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We undertake a systematic investigation of the maxima and minima of the eigenfunctions associated with the first nontrivial eigenvalue of the Laplacian on a metric graph equipped with standard (continuity--Kirchhoff) vertex conditions. This…

Spectral Theory · Mathematics 2021-05-05 James B. Kennedy , Jonathan Rohleder

We study the spectra of quantum graphs with the method of trace identities (sum rules), which are used to derive inequalities of Lieb-Thirring, Payne-P\'olya-Weinberger, and Yang types, among others. We show that the sharp constants of…

Spectral Theory · Mathematics 2015-05-14 Semra Demirel , Evans M. Harrell

Klein quantum dot (KQD) refers to a QD with quasi-bound states and a finite trapping time, which has been observed in experiments focused on graphene recently. In this paper, we develop a numerical method to calculate local density of…

Mesoscale and Nanoscale Physics · Physics 2018-05-10 Jiaojiao Zhou , Shu-guang Cheng , Hua Jiang

We demonstrate that a quantum graph exhibits a $\mathcal{PT}$-symmetry provided the coefficients in the condition describing the wave function matching at the vertices are circulant matrices; this symmetry is nontrivial if they are not…

Mathematical Physics · Physics 2021-10-04 Pavel Exner , Milos Tater

We discuss spectral properties of a charged quantum particle confined to a chain graph consisting of an infinite array of rings under influence of a magnetic field assuming a $\delta$-coupling at the points where the rings touch. We start…

Mathematical Physics · Physics 2020-01-30 Pavel Exner , Stepan Manko

We investigate quantum graphs with infinitely many vertices and edges without the common restriction on the geometry of the underlying metric graph that there is a positive lower bound on the lengths of its edges. Our central result is a…

Mathematical Physics · Physics 2018-10-30 Pavel Exner , Aleksey Kostenko , Mark Malamud , Hagen Neidhardt

We appeal to results from combinatorial random matrix theory to deduce that various random graph $\mathrm{C}^*$-algebras are asymptotically almost surely Kirchberg algebras with trivial $K_1$. This in particular implies that, with high…

Operator Algebras · Mathematics 2025-05-22 Bhishan Jacelon , Igor Khavkine

While stabilizer tableaus have proven exceptionally useful as a descriptive tool for additive quantum codes, they offer little guidance for concrete constructions or coding algorithm analysis. We introduce a representation of stabilizer…

Quantum Physics · Physics 2025-01-31 Andrey Boris Khesin

The explicit solution to the spectral problem of quantum graphs found recently in \cite{Anima}, is used to produce the exact periodic orbit theory description for the probability distributions of spectral statistics, including the…

Quantum Physics · Physics 2007-05-23 Yu. Dabaghian

This paper investigates continuous-time quantum walks on directed bipartite graphs based on a graph's adjacency matrix. We prove that on bipartite graphs, probability transport between the two node partitions can be completely suppressed by…

Quantum Physics · Physics 2016-12-07 Beat Tödtli , Monika Laner , Jouri Semenov , Beatrice Paoli , Marcel Blattner , Jérôme Kunegis

We consider a quantum mechanical particle living on a graph and discuss the behaviour of its wavefunction at graph vertices. In addition to the standard (or delta type) boundary conditions with continuous wavefunctions, we investigate two…

funct-an · Mathematics 2009-09-25 Pavel Exner

We introduce the concept of regular quantum graphs and construct connected quantum graphs with discrete symmetries. The method is based on a decomposition of the quantum propagator in terms of permutation matrices which control the way…

Chaotic Dynamics · Physics 2007-06-13 Simone Severini , Gregor Tanner

In this paper we present an explicit formula for the semigroup governing the solution to hyperbolic systems on a metric graph, satisfying general linear Kirchhoff's type boundary conditions. Further, we use this representation to establish…

Analysis of PDEs · Mathematics 2021-11-17 Jacek Banasiak , Adam Błoch

In this paper we review recent work that has been done on quantum many-particle systems on metric graphs. Topics include the implementation of singular interactions, Bose-Einstein condensation, sovable models and spectral properties of some…

Mathematical Physics · Physics 2020-09-07 Jens Bolte , Joachim Kerner

We discuss spectral properties of an periodic quantum graph consisting of an array of rings coupled either tightly or loosely through connecting links, assuming that the vertex coupling is manifestly non-invariant with respect to the time…

Mathematical Physics · Physics 2022-09-07 Marzieh Baradaran , Pavel Exner , Jiri Lipovsky

Alice and Bob receive a bipartite state (possibly entangled) from some finite collection or from some subspace. Alice sends a message to Bob through a noisy quantum channel such that Bob may determine the initial state, with zero chance of…

Quantum Physics · Physics 2015-11-17 Dan Stahlke

Connectivity is a fundamental property of quantum graphs, previously studied in the operator system model for matrix quantum graphs and via graph homomorphisms in the quantum adjacency matrix model. In this paper, we develop an algebraic…

Operator Algebras · Mathematics 2025-05-29 Kristin Courtney , Priyanga Ganesan , Mateusz Wasilewski

Inspired by a recent result of Davies and Pushnitski, we study resonance asymptotics of quantum graphs with general coupling conditions at the vertices. We derive a criterion for the asymptotics to be of a non-Weyl character. We show that…

Mathematical Physics · Physics 2019-12-10 E. Brian Davies , Pavel Exner , Jiri Lipovsky

Quantum hypergraph states are the natural generalization of graph states. Here we investigate and analytically quantify entanglement and nonlocality for large classes of quantum hypergraph states. More specifically, we connect the geometric…

Quantum Physics · Physics 2026-03-17 Jan Nöller , Otfried Gühne , Mariami Gachechiladze

We prove that closed manifolds admitting a generic metric whose sectional curvature is locally quasi-constant are graphs of space forms. In the more general setting of QC spaces where sets of isotropic points are arbitrary, under suitable…

Differential Geometry · Mathematics 2020-04-08 Louis Funar