title: Entanglement of formation for an arbitrary two-mode Gaussian state.
abstract: We write the optimal pure-state decomposition of any two-mode Gaussian state and show that its entanglement of formation coincides with the Gaussian one. This enables us to develop an insightful approach of evaluating the exact entanglement of formation. Its additivity is finally proven.
authors.affiliation: Centre for Advanced Quantum Physics, University of Bucharest, P.O. Box MG-11, R-077125 Bucharest-Măgurele, Romania.
authors.forename: Paulina
authors.initials: P
authors.lastname: Marian
authors.forename: Tudor A
authors.initials: TA
authors.lastname: Marian