title: Toward Heisenberg-limited spectroscopy with multiparticle entangled states.
abstract: The precision in spectroscopy of any quantum system is fundamentally limited by the Heisenberg uncertainty relation for energy and time. For N systems, this limit requires that they be in a quantum-mechanically entangled state. We describe a scalable method of spectroscopy that can potentially take full advantage of entanglement to reach the Heisenberg limit and has the practical advantage that the spectroscopic information is transferred to states with optimal protection against readout noise. We demonstrate our method experimentally with three beryllium ions. The spectroscopic sensitivity attained is 1.45(2) times as high as that of a perfect experiment with three non-entangled particles.
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA. dil@boulder.nist.gov
authors.forename: D
authors.initials: D
authors.lastname: Leibfried
authors.forename: M D
authors.initials: MD
authors.lastname: Barrett
authors.forename: T
authors.initials: T
authors.lastname: Schaetz
authors.forename: J
authors.initials: J
authors.lastname: Britton
authors.forename: J
authors.initials: J
authors.lastname: Chiaverini
authors.forename: W M
authors.initials: WM
authors.lastname: Itano
authors.forename: J D
authors.initials: JD
authors.lastname: Jost
authors.forename: C
authors.initials: C
authors.lastname: Langer
authors.forename: D J
authors.initials: DJ
authors.lastname: Wineland