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Degree of entanglement for two qubits

Ayman F. Abouraddy·Bahaa E. A. Saleh·Alexander V. Sergienko·Malvin C. Teich
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Abstract

We demonstrate that any pure bipartite state of two qubits may be decomposed into a superposition of a maximally entangled state and an orthogonal factorizable one. Although there are many such decompositions, the weights of the two superposed states are, remarkably, unique. We propose a measure of entanglement based on this decomposition. We also demonstrate that this measure is connected to three measures of entanglement previously set forth: maximal violation of Bell's inequality, concurrence, and two-particle visibility.

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Ayman F. Abouraddy, Bahaa E. A. Saleh, Alexander V. Sergienko, Malvin C. Teich. 2001-10-31. Degree of entanglement for two qubits. https://doi.org/10.1103/physreva.64.050101

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