  We consider the question of whether it is possible to use the entanglement
between spatially separated modes of massive particles to observe nonlocal
quantum correlations. Mode entanglement can be obtained using a single
particle, indicating that it requires careful consideration before concluding
whether experimental observation, e.g. violation of Bell inequalities, is
possible or not. In the simplest setups analogous to optics experiments, that
observation is prohibited by fundamental conservation laws. However, we show
that using auxiliary particles, mode entanglement can be converted into forms
that allow the observation of quantum non-locality. The probability of
successful conversion depends on the nature and number of auxiliary particles
used. In particular, we find that an auxiliary Bose-Einstein condensate allows
the conversion arbitrarily many times with a small error that depends only on
the initial state of the condensate.
