title: Creating polarization-entangled photon pairs from a semiconductor quantum dot using the optical Stark effect.
abstract: In typical epitaxial quantum dots (QDs) the ideally degenerate optical excitons are energy split, preventing the formation of two-photon entanglement in a biexciton decay. We use an external field, here a continuous-wave laser tuned to the QD in the ac Stark limit, to cancel the splitting and create two-photon entanglement. Quantum-state tomography is used to construct the two-photon density matrix. When the splitting is removed it satisfies well-known entanglement tests. Our approach shows that polarization-entangled photons can be routinely produced in semiconductor nanostructures.
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland, USA. andreas.muller@nist.gov
authors.forename: Andreas
authors.initials: A
authors.lastname: Muller
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.forename: John
authors.initials: J
authors.lastname: Lawall
authors.forename: Glenn S
authors.initials: GS
authors.lastname: Solomon