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Maximally entangled mixed states: Creation and concentration

Nicholas A. Peters·Joseph B. Altepeter·David A. Branning·Evan R. Jeffrey·Tzu-Chieh Wei·Paul G. Kwiat
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Abstract

Using correlated photons from parametric downconversion, we extend the boundaries of experimentally accessible two-qubit Hilbert space. Specifically, we have created and characterized maximally entangled mixed states (MEMS) that lie above the Werner boundary in the linear entropy-tangle plane. In addition, we demonstrate that such states can be efficiently concentrated, simultaneously increasing both the purity and the degree of entanglement. We investigate a previously unsuspected sensitivity imbalance in common state measures, i.e., the tangle, linear entropy, and fidelity.

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Nicholas A. Peters, Joseph B. Altepeter, David A. Branning, Evan R. Jeffrey, Tzu-Chieh Wei, Paul G. Kwiat. 2004-04-04. Maximally entangled mixed states: Creation and concentration. https://doi.org/10.1103/physrevlett.92.133601

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