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In this paper, we present a new entanglement monotone for bipartite quantum states. Its definition is inspired by the so-called intrinsic information of classical cryptography and is given by the halved minimum quantum conditional mutual…

Quantum Physics · Physics 2015-06-26 Matthias Christandl , Andreas Winter

The electronic density \rho(r) in atoms, molecules and solids is, in general, a distribution that can be observed experimentally, containing spatial information projected from the total wave function. These density distributions can be…

Quantum Physics · Physics 2017-10-31 J. P. Restrepo Cuartas

Squashed entanglement is a measure for the entanglement of bipartite quantum states. In this paper we present a lower bound for squashed entanglement in terms of a distance to the set of separable states. This implies that squashed…

Quantum Physics · Physics 2012-07-23 Fernando G. S. L. Brandao , Matthias Christandl , Jon Yard

In the framework of Quantum Field Theory, we provide a rigorous, operator algebraic notion of entanglement entropy associated with a pair of open double cones $O \subset \tilde O$ of the spacetime, where the closure of $O$ is contained in…

Mathematical Physics · Physics 2020-03-18 Roberto Longo , Feng Xu

TThe organization and structure of bipartite mixed-state quantum entanglement (QE) are more complex and less well understood compared to bipartite pure-state QE. Bipartite mixed-state QEs and their measures play a crucial role in both…

Quantum Physics · Physics 2025-10-14 Jing-Min Zhu

Theoretical understanding of the scaling of entropies and the mutual information has led to significant advances in the research of correlated states of matter, quantum field theory, and gravity. Measuring von Neumann entropy in quantum…

Electronic quantum entanglement between the central chain and the two electrodes in an infinite one-dimensional two-probe device system is studied. The entanglement entropy is calculated employing the nonequilibrium Green's function method…

Mesoscale and Nanoscale Physics · Physics 2016-03-02 Yao-Sheng Li , Wen-Long You , Xue-Feng Wang

The von Neumann and quantum R\'enyi entropies characterize fundamental properties of quantum systems and lead to theoretical and practical applications in many fields. Quantum algorithms for estimating quantum entropies, using a quantum…

Quantum Physics · Physics 2023-10-13 Youle Wang , Benchi Zhao , Xin Wang

We investigate bipartite entanglement in spin-1/2 systems on a generic lattice. For states that are an equal superposition of elements of a group $G$ of spin flips acting on the fully polarized state $\ket{0}^{\otimes n}$, we find that the…

Quantum Physics · Physics 2007-05-23 Alioscia Hamma , Radu Ionicioiu , Paolo Zanardi

In this paper we examine the average R\'{e}nyi entropy $S_{\alpha}$ of a subsystem $A$ when the whole composite system $AB$ is a random pure state. We assume that the Hilbert space dimensions of $A$ and $AB$ are $m$ and $m n$ respectively.…

Quantum Physics · Physics 2024-04-23 MuSeong Kim , Mi-Ra Hwang , Eylee Jung , DaeKil Park

The well-known Heisenberg--Robertson uncertainty relation for a pair of noncommuting observables, is expressed in terms of the product of variances and the commutator among the operators, computed for the quantum state of a system.…

Quantum Physics · Physics 2019-09-25 David Puertas Centeno , Mariela Portesi

Entanglement measures quantify nonclassical correlations present in a quantum system, but can be extremely difficult to calculate, even more so, when information on its state is limited. Here, we consider broad families of entanglement…

Quantum Physics · Physics 2021-07-07 Matteo Fadel , Ayaka Usui , Marcus Huber , Nicolai Friis , Giuseppe Vitagliano

How to calculate the entanglement entropy between two subsystems for a mixed state has remained an important problem. In this paper, we provide a straightforward method, namely the subtraction approach, to solve this problem for generic…

High Energy Physics - Theory · Physics 2025-09-19 Xin Jiang , Peng Wang , Houwen Wu , Haitang Yang

We study the behavior of bipartite entanglement at fixed von Neumann entropy. We look at the distribution of the entanglement spectrum, that is the eigenvalues of the reduced density matrix of a quantum system in a pure state. We report the…

Quantum Physics · Physics 2013-05-29 Paolo Facchi , Giuseppe Florio , Giorgio Parisi , Saverio Pascazio , Kazuya Yuasa

We describe an efficient theoretical criterion, suitable for indistinguishable particles to quantify the quantum correlations of any pure two-fermion state, based on the Slater rank concept. It represents the natural generalization of the…

Quantum Physics · Physics 2007-05-23 Fabrizio Buscemi , Paolo Bordone , Andrea Bertoni

Quantum entanglement is an essential resource for quantum science and technology. However, entanglement detection and quantification, via typical entanglement measures such as linear entanglement entropy or negativity, can be a very…

Quantum Physics · Physics 2025-06-17 Diego Fallas Padilla , Mingjian Zhu , Han Pu

Instantaneous measurements of non-local observables between space-like separated regions can be performed without violating causality. This feat relies on the use of entanglement. Here we propose novel protocols for this task and the…

Quantum Physics · Physics 2015-05-20 Salman Beigi , Robert Koenig

The operational structure of quantum couplings and entanglements is studied and classified for semifinite von Neumann algebras. We show that the classical-quantum correspondences such as quantum encodings can be treated as diagonal…

Quantum Physics · Physics 2009-11-07 V. P. Belavkin , M. Ohya

We carry out a systematic study of entanglement entropy in relativistic quantum field theory. This is defined as the von Neumann entropy S_A=-Tr rho_A log rho_A corresponding to the reduced density matrix rho_A of a subsystem A. For the…

High Energy Physics - Theory · Physics 2011-02-16 Pasquale Calabrese , John Cardy

We derive several entanglement criteria for bipartite continuous variable quantum systems based on the Shannon entropy. These criteria are more sensitive than those involving only second-order moments, and are equivalent to well-known…

Quantum Physics · Physics 2015-05-14 S. P. Walborn , B. G. Taketani , A. Salles , F. Toscano , R. L. de Matos Filho