Partial scaling transform of multiqubit states as a criterion of separability

Abstract

The partial scaling transform of the density matrix for multiqubit states is introduced to detect entanglement of the quantum state. The transform contains partial transposition as a special case. The scaling transform corresponds to partial time scaling of a subsystem (or partial Planck constant scaling) which was recently used to formulate a separability criterion for continuous variables. A measure of entanglement which is a generalization of negativity measure is introduced being based on tomographic probability description of spin states.