title: Orientation-dependent entanglement lifetime in a squeezed atomic clock.
abstract: We study experimentally the application of a class of entangled states, squeezed spin states, to the improvement of atomic-clock precision. In the presence of anisotropic noise, the entanglement lifetime is strongly dependent on squeezing orientation. We measure the Allan deviation spectrum of a clock operated with a phase-squeezed input state. For averaging times up to 50 s the squeezed clock achieves a given precision 2.8(3) times faster than a clock operating at the standard quantum limit.
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Leroux
authors.forename: Monika H
authors.initials: MH
authors.lastname: Schleier-Smith
authors.forename: Vladan
authors.initials: V
authors.lastname: Vuletić