Colloquia are Wednesdays at 4:00 p.m. in the JILA Auditorium. 

Coffee, tea and cookies will be available in G1B31 (across from G1B20) from 3:30 - 3:50 p.m.

August 24 — "Immobile topological quantum matter: fractons"

  • Presenter: Leo Radzihovsky, Department of Physics, University of Colorado, Boulder
  • Host: Victor Gurarie
  • Abstract: I will discuss a bourgeoning field of "fractons" — a class of models where quasi-particles are strictly immobile or display restricted mobility. Focusing on just a corner of this fast-growing subject, I will explain how one class of such theories — symmetric tensor gauge theories surprisingly emerge from seemingly mundane elasticity of a two-dimensional quantum crystal. The disclination and dislocation crystal defects respectively map onto charges and dipoles of the fracton gauge theory. This fracton-elasticity duality leads to predictions of fractonic phases and quantum phase transitions to their descendants, that are duals of the commensurate crystal, supersolid, smectic, and hexatic liquid crystals. Extensions of this duality to generalized elasticity theories provide a route to discovery of new fractonic models and their potential experimental realizations. 

August 31 — "Time-of-flight quantum tomography of single atom motion in an optical tweezer"

  • Presenter: Cindy Regal, JILA, Department of Physics, University of Colorado, Boulder
  • Host: Konrad Lehnert
  • Abstract: Quantum control of mechanical motion has been achieved in a surprising range of platforms in the past decades. These mechanical quantum systems have both piqued the curiosity of physicists, and enabled new approaches to difficult tasks in manipulating quantum information. Trapped particles offer one opportunity to study isolated quantum motion. Laser-cooled ions routinely demonstrate intriguing phonon control, and recent experiments have now brought trapped dielectric nanoparticles to their quantum ground state. In this talk I describe how time of flight combined with trap evolution can map the full quantum state of a trapped neutral particle. I will present this intuitive method through experiments with a single atom in a non-classical motional state in an optical tweezer, and discuss future applicability to larger mass particles. Single atoms in optical tweezers are now a ubiquitous tool for quantum science, and I will also use this opportunity to tell you how these experiments isolate single neutral atoms in the first place.

September 7 — "Planetary dynamos and the dynamics of rotating, electrically conducting fluids"

  • Presenter: Michael Calkins, Department of Physics, University of Colorado, Boulder
  • Host: Michael Ritzwoller
  • Abstract: Planetary magnetic fields are ubiquitous in the Solar System. These fields are generated by the motion of an electrically conducting fluid within the interiors of the planets. For the Earth, turbulence in the liquid iron outer core has sustained the geomagnetic field for at least 4 billion years. Similar turbulent fluid systems are present in most planets, as well as stars. These flows are thought to be strongly influenced by system rotation (i.e. the Coriolis force) and the magnetic fields that they induce, yielding a unique form of turbulence that is both challenging to investigate and dynamically rich. I will give an overview of what we know about natural dynamos, and how computation and theory are being used to better understand their dynamics. 

September 14 — "Geometric frustration, self-assembly, mechanics, and pathways to complexity"

  • Presenter: Xiaoming Mao, University of Michigan
  • Host: Leo Radzihovsky
  • Abstract: Self-organized complex structures in nature, from hierarchical biopolymers to viral capsids and organisms, offer efficiency, adaptability, robustness, and multifunctionality.  How are these structures assembled? Can we understand the fundamental principles behind their formation, and assemble similar structures in the lab using simple inorganic building blocks?  What’s the purpose of these complex structures in nature, and can we utilize similar mechanisms to program new functions in metamaterials?  In this talk, we will start from the perspective of geometric frustration, to explore answers to these questions.  I will discuss our recent work on developing analytic theories based on crystal structures in non-Euclidean space for the self-assembly of nanoparticles into complex structures, mechanical properties of materials in which geometric frustration causes prestress, as well as our ongoing effort in designing topological mechanical metamaterials with and without geometric frustration.

September 21 — "From BEC to CEO"

  • Presenter: Chris Myatt, LightDeck Diagnostics
  • Host: Leo Radzihovsky
  • Abstract: Can a PhD at CU Physics prepare you to start a company? Can a Post-Doc at NIST be the ticket to entrepreneurship? While the subject of research at these institutions may not be directly applicable to industrial problems—in my case, Bose-Einstein Condensation and quantum computing— the skill sets and tools you develop are on the critical path in preparing you to succeed in high-tech industry and even in starting a company. In this personal story presentation, I will take the audience on my personal journey from a JILA lab to my current position as founder of a diagnostics and testing company, making testing equipment for water, veterinary, and diagnostics applications. My first company manufactured high precision optical devices and systems. I will share the lessons learned, the depth of entrepreneurial activity coming out of the CU Physics department, and thoughts on how to encourage more.

    Dr. Myatt is a Founder of LightDeck Diagnostics.  He is an entrepreneur with a proven track record for building technology companies. Prior to LightDeck, Chris successfully founded and led Precision Photonics Corporation, a successful laser and optical technology supplier that is now a division of IDEX. Chris earned bachelors degrees at Southern Methodist University, and a PhD in Atomic Physics at the University of Colorado. Chris studied Bose-Einstein Condensation under Carl Wieman, and quantum information under David Wineland as a National Research Council Postdoctoral Fellow at NIST Boulder. He is now successfully applying many of the tools developed during his academic years to real-world problems in high tech industry.
     

September 28 — "Imaging black holes: accretion physics at the event horizon"

  • Presenter: Jason Dexter, JILA, Department of Astrophysics and Planetary Sciences, University of Colorado, Boulder
  • Host: Andrew Hamilton
  • Abstract: In the past few years, it has become possible to image black holes. Long baseline interferometry experiments operating at millimeter and near-infrared wavelengths can now achieve event horizon scale angular resolution with sufficient sensitivity to detect synchrotron radiation from hot plasma near the Galactic center black hole, Sgr A*, and the supermassive black hole in M87. I will discuss major results from each experiment, and focus on our group's work using the data to study accretion physics and particle acceleration in the immediate vicinity of an event horizon.

October 5

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October 12

  • Presenter: Tiffany Shaw, University of Chicago
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October 19

  • Presenter: Rob Phillips, California Institute of Technology
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October 26

  • Presenter: Oliver DeWolfe, Department of Physics, University of Colorado, Boulder
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November 2

  • Presenter: Waseem Bakr, Princeton
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November 9

  • Presenter: Chetan Nayak, Microsoft Research
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November 16

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November 23 — No Colloquium, Fall Break 

November 30

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December 7

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For more information about colloquia this semester, contact: Leo Radzihovsky.