  We introduce a new positive linear map for a single qubit. This map is a
decay only in populations of a single-qubit density operator. It is shown that
an n-fold product of this map may be used for a detection of n-partite
inseparability of an n-qubit density operator (i.e., detection of impossibility
of representing a density operator in the form of a convex combination of
products of density operators of individual qubits). This product map is also
investigated in relation to a variant of the entanglement detection method
mentioned by Laskowski and Zukowski.
