title: Quantum phase transitions and continuous observation of spinor dynamics in an antiferromagnetic condensate.
abstract: Condensates of spin-1 sodium display rich spin dynamics due to the antiferromagnetic nature of the interactions in this system. We use Faraday rotation spectroscopy to make a continuous and minimally destructive measurement of the dynamics over multiple spin oscillations on a single evolving condensate. This method provides a sharp signature to locate a magnetically tuned separatrix in phase space which depends on the net magnetization. We also observe a phase transition from a two- to a three-component condensate at a low but finite temperature using a Stern-Gerlach imaging technique. This transition should be preserved as a zero-temperature quantum phase transition.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Jung
authors.forename: S E
authors.initials: SE
authors.lastname: Maxwell
authors.forename: L D
authors.initials: LD
authors.lastname: Turner
authors.forename: E
authors.initials: E
authors.lastname: Tiesinga
authors.forename: P D
authors.initials: PD
authors.lastname: Lett