  Quantum correlations of observables for two particle states have demonstrated
the nonlocal character of the quantum mechanics. However nonlocality can be
exhibited even for noncommuting observables of a single particle system. In
this paper we show nonlocality of position-momentum correlations of a single
particle in the double-slit experiment modeled by an initially correlated
Gaussian wavepacket. The positivity or negativity of the Wigner function for
the state of the particle at the detection screen is related with the
$\sigma_{xp}$ covariances. A Bell's inequality is constructed from the Wigner
function and it is violated for both the positive and negative cases. The case
of positive Wigner function is the analogous of the original EPR state for a
single particle.
