Phases of quantum states in completely positive non-unitary evolution
J. G. Peixoto de Faria, A. F. R. de Toledo Piza, M. Carolina Nemes · Europhysics Letters (EPL) · 2003
We define an operational notion of phases in interferometry for a quantum system undergoing a completely positive non-unitary evolution. This definition is based on the concepts of quantum measurement theory. The suitable generalization of the Pancharatnan connection allows us to determine the dynamical and geometrical parts of the total phase between two states linked by a completely positive map. These results reduce to the known expressions of the total, dynamical and geometrical phases for pure and mixed states evolving unitarily.