This Week @ the SCGP

Tuesday, 9-26-2017
SCGP Weekly Talk: Nikita Nekrasov
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Description: Title: "On the origin of Chern-Simons terms" Abstract: Chern-Simons theory has been used to produce/explain the invariants of three-manifolds, knots, and links. Recently an interest in the higher dimensional versions of CS theory has been revived. I will review these developments and their relation to the fascinating S-duality of certain four dimensional gauge theories.
Wednesday, 9-27-2017
Hydrodynamics Program Seminar: Vipin Varma
Time: 10:30 AM - 12:00 PM
Location: SCGP 313
Description: Title: Transport and fractality in boundary-driven (quasi)disordered chains Abstract: In this talk we report on the response of (quasi)disordered spin-chains at high temperature to boundary driving through reservoirs at its ends. In the strongly interacting regime, we unveil a rich dynamical phase diagram that displays a panoply of transport properties --- for both energy and spin --- as an interplay between interaction and disorder strengths: localized, ballistic, superdiffusive, diffusive, and subdiffusive. These effects occur well away from the many-body localization critical point, and whilst the system is still deep in the ergodic phase. Similar anomalous transport is shown to occur in the quasidisordered system at criticality even without interactions; in addition, the nonequilibrium steady state here exhibits spatial fractality in many of its expectation values, opening an alternative route to experimentally probe a system's fractal properties in contrast to measuring quantum wavefunctions.
Thursday - September 28, 2017
Math Event: Math Colloquium: Nick Trefethen - TBA
Time: 4:00 PM - 5:00 PM
Location: SCGP Rm 102
Description: Title: TBA
Speaker: Nick Trefethen [NYU]

Abstract: TBA
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Friday, 9-29-2017
Hydrodynamics Program Seminar: Abhishodh Prakash (SBU)
Time: 10:30 AM - 12:00 PM
Location: SCGP 313
Description: Title: Eigenstate phases with on-site finite non-Abelian symmetry Abstract: Potter and Vasseur recently conjectured [1] that full many-body localization (MBL) is incompatible with finite non-Abelian symmetries unless it is spontaneously broken down to an Abelian subgroup. In this talk, I will present a numerical investigation of this conjecture by building a local spin Hamiltonian invariant under the action of the simplest non-Abelian group, S_3. Using full entanglement distributions and level statistics, we observe a thermal phase and an MBL phase where S_3 is spontaneously broken down to Z_3 resulting in a spin-glass like order in highly excited states. For a certain parameter range, there appears to be an intermediate region where full MBL is absent while S_3 is intact. I will speculate on the nature of this region. This talk is based on the results from our paper [2] [1] Phys. Rev. B 94, 224206 (2016) [2] arXiv:1706.06062