Atoms interfere one at a time

Physicists in the US say they are the first to directly observe single-atom interference over distances much greater than the atom's coherence length. The experiment involves using optical tweezers and a sequence of laser pulses to "bounce" the atom along two different paths that meet up after about 1 ms. The team says that if the precision of the experiment can be improved, it could provide new information about the possible existence of non-Newtonian gravity at micron distances. The researchers say the technique could also be used to study the tiny force that arises between an atom and a conducting surface, dubbed the "Casimir–Polder effect".