title: Conditional spin squeezing of a large ensemble via the vacuum Rabi splitting.
abstract: We use the vacuum Rabi splitting to perform quantum nondemolition measurements that prepare a conditionally spin squeezed state of a collective atomic psuedospin. We infer a 3.4(6) dB improvement in quantum phase estimation relative to the standard quantum limit for a coherent spin state composed of uncorrelated atoms. The measured collective spin is composed of the two-level clock states of nearly 10(6) (87)Rb atoms confined inside a low finesse F=710 optical cavity. This technique may improve atomic sensor precision and/or bandwidth, and may lead to more precise tests of fundamental physics.
authors.affiliation: JILA, University of Colorado, Boulder, Colorado 80309-0440, USA.
authors.forename: Zilong
authors.initials: Z
authors.lastname: Chen
authors.forename: Justin G
authors.initials: JG
authors.lastname: Bohnet
authors.forename: Shannon R
authors.initials: SR
authors.lastname: Sankar
authors.forename: Jiayan
authors.initials: J
authors.lastname: Dai
authors.forename: James K
authors.initials: JK
authors.lastname: Thompson