title: Entangled photon pairs from semiconductor quantum dots.
abstract: Tomographic analysis demonstrates that the polarization state of pairs of photons emitted from a biexciton decay cascade becomes entangled when spectral filtering is applied. The measured density matrix of the photon pair satisfies the Peres criterion for entanglement by more than 3 standard deviations of the experimental uncertainty and violates Bell's inequality. We show that the spectral filtering erases the "which path" information contained in the photons' color and that the remanent information in the quantum dot degrees of freedom is negligible.
authors.affiliation: Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: N
authors.initials: N
authors.lastname: Akopian
authors.forename: N H
authors.initials: NH
authors.lastname: Lindner
authors.forename: E
authors.initials: E
authors.lastname: Poem
authors.forename: Y
authors.initials: Y
authors.lastname: Berlatzky
authors.forename: J
authors.initials: J
authors.lastname: Avron
authors.forename: D
authors.initials: D
authors.lastname: Gershoni
authors.forename: B D
authors.initials: BD
authors.lastname: Gerardot
authors.forename: P M
authors.initials: PM
authors.lastname: Petroff