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We demonstrate the existence of topological insulators in one dimension protected by mirror and time-reversal symmetries. They are characterized by a nontrivial $\mathbb{Z}_2$ topological invariant defined in terms of the "partial"…

Mesoscale and Nanoscale Physics · Physics 2016-10-27 Alexander Lau , Jeroen van den Brink , Carmine Ortix

We study the behavior of spinless fermions in superconducting state, in which the phases of the superconducting order parameter depend on the direction of the link. We find that the energy of the superconductor depends on the phase…

Strongly Correlated Electrons · Physics 2017-08-04 Igor N. Karnaukhov

We explore the critical properties of a topological transition in a two-dimensional, amorphous lattice with randomly distributed points. The model intrinsically breaks the time-reversal symmetry without an external magnetic field, akin to a…

Mesoscale and Nanoscale Physics · Physics 2025-10-24 Soumya Bera , Johannes Dieplinger , Naba P Nayak

We analyze a measurement scheme that allows determination of the Berry curvature and the topological Chern number of a Hamiltonian with parameters exploring a two-dimensional closed manifold. Our method uses continuous monitoring of the…

Quantum Physics · Physics 2017-07-12 Peng Xu , Alexander Holm Kiilerich , Ralf Blattmann , Yang Yu , Shi-Liang Zhu , Klaus Mølmer

Higher-dimensional Hilbert spaces in quantum simulation, as in all quantum science, expand the range of accessible phenomena. In this work, we experimentally realize a synthetic monopole using an ultracold spin-1 ensemble, where the…

Chern numbers are gaining traction as they characterize topological phases in various physical systems. However, the resilience of the system topology to external perturbations makes it challenging to experimentally investigate transitions…

Quantum Physics · Physics 2022-11-28 Junghyun Lee , Keigo Arai , Huiliang Zhang , Mark J. H. Ku , Ronald L. Walsworth

In order to study continuous models of disordered topological phases, we construct an unbounded Kasparov module and a semifinite spectral triple for the crossed product of a separable $C^*$-algebra by a twisted $\mathbb{R}^d$-action. The…

Mathematical Physics · Physics 2018-07-02 Chris Bourne , Adam Rennie

Topological phase transitions are typically characterized by abrupt changes in a quantized invariant. Here we report a contrasting paradigm in non-Hermitian parity-time symmetric systems, where the topological invariant remains conserved,…

Mesoscale and Nanoscale Physics · Physics 2025-03-31 Kang Yang , Zhi Li , Peng Xue , Emil J. Bergholtz , Piet W. Brouwer

We characterize non-Hermitian band structures by symmetry indicator topological invariants. Enabled by crystalline inversion symmetry, these indicators allow us to short-cut the calculation of conventional non-Hermitian topological…

Mesoscale and Nanoscale Physics · Physics 2021-05-26 Pascal M. Vecsei , M. Michael Denner , Titus Neupert , Frank Schindler

In the presence of crystalline symmetry, topologically ordered states can acquire a host of symmetry-protected invariants. These determine the patterns of crystalline symmetry fractionalization of the anyons in addition to fractionally…

Strongly Correlated Electrons · Physics 2025-08-21 Ryohei Kobayashi , Yuxuan Zhang , Naren Manjunath , Maissam Barkeshli

We theoretically demonstrate that Chern number tunable quantum anomalous Hall effect (QAHE) and second-order topological insulators can be induced in the two-dimensional $\mathbb{Z}_2$ topological insulator (TI), i.e., Kane-Mele model, by…

Mesoscale and Nanoscale Physics · Physics 2025-07-08 Zhengtian Li , Zeyu Li , Zhenhua Qiao

We introduce a second-quantized field theory for Chern insulators in which the Hamiltonian features a static vector potential that has the periodicity of the crystal's lattice and spontaneously breaks time-reversal symmetry in the system's…

Mesoscale and Nanoscale Physics · Physics 2026-01-30 Jason G. Kattan , J. E. Sipe

We study disorder effects in a two-dimensional system with chiral symmetry and find that disorder can induce a quadrupole topological insulating phase (a higher-order topological phase with quadrupole moments) from a topologically trivial…

Mesoscale and Nanoscale Physics · Physics 2021-02-05 Yan-Bin Yang , Kai Li , L. -M. Duan , Yong Xu

We define a $\mathbb{Z}_2$-valued topological and gauge invariant associated to any 1-dimensional, translation-invariant topological insulator which satisfies either particle-hole symmetry or chiral symmetry. The invariant can be computed…

Mathematical Physics · Physics 2023-05-01 Domenico Monaco , Gabriele Peluso

We employ quantum Monte Carlo techniques to calculate the $Z_2$ topological invariant in a two-dimensional model of interacting electrons that exhibits a quantum spin Hall topological insulator phase. In particular, we consider the parity…

Strongly Correlated Electrons · Physics 2013-05-02 Thomas C. Lang , Andrew M. Essin , Victor Gurarie , Stefan Wessel

We establish a connection between the electromagnetic Hall response and band topological invariants in hyperbolic Chern insulators by deriving a hyperbolic analog of the Thouless-Kohmoto-Nightingale-den Nijs (TKNN) formula. By generalizing…

Mesoscale and Nanoscale Physics · Physics 2024-12-03 Canon Sun , Anffany Chen , Tomáš Bzdušek , Joseph Maciejko

We consider the two-dimensional topological Chern insulator in the presence of static disorder. Generic quantum states in this system are Anderson localized. However, topology requires the presence of a subset of critical states, with…

Mesoscale and Nanoscale Physics · Physics 2023-08-29 Mateo Moreno-Gonzalez , Johannes Dieplinger , Alexander Altland

A topologically ordered material is characterized by a rare quantum organization of electrons that evades the conventional spontaneously broken symmetry based classification of condensed matter. Exotic spin transport phenomena such as the…

Mesoscale and Nanoscale Physics · Physics 2009-10-08 D. Hsieh , Y. Xia , L. Wray , D. Qian , A. Pal , J. H. Dil , F. Meier , J. Osterwalder , G. Bihlmayer , C. L. Kane , Y. S. Hor , R. J. Cava , M. Z. Hasan

Computing topological invariants in two-dimensional quasicrystals and super-moire matter is a remarkable open challenge, due to the absence of translational symmetry and the colossal number of sites inherent to these systems. Here, we…

Strongly Correlated Electrons · Physics 2026-04-14 Tiago V. C. Antão , Yitao Sun , Adolfo O. Fumega , Jose L. Lado

The quantum anomalous Hall system with Chern number 2 can be destroyed by sufficiently strong disorder. During its process towards localization, it was found that the electronic states will be directly localized to an Anderson insulator…

Mesoscale and Nanoscale Physics · Physics 2016-01-12 Zhi-Gang Song , Yan-Yang Zhang , Jun-Tao Song , Shu-Shen Li