Attosecond double-slit experiment
  A new scheme for a double-slit experiment in the time domain is presented. Phase-stabilized few-cycle laser pulses open one to two windows (``slits'') of attosecond duration for photoionization. Fringes in the angle-resolved energy spectrum of varying visibility depending on the degree of which-way information are observed. A situation in which one and the same electron encounters a single and a double slit at the same time is discussed. The investigation of the fringes makes possible interferometry on the attosecond time scale. The number of visible fringes, for example, indicates that the slits are extended over about 500as. 
F. Lindner, M. G. Schaetzel, H. Walther, A. Baltuska, E. Goulielmakis,   F. Krausz, D. B. Milosevic, D. Bauer, W. Becker, an...