Attosecond double-slit experiment

A novel application of intense few-cycle laser pulses is demonstrated. Taking advantage of the unique properties of phase-controlled few-cycle pulses, a close analogue of the double-slit scheme has been realized in the time domain. It is distinguished from conventional schemes by a combination of characteristics: {\it (i)} The double slit is realized not in position-momentum but in time-energy domain. {\it (ii)} The role of the slits is played by windows in time of attosecond duration. {\it (iii)} These ``slits'' can be opened or closed by changing the temporal evolution of the field of a few-cycle laser pulse. {\it (iv)} At any given time there is only a single electron in the double-slit arrangement leading to the presence or absence of interference depending on emission direction. The experimental scheme is of similar plainness as the one of the double slit: Few-cycle laser pulses of given absolute phase are focused into a field-free vacuum chamber and intersect a beam of Argon atoms. Photoelectrons emitted parallel to the axis of polarization are detected by two electron detectors located at a distance of about 400\,mm at either side of the focus. The time-of-flight is used to determine the energy of the electrons. The photoelectron spectra exhibit a fringe pattern whose visibility depends on the temporal evolution of the pulses as well as on the emission direction.