title: 3/4-Efficient Bell measurement with passive linear optics and unentangled ancillae.
abstract: It is well known that an unambiguous discrimination of the four optically encoded Bell states is possible with a probability of 50% at best, when using static, passive linear optics and arbitrarily many vacuum-mode ancillae. By adding unentangled single-photon ancillae, we are able to surpass this limit and reach a success probability of at least 75%. We discuss the error robustness of the proposed scheme and a generalization to reach a success probability arbitrarily close to 100%.
authors.affiliation: Institute of Physics, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Ewert
authors.affiliation: Institute of Physics, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: van Loock