title: Exponentially enhanced quantum metrology.
abstract: We show that when a suitable entanglement-generating unitary operator depending on a parameter is applied on N qubits in parallel, a precision of the order of 2(-N) in estimating the parameter may be achieved. This exponentially improves the precision achievable in classical and in quantum nonentangling strategies.
authors.affiliation: Computer Science, University of York, York YO 10 5DD, United Kingdom.
authors.forename: S M
authors.initials: SM
authors.lastname: Roy
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Braunstein