Olivier Giraud 1, Petr Braun 2, 3, Daniel Braun 4
Physical Review A 85 (2012) 032101
We give an explicit parametrization of the set of mixed quantum states and of the set of mixed classical states for a spin–1. Classical states are defined as states with a positive Glauber-Sudarshan P-function. They are at the same time the separable symmetric states of two qubits. We explore the geometry of this set, and show that its boundary consists of a two-parameter family of ellipsoids. The boundary does not contain any facets, but includes straight-lines corresponding to mixtures of pure classical states.
- 1. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
CNRS : UMR8626 – Université Paris XI – Paris Sud - 2. Institute of Physics, Saint-Petersburg University,
Saint-Petersburg University - 3. Fachbereich Physik, Universitaet Duisburg-Essen,
Universitaet Duisburg-Essen - 4. Laboratoire de Physique Théorique – IRSAMC (LPT),
CNRS : UMR5152 – Université Paul Sabatier – Toulouse III