  We review the path-integral quantum Monte Carlo method and discuss its
implementation by multiworm algorithms. We analyze in details the features of
the algorithms, and focus our attention on the computation of the $N$-body
density matrix to study N-body correlations. Finally, we demonstrate the
validity of the algorithms on a system of dipolar bosons trapped in a stack of
$N$ one-dimensional layers in the case of zero and finite inter-layer hopping.
