title: Attosecond synchronization of high-harmonic soft x-rays.
abstract: Subfemtosecond light pulses can be obtained by superposing several high harmonics of an intense laser pulse. Provided that the harmonics are emitted simultaneously, increasing their number should result in shorter pulses. However, we found that the high harmonics were not synchronized on an attosecond time scale, thus setting a lower limit to the achievable x-ray pulse duration. We showed that the synchronization could be improved considerably by controlling the underlying ultrafast electron dynamics, to provide pulses of 130 attoseconds in duration. We discuss the possibility of achieving even shorter pulses, which would allow us to track fast electron processes in matter.
authors.affiliation: Commissariat à l'Energie Atomique, DRECAM/SPAM, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Mairesse
authors.forename: A
authors.initials: A
authors.lastname: de Bohan
authors.forename: L J
authors.initials: LJ
authors.lastname: Frasinski
authors.forename: H
authors.initials: H
authors.lastname: Merdji
authors.forename: L C
authors.initials: LC
authors.lastname: Dinu
authors.forename: P
authors.initials: P
authors.lastname: Monchicourt
authors.forename: P
authors.initials: P
authors.lastname: Breger
authors.forename: M
authors.initials: M
authors.lastname: Kovacev
authors.forename: R
authors.initials: R
authors.lastname: Taïeb
authors.forename: B
authors.initials: B
authors.lastname: Carré
authors.forename: H G
authors.initials: HG
authors.lastname: Muller
authors.forename: P
authors.initials: P
authors.lastname: Agostini
authors.forename: P
authors.initials: P
authors.lastname: Salières