title: Attosecond tracing of correlated electron-emission in non-sequential double             ionization.
abstract: Despite their broad implications for phenomena such as molecular bonding or chemical                 reactions, our knowledge of multi-electron dynamics is limited and their theoretical                 modelling remains a most difficult task. From the experimental side, it is highly                 desirable to study the dynamical evolution and interaction of the electrons over the                 relevant timescales, which extend into the attosecond regime. Here we use                 near-single-cycle laser pulses with well-defined electric field evolution to confine                 the double ionization of argon atoms to a single laser cycle. The measured                 two-electron momentum spectra, which substantially differ from spectra recorded in                 all previous experiments using longer pulses, allow us to trace the correlated                 emission of the two electrons on sub-femtosecond timescales. The experimental                 results, which are discussed in terms of a semiclassical model, provide strong                 constraints for the development of theories and lead us to revise common assumptions                 about the mechanism that governs double ionization.
authors.affiliation: Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany. boris.bergues@mpq.mpg.de
authors.forename: Boris
authors.initials: B
authors.lastname: Bergues
authors.forename: Matthias
authors.initials: M
authors.lastname: Kübel
authors.forename: Nora G
authors.initials: NG
authors.lastname: Johnson
authors.forename: Bettina
authors.initials: B
authors.lastname: Fischer
authors.forename: Nicolas
authors.initials: N
authors.lastname: Camus
authors.forename: Kelsie J
authors.initials: KJ
authors.lastname: Betsch
authors.forename: Oliver
authors.initials: O
authors.lastname: Herrwerth
authors.forename: Arne
authors.initials: A
authors.lastname: Senftleben
authors.forename: A Max
authors.initials: AM
authors.lastname: Sayler
authors.forename: Tim
authors.initials: T
authors.lastname: Rathje
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfeifer
authors.forename: Itzik
authors.initials: I
authors.lastname: Ben-Itzhak
authors.forename: Robert R
authors.initials: RR
authors.lastname: Jones
authors.forename: Gerhard G
authors.initials: GG
authors.lastname: Paulus
authors.forename: Ferenc
authors.initials: F
authors.lastname: Krausz
authors.forename: Robert
authors.initials: R
authors.lastname: Moshammer
authors.forename: Joachim
authors.initials: J
authors.lastname: Ullrich
authors.forename: Matthias F
authors.initials: MF
authors.lastname: Kling