Quantum teleportation over the Swisscom telecommunication network

We present a quantum teleportation experiment in the quantum relay configuration using the installed telecommunication network of Swisscom. In this experiment, the Bell state measurement occurs well after the entanglement has been distributed, at a point where the photon upon which data is teleported is already far away, and the entangled qubits are photons created from a different crystal and laser pulse than the teleported qubit. A raw fidelity of 0.93+/-0.04 has been achieved using a heralded single-photon source.Comment: 6 pages, 7 figures, updated references on May 3rd. To be published in Journal of the Optical Society of America B, Feature issue "Optical Quantum-Information Science", February 200

Quantum master equations for the superconductor--dot entangler

The operation of a source of entangled electron spins, based on a superconductor and two quantum dots in parallel\cite{loss}, is described in detail with the help of quantum master equations. These are derived including the main parasitic processes in a fully consistent and non-perturbative way, starting from a microscopic Hamiltonian. The average current is calculated, including the contribution of entangled and non-entangled pairs. The constraints on the operation of the device are illustrated by a calculation of the various charge state probabilities.Comment: 33 pages, 9 figure

On quantum teleportation with beam-splitter-generated entanglement

Following the lead of Cochrane, Milburn, and Munro [Phys. Rev. A {\bf 62}, 062307 (2000)], we investigate theoretically quantum teleportation by means of the number-sum and phase-difference variables. We study Fock-state entanglement generated by a beam splitter and show that two-mode Fock-state inputs can be entangled by a beam splitter into close approximations of maximally entangled eigenstates of the phase difference and the photon-number sum (Einstein-Podolsky-Rosen -- EPR -- states). Such states could be experimentally feasible with on-demand single-photon sources. We show that the teleportation fidelity can reach near unity when such ``quasi-EPR'' states are used as the quantum channel.Comment: 7 pages (two-column), 7 figures, submitted to Phys. Rev. A. Text unmodified, postscript error correcte

Stable nondegenerate optical parametric oscillation at degenerate frequencies in Na:KTP

We report the realization of a light source specifically designed for the generation of bright continuous-variable entangled beams and for Heisenberg-limited inteferometry. The source is a nondegenerate, single-mode, continuous-wave optical parametric oscillator in Na:KTP, operated at frequency degeneracy and just above threshold, which is also of interest for the study of critical fluctuations at the transition point. The residual frequency-difference jitter is $\pm$ 150 kHz for a 3 MHz cold cavity half-width at half maximum. We observe 4 dB of photon-number-difference squeezing at 200 kHz. The Na:KTP crystal is noncritically phase-matched for a 532 nm pump and polarization crosstalk is therefore practically nonexistent

Measures to Reduce the N2O Formation at Perovskite-Based Lean NOx Trap Catalysts under Lean Conditions

The net oxidising atmosphere of lean burn engines requires a special after-treatment catalyst for NOx removal from the exhaust gas. Lean NOx traps (LNT) are such kind of catalysts. To increase the efficiency of LNTs at low temperatures platinised perovskite-based infiltration composites La0.5Sr0.5Fe1-xMxO3-δ/Al2O3 with M = Nb, Ti, Zr have been developed. In general, platinum based LNT catalysts show an undesired, hazardous formation of N2O in the lean operation mode due to a competing C3H6-selective catalytic reduction (SCR) at the platinum sites. To reduce N2O emissions an additional Rh-coating, obtained by incipient wetness impregnation, besides the Pt coating and a two-layered oxidation catalyst (2 wt.% Pd/20 wt.% CeO2/alumina)-LNT constitution, has been investigated. Though the combined Rh-Pt coating shows a slightly increased NOx storage capacity (NSC) at temperatures above 300 °C, it does not decrease N2O formation. The layered oxidation catalyst-LNT system shows a decrease in N2O formation of up to 60% at 200 °C, increasing the maximum NSC up to 176 µmol/g. Furthermore, the NSC temperature range is broadened compared to that of the pure LNT catalyst, now covering a range of 250–300 °C

Posterior circumflex humeral artery pathology and digital ischemia in elite volleyball: Symptoms, risk factors & suggestions for clinical management

