Past Events

  • Special Condensed Matter Seminar: "Nano-electrodynamics with graphene plasmons"

    David Rittenhouse Laboratory, A4

    Mark Lundeberg, Institute of Photonic Sciences (Castelldefels, Spain).

    I will review my recent work on plasmons in graphene, a naturally appropriate material for studying electron motion at terahertz and mid-infrared frequencies. Graphene plasmons are extremely confined propagating waves (with wavelengths 100 times smaller than light) which have lifetimes up to 500 fs at room temperature, and which can be probed by near field microscopy. Various aspects of these plasmons will be discussed: in-situ tuning and guiding with gate voltages, electrical detection of plasmons, and tuning by the dielectric environment around the graphene.

  • Department Colloquium: "Results from the New Horizons Flyby of Pluto"

    David Rittenhouse Laboratory, A8

    Marc Buie (Southwest Research Institute) hosted by Mariangela Bernardi

    July 2015 saw the culmination of decades of work to get a detailed look at a distant and intriguing world.  As of late 2016, the transmission of all data from the encounter was completed and the project is now turning its attention to the upcoming extended mission flyby of 2014MU69 on 2019 Jan 1.  The encounter was crucial for pinning down seemingly simple quantities such as size and albedo but opened the door to much more in-depth studies of the origin and evolution of Pluto and its constraints on the history of our solar system.

  • Math-Bio seminar: "A flexible inference of complex population histories and recombination from multiple genomes"

    318 Carolyn Lynch Laboratory

    Champak Reddy, CUNY Graduate Center

    Analyzing whole genome sequences provides an unprecedented resolution of the historical demography of populations. In the process, most inferential methods either ignore or simplify the confounding effects of recombination and population history on the observed polymorphism. Going further, we build upon an existing analytic approach that partitions the genome into blocks of equal (and arbitrary) size and summarizes the polymorphism and linkage information as blockwise counts of SFS types (bSFS).

  • Special Condensed Matter Seminar: "Manipulating Charge Carriers for Quantum Transport in Van der Waals Materials Nanostructures"

    David Rittenhouse Laboratory, A4

    Ke Wang, Harvard University

    Since the discovery of graphene via mechanical exfoliation, it has been shown that the electronic properties of solids can undergo dramatic change when the material thickness is reduced to the atomic limit. Recently, the quality of these 2-dimensional (2D) electronic systems has been significantly improved by hexagonal boron nitrides encapsulation, enabling the electron mean free path only limited by the size of the samples. However, mesoscopic transport studies in these systems are relatively unexplored due to the challenges in the device fabrication processes.

  • Special Condensed Matter Seminar: "A Berry Phase Switch in Circular Graphene Resonators"

    David Rittenhouse Laboratory, A4

    Fereshte Ghahari Kermani, National Institute of Standards and Technology

    Berry phase is an example of anholonomy, where the phase of a quantum state may not return to its original value after its parameters cycle around a closed path; instead the quantum system’s wave function may acquire a real, measurable phase difference, known as Berry phase. Berry phase is connected with the geometry of the quantum system having intriguing physical consequences in systems with topological singularities, such as graphene.

  • Astro Seminar: "Massive Neutrinos and Large-scale Structure: Forecasts for SKA"

    David Rittenhouse Laboratory, A4

    Francisco Villaescusa-Navarro (Simons CCA)

    In the first part of the seminar I will discuss some of the effects that massive neutrinos induce on the large-scale structure of the Universe, from their impact on the clustering of halos, galaxies and voids to their signatures on the BAO. In the second part of the seminar I will discuss the possibility of using the hydrogen 21cm line to study cosmology.

  • Math-Bio seminar: "Covariate-corrected biclustering methods for gene-expression and GWAS data"

    318 Carolyn Lynch Laboratory

    Adi Rangan, New York University

    A common goal in data-analysis is to sift through a large matrix and detect any significant submatrices (i.e., biclusters) that have a low numerical rank. To give an example from genomics, one might imagine a data-matrix involving several genetic-measurements taken across many patients. In this context a ‘bicluster’ would correspond to a subset of genetic-measurements that are correlated across a subset of the patients. While some biclusters might extend across most (or all) of the patients, it is also possible for biclusters to involve only a small subset of patients.

  • Special Condensed Matter Seminar: "Shining light on topological insulators and Weyl semimetals"

    David Rittenhouse Laboratory, A4

    Liang Wu, University of California, Berkeley

    The last decade has witnessed an explosion of research investigating the role of topology in band-structure, as exemplified by the wealth of recent works on topological insulators (TIs) and Weyl semimetals (WSMs). In this talk I hope to convince you that optical probes of solids give unique insight into these topological states of matter.

  • Special Condensed Matter Seminar: "Probing Topological Valley Physics in Bilayer Graphene"

    David Rittenhouse Laboratory, A4

    Long Ju, Cornell University

    Graphene has been a model solid state system where novel quantum phenomena emerge from the interplay between symmetry, band topology and reduced dimensionality. In particular, AB-stacked bilayer graphene has a unique bandstructure with an electrically tunable bandgap and a valley-dependent Berry phase. These features result in unusual electrical and optical properties, for which optical spectroscopy/microscopy are powerful characterization tools.

  • Astro Seminar: "Quenching and Bulge Growth Over Cosmic Time in Massive Galaxies"

    David Rittenhouse Laboratory, A4

    Marc Huertas-Company (Paris Observatory)

    The life of a galaxy is a balance between processes that trigger star formation by accelerating gas cooling and others which tend to prevent stars to form by expelling or heating gas.  Over the past years, the picture is emerging that, during most of its life, a galaxy seems to live a rather quiet life, gradually growing in stellar mass through the formation of new stars which are formed at a rate remarkably proportional to its stellar mass, This is interpreted as an indirect evidence that fuel in the form of cold gas is somehow continuously being fed into the galaxies to susta