SiPM used as fast Photon-Counting Module and for Multiphoton Detection

We demonstrate fast counting and multiphoton detection abilities of a Silicon Photo Multiplier (SiPM). In fast counting mode we are able to detect two consecutive photons separated by only 2.3 ns corresponding to 430 MHz. The counting efficiency for small optical intensities at a wavelength of 532 nm was found to be around 8.3% with a dark count rate of 50 kHz at T=-7 degrees Celsius. Using the SiPM in multiphoton detection mode, we find a good signal discrimination for different numbers of simultaneous detected photons.Comment: 11 pages, 13 figure

Distribution of time-bin qubits over 50 km of optical fiber

We report experimental distribution of time-bin entangled qubits over 50 km of optical fibers. Using actively stabilized preparation and measurement devices we demonstrate violation of the CHSH Bell inequality by more than 15 standard deviations without removing the detector noise. In addition we report a proof of principle experiment of quantum key distribution over 50 km of optical fibers using entangled photon.Comment: 4 pages, 4 figure

Long distance quantum teleportation in a quantum relay configuration

A long distance quantum teleportation experiment with a fiber-delayed Bell State Measurement (BSM) is reported. The source creating the qubits to be teleported and the source creating the necessary entangled state are connected to the beam splitter realizing the BSM by two 2 km long optical fibers. In addition, the teleported qubits are analyzed after 2,2 km of optical fiber, in another lab separated by 55 m. Time bin qubits carried by photons at 1310 nm are teleported onto photons at 1550 nm. The fidelity is of 77%, above the maximal value obtainable without entanglement. This is the first realization of an elementary quantum relay over significant distances, which will allow an increase in the range of quantum communication and quantum key distribution.Comment: 4 pages, submitte

Long-Distance Entanglement Distribution with Single-Photon Sources

We present an efficient architecture for quantum repeaters based on single-photon sources in combination with quantum memories for photons. Errors inherent to previous repeater protocols using photon-pair sources are eliminated, leading to a significant gain in efficiency. We establish the requirements on the single-photon sources and on the photon detectors.Comment: 4 pages, 1 figure, 1 tabl

Experimental Test of Relativistic Quantum State Collapse with Moving Reference Frames

An experimental test of relativistic wave-packet collapse is presented. The tested model assumes that the collapse takes place in the reference frame determined by the massive measuring detectors. Entangled photons are measured at 10 km distance within a time interval of less than 5 ps. The two apparatuses are in relative motion so that both detectors, each in its own inertial reference frame, are first to perform the measurement. The data always reproduces the quantum correlations and thus rule out a class of collapse models. The results also set a lower bound on the "speed of quantum information" to 0.66 x 10^7 and 1.5 x 10^4 times the speed of light in the Geneva and the background radiation reference frames, respectively. The very difficult and deep question of where the collapse takes place - if it takes place at all - is considered in a concrete experimental context.Comment: 4 pages + 2 ps figure

Long distance entanglement swapping with photons from separated sources

We report the first experimental realization of entanglement swapping over large distances in optical fibers. Two photons separated by more than two km of optical fibers are entangled, although they never directly interacted. We use two pairs of time-bin entangled qubits created in spatially separated sources and carried by photons at telecommunication wavelengths. A partial Bell state measurement is performed with one photon from each pair which projects the two remaining photons, formerly independent onto an entangled state. A visibility high enough to violate a Bell inequality is reported, after both photons have each travelled through 1.1 km of optical fiber.Comment: 4 pages, 3 figures, submitte

Swiss ethnoveterinary knowledge on medicinal plants - a within-country comparison of Italian speaking regions with north-western German speaking regions

