Measuring the Quantum Entanglement by Informational Operation

Comparing the entanglement in two different quantum states is an important question. In general, quantum states are represented by a density matrix. They are big matrices, so such a description, despite being complete, can be unwieldly. Thus, we compute, from the density matrices, a single number measure. Such measure should faithfully reflect the property while being easy to compute, and for mixed-many body states is still elusive. We introduce a novel measure for this purpose, which bears meaning from quantum informational operation, that is not reflected in previous methods.