Is this you? As a journalist, you can create a free Muck Rack account to customize your profile, list your contact preferences, and upload a portfolio of your best work.
Claim your profile
Articles by Dániel Varjas
Forschungsportal der TU Dresden
Parameter-dependent quantum systems often exhibit energy degeneracy points, whose comprehensive description naturally leads to the application of methods from singularity theory. A prime example is an electronic band structure where two energy levels coincide in a point of momentum space. It may happen, and this case is the focus of our work, that three or more levels coincide at a parameter point, called multifold degeneracy.
Forschungsportal der TU Dresden
In quantum mechanics, the Schrieffer–Wolff (SW) transformation (also called quasi-degenerate perturbation theory) is known as an approximative method to reduce the dimension of the Hamiltonian. We present a geometric interpretation of the SW transformation: We prove that it induces a local coordinate chart in the space of Hermitian matrices near a k-fold degeneracy submanifold.
Author Correction: Establishing coherent momentum-space electronic states in locally ordered materials - Nature Communications
Correction to: Nature Communications https://doi.org/10.1038/s41467-024-51953-y, published online 17 September 2024 The original version of this article contained an error in Fig. 2, where panel (e) displayed incorrect data and had an incorrect label on the y-axis. The correct version of Fig. 2 is: which replaces the previous incorrect version: This has been corrected in both the PDF and HTML versions of the Article.
Establishing coherent momentum-space electronic states in locally ordered materials - Nature Communications
Abstract Rich momentum-dependent electronic structure naturally arises in solids with long-range crystalline symmetry. Reliable and scalable quantum technologies rely on materials that are either not perfect crystals or non-crystalline, breaking translational symmetry. This poses the fundamental questions of whether coherent momentum-dependent electronic states can arise without long-range order, and how they can be characterized.
Weyl-point teleportation
In this work we describe the phenomenon of Weyl-point teleportation. Weyl points usually move continuously in the configuration parameter space of a quantum system when the control parameters are varied continuously. However, there are special transition points in the control space where the continuous motion of the Weyl points is disrupted.
Exceptional dynamics of interacting spin liquids
Abstract We show that interactions in quantum spin liquids can result in non-Hermitian phenomenology that differs qualitatively from mean-field expectations. We demonstrate this in two prominent cases through the effects of phonons and disorder on a Kitaev honeycomb model. Using analytic and numerical calculations, we show the generic appearance of exceptional points and rings depending on the symmetry of the system.
Non-Hermitian topology in monitored quantum circuits
Abstract We demonstrate that genuinely non-Hermitian topological phases and corresponding topological phase transitions can be naturally realized in monitored quantum circuits, exemplified by the paradigmatic non-Hermitian Su-Schrieffer-Heeger model. We emulate this model by a 1D chain of spinless electrons evolving under unitary dynamics and subject to periodic measurements that are stochastically invoked.
Topological Weaire-Thorpe models of amorphous matter
Topological Weaire–Thorpe models of amorphous matter Quentin Marsal, Dániel Varjas, Adolfo G. Grushin Proceedings of the National Academy of Sciences Nov 2020, 202007384; DOI: 10.1073/pnas.2007384117
Topological Phases without Crystalline Counterparts
Abstract We construct a two-dimensional higher-order topological phase protected by a quasicrystalline eightfold rotation symmetry. Our tight-binding model describes a superconductor on the Ammann-Beenker tiling hosting localized Majorana zero modes at the corners of an octagonal sample. In order to analyze this model, we introduce Hamiltonians generated by a local rule, and use this concept to identify the bulk topological properties.
Show More
loading
Actions
Is this you?
As a journalist, you can create a free Muck Rack account to customize your profile, list your contact preferences, and upload a portfolio of your best work.Get in touch with Dániel
Contact Dániel, search articles and posts on X, monitor coverage, and track replies from one place.
Learn more about Muck Rack