Correlations and Counting Statistics of an Atom Laser

We demonstrate time-resolved counting of single atoms extracted from a weakly interacting Bose-Einstein condensate of $^{87}$Rb atoms. The atoms are detected with a high-finesse optical cavity and single atom transits are identified. An atom laser beam is formed by continuously output coupling atoms from the Bose-Einstein condensate. We investigate the full counting statistics of this beam and measure its second order correlation function $g^{(2)}(\tau)$ in a Hanbury Brown and Twiss type experiment. For the monoenergetic atom laser we observe a constant correlation function $g^{(2)}(\tau)=1.00\pm0.01$ and an atom number distribution close to a Poissonian statistics. A pseudo-thermal atomic beam shows a bunching behavior and a Bose distributed counting statistics

Time interval distributions of atoms in atomic beams

We report on the experimental investigation of two-particle correlations between neutral atoms in a Hanbury Brown and Twiss experiment. Both an atom laser beam and a pseudo-thermal atomic beam are extracted from a Bose-Einstein condensate and the atom flux is measured with a single atom counter. We determine the conditional and the unconditional detection probabilities for the atoms in the beam and find good agreement with the theoretical predictions.Comment: 4 pages, 3 figure

Infection rates of natural psyllid populations with ‘Candidatus Phytoplasma mali’ in South Tyrol (Northern Italy)

Apple proliferation is a severe disease of apple trees spreading in many European apple growing areas. It is caused by ‘Candidatus Phytoplasma mali’ that was shown to be transmitted through infected grafting material, via natural root grafts and by sap-sucking insects. Two psyllid species, Cacopsylla picta and C. melanoneura, that are recognised as the vectors of the disease, occur in orchards of South Tyrol (Northern Italy). The aim of this study was to assess the infection rates of natural populations of these insect species with ‘Ca. P. mali’. Two additional psyllid species (C. mali and Trioza urticae), which are frequent in some apple orchards of South Tyrol, were also investigated. A total of 801 specimens from 18 orchards was analysed using a real-time PCR procedure. While no specimen of T. urticae was found to be infected with ‘Ca. P. mali’, the mean infection rate of C. melanoneura and C. mali was below 1 %. The highest infection rate was found for C. picta, with a mean value of 11 % and peaking at 33%. Based on these results, it can be concluded that C. picta plays the major role as the vector of apple proliferation in South Tyrol. Keywords: apple proliferation, Cacopsylla mali, Cacopsylla melanoneura, Cacopsylla picta, pathogen transmission, Trioza urtica

Das Medien-, Informations- und Innovationsverhalten von blinden und sehbehinderten Menschen im Zeitalter des Web 2.0

Viele Menschen in Österreich sind sehbehindert oder blind und im Vergleich zu normal Se- henden sehr eingeschränkt und benachteiligt, was ihre Nachrichten- und Informationsauf- nahme und in weiterer Folge die Teilnahme am gesellschaftlichen Leben und öffentlichen Diskurs betrifft. Betroffene werden nämlich nicht ständig über den visuellen Weg informiert und auf dem Laufenden gehalten, wie es bei der sehenden Bevölkerung Gang und Gäbe ist. Nein, das ist im Falle einer Blindheit oder Sehbehinderung weit komplizierter. Seit sich die Computertechnik und die entsprechenden Hilfsmittel und später das Internet entwickelt ha- ben, hat sich auch für Betroffene Einiges geändert. Nun stehen auch blinden und sehbehin- derten Menschen die „Welt der Technik“ und die „Weiten des Internets“ offen. Auch andere technische Entwicklungen und Neuerungen schreiten immer weiter voran, was in Form von immer neueren, fortschrittlicheren und tauglicheren Innovationen und technischen Helfern für Blinde und Sehbehinderte zum Ausdruck kommt. Was sich im Detail durch diese Entwick- lungen verändert und verbessert hat, soll mit vorliegender Arbeit herausgefunden werden. Auf welche Art und Weise und über welche Medien beziehen Blinde und Sehbehinderte nun ihre Informationen und Nachrichten? Haben sich durch den technischen Fortschritt auch mehr Chancen im beruflichen Bereich eröffnet? Und wie werden betroffene Personen über- haupt von den neuesten Innovationen in Kenntnis gesetzt? Die empirischen Daten werden für vorliegende Arbeit mittels problemzentrierten Interviews erhoben. Die Auswertung erfolgt mit der qualitativen Inhaltsanalyse nach Mayring. Theore- tisch stützt sich diese Arbeit auf die „Innovations- und Diffusionsforschung“ und das Theorie- konstrukt der Konkurrenz zwischen alten und neuen Medien mit „Komplementaritäts- bzw. Substitutionshypothese“

Hybrid apparatus for Bose-Einstein condensation and cavity quantum electrodynamics: Single atom detection in quantum degenerate gases

We present and characterize an experimental system in which we achieve the integration of an ultrahigh finesse optical cavity with a Bose-Einstein condensate (BEC). The conceptually novel design of the apparatus for the production of BECs features nested vacuum chambers and an in-vacuo magnetic transport configuration. It grants large scale spatial access to the BEC for samples and probes via a modular and exchangeable "science platform". We are able to produce \87Rb condensates of five million atoms and to output couple continuous atom lasers. The cavity is mounted on the science platform on top of a vibration isolation system. The optical cavity works in the strong coupling regime of cavity quantum electrodynamics and serves as a quantum optical detector for single atoms. This system enables us to study atom optics on a single particle level and to further develop the field of quantum atom optics. We describe the technological modules and the operation of the combined BEC cavity apparatus. Its performance is characterized by single atom detection measurements for thermal and quantum degenerate atomic beams. The atom laser provides a fast and controllable supply of atoms coupling with the cavity mode and allows for an efficient study of atom field interactions in the strong coupling regime. Moreover, the high detection efficiency for quantum degenerate atoms distinguishes the cavity as a sensitive and weakly invasive probe for cold atomic clouds

Spontal-N: A Corpus of Interactional Spoken Norwegian

Spontal-N is a corpus of spontaneous, interactional Norwegian. To our knowledge, it is the first corpus of Norwegian in which the majority of speakers have spent significant parts of their lives in Sweden, and in which the recorded speech displays varying degrees of interference from Swedish. The corpus consists of studio quality audio- and video-recordings of four 30-minute free conversations between acquaintances, and a manual orthographic transcription of the entire material. On basis of the orthographic transcriptions, we automatically annotated approximately 50 percent of the material on the phoneme level, by means of a forced alignment between the acoustic signal and pronunciations listed in a dictionary. Approximately seven percent of the automatic transcription was manually corrected. Taking the manual correction as a gold standard, we evaluated several sources of pronunciation variants for the automatic transcription. Spontal-N is intended as a general purpose speech resource that is also suitable for investigating phonetic detail

Observing the Formation of Long-range Order during Bose-Einstein Condensation

We have experimentally investigated the formation of off-diagonal long-range order in a gas of ultracold atoms. A magnetically trapped atomic cloud prepared in a highly nonequilibrium state thermalizes and thereby crosses the Bose-Einstein condensation phase transition. The evolution of phase coherence between different regions of the sample is constantly monitored and information on the spatial first-order correlation function is obtained. We observe the growth of the spatial coherence and the formation of long-range order in real time and compare it to the growth of the atomic density. Moreover, we study the evolution of the momentum distribution during the nonequilibrium formation of the condensate.Comment: 4 pages, 4 figure