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We propose a novel variational method for solving the sub-graph isomorphism problem on a gate-based quantum computer. The method relies (1) on a new representation of the adjacency matrices of the underlying graphs, which requires a number…

Quantum Physics · Physics 2022-09-05 Nicola Mariella , Andrea Simonetto

We use an entropy based method to study two graph maximization problems. We upper bound the number of matchings of fixed size $\ell$ in a $d$-regular graph on $N$ vertices. For $\frac{2\ell}{N}$ bounded away from 0 and 1, the logarithm of…

Combinatorics · Mathematics 2012-06-15 Teena Carroll , David Galvin , Prasad Tetali

Studying significant network patterns, known as graphlets (or motifs), has been a popular approach to understand the underlying organizing principles of complex networks. Statistical significance is routinely assessed by comparing to null…

Physics and Society · Physics 2024-11-08 Bingjie Hao , István A. Kovács

The Scaled Relative Graph (SRG) is a geometric tool that maps the action of a multi-valued nonlinear operator onto the 2D plane, used to analyze the convergence of a wide range of iterative methods. As the SRG includes the spectrum for…

Numerical Analysis · Mathematics 2024-12-05 Xinmeng Huang , Ernest K. Ryu , Wotao Yin

The entanglement entropy of a subsystem $A$ of a quantum system is expressed, in the replica method, through analytic continuation with respect to n of the trace of the n-th power of the reduced density matrix $\tr\rho_A^n$. We study the…

Statistical Mechanics · Physics 2010-03-25 F. Gliozzi , L. Tagliacozzo

We study the richness of the ensemble of graphical structures (i.e., unlabeled graphs) of the one-dimensional random geometric graph model defined by $n$ nodes randomly scattered in $[0,1]$ that connect if they are within the connection…

Information Theory · Computer Science 2022-06-24 Mihai-Alin Badiu , Justin P. Coon

Cluster states and graph states in general offer a useful model of the stabilizer formalism and a path toward the development of measurement-based quantum computation. Their defining structure - the stabilizer group - encodes all possible…

Quantum Physics · Physics 2026-01-23 Konrad Szymański , Lina Vandré , Otfried Gühne

We study geometrical aspects of entanglement, with the Hilbert--Schmidt norm defining the metric on the set of density matrices. We focus first on the simplest case of two two-level systems and show that a ``relativistic'' formulation leads…

Quantum Physics · Physics 2013-05-29 Jon Magne Leinaas , Jan Myrheim , Eirik Ovrum

We study the graphs formed from instances of the stable matching problem by connecting pairs of elements with an edge when there exists a stable matching in which they are matched. Our results include the NP-completeness of recognizing…

Discrete Mathematics · Computer Science 2020-10-20 David Eppstein

The state overlap, quantified via $\tr[\rho \sigma]$, is a metric widely used to assess the closeness between two quantum states $\rho$ and $\sigma$. Although global state overlap alone does not directly capture entanglement properties, we…

Building on work of Cai, F\"urer, and Immerman \cite{CFI92}, we show two hardness results for the Graph Isomorphism problem. First, we show that there are pairs of nonisomorphic $n$-vertex graphs $G$ and $H$ such that any sum-of-squares…

Computational Complexity · Computer Science 2014-01-13 Ryan O'Donnell , John Wright , Chenggang Wu , Yuan Zhou

Graph states are fundamental objects in the theory of quantum information due to their simple classical description and rich entanglement structure. They are also intimately related to IQP circuits, which have applications in quantum…

Quantum Physics · Physics 2025-10-20 Soumik Ghosh , Dominik Hangleiter , Jonas Helsen

Similarly to the system Hamiltonian, a subsystem's reduced density matrix is composed of blocks characterized by symmetry quantum numbers (charge sectors). We present a geometric approach for extracting the contribution of individual charge…

Statistical Mechanics · Physics 2018-05-17 Moshe Goldstein , Eran Sela

Scaled Relative Graphs (SRGs) provide a novel graphical frequency-domain method for the analysis of nonlinear systems. However, we show that the current SRG analysis suffers from a pitfall that limit its applicability in analyzing practical…

Systems and Control · Electrical Eng. & Systems 2025-04-14 Julius P. J. Krebbekx , Roland Tóth , Amritam Das

The Scaled Relative Graph (SRG) is a generalization of the Nyquist diagram that may be plotted for nonlinear operators, and allows nonlinear robustness margins to be defined graphically. This abstract explores techniques for shaping the SRG…

Systems and Control · Electrical Eng. & Systems 2022-08-10 Thomas Chaffey , Fulvio Forni , Rodolphe Sepulchre

The entanglement in quantum XY spin chains of arbitrary length is investigated via the geometric (measure of) entanglement. The emergence of entanglement is explained intuitively from the perspective of perturbations. The model is solved…

Quantum Physics · Physics 2011-04-06 Tzu-Chieh Wei , Smitha Vishveshwara , Paul M. Goldbart

We propose a method for constructing multi-qubit entangled quantum states representing weighted tripartite graphs. An expression for the entanglement distance for multi-qubit states corresponding to arbitrary tripartite graph structures is…

Quantum Physics · Physics 2026-05-01 Kh. P. Gnatenko

Entanglement asymmetry is an observable in quantum systems, constructed using quantum-information methods, suited to detecting symmetry breaking in states -- possibly out of equilibrium -- relative to a subsystem. In this paper we define…

High Energy Physics - Theory · Physics 2026-01-27 Francesco Benini , Pasquale Calabrese , Michele Fossati , Amartya Harsh Singh , Marco Venuti

The entanglement in a quantum system that possess an internal symmetry, characterized by the Sz-magnetization or U(1)-charge, is distributed among different sectors. The aim of this letter is to gain a deeper understanding of the…

Statistical Mechanics · Physics 2018-07-25 J. C. Xavier , F. C. Alcaraz , G. Sierra

We investigate boundary critical phenomena from a quantum information perspective. Bipartite entanglement in the ground state of one-dimensional quantum systems is quantified using the Renyi entropy S_alpha, which includes the von Neumann…

Strongly Correlated Electrons · Physics 2007-05-23 Huan-Qiang Zhou , Thomas Barthel , John Ove Fjaerestad , Ulrich Schollwoeck