  A single-particle entangled state can be generated by illuminating a beam
splitter with a single photon. Quantum teleportation utilizing such a
single-particle entangled state can be successfully achieved with a simple
setup consisting only of linear optical devices such as beam splitters and
phase shifters. Application of the locality assumption to a single-particle
entangled state leads to Bell's inequality, a violation of which signifies the
nonlocal nature of a single particle.
