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Liouvillian topology and nonreciprocal dynamics in open Floquet chains
Florian Koch, Yu-Min Hu, Jan Carl Budich
Open quantum systems far from thermal equilibrium can exhibit remarkable physical phenomena including topological properties without a direct equilibrium counterpart. Along these l…
Quantum Hall Effect without Chern Bands
Benjamin Michen, Jan Carl Budich
The quantum Hall effect was originally observed in a two-dimensional electron gas forming Landau levels when exposed to a strong perpendicular magnetic field and was later generali…
Nodal Spectral Functions Stabilized by Non-Hermitian Topology of Quasiparticles
Carl Lehmann, Tommaso Micallo, Jan Carl Budich
In quantum materials, basic observables such as spectral functions and susceptibilities are determined by Green's functions and their complex quasiparticle spectrum rather than by…
Dissipative frequency converter: from Lindblad dynamics to non-Hermitian topology
Florian Koch, Jan Carl Budich
A topological frequency converter represents a dynamical counterpart of the integer quantum Hall effect, where a two-level system enacts a quantized time-averaged power transfer be…
Non-Hermitian topological ohmmeter
Viktor Könye, Kyrylo Ochkan, Anastasiia Chyzhykova +4
Measuring large electrical resistances forms an essential part of common applications such as insulation testing, but suffers from a fundamental problem: the larger the resistance,…
Correlation-Induced Sensitivity and Non-Hermitian Skin Effect of Quasiparticles
Tommaso Micallo, Carl Lehmann, Jan Carl Budich
Non-Hermitian (NH) Hamiltonians have been shown to exhibit unique signatures, including the NH skin effect and an exponential spectral sensitivity with respect to boundary conditio…
Braid Protected Topological Band Structures with Unpaired Exceptional Points
J. Lukas K. König, Kang Yang, Jan Carl Budich +1
We demonstrate the existence of topologically stable unpaired exceptional points (EPs), and construct simple non-Hermitian (NH) tight-binding models exemplifying such remarkable no…
Topological Burning Glass Effect
Simon Körber, Lorenzo Privitera, Jan Carl Budich +1
We reveal a topological burning glass effect, where the local response of a system exhibits a topological quantization that is enhanced by an integer due to its environmental coupl…
Mesoscopic transport signatures of disorder-induced non-Hermitian phases
Benjamin Michen, Jan Carl Budich
We investigate the impact on basic quantum transport properties of disorder-induced exceptional points (EPs) that emerge in a disorder-averaged Green's function description of two-…
Transition from metal to higher-order topological insulator driven by random flux
Chang-An Li, Song-Bo Zhang, Jan Carl Budich +1
Random flux is commonly believed to be incapable of driving full metal-insulator transitions in non-interacting systems. Here we show that random flux can after all induce a full m…
Dynamically Induced Exceptional Phases in Quenched Interacting Semimetals
Carl Lehmann, Michael Schüler, Jan Carl Budich
We report on the dynamical formation of exceptional degeneracies in basic correlation functions of non-integrable one- and two-dimensional systems quenched to the vicinity of a cri…
Exceptional Non-Hermitian Phases in Disordered Quantum Wires
Benjamin Michen, Tommaso Micallo, Jan Carl Budich
We demonstrate the occurrence of nodal non-Hermitian (NH) phases featuring exceptional degeneracies in chiral-symmetric disordered quantum wires, where NH physics naturally arises…
Non-Hermitian Topological Sensors
Jan Carl Budich, Emil J. Bergholtz
We introduce and study a novel class of sensors whose sensitivity grows exponentially with the size of the device. Remarkably, this drastic enhancement does not rely on any fine-tu…
Interacting topological frequency converter
Simon Körber, Lorenzo Privitera, Jan Carl Budich +1
We show that an interacting two-spin model subjected to two circularly polarized drives enables a feasible realization of a correlated topological phase in synthetic dimensions. Th…
Exceptional Topology of Non-Hermitian Systems
Emil J. Bergholtz, Jan Carl Budich, Flore K. Kunst
The current understanding of the role of topology in non-Hermitian (NH) systems and its far-reaching physical consequences observable in a range of dissipative settings are reviewe…
Bulk-boundary correspondence in non-Hermitian systems: stability analysis for generalized boundary conditions
Rebekka Koch, Jan Carl Budich
The bulk-boundary correspondence (BBC), i.e. the direct relation between bulk topological invariants defined for infinite periodic systems and the occurrence of protected zero-ener…
Hyperbolic Nodal Band Structures and Knot Invariants
Marcus Stålhammar, Lukas Rødland, Gregory Arone +2
We extend the list of known band structure topologies to include a large family of hyperbolic nodal links and knots, occurring both in conventional Hermitian systems where their st…
Non-Hermitian Weyl Physics in Topological Insulator Ferromagnet Junctions
Emil J. Bergholtz, Jan Carl Budich
We introduce and investigate material junctions as a generic and tuneable electronic platform for the realization of exotic non-Hermitian (NH) topological states of matter, where t…
Knotted Non-Hermitian Metals
Johan Carlström, Marcus Stålhammar, Jan Carl Budich +1
We report on the occurrence of knotted metallic band structures as stable topological phases in non-Hermitian (NH) systems. These knotted NH metals are characterized by open Fermi…
Symmetry-protected nodal phases in non-Hermitian systems
Jan Carl Budich, Johan Carlström, Flore K. Kunst +1
Non-Hermitian (NH) Hamiltonians have become an important asset for the effective description of various physical systems that are subject to dissipation. Motivated by recent experi…
Biorthogonal Bulk-Boundary Correspondence in Non-Hermitian Systems
Flore K. Kunst, Elisabet Edvardsson, Jan Carl Budich +1
Non-Hermitian systems exhibit striking exceptions from the paradigmatic bulk-boundary correspondence, including the failure of bulk Bloch band invariants in predicting boundary sta…
Dynamical Topological Order Parameters far from Equilibrium
Jan Carl Budich, Markus Heyl
We introduce a topological quantum number -- coined dynamical topological order parameter (DTOP) -- that is dynamically defined in the real-time evolution of a quantum many-body sy…
Topological aspects of phase winding junctions in superconducting wires
Christian Spånslätt, Eddy Ardonne, Jan Carl Budich +1
We theoretically investigate Josephson junctions with a phase shift of in various proximity induced one-dimensional superconductor models. One of the salient experimental signa…
Teleportation-induced entanglement of two nanomechanical oscillators coupled to a topological superconductor
Stefan Walter, Jan Carl Budich
A one-dimensional topological superconductor features a single fermionic zero mode that is delocalized over two Majorana bound states located at the ends of the system. We study a…