Past Events

  • Condensed Matter seminar: "Wavefront Shaping for in vivo Brain Imaging"

    David Rittenhouse Laboratory, A4

    Na Ji, Janelia Research Campus

    There are about the same number of stars in our galaxy as there are neurons in our brain. To study stars and neurons using optical imaging, we face similar challenges of image degradation by aberrations and scattering. Adaptive optics, a form of wavefront shaping, has revolutionized astronomy by allowing ground-based telescopes to obtain high-resolution images of stars through Earth's turbulent atmosphere. Applying wavefront shaping to brain imaging is similarly beneficial.

  • Condensed Matter seminar: “Do entangled polymers possess a shear banding instability?”

    David Rittenhouse Laboratory, A4

    Peter Olmsted, Georgetown University

    The original Doi-Edwards theory (1978) predicted that long entangled polymers should become unstable to homogeneous shear flow for shear rates exceeding the relaxation (reptation) time. At the time this seemed to explain a number of instabilities seen in polymers. However, over the years those instabilities have been explained in other ways, as physics that was left out of the original theory was incorporated into the model. New experiments, however, suggest that the original Doi-Edwards instability could be valid after all.

  • Astro Seminar: "A Possible First Detection of High-Redshift Population III Stars"

    David Rittenhouse Laboratory, A4

    Eli Visbal (Columbia)

    The recent observation of CR7 (Sobral et al. 2015), the brightest Lyman-alpha emitter at z~7, could be the first detection of Pop III stars (i.e. stars formed from primordial/extremely metal-poor gas). CR7 has strong He II 1640 angstrom line emission and no detected metal lines, as predicted for Pop III stars. However, the He II line luminosity corresponds to ~10^7 solar masses of Pop III stars, and such a large Pop III star cluster is generally be expected to be metal-enriched from previous star formation.

  • Department Colloquium: "Physics Opportunities at Future Circular Colliders"

    DRL A8

    Liantao Wang (U of Chicago) Hosted by Joe Kroll

    Following the discovery of the Higgs boson, there has been a lot discussion about the next step in high energy physics. Among different options, a couple of newly proposed next generation circular colliders, including FCC at CERN and CEPC/SPPC in China, have attracted a lot of attention. Through preliminary studies in the past couple of years, an exciting picture of their physics capabilities has emerged. In this talk, I will give an overview on this topic, focusing on some of the most important questions in high energy physics they can help addressing. 

  • Special Energy Cluster Seminar: "Tailoring the flow of light at the nanoscale with hyperbolic metasurfaces"

    Glandt Forum, 3rd Floor, Singh Center

    Alexander High, Harvard University

    Metamaterials offer unprecedented control of the flow of light at nanoscale dimensions, critical for the realization of compact, energy-efficient optical computing. However, three-dimensional (3D) metamaterials suffer from extreme optical losses, limiting their practical utility. Two-dimensional (2D) metasurfaces and, in particular, hyperbolic metasurfaces (HMSs) for propagating surface plasmon polaritons have been predicted to feature much lower loss while still exhibiting optical phenomena akin to those in 3D metamaterials.

  • Condensed Matter seminar: "Valley and spin dependent physics in two-dimensional van der Waals’ materials"

    David Rittenhouse Laboratory, A4

    Kin Fai Mak, Pennsylvania State University

    Electrons in two-dimensional (2D) van der Waals’ materials with a honeycomb lattice structure possess both the valley pseudospin and the spin degree of freedom (DOF). The valley DOF is associated with the degenerate conduction/valence band extrema at the K and the K’ point of the Brillouin zone. When inversion symmetry is broken, interesting valley and spin dependent phenomena, such as spin-valley locking and the valley Hall effect (VHE), emerge.

  • Astro Seminar: "Cross Correlations with CMB Secondaries: Constraining Cosmological Parameters and Cluster Astrophysics"

    David Rittenhouse Laboratory, A4

    Nicholas Battaglia (Princeton)

    High resolution CMB experiments, such as ACT, SPT, and the Planck satellite are making precision measurements of the secondary anisotropies caused by the thermal Sunyaev Zel'dovich (tSZ) effect from galaxy clusters. However, our ability to obtain cosmological information from this tSZ signal is limited by our theoretical understanding of the baryons in clusters and groups. I will discuss how cross-correlation methods are providing new windows into the messy Gastrophysics of the intracluster medium and the potential for these methods to constrain various cosmological parameters.

  • Astro Seminar: "TBA"

    David Rittenhouse Laboratory, A4

    TBD

  • Special Energy Cluster Seminar: "Quantum physics to address global energy challenges"

    Glandt Forum, 3rd Floor, Singh Center

    Michael Biercuk, University of Sydney

    Quantum physics research is providing surprising new avenues to solve longstanding challenges in energy - from lossy power distribution systems to inefficient large-scale fertilizer production.  In this talk, I will explain how learning to build technologies that use exotic quantum effects as resources provides an exciting opportunity to improve the generation, distribution, and use of energy.  My presentation will focus on the specific example of global efforts to build special-purpose quantum c

  • CTL Departmental Workshop

    David Rittenhouse Laboratory, A6

    Philip T. Gressman (UPenn, Math)

    Topic discussion on "Designing Your Own Course"

    Graduate Students of Math, AMCS and other related departments are highly recommended to join in. This counts toward the CTL teaching certificate.

     

    Hosted by Ph.D candidate Jin Woo Jang, Math