Double-slit experiment done using time (instead of space)

Gerhard Paulus of Texas A&M University and co-workers in Berlin, Munich, Sarajevo and Vienna have observed an interference pattern with electrons that pass through a double slit in time, not space, as a result of being ejected from an atom at one of two possible times by a laser pulse.

Paulus and co-workers focused a train of pulses from a Ti:sapphire laser into a chamber containing a gas of argon atoms. The pulses were so short ? just 5 femtoseconds ? that each one contained just a few cycles of the electric field.

The team was able to control the output of the laser so that all the pulses were identical. The researchers could, for example, ensure that each pulse contained two maxima of the electric field (thatis, two peaks with large positive values) and one minimum (a peak with a large negative value). There was a small probability that an atom would be ionized by one or other of the maxima, which therefore played the role of the slits, with the resulting electron being accelerated towards a detector. If the atom was ionized by the minimum, the electron travelled in the opposite direction towards a second detector.

This is really awesome stuff.