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We generalize the concept of topological invariants for mixed states based on the ensemble geometric phase (EGP) introduced for one-dimensional lattice models to two dimensions. In contrast to the geometric phase for density matrices…

Quantum Physics · Physics 2021-09-22 Lukas Wawer , Michael Fleischhauer

Searching for the first topological superfluid (TSF) remains a primary goal of modern science. Here we study the system of attractively interacting fermions hopping in a square lattice with any linear combinations of Rashba or Dresselhaus…

Quantum Gases · Physics 2018-11-28 Yu Yi-Xiang , Fadi Sun , Jinwu Ye , Ningfang Song

We propose a general principle for the low-energy theory of narrow bands with concentrated Berry curvature and Fubini-Study metric in the form of a map to Anderson-"+" models composed of heavy fermions hybridizing and interacting with…

Ultracold atoms in optical lattices form a clean quantum simulator platform which can be utilized to examine topological phenomena and test exotic topological materials. Here we propose an experimental scheme to measure the Chern numbers of…

Quantum Gases · Physics 2019-04-11 Tomasz Szołdra , Krzysztof Sacha , Arkadiusz Kosior

We study the polaritonic bandstructure of two-dimensional atomic lattices coupled to a single excitation of a surface plasmon polariton mode. We show the possibility of realizing topological gaps with different Chern numbers by having…

Optics · Physics 2021-03-31 Rituraj , Meir Orenstein , Shanhui Fan

The interplay between strong electron-electron interactions and band topology can lead to novel electronic states that spontaneously break symmetries. The discovery of flat bands in magic-angle twisted bilayer graphene (MATBG) with…

We show that a suitable combination of geometric frustration, ferromagnetism and spin-orbit interactions can give rise to nearly flat bands with a large bandgap and non-zero Chern number. Partial filling of the flat band can give rise to…

Strongly Correlated Electrons · Physics 2011-06-07 Evelyn Tang , Jia-Wei Mei , Xiao-Gang Wen

Flat band (FB) systems provide ideal playgrounds for studying correlation physics, whereas multi-orbital characteristics in real materials are distinguished from most simple FB models. Here, we propose a systematic and versatile framework…

Mesoscale and Nanoscale Physics · Physics 2026-03-24 Rui-Heng Liu , Xin Liu

The rapid advances in the study of fractional Chern insulators (FCIs) raise a fundamental question: while initially discovered in flat Chern bands motivated by their topological equivalence to Landau levels, is single- particle band…

Strongly Correlated Electrons · Physics 2025-10-17 Hongyu Lu , Wang Yao

We present a class of states with both topological and conventional Landau order that arise out of strongly interacting spinless fermions in fractionally filled and topologically non-trivial bands with Chern number $C=\pm 1$. These quantum…

Strongly Correlated Electrons · Physics 2014-12-11 Stefanos Kourtis , Maria Daghofer

Recent experiments on bilayer graphene twisted near the magic angle have observed spontaneous integer quantum Hall states in the presence of an aligned hexagonal boron nitride (hBN) substrate. These states arise from valley ferromagnetism,…

Strongly Correlated Electrons · Physics 2020-06-18 Patrick J. Ledwith , Grigory Tarnopolsky , Eslam Khalaf , Ashvin Vishwanath

The discovery of zero-field fractional Chern insulators (FCIs) in moir\'e materials has attracted intense interest in the interplay between topology and correlations. Here, we demonstrate that fractionalized topological order can emerge…

Mesoscale and Nanoscale Physics · Physics 2025-10-20 Hui Liu , Raul Perea-Causin , Zhao Liu , Emil J. Bergholtz

We introduce and study two classes of Hubbard models with magnetic flux or with spin-orbit coupling, which have a flat lowest band separated from other bands by a nonzero gap. We study the Chern number of the flat bands, and find that it is…

Strongly Correlated Electrons · Physics 2011-05-17 Hosho Katsura , Isao Maruyama , Akinori Tanaka , Hal Tasaki

We present a theoretical study of mapping between Chern bands and generalized Landau levels in twisted bilayer MoTe$_2$ ($t$MoTe$_2$), where fractional Chern insulators down to zero magnetic fields have been observed. We construct an exact…

Mesoscale and Nanoscale Physics · Physics 2025-03-18 Bohao Li , Fengcheng Wu

Quantum metrology is deeply connected to quantum geometry, through the fundamental notion of quantum Fisher information. Inspired by advances in topological matter, it was recently suggested that the Berry curvature and Chern numbers of…

Quantum Physics · Physics 2024-11-12 Min Yu , Xiangbei Li , Yaoming Chu , Bruno Mera , F. Nur Ünal , Pengcheng Yang , Yu Liu , Nathan Goldman , Jianming Cai

We construct theoretical models for two dimensional(2d) chiral $d_{x^2-y^2}\pm id_{xy}$ topological superconductors and for three dimensional(3d) $d$ wave topological superconductors. Moreover we build models for any 2d class C and 3d class…

Mesoscale and Nanoscale Physics · Physics 2016-03-24 Tong Chern

The geometrically frustrated Kitaev magnets are demonstrated to be fertile playgrounds that allow for the occurrence of exotic phenomena, including topological phases and the thermal Hall effect. Notwithstanding the established consensus…

Strongly Correlated Electrons · Physics 2025-08-06 Zixuan Zou , Qiang Luo

We propose to use generic Chern numbers for a characterization of topological insulators. It is suitable for a numerical characterization of low dimensional quantum liquids where strong quantum fluctuations prevent from developing…

Strongly Correlated Electrons · Physics 2009-11-10 Yasuhiro Hatsugai

There is convincing numerical evidence that fractional quantum Hall (FQH)-like ground states arise in fractionally filled Chern bands (FCB). Here we show that the Hamiltonian theory of Composite Fermions (CF) can be as useful in describing…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Ganpathy Murthy , R. Shankar

An exciting new prospect in condensed matter physics is the possibility of realizing fractional quantum Hall (FQH) states in simple lattice models without a large external magnetic field. A fundamental question is whether qualitatively new…

Strongly Correlated Electrons · Physics 2012-08-29 Maissam Barkeshli , Xiao-Liang Qi