# Entanglement universality of two-qubit X-states

@article{Mendonca2014EntanglementUO,
title={Entanglement universality of two-qubit X-states},
author={Paulo E. M. F. Mendonca and Marcelo Aparecido Marchiolli and Di{\'o}genes Galetti},
journal={Annals of Physics},
year={2014},
volume={351},
pages={79-103}
}
• Published 11 July 2014
• Physics
• Annals of Physics

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## References

SHOWING 1-10 OF 125 REFERENCES
Maximally entangled mixed states of two qubits
• Mathematics
• 2001
In this paper we investigate how much entanglement in a mixed two-qubit system can be created by global unitary transformations. The class of states for which no more entanglement can be created by
Evidence that All States Are Unitarily Equivalent to X States of the Same Entanglement
Strong numerical evidence is presented suggesting that all two-qubit mixed states are equivalent to X states by a single entanglement-preserving unitary (EPU) transformation, so that the concurrence
Relative entropy of entanglement of two-qubit ‘X’ states
Two closest single-qubit states could be diagonalised by the same unitary matrix, which helps to find the relative entropy of entanglement of a two-qubit ‘X’ state. We formulate two binary equations
Entanglement of Formation of an Arbitrary State of Two Qubits
The entanglement of a pure state of a pair of quantum systems is defined as the entropy of either member of the pair. The entanglement of formation of a mixed state is defined as the minimum average
Genuinely multipartite concurrence of N -qubit X matrices
• Physics
• 2012
We find an algebraic formula for the N-partite concurrence of N qubits in an X matrix. X matrices are density matrices whose only nonzero elements are diagonal or antidiagonal when written in an
Volume of the set of separable states
• Physics
• 1998
The question of how many entangled or, respectively, separable states there are in the set of all quantum states is considered. We propose a natural measure in the space of density matrices %
Concurrence versus purity: Influence of local channels on Bell states of two qubits
• Physics
• 2005
We analyze how a maximally entangled state of two qubits (e.g., the singlet $psi_s$) is affected by the action of local channels described by completely positive maps $E$. We analyze the concurrence
Maximizing Genuine Multipartite Entanglement of N Mixed Qubits
• Physics
• 2013
Beyond the simplest case of bipartite qubits, the composite Hilbert space of multipartite systems is largely unexplored. In order to explore such systems, it is important to derive analytic
Entanglement evolution in the presence of decoherence
• Physics
• 2005
The entanglement of two qubits, each defined as an effective two-level, spin 1/2 system, is investigated for the case that the qubits interact via a Heisenberg XY interaction and are subject to
An explicit expression for the relative entropy of entanglement in all dimensions
• Physics
• 2011
The relative entropy of entanglement is defined in terms of the relative entropy between an entangled state and its closest separable state (CSS). Given a multipartite-state on the boundary of the