Eric Sembrat's Test Bonanza

I will describe our studies on hybrid quantum systems that demonstrate the interplay between an ultracold spin ensemble and a mesoscopic optomechanical system. Optomechanical systems, i.e. devices that exhibit a parametric coupling between light and a mesoscopic mechanical resonator, have emerged as a promising arena not only for ultrasensitive sensor technologies but also for fundamental studies of precision measurement, macroscopic quantum effects and decoherence.

However, in contrast to ultracold atomic gases, quantum state preparation of such mesoscopic mechanical systems has proved challenging. I will describe our experimental realization of a hybrid quantum system in which an ultracold atomic gas is optically interfaced to an optomechanical system. Through this interface, the atomic gas mediates a 'spin-photon-phonon' interaction that allows for new forms of nonlinear optomechanical interactions and sympathetic cooling of a mechanical resonator using the ultracold gas.

I will show that the use of such hybrid strategies circumvents many of the limitations prevalent in conventional optomechanical systems and offers a promising route to quantum sensors that surpass the standard quantum limit. Lastly, I will describe recent results on novel phase transitions and emergent critical behavior that arise in these systems due to the interplay between coherent dynamics and dissipation.

What will tomorrow’s classrooms look like? How is what we are doing today preparing us for the future? Project-based learning is skill-based where the skills are life-long. In today's knowledge-centric economy, teamwork is paramount and students in introductory physics classes have diverse abilities and experiences in math and science. Research in team-based learning demonstrates that in the past 20 years, over 99.95% of teams have outperformed their best member by an average of almost 14%; moreover, the worst team typically outperforms the best student in class [1]. How can teams be crafted to maximize productivity and enhance conceptual understanding? What types of projects can be designed and structured to foster conceptual mastery and problem solving in physics? How does one assess the success of these teams and projects? We will actively explore some examples of project-based and team-based learning and offer some strategies for assessing learning outcomes. [1] Michaelsen, L., & Sweet, M. (2008). The essential elements of team-based learning. New Directions for Teaching and Learning, 2008(116), 7-27. *In order to illustrate a few of the team-formation metrics and team-based activities, we kindly ask all colloquia attendees to complete a brief online questionnaire by February 16, 2017, 11:59 PM. In case the above link does not work, the questionnaire resides at: https://docs.google.com/forms/d/e/1FAIpQLSfZD07uImtg88woFcwJKjO-jJn7XY_PpJHEyiwvaz7HGf8ifw/viewform

School of Physics Nonlinear Science & Mathematical Physics Seminar: Prof. Scott Kelly, University of North Carolina at Charlotte

Locomotion in nature generally hinges on the exploitation or breaking of symmetry in a sense that can be made precise using the language of differential geometry.

This talk will describe simple mathematical models for a variety of biologically inspired robotic systems that achieve self-propulsion through cyclic changes in shape, highlighting the role played by symmetry or symmetry-breaking as an enabling factor in each case.

Particular attention will be given to nonlinear phenomena arising in aquatic locomotion, including localized propulsive vortex shedding, dissipation-induced recovery in the presence of viscous drag, and wake energy harvesting within arrays of hydrodynamically coupled swimmers, and links will be discussed between problems in aquatic locomotion and problems in nonholonomic mechanics.
 

Biograph:

Scott David Kelly earned a BS in Mechanical & Aerospace Engineering from Cornell University and an MS and PhD in Mechanical Engineering from the California Institute of Technology. He worked as a research engineer in Biological Systems Modeling at Entelos, Inc. and as a faculty member in Mechanical Science & Engineering at the University of Illinois at Urbana-Champaign, receiving a National Science Foundation CAREER Award in 2005 and a Presidential Early Career Award for Scientists and Engineers (PECASE) in 2006, before moving to UNC Charlotte in 2007.

Professor Kelly's research interests include analytical mechanics, nonlinear dynamics and control, differential geometry, robotics, and systems biology.

Soft Condensed Matter & Physics of Living Systems Seminar: Prof. Alex Travesset, Iowa State University

Materials whose fundamental units are nanoparticles, instead of atoms or molecules, are gradually emerging as major candidates to solve many of the technological challenges of our century. Those materials also display unique structural, dynamical and thermodynamical properties, often reflecting deep underlying geometric and topological constraints.

In this talk, I will focus on crystalline assemblies of nanoparticles, i.e. supercrystals. I will discuss our ongoing program to predict the rational design of nanoparticle materials in three different experimental strategies: DNA programmable self-assembly, evaporation of organic solvents with nanoparticles having hydrocarbon as capping ligands, and a new strategy developed at Ames lab consisting of crystallization of nanoparticle neutral (uncharged) polymer brushes by induced electrostaticphase separation.

I will emphasize the case of binary systems, and the idea that nanoparticles can be viewed as q=1 skyrmions, whose textures (helicities) fully determine the structure of the presumed equilibrium lattice structure.

Biography

Alex Travesset got his PhD from the Universitat de Barcelona in 1997. After Postdoc positions in Syracuse University and University of Illinois at Urbana Champaign, he joined the faculty at the Department of Physics and Astronomy at Iowa State University, where he is now full professor. He also holds an appointment as an associated scientist at the Ames lab.

