Operational measure of entanglement for pure states of bipartite systems

Abstract

We show that the complete information about the amount of entanglement carried by a bipartite pure state of any dimension (qubits, qutrits, etc), is determined by a local quantity that can be measured for either party of the system. This quantity is expressed in terms of averages of certain basic observables. In particular case of two entangled photon beams, this corresponds to the measurement of three Stokes parameters for either beam.