Thus far, in spite of many interesting developments, the overall progress towards a systematic study and classification of various 'strange' metallic states of matter has been rather limited. To that end, it was argued that a recent proliferation of the ideas of holographic correspondence originating from string theory might offer a possible…

Coupled-wire constructions have proven to be useful tools to characterize Abelian and non-Abelian topological states of matter in two spatial dimensions. In many cases, their success has been complemented by the vast arsenal of other theoretical tools available to study such systems. In three dimensions, however, much less is known about…

The excitation spectra of topological phases of matter contain rather `direct' information about their unusual quasiparticles, while the corresponding bulk ground states tend to be rather featureless. Motivated by this observation, we have evaluated the dynamical structure factor of the Kitaev model on the honeycomb lattice, which is unusual…

I will define what it means for time translation symmetry to be spontaneously broken in a quantum system, and show with analytical arguments and numerical simulations that this occurs in a large class of driven systems with discrete time-translation symmetry.

This talk will provide a brief overview of the field of the iron-based superconductivity (FeSC), and discuss several topical issues. In the beginning of the field, iron pnictides were the focus of attention. More recently, iron chalcogenides have taken the center stage, providing not only a renewed hope for even higher superconducting transition…

Many intriguing condensed matter phenomena such as the integer and fractional quantum Hall effect arise due to the non-trivial topological properties of the underlying system. Synthetic materials that consist of ultracold neutral atoms confined in crystal-like structures using laser beams have the potential to simulate and address the complex…

Recent spin polarized scanning tunneling microscopy (SPSTM) experiments in magnetic chains [1] opened new routes for detecting the elusive Majorana fermions (MFs). Within the deep Shiba limit we calculate [2] the spatially resolved tunneling conductance of topological ferromagnetic chains [1,3] measurable by means of SPSTM. Our analysis reveals…

In the semiclassical theory of nonlinear optics, the nonlinear response of the medium is typically treated perturbatively and characterized in terms of just a few phenomenological parameters.  The remaining task, in this case, is to measure these coefficients as a function of frequency, wavevector, temperature, etc.  However, when the medium…

In recent years it was realized that our knowledge of possible quasiparticle excitations is incomplete even for non-interacting systems. I will talk about several novel topological excitations that appear in metals. One of them realizes a new type of Weyl fermion, hosting the behavior very different from its standard quantum field theory…

A defining property of a topological material is the existence of surface bands that cannot be realized but as the termination of a topological bulk. In a Weyl semi-metal these are given by the surface Fermi-arcs, whose open-contour Fermi-surface curves between pairs of surface projections of bulk Weyl points of opposite chirality. We visualize…

Ever since the discovery of time reversal invariant topological insulators, intensive research interests are focused on how to identify new topological phases that are protected by symmetry (known as symmetry protected topological states) and how to search for new topological materials to realize these topological phases. A large variety of…

Biological systems provide an inspiration for creating a new paradigm for materials synthesis. Imagine it were possible to create an inanimate material that could both perform some function, e.g. catalyze a set of reactions, and also self replicate. Changing the parameters governing such a system would allow the possibility of evolving materials…

Phases of the strongly interacting electron fluid which spontaneously break the point-group symmetries of the host crystal can sometimes be characterized as “electron nematic phases.” Such phases increasingly appear to play a significant role in the physics of a variety of “interesting” materials, including the Cu and Fe based high temperature…

Recent experimental observations have been argued to demonstrate that one-dimensional quasicrystals - quasiperiodic slices through two-dimensional crystals - adopt the topological quantum numbers of their higher-dimensional parent lattice, exhibiting an equivalent to the quantum Hall effect. I demonstrate that the mathematics of both…

In this talk I will present recent progress in examining collective spin phenomena’s such as cavity protection, spectral hole burning and amplitude bi-stability in a hybrid solid state system consisting of a superconducting microwave cavity strongly coupled to an ensemble of electron spins in nitrogen-vacancy centers in diamond. I will show how…

Graphene provides an appealing platform to explore electronic analogs of optical effects due to the nonclassical nature of ballistic charge transport. Inspired by guiding of light in fiber optics, we demonstrate a means to guide the flow of electrons at the edges of a graphene crystal near charge neutrality. To visualize these states…

Edges of gapped topological states may host gapless edge modes that cannot be realized as stand-alone systems. Examples include quantum Hall edge states, surface states of topological insulators and super-conductors, etc. In my talk I will examine situations in which these edge states form fractionalized phases of their own. Examples to be…

Quantum vortices in weakly coupled superfluids have a large healing length, so that many particles reside within the vortex core. They are characterized by topologically protected singular points, which in principal should keep their core structure rigid. I will describe how, in practice, the point singularity of a vortex deforms into a line…

One of the central challenges in the study of quantum many-body systems is the exponential complexity of simulating them on a classical computer. A rare bright spot is the heuristic DMRG (Density Matrix Renormalization Group) which has been widely used, ever since its invention almost a quarter century ago, for solving 1D systems. A step towards…

Semi-metallic materials, such as graphene in two dimensions (2D) and various Dirac and Weyl semi-metals in three dimensions (3D), are characterized by nodal band structures that give rise to exotic electronic properties. Their stability requires the presence of lattice symmetries or application of external fields, making them lack the inherent…