Single particle nonlocality with completely independent reference states
  We describe a scheme to demonstrate the nonlocal properties of a single particle by showing a violation of Bell's inequality. The scheme is experimentally achievable as the only inputs are number states and mixed states, which serve as references to `keep track of the experiment'. These reference states are created completely independently of one another and correlated only after all the measurement results have been recorded. This means that any observed nonlocality must solely be due to the single particle state. All the techniques used are equally applicable to massive particles as to photons and as such this scheme could be used to show the nonlocality of atoms. 
J. J. Cooper and J. A. Dunningham