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TQCにおけるモジュラーS行列をめぐって

Jun Ichi Fujii

Published Feb 29, 2016• 0 citations
Publisher

Abstract

The term ‘TQC' means the topological quantum computation, which is one of remarkable theories to realize quantum computers. This theory is related to various fields; theory of quantum groups, Lie algebras, Hopf algebras and conformal field or string theory. But there are few textbooks which readers of other fields can read easily. We wrote a survay[10]easy to observe from the basics of TQC theory to basic quantum gates for quantum computers. But we cannot explain modular S-matrices that is one of the keys in TQC in the preceding survey. So, in this paper, we try to express total basic issue including theories around modular S-matrix. In the many papers for TQC, there are some subtle mistakes and we correct them in this paper. At first we introduce formulae for modular S-matrix in the axiomatic (categorical) approach. Secondly we give an important model for TQC; spin network model based on the Temperly-Lieb-Jones algebra. Finally we mention another important model suk(2). In each levels, Fibannaci anyon is a basic example to explain them.

DOI
10.32287/td00028752

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Bicategorical aspects of topological quantum computation

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Topological quantum computation offers a paradigm shift for fault-tolerant quantum computation. It proposes encoding qubits in the mutual states of quasiparticles (called anyons) of 2-dimensional topologically ordered matter. Unitary ribbon fusion categories describe the algebraic theory of anyons. Although the category of an anyonic theory specifies suitable computational spaces, qubits, and quantum gates, it does not precisely formalise the category of topological quantum computation (TQC). We describe the TQC category using the elements of categorical quantum mechanics (CQM). Given the qubit-based graphical calculus accompanying CQM, called the ZX-calculus, we present the details of the ZX-representation of Fibonacci and Ising anyons. Finally, we propose a bicategorical approach to convene anyonic theory and TQC in one (bi)category. In the second part of the thesis, we discuss how the bicategory of module categories formalises boundary types and their excitations. We show theorems that reduce the data to physically meaningful data. A 2-category capable of describing topological quantum computation with point-like and string-like excitations is speculated to be a fusion 2-category. We discuss the available definition in the literature. The paper particularly lacks a rigorous definition for additive 2-categories; in this thesis, we give a definition. We propose the idea of typing higher-ranked matrices in additive 2-categories. Lastly, we overview the complete definition of monoidal 2-categories and recover Kapranov and Voevodsky's definition from the algebraic definition of tricategory by Gurski. This definition and the detailed list of data are the complete ingredients physicists need for quantum computation with higher dimensional excitations.

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A paradigm to build a quantum computer, based on topological invariants is highlighted. The identities in the ensemble of knots, links and braids originally discovered in relation to topological quantum field theory are shown: how they define Artin braid group -- the mathematical basis of topological quantum computation (TQC). Vector spaces of TQC correspond to associated strings of particle interactions, and TQC operates its calculations on braided strings of special physical quasiparticles -- anyons -- with non-Abelian statistics. The physical platform of TQC is to use the topological quantum numbers of such small groups of anyons as qubits and to perform operations on these qubits by exchanging the anyons, both within the groups that form the qubits and, for multi-qubit gates, between groups. By braiding two or more anyons, they acquire up a topological phase or Berry phase similar to that found in the Aharonov-Bohm effect. Topological matter such as fractional quantum Hall systems and novel discovered topological insulators open the way to form system of anyons -- Majorana fermions -- with the unique property of encoding and processing quantum information in a naturally fault-tolerant way. In the topological insulators, due to its fundamental attribute of topological surface state occurrence of the bound, Majorana fermions are generated at its heterocontact with superconductors. One of the key operations of TQC -- braiding of non-Abelian anyons: it is illustrated how it can be implemented in one-dimensional topological isolator wire networks.

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Abstract TQFTs, or anyon theories, have a large amount of addition mathematical structure which we explore in this chapter. We show that the quantum dimension which defines the weight of a loop in the diagram algebra is the same as the quantum dimension that describes the size of the many-anyon Hilbert space. We define the S-matrix in terms of diagrams, and the T-matrix in terms of twists. We show how the S- and T-matrices are related to the modular group of diffeomorphisms of the torus, and related further to the notion of central charge. We discuss how the many constraints on TQFTs enables one to develop a table of all possible sufficiently “small” TQFTs given certain very general conditions. We give tables for both modular and super-modular theories. We introduce the Kirby Color or Omega Strand as an important tool.

