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We prove upper and lower bounds for the number of zeroes of linear combinations of Schr\"odinger eigenfunctions on metric (quantum) graphs. These bounds are distinct from both the interval and manifolds. We complement these bounds by giving…

Mathematical Physics · Physics 2023-10-09 Ram Band , Philippe Charron

We study the semiclassical behaviour of eigenfunctions of quantum systems with ergodic classical limit. By the quantum ergodicity theorem almost all of these eigenfunctions become equidistributed in a weak sense. We give a simple derivation…

Mathematical Physics · Physics 2009-11-11 Roman Schubert

We prove quantum ergodicity and quantum mixing for sequences of finite Schreier graphs converging to an infinite Cayley graph whose adjacency operator has absolutely continuous spectrum. Under Benjamini-Schramm convergence (or strong…

Spectral Theory · Mathematics 2026-02-11 Charles Bordenave , Cyril Letrouit , Mostafa Sabri

We address the question of convergence of Schr\"odinger operators on metric graphs with general self-adjoint vertex conditions as lengths of some of graph's edges shrink to zero. We determine the limiting operator and study convergence in a…

Spectral Theory · Mathematics 2019-10-23 Gregory Berkolaiko , Yuri Latushkin , Selim Sukhtaiev

For general quantum systems the semiclassical behaviour of eigenfunctions in relation to the ergodic properties of the underlying classical system is quite difficult to understand. The Wignerfunctions of eigenstates converge weakly to…

Dynamical Systems · Mathematics 2009-11-13 Cheng-Hung Chang , Tyll Krueger , Roman Schubert , Serge Troubetzkoy

We consider discrete Schr\"odinger operators with periodic potentials on periodic graphs perturbed by guided non-positive potentials, which are periodic in some directions and finitely supported in other ones. The spectrum of the…

Spectral Theory · Mathematics 2017-05-16 Evgeny Korotyaev , Natalia Saburova

In this paper we construct a sequence of eigenfunctions of the ``quantum Arnold's cat map'' that, in the semiclassical limit, show a strong scarring phenomenon on the periodic orbits of the dynamics. More precisely, those states have a…

Chaotic Dynamics · Physics 2009-11-07 F. Faure , S. Nonnenmacher , S. De Bievre

We study the ergodic properties of quantized ergodic maps of the torus. It is known that these satisfy quantum ergodicity: For almost all eigenstates, the expectation values of quantum observables converge to the classical phase-space…

Mathematical Physics · Physics 2007-05-23 Jens Marklof , Zeev Rudnick

We pick up a solvable ${\cal PT}-$symmetric quantum square well on an interval of $x \in := (-L,L)\mathbb{G}^{(2)}$ (with an $\alpha-$dependent non-Hermiticity given by Robin boundary conditions) and generalize it. In essence, we just…

Quantum Physics · Physics 2013-01-15 Miloslav Znojil

In this paper, we prove quantum ergodicity (a form of delocalization for eigenfunctions) for the Dirichlet truncations of the adjacency matrix on $\mathbb{Z}^d$. We also extend the result to the cases of finite range observables and…

Spectral Theory · Mathematics 2025-05-06 Hongyi Cao , Shengquan Xiang

We investigate the properties of the zeros of the eigenfunctions on quantum graphs (metric graphs with a Schr\"odinger-type differential operator). Using tools such as scattering approach and eigenvalue interlacing inequalities we derive…

Mathematical Physics · Physics 2013-03-06 Ram Band , Gregory Berkolaiko , Uzy Smilansky

We prove a quantum ergodicity theorem in position space for the eigenfunctions of a Schr\"odinger operator $-\Delta+V$ on a rectangular torus $\mathbb{T}^2$ for $V\in L^2(\mathbb{T}^2)$ with an algebraic rate of convergence in terms of the…

Mathematical Physics · Physics 2023-09-18 Henrik Ueberschaer

The theory of scarring of eigenfunctions of classically chaotic systems by short periodic orbits is extended in several ways. The influence of short-time linear recurrences on correlations and fluctuations at long times is emphasized. We…

chao-dyn · Physics 2009-08-14 L. Kaplan , E. J. Heller

We propose an approach to quantize discrete networks (graphs with discrete edges). We introduce a new exact solution of discrete Schrodinger equation that is used to write the solution for quantum graphs. Formulation of the problem and…

Quantum Physics · Physics 2024-11-22 M. Akramov , C. Trunk , J. Yusupov , D. Matrasulov

For a large class of quantized ergodic flows the quantum ergodicity theorem due to Shnirelman, Zelditch, Colin de Verdi\`ere and others states that almost all eigenfunctions become equidistributed in the semiclassical limit. In this work we…

chao-dyn · Physics 2009-10-30 A. Bäcker , R. Schubert , P. Stifter

We prove sharp upper bounds for eigenvalues of Schr\"odinger operators on quantum graphs with $\delta$-coupling (also known as Robin) conditions at all vertices. The bounds depend on the geometry of the graph, on the potential, and the…

Spectral Theory · Mathematics 2025-05-21 Duc Hoang Cao

A discrete analog of quantum unique ergodicity was proved for Cayley graphs of quasirandom groups by Magee, Thomas and Zhao. They show that for large graphs there exist real orthonormal basis of eigenfunctions of the adjacency matrix such…

Mathematical Physics · Physics 2024-12-24 Jon Harrison , Clare Pruss

We review quantum chaos on graphs. We construct a unitary operator which represents the quantum evolution on the graph and study its spectral and wavefunction statistics. This operator is the analogue of the classical evolution operator on…

Chaotic Dynamics · Physics 2007-05-23 Tsampikos Kottos

We provide a purely variational proof of the existence of eigenvalues below the bottom of the essential spectrum for the Schr\"odinger operator with an attractive $\delta$-potential supported by a star graph, i.e. by a finite union of rays…

Mathematical Physics · Physics 2017-04-27 Konstantin Pankrashkin

We present a quantum ergodicity theorem for fixed spectral window and sequences of compact hyperbolic surfaces converging to the hyperbolic plane in the sense of Benjamini and Schramm. This addresses a question posed by Colin de…

Spectral Theory · Mathematics 2018-02-21 Etienne Le Masson , Tuomas Sahlsten