title: Cluster-state quantum computing enhanced by high-fidelity generalized measurements.
abstract: We introduce and implement a technique to extend the quantum computational power of cluster states by replacing some projective measurements with generalized quantum measurements (POVMs). As an experimental demonstration we fully realize an arbitrary three-qubit cluster computation by implementing a tunable linear-optical POVM, as well as fast active feedforward, on a two-qubit photonic cluster state. Over 206 different computations, the average output fidelity is 0.9832+/-0.0002; furthermore the error contribution from our POVM device and feedforward is only of O(10(-3)), less than some recent thresholds for fault-tolerant cluster computing.
authors.affiliation: Institute for Quantum Computing and Department of Physics & Astronomy, University of Waterloo, Waterloo, Canada, N2L 3G1.
authors.forename: D N
authors.initials: DN
authors.lastname: Biggerstaff
authors.forename: R
authors.initials: R
authors.lastname: Kaltenbaek
authors.forename: D R
authors.initials: DR
authors.lastname: Hamel
authors.forename: G
authors.initials: G
authors.lastname: Weihs
authors.forename: T
authors.initials: T
authors.lastname: Rudolph
authors.forename: K J
authors.initials: KJ
authors.lastname: Resch