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We begin with the characterization of quantum graphs as left ideals in $\mathcal M \otimes_{eh} \mathcal M$ (the extended Haagerup tensor product of $\mathcal M$ with itself) to avoid technicalities surrounding representation dependence of…

Operator Algebras · Mathematics 2026-05-14 Jennifer Zhu

In this paper, we investigate the existence of quantum fractional revival in unitary Cayley graphs over finite commutative rings with identity. We characterize all finite local rings that permit quantum fractional revival in their unitary…

Rings and Algebras · Mathematics 2026-01-15 Saowalak Jitngam , Poom Kumam , Songpon Sriwongsa

The paper deals with some spectral properties of (mostly infinite) quantum and combinatorial graphs. Quantum graphs have been intensively studied lately due to their numerous applications to mesoscopic physics, nanotechnology, optics, and…

Mathematical Physics · Physics 2009-11-10 Peter Kuchment

In this paper, we try to determine exact or bounds on the choosability, or list chromatic numbers of some Cayley graphs, typically some Unitary Cayley graphs and Cayley graphs on Dihedral groups.

Combinatorics · Mathematics 2024-02-27 Prajnanaswaroopa S

For a finite not necessarily compact metric graph, one considers the differential expression $-\frac{d^2}{d x^2}$ on each edge. The boundary conditions at the vertices of the graph yielding quasi-m-accretive as well as m-accretive operators…

Analysis of PDEs · Mathematics 2021-03-29 Amru Hussein

We summarize different approaches to the theory of quantum graphs and provide several ways to construct concrete examples. First, we classify all undirected quantum graphs on the quantum space $M_2$. Secondly, we apply the theory of…

Quantum Algebra · Mathematics 2022-12-15 Daniel Gromada

We clarify the correspondence between the two approaches to quantum graphs: via quantum adjacency matrices and via quantum relations. We show how the choice of a (possibly non-tracial) weight manifests itself on the quantum relation side…

Operator Algebras · Mathematics 2024-12-11 Mateusz Wasilewski

This work explores the spectra of quantum graphs where the Schr\"odinger operator on the edges is equipped with a potential. The scattering approach, which was originally introduced for the potential free case, is extended to this case and…

Mathematical Physics · Physics 2015-06-11 Ralf Rueckriemen , Uzy Smilansky

In contrast to the usual quantum systems which have at most a finite number of open spectral gaps if they are periodic in more than one direction, periodic quantum graphs may have gaps arbitrarily high in the spectrum. This property of…

Quantum Physics · Physics 2020-05-26 Pavel Exner , Ondřej Turek

We present some observations on a restricted variant of unitary Cayley graphs modulo n, and the implications for a decomposition of elements of symplectic operators over the integers modulo n. We define quadratic unitary Cayley graphs G_n,…

Combinatorics · Mathematics 2010-06-14 Niel de Beaudrap

We consider discrete Schr\"odinger operators $H_{\mu Q}=\Delta+\mu Q$ with real periodic potentials $Q$ on periodic graphs, where $\Delta$ is the adjacency operator and $\mu\in\mathbb R$ is a coupling constant. The spectra of the operators…

Spectral Theory · Mathematics 2026-04-01 Natalia Saburova

Current methods of graph signal processing rely heavily on the specific structure of the underlying network: the shift operator and the graph Fourier transform are both derived directly from a specific graph. In many cases, the network is…

Signal Processing · Electrical Eng. & Systems 2023-03-31 Kathryn Beck , Mahya Ghandehari , Jeannette Janssen , Nauzer Kalyaniwalla

Families of expander graphs were first constructed by Margulis from discrete groups with property (T). Within the framework of quantum information theory, several authors have generalised the notion of an expander graph to the setting of…

Operator Algebras · Mathematics 2025-02-05 Michael Brannan , Eric Culf , Matthijs Vernooij

The Cayley graphs of finite groups are known to provide several examples of families of expanders, and some of them are Ramanujan graphs. Babai studied isospectral non-isomorphic Cayley graphs of the dihedral groups. Lubotzky, Samuels and…

Combinatorics · Mathematics 2022-02-09 Arindam Biswas , Jyoti Prakash Saha

We construct pairs of marked groups with isomorphic Cayley graphs but different Borel chromatic numbers for the free parts of their shift graphs. This answers a question of Kechris and Marks. We also show that these graphs have different…

Logic · Mathematics 2019-06-03 Felix Weilacher

The paper concerns the automorphism groups of Cayley graphs over cyclic groups which have a rational spectrum (rational circulant graphs for short). With the aid of the techniques of Schur rings it is shown that the problem is equivalent to…

Combinatorics · Mathematics 2010-08-05 Mikhail Klin , István Kovács

The basic idea of quantum complexity geometry is to endow the space of unitary matrices with a metric, engineered to make complex operators far from the origin, and simple operators near. By restricting our attention to a finite subgroup of…

High Energy Physics - Theory · Physics 2019-02-20 Henry W. Lin

In this work, we try to enunciate the Total chromatic number of some Cayley graphs like the Cayley graph on Symmetric group, Alternating group, Dihedral group with respect to some generating sets and some other regular graphs.

Combinatorics · Mathematics 2023-07-04 Prajnanaswaroopa S

We investigate the bottom of the spectra of infinite quantum graphs, i.e., Laplace operators on metric graphs having infinitely many edges and vertices. We introduce a new definition of the isoperimetric constant for quantum graphs and then…

Spectral Theory · Mathematics 2018-12-17 Aleksey Kostenko , Noema Nicolussi

We survey the known group properties that a sequence of finite groups or group actions needs to satisfy to admit subsets of bounded cardinality producing expander Cayley or Schreier graphs. We prove that an infinite amenable group and…

Group Theory · Mathematics 2025-11-21 Luca Sabatini