  We give separability criteria for general multi-qubit states in terms of
diagonal and anti-diagonal entries. We define two numbers which are obtained
from diagonal and anti-diagonal entries, respectively, and compare them to get
criteria. They give rise to characterizations of separability when all the
entries are zero except for diagonal and anti-diagonal, like
Greenberger-Horne-Zeilinger diagonal states. The criteria is strong enough to
get nonzero volume of entanglement with positive partial transposes.
