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We analyze implementations of bipartite unitaries by means of local operations and classical communication (LOCC) assisted by shared entanglement. We employ concepts and techniques developed in quantum Shannon theory to study an asymptotic…

Quantum Physics · Physics 2018-03-26 Eyuri Wakakuwa , Akihito Soeda , Mio Murao

Understanding multipartite entanglement is vital, as it underpins a wide range of phenomena across physics. The study of transformations of states via Local Operations assisted by Classical Communication (LOCC) allows one to quantitatively…

Quantum Physics · Physics 2021-09-01 Antoine Neven , David Gunn , Martin Hebenstreit , Barbara Kraus

We prove that the entangling capacity of a two-qubit unitary operator without local ancillas, both with and without the restriction to initial product states, as quantified by the maximum attainable concurrence, is directly related to the…

Quantum Physics · Physics 2016-09-08 Anthony Chefles

Any pure two-qubit state can be represented by six real angles, with a natural parameterization indicated by the bipartite structure. After explicitly identifying all of these angles for the first time, it is found that the parameters can…

Quantum Physics · Physics 2016-01-19 K. B. Wharton

We examine the problem of determining if a 2-local Hamiltonian is stoquastic by local basis changes. We analyze this problem for two-qubit Hamiltonians, presenting some basic tools and giving a concrete example where using unitaries beyond…

Quantum Physics · Physics 2019-05-08 Joel Klassen , Barbara M. Terhal

We give an universal algorithm for testing the local unitary equivalence of states for multipartite system with arbitrary dimensions.

Quantum Physics · Physics 2010-09-03 Adam Sawicki , Marek Kuś

Two different measures of operator entanglement of two-qubit gates, namely, Schmidt strength and linear entropy, are studied. While these measures are shown to have one-to-one relation between them for Schmidt number 2 class of gates, no…

Quantum Physics · Physics 2015-05-28 S. Balakrishnan , R. Sankaranarayanan

We present a method to find the decompositions of tripartite entangled pure states which are smaller than two successive Schmidt decompositions. The method becomes very simple when one of the subsystems is a qubit. In this particular case,…

Quantum Physics · Physics 2009-11-11 Marcio F. Cornelio , A. F. R. de Toledo Piza

We solve the entanglement classification under stochastic local operations and classical communication (SLOCC) for all multipartite symmetric states in the general $N$-qubit case. For this purpose, we introduce 2 parameters playing a…

Quantum Physics · Physics 2015-05-13 T. Bastin , S. Krins , P. Mathonet , M. Godefroid , L. Lamata , E. Solano

Consistency with relativistic causality narrows down dramatically the class of measurable observables. We argue that by weakening the preparation role of ideal measurements, many of these observables become measurable. Particularly, we show…

Quantum Physics · Physics 2009-11-07 Berry Groisman , Benni Reznik

The Schmidt number of a mixed state characterizes the minimum Schmidt rank of the pure states needed to construct it. We investigate the Schmidt number of an arbitrary mixed state by constructing a Schmidt number witness that detects it. We…

Quantum Physics · Physics 2009-11-06 Anna Sanpera , Dagmar Bruss , Maciej Lewenstein

We analyze how entanglement between two components of a bipartite system behaves under the action of local channels of the form $\cE\otimes\cI$. We show that a set of maximally entangled states is by the action of $\cE\otimes\cI$…

Quantum Physics · Physics 2009-11-11 Mario Ziman , Vladimir Buzek

We refine recent local unitary entanglement classification for symmetric pure states of $n$ qubits (that is, states invariant under permutations of qubits) using local unitary stabilizer subgroups and Majorana configurations. Stabilizer…

Quantum Physics · Physics 2010-11-25 Curt D. Cenci , David W. Lyons , Scott N. Walck

A scheme for multiparty quantum state sharing of an arbitrary two-particle state is presented with Einstein-Podolsky-Rosen pairs. Any one of the $N$ agents has the access to regenerate the original state with two local unitary operations if…

Quantum Physics · Physics 2007-05-23 Fu-Guo Deng , Xi-Han Li , Chun-Yan Li , Ping Zhou , Hong-Yu Zhou

We show that all multipartite pure states that are SLOCC equivalent to the $N$-qubit $W$ state, can be uniquely determined (among arbitrary states) from their bipartite marginals. We also prove that only $(N-1)$ of the bipartite marginals…

Quantum Physics · Physics 2014-09-23 Swapan Rana , Preeti Parashar

The Schmidt number characterizes the quantum entanglement of a bipartite mixed state and plays a significant role in certifying entanglement of quantum states. We derive a Schmidt number criterion based on the trace norm of the correlation…

Quantum Physics · Physics 2024-12-16 Zhen Wang , Bao-Zhi Sun , Shao-Ming Fei , Zhi-Xi Wang

We consider one copy of a quantum system prepared in one of two non-orthogonal pure product states of multipartite distributed among separated parties. We show that there exist protocols which obtain optimal probability in the sense of…

Quantum Physics · Physics 2009-11-07 Yi-Xin Chen , Dong Yang

We report an exhaustive numerical analysis of violations of local realism by two qutrits in all possible pure entangled states. In Bell type experiments we allow any pairs of local unitary U(3) transformations to define the measurement…

Quantum Physics · Physics 2015-06-03 Jacek Gruca , Wieslaw Laskowski , Marek Zukowski

We consider generic pure $n$-qubit states and a general class of pure states of arbitrary dimensions and arbitrarily many subsystems. We characterize those states which can be reached from some other state via Local Operations assisted by…

Quantum Physics · Physics 2017-02-01 C. Spee , J. I. de Vicente , D. Sauerwein , B. Kraus

By introducing the concept of $\epsilon$-convertibility, we extend Nielsen's and Vidal's theorems to the entanglement transformation of infinite-dimensional systems. Using an infinite-dimensional version of Vidal's theorem we derive a new…

Quantum Physics · Physics 2009-09-29 Masaki Owari , Samuel L. Braunstein , Kae Nemoto , Mio Murao