title: Evolution of entanglement between distinguishable light states.
abstract: We investigate the evolution of quantum correlations over the lifetime of a multiphoton state. Measurements reveal time-dependent oscillations of the entanglement fidelity for photon pairs created by a single semiconductor quantum dot. The oscillations are attributed to the phase acquired in the intermediate, nondegenerate, exciton-photon state and are consistent with simulations. We conclude that emission of photon pairs by a typical quantum dot with finite polarization splitting is in fact entangled in a time-evolving state, and not classically correlated as previously regarded.
authors.affiliation: Toshiba Research Europe Limited, 208 Cambridge Science Park, Cambridge, United Kingdom.
authors.forename: R Mark
authors.initials: RM
authors.lastname: Stevenson
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hudson
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Bennett
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Young
authors.forename: Christine A
authors.initials: CA
authors.lastname: Nicoll
authors.forename: David A
authors.initials: DA
authors.lastname: Ritchie
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Shields