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PHYSICS COLLOQUIUM SCHEDULE
Fall 2019
The Colloquia are in Room 1002 NPB on Thursday at 4:05 PM
Refreshments will be served starting at 3:15 PM in NPB 2205

Contact: A. Hebard afh@phys.ufl.edu)
Department of Physics Colloquium Committee:
Hebard (chair), Fulda, Matchev, Mitselmakher, Wang


August 22

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August 29
  Speaker Graduate Student Meeting with Dr. Xiaoguang Zhang 4:00pm in 1002 NPB
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September 5
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September 12
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September 19
  Speaker Kathryn McGill, UF Physics
  Title Physics Education Research (PER): A User’s Guide
  Abstract What is Physics Education Research (PER)? What does it say about physics education and the learning of physics? How long has this field existed, anyway? These are just a few of the questions I will answer in my talk. Additionally, I will present an overview of the implementation of PER-based methods in the UF Department of Physics, as well as introduce some PER studies being conducted by the UF physics lecturers.
Host Arthur Hebard

September 26
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October 3
  Speaker Kun Yang (Florida State University)
Title Condensed Matter Physics: What Happened Since Ashcroft/Mermin and Where Is It Going?
  Abstract The classic textbook by Ashcroft and Mermin, titled Solid State Physics, has dominated education of graduate students in the field of condensed matter physics since its publication in 1976. Tremendous progress has been made in this field over the past 40 years, and a modern textbook replacing this aging classic is in urgent need. In this talk I will report our attempt [1] to meet this need, and discuss the recent developments in condensed matter physics along the way, emphasizing its synergy with other fields. [1] Modern Condensed Matter Physics, Steven M. Girvin and Kun Yang
Host Dmitrii Maslov

October 10
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October 17
  Speaker Michael Turner (University of Chicago)
  Title Sakurai Prize Celebration
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Host David Tanner

October 24
  Speaker James Fry (UF Physics)
  Title The 2019 Noble Prize in Physics - A Personal Perspective
  Abstract TBD
Host Hebard/Hirschfield

October 31
  Speaker Anupam Garg (Northwestern University)
Title "Magnets that find it hard to relax"
  Abstract Many processes in nature, such as alpha decay of U-238, or the conversion of ortho to para hydrogen, take place very slowly, and in each case, an investigation into the causes teaches us important physics. In this talk, we will discuss magnetic relaxation in single molecule magnets such as Fe8, which is also very slow, but for completely different reasons than the previous two examples.

At low temperatures, Fe8 displays spectacular quantum dynamics wherein the spin angular momentum degree of freedom of one molecule tunnels through 20 units of hbar, with a tunnel splitting of ~ 1 pico eV, or about 1kHz in frequency units. This splitting is about 106 times smaller than the energy bias on a typical molecule in Fe8 crystals due to the dipole-dipole interaction. As a result, tunneling is strongly inhibited by energy conservation, and essentially impossible. The overall relaxation of magnetization is thus exceptionally slow, and understanding it is a challenging problem in classical many-body physics.

We will describe the theoretical model for how we believe Fe8 relaxes, along with Monte Carlo simulations and kinetic equations for the spin and dipolar-field distributions. We apply these approaches to various experimental protocols. The agreement between simulations, kinetic equation, and experiments is very good in most respects, but not so good for ultra long times and ultra-slow phenomena. The problem of how an initially demagnetized sample can be magnetized is particularly interesting and still open, and entails a situation where the magnetization relaxes
Host Mark Meisel

November 7
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November 14

  Speaker Mark Dykman (Michigan State University)
  Title Physics of and with nonlinear oscillators
  Abstract Recent progress in nano- and micromechanics and the emergence of circuit quantum electrodynamics have brought forward the need to understand mesoscopic vibrational systems. Because these systems are small, nonlinearity and quantum and classical fluctuations play a significant role in their dynamics. We will discuss some consequences of the interplay of fluctuations and nonlinearity. Mesoscopic oscillators make it possible also to study physics far from thermal equilibrium in the well-characterized setting. Of particular interest in this respect is the Floquet dynamics, including the “time-crystal” effect in coupled nonlinear oscillators.
Host Yoonseok Lee

