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We use Nuclear Magnetic Resonance (NMR) to experimentally generate a bound entangled (more precisely: pseudo bound entangled) state, i.e. a quantum state which is non-distillable but nevertheless entangled. Our quantum system consists of…

Quantum Physics · Physics 2010-11-08 H. Kampermann , X. Peng , D. Bruss , D. Suter

We consider the entanglement marginal problem, which consists of deciding whether a number of reduced density matrices are compatible with an overall separable quantum state. To tackle this problem, we propose hierarchies of semidefinite…

Quantum Physics · Physics 2021-11-30 Miguel Navascues , Flavio Baccari , Antonio Acin

The preprocessing stage of Shor's algorithm generates a class of quantum states referred to as periodic states, on which the quantum Fourier transform is applied. Such states also play an important role in other quantum algorithms that rely…

Quantum Physics · Physics 2010-05-21 Yonatan Most , Yishai Shimoni , Ofer Biham

Discordant states appear in a large number of quantum phenomena and seem to be a good indicator of divergence from classicality. While there is evidence that they are essential for a quantum algorithm to have an advantage over a classical…

Quantum Physics · Physics 2013-10-04 Aharon Brodutch

Entanglement distribution is key to the success of secure communication schemes based on quantum mechanics, and there is a strong need for an ultimate architecture able to overcome the limitations of recent proposals such as those based on…

Quantum Physics · Physics 2015-09-10 Alexander Streltsov , Remigiusz Augusiak , Maciej Demianowicz , Maciej Lewenstein

We study the use of entanglement purification for quantum communication over long distances. For distances much longer than the coherence length of a corresponding noisy quantum channel, the fidelity of transmission is usually so low that…

Quantum Physics · Physics 2008-12-18 W. Dür , H. - J. Briegel , J. I. Cirac , P. Zoller

Quantum algorithms allow to outperform their classical counterparts in various tasks, most prominent example being Shor's algorithm for efficient prime factorization on a quantum computer. It is clear that one of the reasons for the speedup…

In this paper we consider the notion of quantum entanglement from the perspective of the logos categorical approach [26, 27]. Firstly, we will argue that the widespread distinctions, on the one hand, between pure states and mixed states,…

Quantum Physics · Physics 2018-07-24 Christian de Ronde , César Massri

We discuss the concept of how entanglement changes with respect to different factorizations of the total algebra which describes the quantum states. Depending on the considered factorization a quantum state appears either entangled or…

Quantum Physics · Physics 2011-11-15 Walter Thirring , Reinhold A. Bertlmann , Philipp Köhler , Heide Narnhofer

Coherently manipulating multipartite quantum correlations leads to remarkable advantages in quantum information processing. A fundamental question is whether such quantum advantages persist only by exploiting multipartite correlations, such…

Quantum Physics · Physics 2016-07-05 Xiao Yuan , Ke Liu , Yuan Xu , Weiting Wang , Yuwei Ma , Fang Zhang , Zhaopeng Yan , R. Vijay , Luyan Sun , Xiongfeng Ma

The characterization of quantum correlations is crucial to the development of new quantum technologies and to understand how dramatically quantum theory departs from classical physics. Here we systematically study single- and multiparticle…

Quantum Physics · Physics 2020-06-05 Rejane Alves de Brito , Bertúlio de Lima Bernardo

Quantum entanglement is an essential feature of many-body systems that impacts both quantum information processing and fundamental physics. The growth of entanglement is a major challenge for classical simulation methods. In this work, we…

Quantum Physics · Physics 2025-07-15 Qi Zhao , You Zhou , Andrew M. Childs

Measuring entanglement is a demanding task in the field of quantum computation and quantum information theory. Recently, some authors experimentally demonstrated an embedding quantum simulator, using it to efficiently measure two-qubit…

Quantum Physics · Physics 2018-11-01 Saeed Haddadi , Mohammad Bohloul

Entanglement assistance is known to reduce the quantum communication complexity of evaluating functions with distributed inputs. But does the type of entanglement matter, or are EPR pairs always sufficient? This is a natural question…

Quantum Physics · Physics 2019-07-17 Matthew Coudron , Aram W. Harrow

We exhibit the intriguing phenomena of "Less is More" using a set of multipartite entangled states. We consider the quantum communication protocols for the {\em exact} teleportation, superdense coding, and quantum key distribution. We find…

Quantum Physics · Physics 2016-01-20 P. Agrawal , Satyabrata Adhikari , Sumit Nandi

There has been a surge of progress in recent years in developing algorithms for testing and learning quantum states that achieve optimal copy complexity. Unfortunately, they require the use of entangled measurements across many copies of…

Quantum Physics · Physics 2020-04-20 Sebastien Bubeck , Sitan Chen , Jerry Li

Genuineness and distillability of entanglement play a key role in quantum information tasks, and they are easily disturbed by the noise. We construct a family of multipartite states without genuine entanglement and distillability sudden…

Quantum Physics · Physics 2021-02-05 Mengyao Hu , Lin Chen

Deviations from classical physics when distant quantum systems become correlated are interesting both fundamentally and operationally. There exist situations where the correlations enable collaborative tasks that are impossible within the…

Quantum Physics · Physics 2019-05-08 Farid Shahandeh , Austin P. Lund , Timothy C. Ralph

An iterative random procedure is considered allowing an entanglement purification of a class of multi-mode quantum states. In certain cases, a complete purification may be achieved using only a single signal state preparation. A physical…

Quantum Physics · Physics 2009-11-10 J Clausen , L Knoell , D-G Welsch

We establish a framework which allows one to construct novel schemes for measurement-based quantum computation. The technique further develops tools from many-body physics - based on finitely correlated or projected entangled pair states -…

Quantum Physics · Physics 2009-11-13 D. Gross , J. Eisert