Calendar

< 2020 >
May 31 - June 06
  • 31
    May 31, 2020
    No events
  • 01
    June 1, 2020
    No events
  • 02
    June 2, 2020

    CMSA Geometry Seminar: Equivariant Floer theory and SYZ mirror symmetry

    9:30 AM-10:30 AM
    June 2, 2020

    In this talk, we will first review a symplectic realization of the SYZ program and some of its applications. Then I will explain some recent works on equivariant Lagrangian Floer theory and disc potentials of immersed SYZ fibers. They are joint works with Hansol Hong, Yoosik Kim and Xiao Zheng.

    via Zoom: https://harvard.zoom.us/j/94717938264

    Kitaev's finite group model as an error correcting code

    10:00 AM-11:00 AM
    June 2, 2020

    Kitaev’s quantum double models in 2D provide some of the most commonly studied examples of topological quantum order.  In particular, the ground space is thought to yield a quantum error-correcting code.  We offer an explicit proof that this is the case for arbitrary finite groups. Actually, a stronger claim is shown: any two states with zero energy density in some contractible region must have the same reduced state in that region.  Alternatively, the local properties of a gauge-invariant state are fully determined by specifying that its holonomies in the region are trivial. This implies that Kitaev’s model satisfies both TQO1 and TQO2 conditions of Bravyi-Hastings-Michalakis, and so it is a topological order in the sense of B-H-M. We note that the methods developed by P. Naaijkens (PhD thesis, 2012) under a different context can be adapted to provide another proof of this result. We also note that more recently Q. Yang and Z. Wang proved the same result for the more general class of Levin-Wen models, but their method of proof is very different.

    via Zoom: https://harvard.zoom.us/j/779283357

  • 03
    June 3, 2020

    CMSA Quantum Matter/Quantum Field Theory Seminar: Magnetic Black Holes

    10:30 AM-12:00 PM
    June 3, 2020

    We discuss properties of magnetically charged black holes in the Standard Model. We will discuss how the electroweak symmetry is restored around the black hole. In addition, the Hawking evaporation rate is greatly enhanced by a factor of the charge of the black hole.
    These provide interesting candidates for primordial black holes which can have a relatively low mass.

    via Zoom Video Conferencing:  https://harvard.zoom.us/s/977347126

     

    Slices of Thurston's Master Teapot

    4:00 PM-5:30 PM
    June 3, 2020

    Thurston’s Master Teapot is the closure of the set of all points $(z,\lambda) \in \mathbb{C} \times \mathbb{R}$ such that $\lambda$ is the growth rate of a critically periodic unimodal self-map of an interval and $z$ is a Galois conjugate of $\lambda$. I will present a new characterization of which points are in this set. This characterization gives a way to think of each horizontal slice of the Master Teapot as an analogy of the Mandelbrot set for a “restricted iterated function system.”  An application of this characterization is that the Master Teapot is not invariant under the map $(z,\lambda) \mapsto (-z,\lambda)$. This presentation is based on joint work with Chenxi Wu.

    Zoom: https://harvard.zoom.us/j/972495373

  • 04
    June 4, 2020

    CMSA Condensed Matter/Math Seminar: Coupled layers, p-string condensate, and exactly solvable fracton models

    10:30 AM-12:00 PM
    June 4, 2020
    In this talk, I will introduce a class of gapped fracton models, dubbed “cage-net fracton models”.  I will first review the coupled layer construction for exactly solvable fracton models. This construction leads to a general mechanism to obtain cage-net fracton models through a “p-string condensation”, where the extended one-dimensional particle strings built out of pointlike excitations are condensed. This p-string condensation generalizes the concept of anyon condensation in a conventional topological order and allows us to establish the properties of the fracton phase, such as its ground-state wave function, the spectrum and the mobility of excitations. To illustrate the main idea, I will focus on a simple example: doubled-Ising cage-net model. I will show that there are intrinsic non-Abelian excitations with restricted-mobility in this model and they cannot be understood as bound states among two-dimensional non-Abelian anyons and Abelian particles. If time permits, I will discuss another class of exactly solvable fracton models based on a generalization of the twisted gauge theory.
    via Zoom Video Conferencing: https://harvard.zoom.us/s/977347126
  • 05
    June 5, 2020
    No events
  • 06
    June 6, 2020
    No events