PLEASE NOTE THIS TALK FROM 10/8 HAS BEEN RESCHEDLED TO 10/22/2019 -- THANK YOU!

Unlike their classical counterparts, quantum antiferromagnetic systems exhibit ground state frustration effects even in one dimension. A case in point is the SU(2S+1) invariant spin chain, with the interaction between pairs of neighboring S-spins given by…

We aim at presenting a simple context where known results on Anderson localization for systems of non-interacting particles in a random environment may be extended to systems with weak interactions.

Using the fractional moment method it is shown that, within the Hartree-Fock…

The quantum random energy model serves as a simple cornerstone, and a testing ground, for a number of fields. It is the simplest of all mean-field spin glass models in which quantum effects due to the presence of a transversal field are studied. Renewed interest in its spectral properties arose recently in…

The one-dimensional AKLT spin chain is the prototypical example of a frustration-free quantum spin system with a spectral gap above its ground state. Affleck, Kennedy, Lieb, and Tasaki conjectured that the two-dimensional version of their model on the hexagonal lattice also exhibits a spectral gap. In this talk, we introduce a family of…

In recent years, there has been a surge of activities in proposing "exactly solvable" quantum spin chains with surprising high amount of ground state entanglement--exponentially more than critical systems that have $\log(n)$ von Neumann entropy. We discuss these models from first principles. For a spin chain of length $n$, we prove that the…

Abstract: We show how in the strongly-disordered, gapless regime, the topological properties of chiral chains (class AIII 1D in the Kitaev table) can be read off from the Lyapunov spectrum of the system at zero energy, and prove that these objects are topologically stable in the strongly-disordered gapless regime.

(Based on joint…

Consider a metallic field emitter shaped like a thin needle, at the tip of which a large electric field is applied. Electrons spring out of the metal under the influence of the field. The celebrated and widely used Fowler-Nordheim equation predicts a value for the current outside the metal. In this talk, I will show…

In this talk I present theoretical evidence, based on non-perturbative semi-classical quantization techniques, that what appears as the annihilation of Positronium (Ps) may in reality be just another electromagnetic transition from the hydrogenic pseudo-ground state of Ps to a true quantum-mechanical ground state near zero energy, caused by…

Abstract: Hermitian random matrix models are known to exhibit phase transitions regarding both their local eigenvalue statistics and in the eigenvectors’ localisation properties. The poster child of such is the Rosenzweig-Porter model, which is based on the interpolation between a random diagonal matrix and GOE. Interestingly, this model has…

Abstract:

Rayleigh's stability analysis of cylindrical Couette flow, of 1916, is in contradiction with observation, but it is still widely quoted and no one seems to know what the reason is that it fails. I shall identify the mistake as one that is endemic in the literature. Briefly, the argument depends on the Navier-Stokes…

Abstract:

I will present a class of hard-core lattice particle systems which exhibit a crystalline phase at high densities. The key ingredient of the proof is to show that the Gaunt-Fisher high-fugacity expansion is convergent for such models, which we acomplish using methods from Pirogov-Sinai theory…

Abstract:

We study one dimensional insulators obeying a chiral symmetry in the single-particle picture where the Fermi energy is assumed to lie within a mobility gap. Topological invariants are defined for infinite (bulk) or half-infinite (edge) systems, and it is shown that for a given bulk system with…

Abstract: Discussed is the Euler-type hydrodynamics for one-dimensional integrable quantum systems, as the Lieb-Liniger delta Bose gas and the XXZ chain. Of particular interest are domain wall initial states. We will use classical hard rods as an illustration of the underlying structure.

Abstract:

Semigroups of completely positive trace preserving maps satisfying a certain detailed balance condition are gradient flow driven by dissipation of the quantum relative entropy with respect to a non-commutative analog of the 2-Wasserstein metric on the space of probability densities on Euclidean…

Abstract: Certain strongly disordered many-body quantum systems are incapable of reaching thermal equilibrium. The nature of this so-called many-body localized (MBL) phase has recently been an active area of research. The phenomenon can be understood through perturbative approximations, but rare regions with weak disorder (Griffiths regions)…

Abstract:

A loop configuration on the hexagonal (honeycomb) lattice is a finite subgraph of the lattice in which every vertex has degree 0 or 2, so that every connected component is isomorphic to a cycle. The loop O(n) model on the hexagonal lattice is a random loop configuration, with the energy of of a loop configuration taken to…

Abstract:

Given n uniform points on the surface of a two-dimensional sphere, how can we partition the sphere fairly among them ? "Fairly" means that each region has the same area. It turns out that if the given points apply a two-dimensional gravity force to the rest of the sphere, then the basins…

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