Locomotion in nature generally hinges on the exploitation or breaking of symmetry in a sense that can be made precise using the language of differential geometry. This talk will describe simple mathematical models for a variety of biologically inspired robotic systems that achieve self-propulsion through cyclic changes in shape, highlighting the role played by symmetry or symmetry-breaking as an enabling factor in each case.

Particular attention will be given to nonlinear phenomena arising in aquatic locomotion, including localized propulsive vortex shedding, dissipation-induced recovery in the presence of viscous drag, and wake energy harvesting within arrays of hydrodynamically coupled swimmers, and links will be discussed between problems in aquatic locomotion and problems in nonholonomic mechanics.

Biography:
Scott David Kelly earned a BS in Mechanical & Aerospace Engineering from Cornell University and an MS and PhD in Mechanical Engineering from the California Institute of Technology. He worked as a research engineer in Biological Systems Modeling at Entelos, Inc. and as a faculty member in Mechanical Science & Engineering at the University of Illinois at Urbana-Champaign, receiving a National Science Foundation CAREER Award in 2005 and a Presidential Early Career Award for Scientists and Engineers (PECASE) in 2006, before moving to UNC Charlotte in 2007. Professor Kelly's research interests include analytical mechanics, nonlinear dynamics and control, differential geometry, robotics, and systems biology.

"This event is free and open to the public."

The Physics of Music, by Michael Ruiz, University of North Carolina, Ashville.

We will first use a musical ear-training exercise in conjunction with Lissajous figures to establish the simplest ratios for the frequencies of the major scale. We will call this scale the musician’s scale. Then we will proceed to use strings and pipes to arrive at the harmonic series, which we will call the physicist’s scale.

We will show how the I, V, and IV harmonies pervasive in Western music emerge naturally from our analyses. We will give examples in classical music and jazz, including live piano performance.

Bringing physics to the public through food and the process of cooking. The 6th Squishy Physics Saturday will discuss Gelation, Sous Vide, and Caramelization. Lectures and demonstrations will be carried out by Helluva Engineer and Chef Tim Ma, and by Pia Sörensen, Preceptor of Food Science at Harvard University. Gelation is everywhere in cooking. It is the process by which a small amount of chain-like molecules, which we call polymers, become a network that is solid-like, despite much of the material is still a liquid. For example, 2 teaspoons (7 g) of gelatin is enough to completely solidify 2 cups (450 g) of water! Everytime you cook and egg, thicken a sauce with a starch, or even just use some jam, you are taking advantage of some sort of polymer gelation. If gelation is part of the science of texture, then caramelization is part of the science of flavor. Take some sugar molecules, heat them up, and watch as the sugar breaks down and then recombines in hundreds and thousands of different ways. From a single type of molecule that only tastes “sweet”, caramelization results in the “nutty”, “rum-like”, or even “toasted” flavors that we all know and love. The 6th Squishy Physics Saturday will touch on these things and a few more …. We look forward to seeing you! Admission is free but registration is required: http://squishy.physics.gatech.edu/

Magnons are the quanta of waves of spin precession in magnetically ordered media. In thermal equilibrium, they can be considered as a gas of quasiparticles obeying the Bose-Einstein statistics with zero chemical potential and a temperature dependent density.

We will discuss the room-temperature kinetics and thermodynamics of the magnons gas in yttrium iron garnet films driven by a microwave pumping and investigated by means of the Brillouin light scattering spectroscopy.

We show that the thermalization of the driven magnon gas results in a quasi-equilibrium state described the Bose-Einstein statistics with a non-zero chemical potential, the latter being dependent on the pumping power. For high enough pumping powers Bose-Einstein condensation (BEC) of magnons can be experimentally achieved at room temperature. Spatio-temporal kinetics of the BEC-condensate will be discussed in detail.

Among others interference of two condensates, persistent quantized vortices, and propagating waves of the condensate density will be addressed. Finally, our recent experiments on moving condensates will be discussed.

Fundamental processes governing dynamics of hot magnetized plasmas determine behavior of many systems in the Universe across a wide range of scales.Notable examples include laboratory fusion experiments, the magnetospheres of Earth and of other planets, stellar atmospheres, astrophysical jets, and accretion disks.

In this talk I will review recent work on two inherently linked phenomena that are thought to be of crucial importance to dynamics of magnetized plasmas: magnetic reconnection and plasma turbulence. Plasma turbulence is a ubiquitous phenomenon often representing the dominant mechanism of energy and particle transport. Magnetic reconnection, a process of fast topological rearrangement of magnetic field, is one of the most important processes associated with energy storage and release. It is thought to be behind such spectacular events as coronal mass ejections and magnetospheric storms.

Focusing on the issues pertinent to Space Weather, i.e. dynamics of the Earth’s space environment and of the Earth-Sun connection, I will discuss how the magnetic reconnection and plasma turbulence are linked together, why understanding of this link requires incorporating of microscopic kinetic processes into large-scale models, and why all of these issues represent a fascinating theoretical problem with far-reaching practical implications. Computer simulations taking advantage of the largest available supercomputers underpin most of the presented work and I will discuss some of the challenges and opportunities in both modeling and data analysis arising with the push towards exascale computing.