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Modular Tensor Categories as Algebraic Framework for Topological Quantum Computation — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: Modular tensor categories (MTCs) provide the algebraic backbone for topological quantum computation, with S and T matrices encoding anyon braiding and fusion rules. | MATH: MTC data: fusion rules \(N^k_{ij}\), \(S\)-matrix (modular transformation \(\tau \to -1/\tau\)), \(T\)-matrix (diagonal, \(\theta_a = e^{2\pi i h_a}\) topological spins), satisfying \(S^2 = C\) (charge conjugation), \((ST)^3 = e^{2\pi i c/8} S^2\) (where \(c\) is the chiral central charge). The entries of \(S\) and \(T\) lie in a cyclotomic field \(\mathbb{Q}(\zeta_N)\), \(\zeta_N = e^{2\pi i/N}\). For the Fibonacci anyon MTC: \(S = \frac{1}{\sqrt{\phi+2}}\begin{pmatrix} 1 & \phi \\ \phi & -1 \end{pmatrix}\), \(T = \text{diag}(1, e^{4\pi i/5})\), where \(\phi = (1+\sqrt{5})/2\). | CONNECTION: **Direct hit**: The Fibonacci MTC's \(S\)-matrix contains \(\phi = 1.618\) and \(\phi+2 = \phi^2+1 = 3.618\), whose inverse square root yields \(1/\sqrt{3.618} \approx 0.5257\). The golden ratio appears intrinsically. Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

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In and around abelian anyon models *

Liang Wang, Zhenghan Wang

Abstract Anyon models are algebraic structures that model universal topological properties in topological phases of matter and can be regarded as mathematical characterization of topological order in two spacial dimensions. It is conjectured that every anyon model, or mathematically unitary modular tensor category, can be realized as the representation category of some chiral conformal field theory, or mathematically vertex operator algebra/local conformal net. This conjecture is known to be true for abelian anyon models providing support for the conjecture. We reexamine abelian anyon models from several different angles. First anyon models are algebraic data for both topological quantum field theories and chiral conformal field theories. While it is known that each abelian anyon model can be realized by a quantum abelian Chern–Simons (CS) theory and chiral conformal field theory, the construction is not algorithmic. Our goal is to provide such an explicit algorithm for a K -matrix in CS theory and a positive definite even one for a lattice conformal field theory. Secondly anyon models and chiral conformal field theories underlie the bulk-edge correspondence for topological phases of matter. But there are interesting subtleties in this correspondence when stability of the edge theory and topological symmetry are taken into consideration. Therefore, our focus is on the algorithmic reconstruction of extremal chiral conformal field theories with small central charges. Finally we conjecture that a much stronger reconstruction holds for abelian anyon models: every abelian anyon model can be realized as the representation category of some non-lattice extremal vertex operator algebra generalizing the moonshine realization of the trivial anyon model.

arXiv:2004.12048•Journal of Physics A Mathematical and Theoretical•Nov 2, 2020•69 citations

Paper XXVI: Quantum Computation from Hopf Solitons — Topological Confinement of a Singlet–Triplet Orientation Qubit

Alexander Novickis

Abstract We propose the Hopf soliton vacuum --- the topological field-theoretic framework of Papers I--XV --- as a 3+1-dimensional platform for topological quantum computation (TQC). A qubit is encoded in the mutual linking number $L \in \{0, 1\}$ of a Hopf soliton pair: $|0\rangle$ corresponds to an unlinked pair, $|1\rangle$ to a linked pair. Since linking number is an integer topological invariant, the qubit is passively protected against decoherence --- errors require reconnection events exponentially suppressed at energies below the soliton mass gap $\Delta$. The SU(2)$_1$ Chern-Simons theory governing the Hopf vacuum (Paper V) provides the R-matrix $R = e^{i\pi/4}$ for soliton exchange, yielding Abelian (semionic) braiding. While SU(2)$_1$ alone is not universal, the 3+1D loop braid group provides additional operations (leapfrogging) beyond 2+1D braiding, and universality can be achieved via magic state distillation. We construct a gate set from soliton self-linking (single-qubit rotations) and inter-pair braiding (entangling gates), showing that topological protection yields error rates exponentially small in the ratio of system size to correlation length. Physical implementations include liquid crystal Hopfions, BEC vortex knots, and photonic topological states. This is a theoretical proposal: no experimental realization currently exists. > [!warning] Speculative Content > This paper is a theoretical proposal. The identification of Hopf soliton pairs as a TQC platform is new and untested. Standard TQC theory (Kitaev, Freedman et al., Nayak et al.) is well-established; the application to Hopf solitons is speculative. We clearly distinguish established results from proposals throughout. Keywords physics quantum computing topology anyons braiding TQC hopf solitons Type Preprint License CC BY 4.0 Date 2026-03-22 Subject Theoretical Physics DOI 10.5281/zenodo.19108219 © 2026 Alexander Novickis. Licensed under Creative Commons Attribution 4.0 International.

