A striking feature of non-Hermitian systems is the presence of two types of topology. One generalizes Hermitian topological phases, and another is intrinsic to non-Hermitian systems, called line-gap topology and point-gap topology. Whereas the bulk-boundary correspondence is a fundamental principle in the former topology, its role in the latter…

**Matan Uzan - "de Haas-van Alphen spectroscopy and magnetic breakdown in moiré graphene"**

(Followed by Prof. Berthold Jaeck)

Quantum oscillations(QO) originating from the quantization of the electron cyclotron orbits provide ultrasensitive diagnostics of electron bands and interactions in novel materials. We…

- Matan UzanAffiliationWeizmann Institute
- Prof. Berthold Jaeck

Understanding strongly correlated topological quantum phases has been a longstanding challenge. Moiré materials present a unique opportunity as they allow us to engineer flat topological bands and vary the carrier density throughout entire bands in situ using electrostatic gates. I will open the talk by presenting nanoscale images of…

Many of the topological Weyl semimetals host also a Kagome crystal structure that together result in extremely rich electronic phenomenology. The bulk Weyl nodes and the diverging Berry curvature associated with them give rise to an intricate bulk-boundary correspondence hosting open-contour Fermi-arc modes on certain surfaces. The Kagome…

The discovery of magic angle twisted bilayer graphene (MATBG), where two sheets of monolayer graphene are precisely stacked at a specific angle, has opened a plethora of grand new opportunities in the field of topology, superconductivity, and other strongly correlated effect. In twisted van der Waals materials, lattice mismatch can generate…

The fractional quantum anomalous Hall effect (FQAHE), the analog of the fractional quantum Hall effect at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The demonstration of FQAHE could lead to non-Abelian anyons which form the basis of topological quantum computation…

Quantum geometry quantifies the momentum space textures of the Bloch wavefunctions and impacts substantially the physics of multiband systems. This is also true for van der Waals semiconductors, which are usually described within a parabolic, effective mass, approximation. In this talk, I will start by a general discussion on quantum geometry,…

Topological superconductivity is a sought-after state of matter, particularly in bulk crystalline materials. UTe2 is a recently-discovered contender for topological superconductivity, but its superconducting order parameter remains a matter of contention. In this talk, I will first present a brief overview of key experimental results on the…

While Laughlin identified the fractional quantum Hall state as a consequence of an “incompressible quantum fluid”, well-described by his model wavefunction which exhibits “flux attachment”, no fundamental explanation of the energetics driving “flux attachment” has emerged. A new picture reveals that a…

Studying non-abelian anyons is exciting due to their unique braiding statistics. The 5/2 quantum Hall state has been long proposed to host such localized quasiparticles in the 2D bulk. Resting on ‘bulk-edge’ correspondence, their gapless edge modes are expected to mirror the topological order of the 5/2 quantum state. Supporting an odd number…

Molecular beam epitaxy (MBE) is an epitaxial process by which we could grow single-crystal thin films, heterostructures, and superlattices with the highest achievable purity. Therefore, MBE is known as one of the most advanced and controllable material synthesis methods. In this talk, I will briefly introduce the MBE growth mechanism and then…

It is by now well-understood that gapped ground states of local Hamiltonians can be classified topologically, and the nontrivial states exhibit a variety of interesting topological phenomena. In this talk I’ll discuss how the topological classification can be generalized to disordered ensembles and mixed states. I’ll focus on short-range…

In 1937, Ettore Majorana suggested that a particle, which is its own antiparticle might exist. This triggered the interest of high-energy physicists, but, despite the big efforts, there is no evidence of such a particle [1]. In condensed matter, a quasiparticle with such property can be created, i.e. a Majorana zero mode (MZM). MZMs are non…

Title/Abstract TBA

Abstract: The fermion sign problem tends to stymie exploration of

highly entangled phases of fermions, such as those relevant for heavy

fermion quantum criticality. In this talk, I will present recent

progress in simulating Fermi and non-Fermi liquids in the context of

Kondo lattice systems. One of the new ideas is…

Abstract: We propose an externally imposed superlattice potential as a platform for manipulating topological phases, which has both advantages and disadvantages compared to a moire superlattice. In the first example, we apply the superlattice potential to the 2D surface of a 3D topological insulator. The superlattice potential creates tunable…

Raman scattering, invented at the end of the last pandemic, can provide a wealth of information on the fractional, magnetic, lattice and charge excitations at the heart of quantum materials and devices. I will first discuss how Raman provides direct evidence for coupled phonon-electron fluids in topological semimetals, helping to explain their…

**Abstract**: Twisted van der Waals materials provide a new venue to explore flat electronic bands and the interaction-driven states they host. While many such phases have been reported, little is known about their excitations or how they depend on externally applied fields. In this talk, I will present two examples where…

In solid materials, electrons are usually described by the non-relativistic Schrodinger equation since electron velocity is much slower than the speed of light. However, the relativistic Dirac/Weyl equation can emerge as a low-energy effective theory for electrons in certain materials. These systems are…

Ultracold atoms offer a unique platform to perform quantum simulations of quantum materials and many-body systems. When atoms with spin are arranged in an optical lattice in form of a Mott insulator, they realize paradigmatic Heisenberg spin models, where only neighboring spins interact. Until very recently, all experimental studies with cold…

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