Description of quantum entanglement with nilpotent polynomials: extensive characterization of entanglement and canonical forms

Abstract

We propose a general method for introducing extensive characteristics of quantum entanglement. The method relies on polynomials of nilpotent raising operators, that create entangled states acting on a reference vacuum state. By introducing the notion of tanglemeter (the logarithm of the state vector represented in a special canonical form and expressed via polynomials of nilpotent variables), we show how this description provides a simple criterion for entanglement as well as a universal method for constructing the invariants characterizing entanglement.