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We investigate the quantum state discrimination task for sets of linear independent pure states with an intrinsic ordering. This structured discrimination problems allow for a novel scheme that provides a certified level of error, that is,…

Quantum Physics · Physics 2019-11-06 Esteban Martínez-Vargas , Ramon Munoz-Tapia

We investigate the separability of quantum states based on covariance matrices. Separability criteria are presented for multipartite states. The lower bound of concurrence proposed in Phys. Rev. A. 75, 052320 (2007) is improved by…

Quantum Physics · Physics 2009-09-29 Ming Li , Shao-Ming Fei , Zhi-Xi Wang

This article delves into an analysis of the intrinsic entanglement and separability feature in quantum states as depicted by graph Laplacian. We show that the presence or absence of edges in the graph plays a pivotal role in defining the…

Quantum Physics · Physics 2024-01-05 Anoopa Joshi , Parvinder Singh , Atul Kumar

We define a new measure of quantum correlations in bipartite quantum systems given by the Bures distance of the system state to the set of classical states with respect to one subsystem, that is, to the states with zero quantum discord. Our…

Quantum Physics · Physics 2013-12-23 Dominique Spehner , Miguel Orszag

The computational power of quantum computers poses major challenges to new design tools since representing pure quantum states typically requires exponentially large memory. As shown previously, decision diagrams can reduce these memory…

Quantum Physics · Physics 2023-11-08 Alwin Zulehner , Stefan Hillmich , Igor L. Markov , Robert Wille

Entanglement is a central feature of quantum theory. Mathematical properties and physical applications of pure state entanglement make it a template to study quantum correlations. However, an extension of entanglement measures to mixed…

Quantum Physics · Physics 2017-07-19 Aharon Brodutch , Daniel R. Terno

Quantum graph neural networks offer a powerful paradigm for learning on graph-structured data, yet their explainability is complicated by measurement-induced stochasticity and the combinatorial nature of graph structure. In this paper, we…

Machine Learning · Computer Science 2025-10-08 Haribandhu Jena , Jyotirmaya Shivottam , Subhankar Mishra

We study the level surfaces of quantum discord for a class of two-qubit states with parallel nonzero Bloch vectors. The dynamic behavior of quantum discord under decoherence is investigated. It is shown that a class of X states has sudden…

Quantum Physics · Physics 2011-04-12 Bo Li , Zhi-Xi Wang , Shao-Ming Fei

Quantum walks have frequently envisioned the behavior of a quantum state traversing a classically defined, generally finite, graph structure. While this approach has already generated significant results, it imposes a strong assumption: all…

Quantum Physics · Physics 2024-05-28 John C Vining , Howard A. Blair

We present a reliable algorithm to evaluate quantum discord for general two--qubit states, amending and extending an approach recently put forward for the subclass of X--states. A closed expression for the discord of arbitrary states of two…

Quantum Physics · Physics 2011-05-23 Davide Girolami , Gerardo Adesso

We present "Diagrams of States", a way to graphically represent and analyze how quantum information is elaborated during the execution of quantum circuits. This introductory tutorial illustrates the basics, providing useful examples of…

Quantum Physics · Physics 2009-04-20 Sara Felloni , Alberto Leporati , Giuliano Strini

We investigate the equidistribution of the eigenfunctions on quantum graphs in the high-energy limit. Our main result is an estimate of the deviations from equidistribution for large well-connected graphs. We use an exact field-theoretic…

Chaotic Dynamics · Physics 2009-11-13 S. Gnutzmann , J. P. Keating , F. Piotet

Quantum metrology exploits quantum mechanical effects to increase the precision of measurements of physical quantities. A wide variety of applications are currently being developed for scientific and technological purposes, however, most…

Quantum Physics · Physics 2026-02-16 B. J. Alexander , Ş. K. Özdemir , M. S. Tame

Graph theory provides fundamental concepts for many fields of science like statistical physics, network analysis and theoretical computer science. Here we give a pedagogical introduction to graph theory, divided into three sections. In the…

Disordered Systems and Neural Networks · Physics 2007-05-23 Alexander K. Hartmann , Martin Weigt

We study multi-qubit variational quantum states that can be considered as vertex- and edge-weighted graph. These states are constructed as single-layer variational circuits with $RX$ rotations and $RZZ$ entangling gates, corresponding to…

Quantum Physics · Physics 2026-04-22 Kh. P. Gnatenko , A. Kaczmarek

Decisions suggested by improperly designed software systems might be prone to discriminate against people based on protected characteristics, such as gender and ethnicity. Previous studies attribute such undesired behavior to flaws in…

Software Engineering · Computer Science 2025-09-26 Qusai Ramadan , Jukka Ruohonen , Abhishek Tiwari , Adam Alami , Zeyd Boukhers

The "noncommutative graphs" which arise in quantum error correction are a special case of the quantum relations introduced in [N. Weaver, Quantum relations, Mem. Amer. Math. Soc. 215 (2012), v-vi, 81-140]. We use this perspective to…

Operator Algebras · Mathematics 2017-06-30 Nik Weaver

A set of Pauli stings is well characterized by the graph that encodes its commutatitivity structure, i.e., by its frustration graph. This graph provides a natural interface between graph theory and quantum information, which we explore in…

Quantum Physics · Physics 2025-11-18 Zhen-Peng Xu , Jie Wang , Qi Ye , Gereon Koßmann , René Schwonnek , Andreas Winter

We propose a universal decomposition of unitary maps over a tensorial power of C^2, introducing the key concept of "phase maps", and investigate how this decomposition can be used to implement unitary maps directly in the measurement-based…

Quantum Physics · Physics 2007-05-23 Niel de Beaudrap , Vincent Danos , Elham Kashefi

Quantum discord is a more general measure of quantum correlations than entanglement and has been proposed as a resource in certain quantum information processing tasks. The computation of discord is mostly confined to two-qubit systems for…

Quantum Physics · Physics 2015-06-05 Indrani Bose , Amit Kumar Pal