title: Preparation of Entangled States through Hilbert Space Engineering.
abstract: We apply laser fields to trapped atomic ions to constrain the quantum dynamics from a simultaneously applied global microwave field to an initial product state and a target entangled state. This approach comes under what has become known in the literature as "quantum Zeno dynamics" and we use it to prepare entangled states of two and three ions. With two trapped ^{9}Be^{+} ions, we obtain Bell state fidelities up to 0.990_{-5}^{+2}; with three ions, a W-state fidelity of 0.910_{-7}^{+4} is obtained. Compared to other methods of producing entanglement in trapped ions, this procedure can be relatively insensitive to certain imperfections such as fluctuations in laser intensity.
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Gaebler
authors.affiliation: The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark.
authors.forename: F
authors.initials: F
authors.lastname: Reiter
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: T R
authors.initials: TR
authors.lastname: Tan
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: R
authors.initials: R
authors.lastname: Bowler
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Wan
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: A
authors.initials: A
authors.lastname: Keith
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: E
authors.initials: E
authors.lastname: Knill
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: S
authors.initials: S
authors.lastname: Glancy
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: K
authors.initials: K
authors.lastname: Coakley
authors.affiliation: The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark.
authors.forename: A S
authors.initials: AS
authors.lastname: Sørensen
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: D
authors.initials: D
authors.lastname: Leibfried
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Wineland