title: Detecting quantum states with a positive Wigner function beyond mixtures of Gaussian states.
abstract: We propose a criterion giving a sufficient condition for quantum states of a harmonic oscillator not to be expressible as a convex mixture of Gaussian states. This nontrivial property is inherent to, e.g., a single-photon state and the criterion thus allows one to reveal a signature of the state even in quantum states with a positive Wigner function. The criterion relies on directly measurable photon number probabilities and enables detection of this manifestation of a single-photon state in quantum states produced by solid-state single-photon sources in a weak coupling regime.
authors.affiliation: Department of Optics, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic.
authors.forename: Radim
authors.initials: R
authors.lastname: Filip
authors.forename: Ladislav
authors.initials: L
authors.lastname: Mišta