One of the key issues regarding the cuprate high temperature superconductors is the evolution of the electronic structure when charge carriers are doped into the parent Mott insulator. We have performed scanning tunneling microscopy studies on the parent Ca2CuO2Cl2 Mott insulator and severely underdoped Bi2Sr2-xLaxCuO6 in the antiferromagnetic…

Iron-based superconductors (Fe-SCs), with their highest transition temperature (Tc) at 57K, have been added since 2008 to the family of high-Tc superconductors which has been solely occupied by copper-based superconductors (Cu-SCs) for more than 20 years. Both Fe-SCs and Cu-SCs, with a transition element playing crucial roles in their…

Search for topological materials becomes significantly simplified within the framework of some special class of Wannier functions. I will explain this technique in some details and give an overview of the ongoing work on global search for candidate topological materials. I will also describe the Wannier-based construction of microscopic models…

Topological phases and phenomena in photonics have attracted a lot of research interests since the pioneering work by Haldane. In this talk, I will first show our realization of the photonic analog of quantum anomalous Hall effect. At the edge, there exists topologically-protected one-way edge waveguides with Chern numbers of one, two, three and…

Since its (re-)discovery in the second half of the 20th century, the lattice of corner-sharing triangles called kagome has become one of the paradigmatic models for exotic quantum electronic states of matter. The Hubbard model on the kagome lattice exhibits many fascinating phases subject to contemporary research in condensed matter physics,…

In my talk I will present fresh findings on the possibility of producing a topological polariton (nicknamed topolariton) in trivial quantum-wells coupled to extended optical cavities. The idea of a topolariton emerges naturally from the concept of Floquet topological insulators. First, I will review how an external periodic drive can lead to a…

Much interest in the superconducting proximity effect in 3D topological insulators (TIs) has been driven by the potential to induce exotic Majorana bound states. Most candidate materials for 3D TI, however, are bulk metals, with bulk states at the Fermi level coexisting with well-defined surface states exhibiting spin-momentum locking. In such…

No abstract available.

An elegant idea for the creation of entangled electrons in a solid-state device is to split Cooper pairs, which are in a spin singlet state, by coupling a superconductor to two parallel quantum dots (QDs) in a Y-junction geometry [1]. Cooper pair splitting (CPS) was investigated recently in devices based on InAs nanowires [2,3] and carbon…

Using high resolution ARPES we analyze the electronic scattering rates of cuprate superconductors as a function of temperature, energy, and doping. In the normal state we show the smooth and continual evolution from the heavily overdoped Fermi liquid limit to the optimally doped Marginal Fermi liquid limit and beyond, with these results showing…

As femtosecond laser interacts with matter in fundamentally different ways than how continuous wave (CW) or nano-second laser interacts, it gives rise to many interesting phenomena which may open doors for exciting future applications, like plasmon coupled high harmonic generation [Park 2011] nano-electronics [Chimmalgi 2005], etc. CW and nano…

Electron puddles created by doping of a 2D topological insulator may violate the ideal helical edge conductance. Because of a long electron dwelling time, even a single puddle may lead to a significant inelastic backscattering. We find the resulting correction to the perfect edge conductance. Generalizing to multiple puddles, we assess the…

We are studying the transport properties of hybrid S-TI-S devices fabricated by depositing superconductor electrodes onto topological insulators. In top-gated Nb-Bi2Se3-Nb junctions, we have measured the Josephson supercurrent and conductance as a function of geometry, temperature, and gate voltage in order to determine the nature of the charge…

Recent advances in preparing, probing and manipulating ultracold atomic gases enable studying condensed matter physics in a very controlled setting. In the first part of my talk, I will describe quantum gas microscopy, a powerful tool for imaging and manipulating strongly interacting quantum gases containing thousands of atoms at the single atom…

In this talk I will review recent theoretical work on a new class of topological material systems - topological Kondo insulators, which appear as a result of interplay between strong correlations and spin-orbit interactions. I will start with introducing the by now standard theory of topological band insulators and explain the Fu-Kane method to…

Using a controlled weak-coupling renormalization group approach, we establish the mechanism of unconventional superconductivity in the vicinity of spin or charge ordered excitonic states for the case of electrons on the Bernal stacked bilayer honeycomb lattice. With one electron per site this system exhibits nearly parabolically touching…

Abstacts not available for these talks.

The recently discovered topological crystalline insulators harbor Dirac surface states protected by a discrete set of crystalline space group symmetries and show immense promise for novel quantum applications. In this talk, I will present a first principles investigation as well as a model Hamiltonian of the nontrivial surface states and their…

Since the discovery that electrons in graphene behave as massless Dirac fermions, the single-atom-thick material has become a fertile playground for testing exotic predictions of quantum electrodynamics, such as Klein tunneling and the fractional quantum Hall effect. Now add to that list atomic collapse, the spontaneous formation of electrons and…

Quantum point contacts (QPCs) are the basic building blocks of any mesoscopic structure, and display quantized conductance, reflecting the quantization of the number of transparent channels. An additional feature, coined the "0.7 anomaly", has been observed in almost all QPCs, and has been a subject of intensive debate in the last couple of…