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Topological Approaches to 2D Multielectron Correlated States

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Physics".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 3381

Special Issue Editors


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Guest Editor
Wrocław University of Science and Technology, Wroclaw, Poland
Interests: physics of low dimensional systems

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Guest Editor
Department of Quantum Technologies, Wrocław University of Science and Technology, Wroclaw, Poland
Interests: topology methods in quantum physics

Special Issue Information

Dear Colleagues,

In recent years, a vast field of topological methods has dynamically flourished: multi-electron interacting planar quantum systems in the magnetic or Berry fields. Topological insulators, spin Hall systems, fractional and integer quantum Hall effect in graphene monolayer and bilayer, competition of superfluidity of inter-layer excitons in double Hall systems with correlated Hall states drew attention to the topological non-local conditioning of multi-electron correlation organization in 2D in the presence of a magnetic field and made a significant contribution to the development of over 30-years old quantum Hall physics – one of the most important and illuminating domains in condensed matter. Recently there was a rapid development of the Hall experiment in new materials, as well as a new topological perspective on correlations in various types of topological insulators and their experimental implementation also in optical planar networks. The Haldane states for planar systems without a magnetic field or Kosterlitz Tauless's phase transitions (NP 2016) emphasised that the topological quantum effects are impossible to be understood in the framework of local quantum physics. The relationship of topological phases with long range multi-particle quantum entanglement distinguishes the associated quantum transitions from standard phase transitions with spontaneous symmetry violation and desribed in terms of binary quantum entanglement. We propose this Special Issue of Materials to seek out papers in this dynamically developing area of quantum physics of correlated states.

Prof. Lucjan Jacak
Dr. Janusz E. Jacak
Guest Editors

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Keywords

  • Topology methods in quantum physics 
  • Correlations in integer and fractional quantum Hall effects 
  • Topological insulators 
  • Superfluidity of excitons in bilayer Hall systems
  • Graphene monolayer and bilayer 
  • Hall states without Landau levels 
  • Homotopy phases in 2D electron systems at magnetic and Berry fields 
  • Topological structure of composite fermions 
  • Spin Hall systems
  • Long range quantum entanglement in topological phases 
  • Topology in planar optical lattices 
  • Topological invariants and braid groups 
  • Exact diagonalization of small Hall systems 
  • New material for demonstration of IQHE and FQHE 
  • Path integration in multiply-connected configuration spaces 
  • Correlation patterns in higher Landau levels 
  • Anyons and fractional statistics 
  • Chern-Simons field approach to 2D correlated states

Published Papers (2 papers)

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Research

20 pages, 746 KiB  
Article
Limits of Applicability of the Composite Fermion Model
by Janusz E. Jacak
Materials 2021, 14(15), 4267; https://doi.org/10.3390/ma14154267 - 30 Jul 2021
Viewed by 1376
Abstract
The popular model of composite fermions, proposed in order to rationalize FQHE, were insufficient in view of recent experimental observations in graphene monolayer and bilayer, in higher Landau levels in GaAs and in so-called enigmatic FQHE states in the lowest Landau level of [...] Read more.
The popular model of composite fermions, proposed in order to rationalize FQHE, were insufficient in view of recent experimental observations in graphene monolayer and bilayer, in higher Landau levels in GaAs and in so-called enigmatic FQHE states in the lowest Landau level of GaAs. The specific FQHE hierarchy in double Hall systems of GaAs 2DES and graphene also cannot be explained in the framework of composite fermions. We identify the limits of the usability of the composite fermion model by means of topological methods, which elucidate the phenomenological assumptions in composite fermion structure and admit further development of FQHE understanding. We demonstrate how to generalize these ideas in order to explain experimentally observed FQHE phenomena, going beyond the explanation ability of the conventional composite fermion model. Full article
(This article belongs to the Special Issue Topological Approaches to 2D Multielectron Correlated States)
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23 pages, 1320 KiB  
Article
Topological Classification of Correlations in 2D Electron Systems in Magnetic or Berry Fields
by Janusz E. Jacak
Materials 2021, 14(7), 1650; https://doi.org/10.3390/ma14071650 - 27 Mar 2021
Cited by 1 | Viewed by 1585
Abstract
Recent topology classification of 2D electron states induced by different homotopy classes of mappings of the planar Brillouin zone into Bloch space can be supplemented by a homotopy classification of various phases of multi-electron homotopy patterns induced by Coulomb interaction between electrons. The [...] Read more.
Recent topology classification of 2D electron states induced by different homotopy classes of mappings of the planar Brillouin zone into Bloch space can be supplemented by a homotopy classification of various phases of multi-electron homotopy patterns induced by Coulomb interaction between electrons. The general classification of such type is presented. It explains the topologically protected correlations responsible for integer and fractional Hall effects in 2D multi-electron systems in the presence of perpendicular quantizing magnetic field or Berry field, the latter in topological Chern insulators. The long-range quantum entanglement is essential for homotopy correlated phases in contrast to local binary entanglement for conventional phases with local order parameters. The classification of homotopy long-range correlated phases induced by the Coulomb interaction of electrons has been derived in terms of homotopy invariants and illustrated by experimental observations in GaAs 2DES, graphene monolayer, and bilayer and in Chern topological insulators. The homotopy phases are demonstrated to be topologically protected and immune to the local crystal field, local disorder, and variation of the electron interaction strength. The nonzero interaction between electrons is shown, however, to be essential for the definition of the homotopy invariants, which disappear in gaseous systems. Full article
(This article belongs to the Special Issue Topological Approaches to 2D Multielectron Correlated States)
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