•Mar 19, 2026•0 citations
The term ‘TQC' means the topological quantum computation, which is one of remarkable theories to realize quantum computers. This theory is related to various fields; theory of quantum groups, Lie algebras, Hopf algebras and conformal field or string theory. But there are few textbooks which readers of other fields can read easily. We wrote a survay[10]easy to observe from the basics of TQC theory to basic quantum gates for quantum computers. But we cannot explain modular S-matrices that is one of the keys in TQC in the preceding survey. So, in this paper, we try to express total basic issue including theories around modular S-matrix. In the many papers for TQC, there are some subtle mistakes and we correct them in this paper. At first we introduce formulae for modular S-matrix in the axiomatic (categorical) approach. Secondly we give an important model for TQC; spin network model based on the Temperly-Lieb-Jones algebra. Finally we mention another important model suk(2). In each levels, Fibannaci anyon is a basic example to explain them.
Topological quantum computation offers a paradigm shift for fault-tolerant quantum computation. It proposes encoding qubits in the mutual states of quasiparticles (called anyons) of 2-dimensional topologically ordered matter. Unitary ribbon fusion categories describe the algebraic theory of anyons. Although the category of an anyonic theory specifies suitable computational spaces, qubits, and quantum gates, it does not precisely formalise the category of topological quantum computation (TQC). We describe the TQC category using the elements of categorical quantum mechanics (CQM). Given the qubit-based graphical calculus accompanying CQM, called the ZX-calculus, we present the details of the ZX-representation of Fibonacci and Ising anyons. Finally, we propose a bicategorical approach to convene anyonic theory and TQC in one (bi)category. In the second part of the thesis, we discuss how the bicategory of module categories formalises boundary types and their excitations. We show theorems that reduce the data to physically meaningful data. A 2-category capable of describing topological quantum computation with point-like and string-like excitations is speculated to be a fusion 2-category. We discuss the available definition in the literature. The paper particularly lacks a rigorous definition for additive 2-categories; in this thesis, we give a definition. We propose the idea of typing higher-ranked matrices in additive 2-categories. Lastly, we overview the complete definition of monoidal 2-categories and recover Kapranov and Voevodsky's definition from the algebraic definition of tricategory by Gurski. This definition and the detailed list of data are the complete ingredients physicists need for quantum computation with higher dimensional excitations.
A paradigm to build a quantum computer, based on topological invariants is highlighted. The identities in the ensemble of knots, links and braids originally discovered in relation to topological quantum field theory are shown: how they define Artin braid group -- the mathematical basis of topological quantum computation (TQC). Vector spaces of TQC correspond to associated strings of particle interactions, and TQC operates its calculations on braided strings of special physical quasiparticles -- anyons -- with non-Abelian statistics. The physical platform of TQC is to use the topological quantum numbers of such small groups of anyons as qubits and to perform operations on these qubits by exchanging the anyons, both within the groups that form the qubits and, for multi-qubit gates, between groups. By braiding two or more anyons, they acquire up a topological phase or Berry phase similar to that found in the Aharonov-Bohm effect. Topological matter such as fractional quantum Hall systems and novel discovered topological insulators open the way to form system of anyons -- Majorana fermions -- with the unique property of encoding and processing quantum information in a naturally fault-tolerant way. In the topological insulators, due to its fundamental attribute of topological surface state occurrence of the bound, Majorana fermions are generated at its heterocontact with superconductors. One of the key operations of TQC -- braiding of non-Abelian anyons: it is illustrated how it can be implemented in one-dimensional topological isolator wire networks.
Abstract TQFTs, or anyon theories, have a large amount of addition mathematical structure which we explore in this chapter. We show that the quantum dimension which defines the weight of a loop in the diagram algebra is the same as the quantum dimension that describes the size of the many-anyon Hilbert space. We define the S-matrix in terms of diagrams, and the T-matrix in terms of twists. We show how the S- and T-matrices are related to the modular group of diffeomorphisms of the torus, and related further to the notion of central charge. We discuss how the many constraints on TQFTs enables one to develop a table of all possible sufficiently “small” TQFTs given certain very general conditions. We give tables for both modular and super-modular theories. We introduce the Kirby Color or Omega Strand as an important tool.
