  There has been a great deal of debate surrounding the issue of whether it is
possible for a single photon to exhibit nonlocality. A number of schemes have
been proposed that claim to demonstrate this effect, but each has been met with
significant opposition. The objections hinge largely on the fact that these
schemes use unobservable initial states and so, it is claimed, they do not
represent experiments that could actually be performed. Here we show how it is
possible to overcome these objections by presenting an experimentally feasible
scheme that uses realistic initial states. Furthermore, all the techniques
required for photons are equally applicable to atoms. It should, therefore,
also be possible to use this scheme to verify the nonlocality of a single
massive particle.
