title: Quantum metrology: dynamics versus entanglement.
abstract: A parameter whose coupling to a quantum probe of n constituents includes all two-body interactions between the constituents can be measured with an uncertainty that scales as 1/n3/2, even when the constituents are initially unentangled. We devise a protocol that achieves the 1/n3/2 scaling without generating any entanglement among the constituents, and we suggest that the protocol might be implemented in a two-component Bose-Einstein condensate.
authors.affiliation: Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
authors.forename: Sergio
authors.initials: S
authors.lastname: Boixo
authors.forename: Animesh
authors.initials: A
authors.lastname: Datta
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Davis
authors.forename: Steven T
authors.initials: ST
authors.lastname: Flammia
authors.forename: Anil
authors.initials: A
authors.lastname: Shaji
authors.forename: Carlton M
authors.initials: CM
authors.lastname: Caves