer lithography, which enables wafer-scale production of ultra-long (up to centimeters) and sub-10- nm wide gaps in various metals. The resulting nanogaps have been used for a wide range of optical and electrical experiments, including extraordinary optical transmission through single-digit nanometer gaps, ultralow-power electronic trapping of quantum dots and biomolecules, and surface-enhanced spectroscopies, to name a few. I will present potential applications of this enabling technology in biosensing.

Thursday, February 16th, 2017

     Speaker: Prof. Richard Field, University of Florida

     Title: Toward an Understanding of Hadron-Hadron Collisions: From Feynman-Field to the LHC

     Abstract: In 1973 I received a 2 year post-doctoral position in Theoretical Elementary Particle Physics at CALTECH in Pasadena, California.  When I arrived at CALTECH I met Richard Feynman and we began a quest to understand the source of the high transverse particles (pions and kaons) that had just been observed at the ISR proton-proton collider at CERN at a center-of-mass energy of W = 53 GeV.  Feynman-Field phenomenology resulted in predictions of large transverse momentum particle and “jet” production in hadron-hadron collisions based on the theory of Quantum Chromodynamics (QCD).  The goal was to show that QCD was indeed the correct theory of the strong interactions.  We constructed the “Field-Feynman” fragmentation model of how the outgoing partons produced hadrons, which for the first time allowed us to simulate, on an event-by-event basis, everything that occurs in a hadron-hadron collision.  In 1998 I joined the CDF Experimental Collaboration at Tevatron (W = 1.8 TeV) at Fermilab in Batavia, Illinois.  My plan was to produce data that could be used to improve the QCD Monte Carlo models we use to simulate hadron-hadron collisions.  Later, as a member of the CMS Experimental Collaboration at the LHC (W = 13 TeV) at CERN in Geneva, Switzerland, I continued this plan.  The QCD Monte Carlo models have improved greatly over the years and QCD has become an integral part of the “Standard Model”.  From 7 GeV pions to 1 TeV jets.  It has been wonderful journey from the “old days” of Feynman-Field collider phenomenology to the Tevatron and the LHC. I would like to share some of this journey with you.

Tuesday, February 21st, 2017   NOTE SPECIAL TIME

Snacks at 2:45pm and Colloquium at 3:00pm

     Speaker: Dr. Jian-Huang She, Cornell University

     Title: Novel superconductors from quantum paramagnets

     Abstract: Superconductivity has been around for more than 100 years. A major challenge still remains as to how to understand strongly correlated superconductors with predictive power. Here we propose a new paradigm for superconductivity building on quantum paramagnets.  Such a paradigm enables us to propose a new design pattern, namely a metal/quantum-paramagnet heterostructure, which hosts superconductivity with nontrivial topological properties. Furthermore we use such a paradigm to provide a unified framework that explains the various puzzling phenomena of a new iron-based superconductor FeSe: its exotic spin dynamics, nematicity without magnetic ordering, and unconventional superconductivity.

Thursday, February 23rd, 2017

     Speaker: Prof. Carlos Wagner, Argonne National Lab/University of Chicago

     Title: Open Questions in Particle Physics

     Abstract: Almost a century after the conceptual revolutions brought by the theories of relativity and quantum mechanics, the Standard Model has been established as the correct effective theory describing all physical phenomena in nature, with the exception of gravity. Precision measurements of the recently discovered Higgs boson haveprovided the first clues on the origin of the mass of all known fundamental particles.  As great as these achievementshave been, there are several outstanding questions that remain to be answered. In this talk, after reviewing the current status of the field of particle physics, I will describe the efforts directed to answer those questions and to understand the dynamical origin of the ordinary matter as well as the dark matter in the Universe.

Thursday, March 2nd, 2017

     Speaker: Dr. Ching-Kit (Chris) Chan, University of California Los Angeles

     Title: Driving Dirac and Weyl materials

     Abstract: The discovery of topological materials revolutionized condensed matter physics over the last decade. The topological richness of the electronic band structure brings in many exotic physical properties such as topological robustness, bulk-edge correspondence and quantum anomalies. Collaborative efforts between theorists and experimentalists in this research area have led to remarkable developments from fundamental understanding of topological phases to material applications. Discovering and manipulating topological matter is one of the most exciting research directions in condensed matter physics nowadays.

These excitements are further elevated by recent progresses in laser-driven topological materials. It is typically difficult to understand physical systems driven far away from equilibrium. However, when a material is driven periodically in time, a well-defined quasi-Hamiltonian exists which permits equilibrium descriptions and fruitful concepts borrowed from solid state physics. The corresponding quasi-energies, known as the Floquet bands, are analogous to Bloch bands in lattice crystals with spatial periodicity. In this Colloquium, I will first review the current experimental situation on the observation of Floquet-Bloch bands by laser-driving 2D Dirac electrons on the surface of a 3D topological insulator. I will then discuss theoretical proposals of driving the 3D generalization---Weyl fermions in semimetal materials. We shall see how the coupling between chiral fermions and chiral photons induces interesting anomalous transport effects and topological phase transitions. I will also present a photogalvanic application of Weyl semimetals for detecting infrared radiations.

Thursday, March 9th, 2017 - Reserved

Thursday, March 23rd, 2017 - Reserved

Thursday, March 30th, 2017 - Reserved

Thursday, April 6th, 2017 - Vaden Miles Lecture

     Speaker: Prof. Adam Riess, Johns Hopkins University
                    Nobel Prize in Physics (2011)

      Title:  Supernovae and the Discovery of the Accelerating Universe

Abstract: In 1929 Edwin Hubble discovered that our Universe is expanding. Eighty years later, the Space Telescope which bears his name is being used to study an even more surprising phenomenon, that the expansion is speeding up.  The origin of this effect is not known, but is broadly attributed to a type of "dark energy" first posited to exist by Albert Einstein and now dominating the mass-energy budget of the Universe. I will describe how our team discovered the acceleration of the Universe and why understanding the nature of dark energy presents one of the greatest remaining challenges in astrophysics and cosmology.

Thursday, April 13th, 2017

     Speaker: Prof. Stacy McGaugh, Case Western Reserve University

      Title:  The Radial Acceleration Relation in Rotationally Supported Galaxies

      Abstract: We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

WSU colloquia from years past may be found here.