Past Events

  • Dissertation Defense: "Hard-, Soft- and Sticky Spheres for Dynamical Studies of Disordered Colloidal Packings"

    LRSM, Reading Room

    Matthew Gratale (UPenn)

  • High Energy Theory: "Effective Field Theory of Dissipative Fluids"

    David Rittenhouse Laboratory, 2N36

    Hong Liu (MIT)

  • ABO Seminars: "Label-free Optical Micro Imaging of Tissue Histology in Vivo"

    Donner Building 3400 Spruce Street Donner Auditorium, Basement *Pizza served at 11:45am*

    Xingde Li (Johns Hopkins University)

    This seminar will focus on our recent progresses on developing high-resolution biophotonic imaging technologies, particularly the second-generation optical coherence tomography (OCT) endoscopy and multiphoton endomicroscopy. These technologies have shown significant translational potential for imaging tissue microanatomies in vivo at a resolution approaching or at standard histopathology but without the need for tissue removal, staining or processing.

  • Department Colloquium: "The Universe as a Lab for Fundamental Physics: Results from Spider and Future Suborbital Missions"

    David Rittenhouse Laboratory, A8

    William Jones (Princeton) Hosted by James Aguirre

    I will describe our recent results from observations of the Cosmic Microwave Background, including a status report on the recent flight of the Spider experiment, a balloon borne CMB polarimeter.  I will also discuss a convergence of observational needs and technological capabilities that provide intriguing opportunities for improving our understanding of both the late- and early-time evolution of the Universe.

     

    *Refreshments served @ 3:30pm, DRL 2nd Floor Faculty Lounge*

  • 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.