Systematic generation of entanglement measures for pure states

Abstract

We propose a method to generate entanglement measures systematically by using the irreducible decomposition of some copies of a state under the local unitary (LU) transformations. It is applicable to general multipartite systems. We show that there are entanglement monotones corresponding to singlet representations of the LU group. They can be evaluated efficiently in an algebraic way, and experimentally measurable by local projective measurements of the copies of the state. Nonsinglet representations are also shown to be useful to classify entanglement. Our method reproduces many well-known measures in a unified way. © 2008 The American Physical Society.