title: Tomography of a high-purity narrowband photon from a transient atomic collective excitation.
abstract: We demonstrate efficient heralded generation of high purity narrow-bandwidth single photons from a transient collective spin excitation in a hot atomic vapor cell. Employing optical homodyne tomography, we fully reconstruct the density matrix of the generated photon and observe a Wigner function reaching the zero value without correcting for any inefficiencies. The narrow bandwidth of the photon produced is accompanied by a high generation rate yielding a high spectral brightness. The source is, therefore, compatible with atomic-based quantum memories as well as other applications in light-atom interfacing. This Letter paves the way to preparing and measuring arbitrary superposition states of collective atomic excitations.
authors.affiliation: Institute for Quantum Information Science, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: A
authors.initials: A
authors.lastname: MacRae
authors.forename: T
authors.initials: T
authors.lastname: Brannan
authors.forename: R
authors.initials: R
authors.lastname: Achal
authors.forename: A I
authors.initials: AI
authors.lastname: Lvovsky