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We determine the quantum automorphism groups of finite graphs. These are quantum subgroups of the quantum permutation groups defined by Wang. The quantum automorphism group is a stronger invariant for finite graphs than the usual one. We…

Quantum Algebra · Mathematics 2007-05-23 Julien Bichon

We present quantum complexity lower and upper bounds for independent set problems in graphs. In particular, we give quantum algorithms for computing a maximal and a maximum independent set in a graph. We present applications of these…

Quantum Physics · Physics 2007-05-23 Sebastian Doern

The categories of representations of compact quantum groups of automorphisms of certain inclusions of finite dimensional C*-algebras are shown to be isomorphic to the categories of Fuss-Catalan diagrams.

Quantum Algebra · Mathematics 2009-10-31 Teodor Banica

We consider the dynamics on a quantum graph as the limit of the dynamics generated by a one-particle Hamiltonian in R^2 with a potential having a deep strict minimum on the graph, when the width of the well shrinks to zero. For a generic…

Mathematical Physics · Physics 2009-11-11 Gianfausto Dell'Antonio , Lucattilio Tenuta

The quantum even-dimensional balls are defined as the $C^*$-algebras generated by certain graphs. We exhibit a polynomial algebra for each even-dimensional quantum ball, and classify the irreducible representations of it.

Operator Algebras · Mathematics 2019-11-13 Colin MacLaurin

We develop an equivariant theory of graphs with respect to quantum symmetries and present a detailed exposition of various examples. We portray unitary tensor categories as a unifying framework encompassing all finite classical simple…

Operator Algebras · Mathematics 2026-01-06 Michael Brannan , Roberto Hernández Palomares

We introduce a notion of quantum function, and develop a compositional framework for finite quantum set theory based on a 2-category of quantum sets and quantum functions. We use this framework to formulate a 2-categorical theory of quantum…

Quantum Physics · Physics 2018-09-07 Benjamin Musto , David Reutter , Dominic Verdon

A construction of the noncommutative-geometric counterparts of classical classifying spaces is presented, for general compact matrix quantum structure groups. A quantum analogue of the classical concept of the classifying map is introduced…

q-alg · Mathematics 2008-02-03 Mico Durdevic

We study the problem of counting the number of homomorphisms from an input graph $G$ to a fixed (quantum) graph $\bar{H}$ in any finite field of prime order $\mathbb{Z}_p$. The subproblem with graph $H$ was introduced by Faben and Jerrum…

Computational Complexity · Computer Science 2022-08-19 J. A. Gregor Lagodzinski , Andreas Göbel , Katrin Casel , Tobias Friedrich

An analog of Kreimer's coproduct from renormalization of Feynman integrals in quantum field theory, endows an analog of Kontsevich's graph complex with a dg-coalgebra structure. The graph complex is generated by orientation classes of…

Quantum Algebra · Mathematics 2007-05-23 Lucian M. Ionescu

Global control offers a promising route to scalable quantum computing. A recent conjecture by Hu et al. (arXiv:2508.19075) proposes that any connected qubit graph equipped with global Ising-type interactions and tunable global transverse…

Quantum Physics · Physics 2026-04-22 Roberto Gargiulo , Roberto Menta , Vittorio Giovannetti , Robert Zeier

We introduce a quantum automorphism group for hypergraphs, which turns out to generalize the quantum automorphism group of Bichon for classical graphs. Further, we show that our quantum automorphism group acts on hypergraph C*-algebras as…

Operator Algebras · Mathematics 2024-05-21 Nicolas Faroß

An orthogonal representation of a graph is an assignment of nonzero real vectors to its vertices such that distinct non-adjacent vertices are assigned to orthogonal vectors. We prove general lower bounds on the dimension of orthogonal…

Combinatorics · Mathematics 2018-11-29 Ishay Haviv

k-graphs are higher-rank analogues of directed graphs which were first developed to provide combinatorial models for operator algebras of Cuntz-Krieger type. Here we develop the theory of covering spaces for k-graphs, obtaining a…

Operator Algebras · Mathematics 2008-05-23 David Pask , John Quigg , Iain Raeburn

Let $G$ be a simple finite graph, and let $\mathcal U_G$ be the related quantum graph. We study the game algebra $C(\mathrm{Qut}(\mathcal U_G))$ of quantum automorphism of $\mathcal U_G$. Moreover, we prove that for any graph $G$ with…

Operator Algebras · Mathematics 2026-03-31 Olha Ostrovska , Vasyl Ostrovskyi , Lyudmila Turowska

We classify instances of quantum pseudo-telepathy in the graph isomorphism game, exploiting the recently discovered connection between quantum information and the theory of quantum automorphism groups. Specifically, we show that graphs…

Quantum Physics · Physics 2019-05-14 Benjamin Musto , David Reutter , Dominic Verdon

We define the Cartesian, Categorical, and Lexicographic, and Strong products of quantum graphs. We provide bounds on the quantum chromatic number of these products in terms of the quantum chromatic number of the factors. To adequately…

Operator Algebras · Mathematics 2024-08-23 Rolando de Santiago , A. Meenakshi McNamara

It is shown how nonlinear versions of quantum mechanics can be refolmulated in terms of a (linear) C*-algebraic theory. Then also their symmetries are described as automorphisms of the correspondong C*-algebra. The requirement of…

Quantum Physics · Physics 2012-12-11 Pavel Bona

Homomorphism indistinguishability is a way of characterising many natural equivalence relations on graphs. Two graphs $G$ and $H$ are called homomorphism indistinguishable over a graph class $\mathcal{F}$ if for each $F \in \mathcal{F}$,…

Quantum Physics · Physics 2026-04-21 Tim Seppelt , Gian Luca Spitzer

Motivated by applications in background-independent quantum gravity, we discuss the quantization of labeled and unlabeled finite multigraphs with a maximum edge count. We provide a unified way to represent quantum multigraphs with labeled…

Mathematical Physics · Physics 2025-09-11 Kassahun H. Betre , Nathan Lewis