BACKGROUND: Ethnoveterinary knowledge in Europe may play an important role as a basis for sustainable treatment options for livestock. Aims of our study were (a) to compare the ethnoveterinary practices of two culturally and sociodemographically different regions of Switzerland, (b) to compare results with earlier ethnoveterinary studies conducted in Switzerland and in adjacent Italian regions and, (c) to evaluate possible reasons for regional differences in European ethnoveterinary medicine. METHODS: 25 interviews were conducted in 2014 in all Italian speaking regions (ItR) of Switzerland, and 31 interviews were held in five north-western German speaking Cantons (GeC). Semi-structured questionnaires were used to collect detailed information regarding plant species, mode of preparation, dosage, route of administration, category of use, origin of knowledge, frequency of use, and satisfaction with outcomes of the treatments. RESULTS: A total of 162 homemade remedies in ItR and 219 in GeC were reported, out of which 125 and 145, respectively, were reported to contain only one plant species (homemade single species herbal remedy report, HSHR). 44 ItR and 43 GeC plant species were reported to treat livestock, of which only a half were used in both regions. For each HSHR, we classified the treatment intention of all use reports (UR), leading to a total of 205 and 219 UR in ItR and GeC respectively. While cattle were the most often treated livestock species in both study regions, in ItR 40% of UR were administered to small ruminants. Main indications in both regions were gastrointestinal diseases and skin afflictions, but in ItR a high number of URs were reported as antiparasitics. URs were mainly handed down from the past generation, but in GeC the source of knowledge for 20% of URs were from courses. Regarding the used plant species, ItR showed a higher concordance with Swiss than Italian studies, but with some differences to all regions. A total of 22 (14 ItR; 8 GeC) plant species in this study have not been reported before in ethnoveterinary studies of Swiss and Italian alpine regions. CONCLUSIONS: ItR and GeC, show differences and similarities with respect to their own ethnoveterinary practices and earlier Swiss and Italian ethnoveterinary studies. Linguistic, geographical, as well as social and farm-structural conditions influence the regional ethnoveterinary knowledge. However, political borders seem to be more important than language or geographical barriers

Dispersion spreading of biphotons in optical fibres and two-photon interference

We present the first observation of two-photon polarization interference structure in the second-order Glauber's correlation function of two-photon light generated via type-II spontaneous parametric down-conversion. In order to obtain this result, two-photon light is transmitted through an optical fibre and the coincidence distribution is analyzed by means of the START-STOP method. Beyond the experimental demonstration of an interesting effect in quantum optics, these results also have considerable relevance for quantum communications.Comment: Accepted for publication in Phys.Rev.Let

Cultural Recovery and Determination of Antimicrobial Susceptibility in Helicobacter pylori by Using Commercial Transport and Isolation Media

Abstract : Background: : Antimicrobial resistance of Helicobacter pylori is the main reason for eradication failure. We have studied the feasibility of a commercial transport medium for cultural recovery and subsequent drug susceptibility testing. Patients and Methods: : From March to December 2000, 79 consecutive gastric biopsies, positive in a rapid urease test, were transferred into a commercial transport medium and sent within 24 hours from the district hospital to the microbiological laboratory for culture and susceptibility testing. A commercial agar plate and an in-house Wilkins-Chalgren agar plate were used for culture. Susceptibility data were compared with data collected from 1992 to 2003 in the University Hospital of Zurich. Results: : Cultural recovery and susceptibility testing of H. pylori was successful in 55 of 79 patients. In 17 cases cultural recovery failed because of technical problems (n = 14), long transport time (n = 1) and unknown reason (n = 2). Failure of susceptibility testing (n = 7) was mainly due to fungal overgrowth. Resistance to metronidazole and clarithromycin was found in 15 (27%) and in 12 patients (22%), respectively; resistance to amoxicillin was not observed. Five patients (9%) showed resistance both to metronidazole and to clarithromycin. Eradication therapy failed in all patients with macrolide resistance. Resistance rates were higher in females than in males; 30% vs 12% for clarithromycin and 33% vs 20% for metronidazole. Resistance to metronidazole was significantly lower in Swiss patients (15%) than in non-Swiss patients (39%). Conclusion: : Antimicrobial resistance data can reliably be obtained by sending the biopsy specimen in a commercial transport medium to a microbiological laboratory. This is especially important after eradication failure. Resistance to metronidazole and clarithromycin is highly prevalent and more common in women and non-Swiss patient