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We use the concept of \textit{entangled graphs} with weighted edges to present a classification for four-qubit entanglement which is based neither on the LOCC nor the SLOCC. Entangled graphs, first introduced by Plesch et al. [Phys. Rev. A…

Quantum Physics · Physics 2016-04-26 Masoud Gharahi Ghahi , Seyed Javad Akhtarshenas

In the standard geometric approach, the entanglement of a pure state is $\sin^2\theta$, where $\theta$ is the angle between the entangled state and the closest separable state of products of normalised qubit states. We consider here a…

Quantum Physics · Physics 2015-05-18 M. E. Carrington , R. Kobes , G. Kunstatter , D. Ostapchuk , G. Passante

Quantifying entanglement is an important issue in quantum information theory. Here we consider the entanglement measures through the trace norm in terms of two methods, the modified measure and the extended measure for bipartite states. We…

Quantum Physics · Physics 2023-02-09 Xian Shi , Lin Chen , Yixuan Liang

Quantifying experimentally created entanglement could in principle be accomplished by measuring the entire density matrix and calculating an entanglement measure of choice thereafter. Due to the tensor-structure of the Hilbert space, this…

Quantum Physics · Physics 2015-05-18 H. Wunderlich , S. Virmani , M. B. Plenio

The geometric measure of entanglement of a pure quantum state is defined to be its distance to the space of product (seperable) states. Given an $n$-partite system composed of subsystems of dimensions $d_1,\ldots, d_n$, an upper bound for…

Quantum Physics · Physics 2018-05-09 Liqun Qi , Guofeng Zhang , Guyan Ni

Quantifying entanglement is a work in progress which is important for the active field of quantum information and computation. A measure of bipartite pure state entanglement is proposed here, named entanglement coherence, which is…

Quantum Physics · Physics 2022-02-15 Neha Pathania , Tabish Qureshi

Quantum networks are essential to quantum information distributed applications, and communicating over them is a key challenge. Complex networks have rich and intriguing properties, which are as yet unexplored in the quantum setting. Here,…

Quantum Physics · Physics 2009-12-15 M. Cuquet , J. Calsamiglia

Recently, an explicit relation between a measure of entanglement and a geometric entity has been reported in Quantum Inf. Process. (2016) 15:1629-1638. It has been shown that if a qubit gets entangled with another ancillary qubit then…

Quantum Physics · Physics 2019-04-10 Pratapaditya Bej , Prasenjit Deb

We develop a comprehensive axiomatic framework for quantum-inspired distance metrics on projective Hilbert spaces, providing a unified foundation that organizes and generalizes existing measures in quantum information theory. Starting from…

Quantum Physics · Physics 2026-03-03 Maryam Bagherian

Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise,…

This thesis is an attempt to enhance understanding of the following questions A- Given a multipartite quantum state (possibly mixed), how to find out whether it is entangled or separable? (Detection of entanglement.) B- Given an entangled…

Quantum Physics · Physics 2009-05-05 Ali Saif M. Hassan

We investigate the properties of different levels of entanglement in graph states which correspond to connected graphs. Combining the operational definition of graph states and the postulates of entanglement measures, we prove that in…

Quantum Physics · Physics 2008-07-11 Jian-Ming Cai , Zheng-Wei Zhou , Guang-Can Guo

We give an explicit expression for the geometric measure of entanglement for three qubit states that are linear combinations of four orthogonal product states. It turns out that the geometric measure for these states has three different…

Quantum Physics · Physics 2008-09-03 Levon Tamaryan , DaeKil Park , Jin-Woo Son , Sayatnova Tamaryan

We derive an explicit expression for geometric measure of entanglement for spin and other quantum system. A relation of entanglement in pure state with the mean value of spin is given, thus, at the experimental level the local measurement…

Quantum Physics · Physics 2015-10-12 Andrzej M. Frydryszak , Volodymyr M. Tkachuk

The notion of distance in Hilbert space is relevant in many scenarios. In particular, distances between quantum states play a central role in quantum information theory. An appropriate measure of distance is the quantum Jensen Shannon…

Quantum Physics · Physics 2008-04-24 A. P. Majtey , A. Borras , M. Casas , P. W. Lamberti , A. Plastino

Graph states are multi-particle entangled states that correspond to mathematical graphs, where the vertices of the graph take the role of quantum spin systems and edges represent Ising interactions. They are many-body spin states of…

Quantum Physics · Physics 2007-05-23 M. Hein , J. Eisert , H. J. Briegel

We report the creation of a wide range of quantum states with controllable degrees of entanglement and entropy using an optical two-qubit source based on spontaneous parametric downconversion. The states are characterised using measures of…

Quantum Physics · Physics 2009-11-07 A. G. White , D. F. V. James , W. J. Munro , P. G. Kwiat

This paper explores the fundamental relationship between the geometry of entanglement and von Neumann entropy, shedding light on the intricate nature of quantum correlations. We provide a comprehensive overview of entanglement, highlighting…

Quantum Physics · Physics 2024-06-03 Ramita Sarkar , Soumik Mahanti , Prasanta K. Panigrahi

This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many…

Quantum Physics · Physics 2008-08-12 Hyeyoun Chung

Using the natural connection equivalent to the SU(2) Yang-Mills instanton on the quaternionic Hopf fibration of $S^7$ over the quaternionic projective space ${\bf HP}^1\simeq S^4$ with an $SU(2)\simeq S^3$ fiber the geometry of entanglement…

Quantum Physics · Physics 2008-11-26 Peter Levay