FINDING: Modular tensor categories (MTCs) provide the algebraic backbone for topological quantum computation, with S and T matrices encoding anyon braiding and fusion rules. | MATH: MTC data: fusion rules NijkN^k_{ij}Nijk​, SSS-matrix (modular transformation τ→−1/τ\tau \to -1/\tauτ→−1/τ), TTT-matrix (diagonal, θa=e2πiha\theta_a = e^{2\pi i h_a}θa​=e2πiha​ topological spins), satisfying S2=CS^2 = CS2=C (charge conjugation), (ST)3=e2πic/8S2(ST)^3 = e^{2\pi i c/8} S^2(ST)3=e2πic/8S2 (where ccc is the chiral central charge). The entries of SSS and TTT lie in a cyclotomic field Q(ζN)\mathbb{Q}(\zeta_N)Q(ζN​), ζN=e2πi/N\zeta_N = e^{2\pi i/N}ζN​=e2πi/N. For the Fibonacci anyon MTC: S=1ϕ+2(1ϕϕ−1)S = \frac{1}{\sqrt{\phi+2}}\begin{pmatrix} 1 & \phi \\ \phi & -1 \end{pmatrix}S=ϕ+2​1​(1ϕ​ϕ−1​), T=diag(1,e4πi/5)T = \text{diag}(1, e^{4\pi i/5})T=diag(1,e4πi/5), where ϕ=(1+5)/2\phi = (1+\sqrt{5})/2ϕ=(1+5​)/2. | CONNECTION: **Direct hit**: The Fibonacci MTC's SSS-matrix contains ϕ=1.618\phi = 1.618ϕ=1.618 and ϕ+2=ϕ2+1=3.618\phi+2 = \phi^2+1 = 3.618ϕ+2=ϕ2+1=3.618, whose inverse square root yields 1/3.618≈0.52571/\sqrt{3.618} \approx 0.52571/3.618​≈0.5257. The golden ratio appears intrinsically. Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
Abstract Anyon models are algebraic structures that model universal topological properties in topological phases of matter and can be regarded as mathematical characterization of topological order in two spacial dimensions. It is conjectured that every anyon model, or mathematically unitary modular tensor category, can be realized as the representation category of some chiral conformal field theory, or mathematically vertex operator algebra/local conformal net. This conjecture is known to be true for abelian anyon models providing support for the conjecture. We reexamine abelian anyon models from several different angles. First anyon models are algebraic data for both topological quantum field theories and chiral conformal field theories. While it is known that each abelian anyon model can be realized by a quantum abelian Chern–Simons (CS) theory and chiral conformal field theory, the construction is not algorithmic. Our goal is to provide such an explicit algorithm for a K -matrix in CS theory and a positive definite even one for a lattice conformal field theory. Secondly anyon models and chiral conformal field theories underlie the bulk-edge correspondence for topological phases of matter. But there are interesting subtleties in this correspondence when stability of the edge theory and topological symmetry are taken into consideration. Therefore, our focus is on the algorithmic reconstruction of extremal chiral conformal field theories with small central charges. Finally we conjecture that a much stronger reconstruction holds for abelian anyon models: every abelian anyon model can be realized as the representation category of some non-lattice extremal vertex operator algebra generalizing the moonshine realization of the trivial anyon model.
Abstract We propose the Hopf soliton vacuum --- the topological field-theoretic framework of Papers I--XV --- as a 3+1-dimensional platform for topological quantum computation (TQC). A qubit is encoded in the mutual linking number L∈{0,1}L \in \{0, 1\}L∈{0,1} of a Hopf soliton pair: ∣0⟩|0\rangle∣0⟩ corresponds to an unlinked pair, ∣1⟩|1\rangle∣1⟩ to a linked pair. Since linking number is an integer topological invariant, the qubit is passively protected against decoherence --- errors require reconnection events exponentially suppressed at energies below the soliton mass gap Δ\DeltaΔ. The SU(2)1_11​ Chern-Simons theory governing the Hopf vacuum (Paper V) provides the R-matrix R=eiπ/4R = e^{i\pi/4}R=eiπ/4 for soliton exchange, yielding Abelian (semionic) braiding. While SU(2)1_11​ alone is not universal, the 3+1D loop braid group provides additional operations (leapfrogging) beyond 2+1D braiding, and universality can be achieved via magic state distillation. We construct a gate set from soliton self-linking (single-qubit rotations) and inter-pair braiding (entangling gates), showing that topological protection yields error rates exponentially small in the ratio of system size to correlation length. Physical implementations include liquid crystal Hopfions, BEC vortex knots, and photonic topological states. This is a theoretical proposal: no experimental realization currently exists. > [!warning] Speculative Content > This paper is a theoretical proposal. The identification of Hopf soliton pairs as a TQC platform is new and untested. Standard TQC theory (Kitaev, Freedman et al., Nayak et al.) is well-established; the application to Hopf solitons is speculative. We clearly distinguish established results from proposals throughout. Keywords physics quantum computing topology anyons braiding TQC hopf solitons Type Preprint License CC BY 4.0 Date 2026-03-22 Subject Theoretical Physics DOI 10.5281/zenodo.19108219 © 2026 Alexander Novickis. Licensed under Creative Commons Attribution 4.0 International.