148 citations · 1.2k across the 33 of their papers we have counts for
20 papers · 1 filter
Computational quantum transport: a scattering approach perspective
Xavier Waintal, Michael Wimmer, Anton Akhmerov +5
This review is devoted to the different techniques that have been developed to compute the phase-coherent transport properties of quantum nanoelectronic systems connected to electr…
Isotropic 3D topological phases with broken time reversal symmetry
Helene Spring, Anton R. Akhmerov, Daniel Varjas
Axial vectors, such as current or magnetization, are commonly used order parameters in time-reversal symmetry breaking systems. These vectors also break isotropy in three dimension…
Structural spillage: an efficient method to identify non-crystalline topological materials
Daniel Muñoz-Segovia, Paul Corbae, Dániel Varjas +3
While topological materials are not restricted to crystals, there is no efficient method to diagnose topology in non-crystalline solids such as amorphous materials. Here we introdu…
Pfaffian invariant identifies magnetic obstructed atomic insulators
Isidora Araya Day, Anastasiia Varentcova, Daniel Varjas +1
We derive a topological invariant that extends beyond symmetry eigenvalues and Wilson loops and classifies two-dimensional insulators with a symmet…
Obstructed insulators and flat bands in topological phase-change materials
Quentin Marsal, Dániel Varjas, Adolfo G. Grushin
Phase-change materials are ubiquitous in technology because of their ability to transition between amorphous and crystalline phases fast and reversibly, upon shining light or passi…
Topological defects in a double-mirror quadrupole insulator displace diverging charge
Isidora Araya Day, Anton R. Akhmerov, Daniel Varjas
We show that topological defects in quadrupole insulators do not host quantized fractional charges, contrary to what their Wannier representation indicates. In particular, we test…
Birth Quota of Non-Generic Degeneracy Points
Gergő Pintér, György Frank, Dániel Varjas +1
Weyl points are generic and stable features in the energy spectrum of Hamiltonians that depend on a three-dimensional parameter space. Non-generic isolated two-fold degeneracy poin…
Non-Hermitian topology in monitored quantum circuits
Christoph Fleckenstein, Alberto Zorzato, Daniel Varjas +3
We demonstrate that genuinely non-Hermitian topological phases and corresponding topological phase transitions can be naturally realized in monitored quantum circuits, exemplified…
Weyl-point teleportation
György Frank, Dániel Varjas, Gergő Pintér +1
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 contro…
Topological charge distributions of an interacting two-spin system
György Frank, Dániel Varjas, Péter Vrana +2
Quantum systems are often described by parameter-dependent Hamiltonians. Points in parameter space where two levels are degenerate can carry a topological charge. Here we theoretic…
Amorphous topological phases protected by continuous rotation symmetry
Helene Spring, Anton R. Akhmerov, Daniel Varjas
Protection of topological surface states by reflection symmetry breaks down when the boundary of the sample is misaligned with one of the high symmetry planes of the crystal. We de…
Minimal Zeeman field requirement for a topological transition in superconductors
Kim Pöyhönen, Daniel Varjas, Michael Wimmer +1
Platforms for creating Majorana quasiparticles rely on superconductivity and breaking of time-reversal symmetry. By studying continuous deformations to known trivial states, we fin…
Hybrid kernel polynomial method
Muhammad Irfan, Sathish R. Kuppuswamy, Daniel Varjas +4
The kernel polynomial method allows to sample overall spectral properties of a quantum system, while sparse diagonalization provides accurate information about a few important stat…
Interplay between boundary conditions and Wilson's mass in Dirac-like Hamiltonians
A. L. Araújo, R. P. Maciel, R. G. F. Dornelas +2
Dirac-like Hamiltonians, linear in momentum , describe the low-energy physics of a large set of novel materials, including graphene, topological insulators, and Weyl fermions. W…
Topological phases without crystalline counterparts
Daniel Varjas, Alexander Lau, Kim Pöyhönen +3
Recent years saw the complete classification of topological band structures, revealing an abundance of topological crystalline insulators. Here we theoretically demonstrate the exi…
Computation of topological phase diagram of disordered PbSnTe using the kernel polynomial method
Daniel Varjas, Michel Fruchart, Anton R. Akhmerov +1
We present an algorithm to determine topological invariants of inhomogeneous systems, such as alloys, disordered crystals, or amorphous systems. Based on the kernel polynomial meth…
The influence of lattice termination on the edge states of the quantum spin Hall insulator monolayer -WTe
Alexander Lau, Rajyavardhan Ray, Daniel Varjas +1
We study the influence of sample termination on the electronic properties of the novel quantum spin Hall insulator monolayer -WTe. For this purpose, we construct an accura…
Spin-orbit interaction and induced superconductivity in an one-dimensional hole gas
F. K. de Vries, J. Shen, R. J. Skolasinski +11
Low dimensional semiconducting structures with strong spin-orbit interaction (SOI) and induced superconductivity attracted much interest in the search for topological superconducto…
Orbital contributions to the electron g-factor in semiconductor nanowires
Georg W. Winkler, Dániel Varjas, Rafal Skolasinski +3
Recent experiments on Majorana fermions in semiconductor nanowires [Albrecht et al., Nat. 531, 206 (2016)] revealed a surprisingly large electronic Landé g-factor, several times la…
Dynamical piezoelectric and magnetopiezoelectric effects in polar metals from Berry phases and orbital moments
Daniel Varjas, Adolfo G. Grushin, Roni Ilan +1
The polarization of a material and its response to applied electric and magnetic fields are key solid-state properties with a long history in insulators, although a satisfactory th…