title: Maximally entangled mixed states: creation and concentration.
abstract: Using correlated photons from parametric down-conversion, we extend the boundaries of experimentally accessible two-qubit Hilbert space. Specifically, we have created and characterized maximally entangled mixed states 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.
authors.affiliation: Physics Department, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Peters
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Altepeter
authors.forename: David
authors.initials: D
authors.lastname: Branning
authors.forename: Evan R
authors.initials: ER
authors.lastname: Jeffrey
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Wei
authors.forename: Paul G
authors.initials: PG
authors.lastname: Kwiat