November 21

  Speaker Douglas Glenzinski (Fermi Lab)
  Title A Rare Opportunity - the Mu2e Experiment at Fermilab
  Abstract The muon, a heavy cousin of the electron, was discovered in 1936. Since that time they have only ever been observed to do one of two things: 1) interact with a nucleus, or 2) decay into an electron and two neutrinos. But a new experiment at Fermilab - the Mu2e experiment - is going to look for a third thing: a muon interacting with a nucleus to produce an electron and nothing else. This is a process that's predicted to occur very very rarely, maybe once every quadrillion muon decays, (or less!). But this very rare decay may hold the key to understanding physics at its most fundamental level. The Mu2e experiment is an ambitious endeavor whose goal is to observe this very rare decay for the first time - a discovery that could help reveal a new paradigm of particle physics. I will describe the experimental challenges, both in terms of detector technology and data analysis, involved in searching for such a subtle process.
Host Jacobo Konigsberg



PHYSICS COLLOQUIUM SCHEDULE

Spring 2020
The Colloquia are in Room 1002 NPB on Thursday at 4:05 PM
Refreshments will be served starting at 3:15 PM in NPB 2205

Contact: A. Hebard afh@phys.ufl.edu)
Department of Physics Colloquium Committee:
Hebard (chair), Fulda, Matchev, Mitselmakher, Wang


January 9

  Speaker Bob Schrieffer Memorial Colloquium
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January 16
  Speaker Faculty search candidates
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January 23
  Speaker Michael Johnson (Center for Astrophysics, Harvard University)
  Title Imaging a Black Hole with the Event Horizon Telescope
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  Host Cliff Will

January 30
  Speaker Faculty search candidates
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February 6
  Speaker Danny Caballero (Michigan State University)
  Title TBD
  Abstract TBD
  Host Shawn Weatherford

February 13
  Speaker Margaret Cheung (University of Houston)
  Title Proteins in a crowd under heat and pressure
  Abstract In order to function, many proteins fold into a well-packed structure, and yet the folded phase must remain sufficiently flexible. It is unclear how proteins satisfy these contradictory constraints, especially in the crowded environment of a cell. I will present the theoretical and computational work from my group, which is in collaboration with experimentalists from the Gruebele group, addressing this challenging issue. We propose that these properties can coexist by tuning where the protein operates within its temperature-pressure-crowding phase diagram. Phase diagrams may contain ‘critical points’ where the difference between any two phases disappears, such as when liquid and vapor water become indistinguishable. We show that a protein can also have such a critical point. The enzyme phosphoglycerate kinase (PGK), which is involved in producing the ‘energy molecule of the cell,’ turns out to have a very crowding-sensitive critical point, above which the protein forms new structures. To paint a complete picture of the critical point for this protein, we expand upon the conventional temperature-pressure folding phase diagram by adding a third dimension: the degree of crowding (or volume-exclusion) from surrounding macromolecules. From simulations, we observe an intricate phase diagram, which contains a critical point that moves to lower a temperature as the crowding increases. We complement our simulation results by deriving a new thermodynamic equation of state that includes the critical line in the entire 3-dimensional phase diagram. To test our computational model, we observe folding transitions of PGK by fluorescence experiments, which validate the predicted critical point behavior. Our findings suggest that being near a critical point at physiologic conditions would be advantageous for enzymatic function because a protein may sample widely different conformations without passing a costly thermodynamic barrier.
  Host Arthur Hebard

February 20
  Speaker Faculty search candidates
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February 27
  Speaker Faculty search candidates
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March 5
  Speaker APS meeting and spring break
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March 12
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March 19

  Speaker Aasish Clerk (University of Chicago)
  Title TBD
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  Host Selman Hershfield

March 26
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April 2
  Speaker Eduardo Fradkin (University of Illinois)
Title TBD
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Host Wang

April 9
  Speaker Paul Canfield (Iowa State University)
  Title TBD
Abstract TBD
  Host James Hamlin

APRIL 16
Speaker Jonathan Feng (University of California Irvine)
  Title TBD
Abstract TBD
  Hosts Konstantin Matchev and Wei Xue