Description of entanglement in terms of quantum phase
Luis Lorenzo Sánchez-Soto, Julián Delgado, A. B. Klimov, Gunnar G. Bjork · Physical Review A · 2002
We explore the role played by the phase in an accurate description of the entanglement of bipartite systems. We first present an appropriate polar decomposition that leads to a truly Hermitian operator for the phase of a single qubit. We also examine the positive operator-valued measures that can describe the qubit phase properties. When dealing with two qubits, the relative phase seems to be a natural variable to understand entanglement. In this spirit, we propose a measure of entanglement based on this variable.