Covariance matrix criterion for separability

We review an approach to the separability problem using covariance matrices of locally measurable observables. This approach leads to a strong entanglement criterion which we call covariance matrix criterion (CMC). We consider some corollaries of the CMC that in general allow to detect many bound entangled states. In particular we give a new example which sheds some light on the connections between different entanglement criteria derived from the general CMC.