  We address some of the most commonly raised questions about entanglement,
especially with regard to so-called occupation number entanglement. To answer
unambiguously whether entanglement can exist in a one-atom delocalized state,
we propose an experiment capable of showing violations of Bell's inequality
using only this state and local operations. As a byproduct, this experiment
suggests a means of creating an entangled state of two different chemical
species. By comparison with a massless system, we argue that there should be no
fundamental objection to such a superposition and its creation may be within
reach of present technology.
