Past Events

  • Condensed Matter Seminar: "Structure and Topology of Band Structures in the 1651 Magnetic Space Groups"

    David Rittenhouse Laboratory, A4

    Ashvin Vishwanath (Harvard University)

    We describe a powerful theoretical approach to studying electronic band structures, which associates them with elements of a vector space. The set of consistent band structures in a space group can then be expanded in terms of a small set of basis vectors. We calculate the dimension of this vector space, and the necessary electron fillings to obtain band insulators in all magnetic space groups.

  • Condensed Matter Seminar: "Enhanced optical and magnetic microscopy by orientation-dependent modulation of single-molecule and nitrogen-vacancy-center emission"

    David Rittenhouse Laboratory, A4

    Mikael Backlund (Harvard University)

    Selection rules impose geometrical constraints on the interactions of light and matter. In
    particular, an emitter with a well-defined orientation will emit photons of a characteristic
    polarization and wavevector distribution, even as viewed in the far field. Knowledge of these
    distributions can be leveraged to enhance a number of state-of-the-art microscopy techniques. In
    the first part of the talk I will discuss such an approach to single-molecule localization
    microscopy, relevant for single-molecule tracking and super-resolution imaging. It is known that

  • Condensed Matter Seminar: "Controlling Strong Light Matter Coupling with Photonic Crystals"

    David Rittenhouse Laboratory, A4

    Hui Deng (University of Michigan)

    Microcavity exciton-polaritons provide a unique photonic platform that manifests non-equilibrium quantum orders. It combines strong nonlinearity and rich many-body physics of matter with robust coherence and ready accessibility of light, allowing diverse quantum phenomena at high temperature, on a photonic chip. To go beyond 2D condensation physics, it becomes important to control the fundamental properties of polaritons without destroying the quantum orders.

  • Condensed Matter Seminar: "Soft matter physics in the gut"

    David Rittenhouse Laboratory, A4

    Sujit S. Datta (Princeton University)

    The gut governs digestion and nutrient absorption, is a promising target for drug delivery, and teems with micro-organisms that can have remarkably strong effects on host health. Despite its importance, however, little is known about how the structure and function of the gut are influenced by many of the soft materials that transit through it regularly.

  • Condensed Matter Seminar: "Mechanical Cell Biology of Microbes"

    David Rittenhouse Laboratory, A4

    Enrique Rojas (Stanford University)

    Research in microbial physiology has traditionally focused on understanding biochemical pathways and, more recently, on elucidating the surprisingly complex structure of microbial cytoplasm.  On the other hand, the whether mechanical forces also play a role in controlling sub-cellular processes in microbes has been overlooked. I will highlight several novel paradigms by which microbes use mechanical (and electrical) factors as signals to control cell growth, division, and survival, and highlight how the remarkable mechanical properties of the cells are critical for these p

  • Condensed Matter Seminar: "Topological protection of photons"

    David Rittenhouse Laboratory, A4

    Mikael Rechtsman (Penn State University)

    Topological insulators are solid-state materials whose transport properties are immune to defects and disorder due to underlying topological order.  Perhaps the first such phenomenon was the quantum Hall effect, wherein the Hall conductivity is quantized and hence extremely robust.  In this talk, I will present the experimental observation of the topological protection of the transport of photons (rather than electrons in the solid state) in complex dielectric structures.  I will then present the obser