title: Demonstration of an optical quantum controlled-NOT gate without path interference.
abstract: We report the first experimental demonstration of an optical quantum controlled-NOT gate without any path interference, where the two interacting path interferometers of the original proposals have been replaced by three partially polarizing beam splitters with suitable polarization dependent transmittance and reflectance. The performance of the device is evaluated using a recently proposed method, by which the quantum process fidelity and the entanglement capability can be estimated from the 32 measurement results of two classical truth tables, significantly less than the 256 measurement results required for full quantum tomography.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Okamoto
authors.forename: Holger F
authors.initials: HF
authors.lastname: Hofmann
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Keiji
authors.initials: K
authors.lastname: Sasaki