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Finding ways to test the behaviour of quantum devices is a timely enterprise, especially in the light of the rapid development of quantum technologies. Device-independent self-testing is one desirable approach, as it makes minimal…

Quantum Physics · Physics 2018-09-26 Ivan Šupić , Andrea Coladangelo , Remigiusz Augusiak , Antonio Acín

A scheme to achieve dense quantum coding for the quadrature amplitudes of the electromagnetic field is presented. The protocol utilizes shared entanglement provided by nondegenerate parametric down conversion in the limit of large gain to…

Quantum Physics · Physics 2009-10-31 Samuel L. Braunstein , H. J. Kimble

A highly entangled bipartite quantum state is more advantageous for the quantum dense coding protocol than states with low entanglement. Such a correspondence, however, does not exist even for pure quantum states in the multipartite domain.…

Quantum Physics · Physics 2014-08-26 Tamoghna Das , R. Prabhu , Aditi Sen De , Ujjwal Sen

We present an efficient and economic scheme for five-party quantum state sharing of an arbitrary m-qubit state with $2m$ three-particle Greenberger-Horne-Zeilinger (GHZ) states and three-particle GHZ-state measurements. It is more…

Quantum Physics · Physics 2010-05-04 Yu-Bo Sheng , Fu-Guo Deng , Hong-Yu Zhou

We reckon the behaviour of spin squeezing in tripartite unsqueezed maximally entangled Green- berger-Horne-Zeilinger (GHZ) and W states under various decoherence channels with Kitagawa- Ueda (KU) criteria. In order to search spin squeezing…

Quantum Physics · Physics 2018-01-15 Kapil K. Sharma

How entangled is a randomly chosen bipartite stabilizer state? We show that if the number of qubits each party holds is large the state will be close to maximally entangled with probability exponentially close to one. We provide a similar…

Quantum Physics · Physics 2007-05-23 Graeme Smith , Debbie Leung

We provide a complete analysis of mixed three-qubit states composed of a GHZ state and a W state orthogonal to the former. We present optimal decompositions and convex roofs for the three-tangle. Further, we provide an analytical method to…

Quantum Physics · Physics 2007-05-23 Robert Lohmayer , Andreas Osterloh , Jens Siewert , Armin Uhlmann

A scheme for the deterministic joint remote preparation of a four- qubit cluster-type state using only two Greenberger-Horne-Zeilinger (GHZ) states as quantum channels is presented. In this scheme, the first sender per- forms a two-qubit…

Quantum Physics · Physics 2016-10-04 Hai-bin Wang , Xiao-Yan Zhou , Xing-xing An , Meng-Meng Cui , De-sheng Fu

The quantum coherence of a multipartite system is investigated when some of the parties are moving with uniform acceleration and the analysis is carried out using the single mode approximation. Due to acceleration the quantum coherence is…

The familiar Greenberger-Horne-Zeilinger (GHZ) states can be rewritten by entangling the Bell states for two qubits with a state of the third qubit, which is dubbed entangled entanglement. We show that in this way we obtain all 8…

Quantum Physics · Physics 2015-10-06 Gabriele Uchida , Reinhold A. Bertlmann , Beatrix C. Hiesmayr

We study dynamics of genuine entanglement for quantum states of three and four qubits under non-Markovian dephasing. Using a computable entanglement monotone for multipartite systems, we find that GHZ state is quite resilient state whereas…

Quantum Physics · Physics 2015-06-23 Mazhar Ali

We give a complete solution for the three-tangle of mixed three-qubit states composed of a generalized GHZ state, a|000>+b|111>, and a generalized W state, c|001>+d|010>+f|100>. Using the methods introduced by Lohmayer et al. we provide…

Quantum Physics · Physics 2009-01-06 Christopher Eltschka , Andreas Osterloh , Jens Siewert , Armin Uhlmann

Many quantum state preparation methods rely on a combination of dissipative quantum state initialization, followed by unitary evolution to a desired target state. Here we demonstrate the usefulness of quantum measurement as an additional…

Quantum Physics · Physics 2020-07-01 Byron Alexander , Hermann Uys , John J. Bollinger

We examine dense coding with an arbitrary pure entangled state sharing between the sender and the receiver. Upper bounds on the average success probability in approximate dense coding and on the probability of conclusive results in…

Quantum Physics · Physics 2009-11-13 Yuan Feng , Runyao Duan , Zhengfeng Ji

We present a method to determine the decay of multiparticle quantum correlations as quantified by the geometric measure of entanglement under the influence of decoherence. With this, we compare the robustness of entanglement in GHZ-,…

Quantum Physics · Physics 2008-12-10 O. Gühne , F. Bodoky , M. Blaauboer

We introduce a class of mixed multiqubit states, that corresponds to a randomized version of graph states. Such states arise when a graph state is prepared with noisy or imperfect controlled-Z gates. We study the entanglement features of…

Quantum entanglement is a key resource in many quantum protocols, such as quantum teleportation and quantum cryptography. Yet entanglement makes protocols presented in Dirac notation difficult to verify. This is why Coecke and Duncan have…

Quantum Physics · Physics 2012-10-03 Anne Hillebrand

Genuine 3-qubit entanglement comes in two different inconvertible types represented by the Greenberger-Horne-Zeilinger (GHZ) state and the W state. We describe a specific method based on local positive operator valued measures and classical…

Quantum Physics · Physics 2009-11-11 P. Walther , K. J. Resch , A. Zeilinger

We have presented a theoretical extended version of dense coding protocol using entangled position state of two particles shared between two parties. A representation of Bell states and the required unitary operators are shown utilizing…

Quantum Physics · Physics 2009-11-10 O. Akhavan , A. T. Rezakhani , M. Golshani

We study the stability of superpositions of macroscopically distinct quantum states under decoherence. We introduce a class of quantum states with entanglement features similar to Greenberger-Horne-Zeilinger (GHZ) states, but with an…

Quantum Physics · Physics 2011-03-18 F. Fröwis , W. Dür