The presence of unique quantum correlations is the core of quantum
information processing and general quantum theory. We address the fundamental
question of how quantum correlations of a generic quantum system can be probed
using correlation functions defined for quasiprobability distributions. In
particular we discuss the possibility of probing the negativity of a
quasiprobability by comparing moments of the Wigner function. We show that one
must take at least the fourth moments to find the negativity in general and the
eighth moments for states with a rotationally invariant Wigner function.Comment: 5 pages, published versio
