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We report on the measurement of topological invariants in an electromagnetic topological insulator analog formed by a microwave network, consisting of the winding numbers of scattering matrix eigenvalues. The experiment can be regarded as a…

We explore the topological properties of double-Weyl semimetals with cold atoms in optical lattices. We first propose to realize a tight-binding model of simulating the double-Weyl semimetal with a pair of double-Weyl points by engineering…

Quantum Gases · Physics 2017-06-23 Xue-Ying Mai , Dan-Wei Zhang , Zhi Li , Shi-Liang Zhu

We revisit the question of whether a two-dimensional topological insulator may arise in a commensurate N\'eel antiferromagnet, where staggered magnetization breaks both the elementary translation and time reversal, but retains their product…

Strongly Correlated Electrons · Physics 2016-04-07 Frédéric Bègue , Pierre Pujol , Revaz Ramazashvili

Topological invariants play a key role in the characterization of topological states. Due to the existence of exceptional points, it is a great challenge to detect topological invariants in non-Hermitian systems. We put forward a dynamic…

Quantum Physics · Physics 2020-04-22 Bo Zhu , Yongguan Ke , Honghua Zhong , Chaohong Lee

The study of topological property of band insulators is an interesting branch of condensed matter physics. Two types of topologically nontrivial insulators have been extensively studied. The first type is characterized by a nonzero TKNN…

Materials Science · Physics 2011-11-15 Yi-Dong Wu

Many magnetic point-group symmetries induce a topological classification on crystalline insulators, dividing them into those that have a nonzero quantized Chern-Simons magnetoelectric coupling ("axion-odd" or "topological"), and those that…

Mesoscale and Nanoscale Physics · Physics 2020-04-29 Nicodemos Varnava , Ivo Souza , David Vanderbilt

While non-Hermitian (NH) topological phases and phenomena have been observed across various quantum systems, directly measuring NH topological invariants remains a significant challenge. In this study, we present a generic and unified…

Quantum Gases · Physics 2025-03-13 Xiao-Dong Lin , Long Zhang

Atom interferometers have been used to measure acceleration with at best a $T^2$ scaling in sensitivity as the interferometer time $T$ is increased. This limits the sensitivity to acceleration which is theoretically achievable by these…

We introduce and analyze a class of one dimensional insulating Hamiltonians which, when adiabatically varied in an appropriate closed cycle, define a "$Z_2$ pump". For an isolated system a single closed cycle of the pump changes the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Liang Fu , C. L. Kane

Topology is central to understanding and engineering materials that display robust physical phenomena immune to imperfections. Different topological phases of matter are characterised by topological invariants. In energy-conserving…

We introduce and study the Wilson loops in a general 3D topological field theories (TFTs), and show that the expectation value of Wilson loops also gives knot invariants as in Chern-Simons theory. We study the TFTs within the…

High Energy Physics - Theory · Physics 2011-11-15 Jian Qiu , Maxim Zabzine

Topological insulators, along with Chern insulators and Quantum Hall insulator phases, are considered as paradigms for symmetry protected topological phases of matter. This article reports the experimental realization of the time-reversal…

Mesoscale and Nanoscale Physics · Physics 2021-01-01 Priya Tiwari , Saurabh Kumar Srivastav , Sujay Ray , Tanmoy Das , Aveek Bid

We show that topological transitions in electronic spin transport are feasible by a controlled manipulation of spin-guiding fields. The transitions are determined by the topology of the fields texture through an effective Berry phase…

Recent realizations of exotic topological states in condensed matter and cold atoms have advanced the exploration for topological characteristics, such as invariant topological orders and band inversion. Here we construct a 1D optical…

Optics · Physics 2018-09-14 Jun Jiang , Zhiwei Guo , Weiwei Zhu , Yang Long , Haitao Jiang , Jie Ren , Hong Chen

The discovery of magnetic fields close to the M87 black hole using Very Long Baseline Interferometry (VLBI) by the Event Horizon Telescope collaboration utilized the novel concept of "closure traces", that are immune to element-based…

General Relativity and Quantum Cosmology · Physics 2022-03-01 Joseph Samuel , Rajaram Nityananda , Nithyanandan Thyagarajan

A time-reversal invariant topological insulator can be generally defined by the effective topological field theory with a quantized \theta coefficient, which can only take values of 0 or \pi. This theory is generally valid for an…

Strongly Correlated Electrons · Physics 2012-09-25 Zhong Wang , Xiao-Liang Qi , Shou-Cheng Zhang

Wilson loops are among the most fundamental gauge-invariant observables in quantum field theory, encoding the global structure of gauge fields through their holonomy along closed contours. Originally introduced as order parameters for…

High Energy Physics - Theory · Physics 2026-02-20 Tetiana Obikhod , Ievgenii Petrenko

We investigate topological phase transitions for the Haldane and Kane-Mele model in a lattice with $p6$ symmetry, which consists of triangles and hexagons arranged in a two-dimensional geometry. For the Haldane model, which breaks…

Mesoscale and Nanoscale Physics · Physics 2026-03-26 Xinyang Li , Lumen Eek , Jasper van Wezel , Cristiane Morais Smith

We study the topological band theory of time reversal invariant topological insulators and interpret the topological $\mathbb{Z}_2$ invariant as an obstruction in terms of Stiefel--Whitney classes. The band structure of a topological…

Mathematical Physics · Physics 2016-04-12 Ralph M. Kaufmann , Dan Li , Birgit Wehefritz-Kaufmann

We propose a simple scheme for tomography of band-insulating states in one- and two-dimensional optical lattices with two sublattice states. In particular, the scheme maps out the Berry curvature in the entire Brillouin zone and extracts…

Quantum Gases · Physics 2014-07-29 Philipp Hauke , Maciej Lewenstein , André Eckardt