Objectives: To assess the association between posterior circumflex humeral artery (PCHA) pathology (PCHAP), symptoms and associated risk factors, in elite volleyball players, and to suggest profiles for clinical management and monitoring. Design: Cross-sectional study. Methods: A questionnaire assessed symptoms of digital ischemia (DI) in the dominant hand and risk factors among 278 elite indoor and beach volleyball players of whom 6.1% (17/278) was diagnosed with PCHAP using ultrasound. Odds Ratios (OR) including 95% confidence intervals (95%CI) were calculated using binary logistic regression. Results: All 278 players completed the questionnaire. Three participants with PCHAP were symptomatic (18%). Ninety-three of 96 symptomatic participants had no PCHAP (OR = 0.39; 95% CI 0.13–1.13). Total years playing volleyball (OR 1.14; 95% CI 1.03–1.25) and age (OR 1.17; 95% CI 1.00–1.29) were dose-response related risk factors: a volleyball career of ≥17 years and age of ≥27 years were associated with a 9-fold and 14-fold increased risk of PCHAP, respectively. Conclusions: The volleyball career duration and age are dose-response related risk factors for PCHAP among elite indoor and beach volleyball players. DI symptoms are prevalent in a minority of athletes with PCHAP (3/17; 18%). To enable worldwide standardized care for these athletes at risk, four profiles for clinical management and monitoring have been suggested based on questionnaire and ultrasound outcomes

Structural and functional properties of SrTi1−x_{1−x}Fex_{x}O3−δ_{3−δ} (0⩽x⩽1) for the use as oxygen transport membrane

Perovskitic oxides are widely investigated as oxygen transport membrane materials for the efficient generation of pure oxygen or the use in membrane reactors. However, most of high performance perovskites suffer from low stability in operation conditions. Therefore, solid solutions of SrTi1−xFexO3−δ (STF) are investigated due to the initial high stability of the strontium titanate host lattice. Self-synthesized powders with substitution of Ti by 0%, 25%, 35%, 50%, 75%, and 100% Fe were studied. Crystal structure, functional properties i.e., diffusion coefficient, surface exchange rates, and oxygen permeation rates as well as membrane fabrication and operation related material properties i.e. sintering behaviour and thermal/chemical expansion were investigated. Substitution of Ti by Fe increases oxygen mobility and, hence, oxygen permeation rates, but reduces stability in operation relevant atmospheres such as Ar/4%H2 or CO2. At the same time thermal/chemical expansion increases. This makes the fabrication of supported thin membranes and their integration into membrane modules more challenging. It turned out that 25–35% Fe substituting Ti seems to be a good compromise between structural and functional properties. Oxygen permeation rates achieved are comparable to that of standard materials such as La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF). At the same time stability is higher and thermal expansion coefficients lower compared to LSCF, which makes STF with limited Fe-content (max. 35%) a promising oxygen transport membrane material

Lanthanide element variation in rare earth doped ceria – FeCo2O4 dual phase oxygen transport membranes

The increased interest in dual-phase membrane materials for oxygen separation leads to the continuous optimization of their composition. Rare-earth doped ceria is a promising candidate as the ion-conducting phase in the membrane. Spinel-structured FeCo2O4 was investigated as an electronic conducting phase forming an additional electronic conducting perovskite-structured phase during sintering when combined with Ce1−xLnxO2−δ. The influence of rare-earth lanthanide elements, i.e., Gd and Sm, as well as their concentration, i.e. x = 0.1 and 0.2, on the final phase composition and microstructure as well as its related functional properties in particular oxygen permeation is analyzed. 20 mol.% doping of either Gd or Sm reveals a multi-phase microstructure after sintering. Moreover, segregation of Gd/Sm, iron, and cobalt is found at the ceria-ceria grain boundaries in Ce0.8Sm0.2O2−δ- and Ce0.9Gd0.1O2−δ-based composites. In contrast, 10 mol.% Gd–doping leads to a dual-phase membrane material without the formation of any other phase. In all cases, the percolation threshold is reached at approx. 20 vol% of the electron-conducting phase in the system leading to similar maximum permeation rates determined by the ionic conductivity of the ceria phase

Diagnostic properties of the SPIQuestionnaire to detect Posterior Circumflex Humeral Artery Disease in elite volleyball players: a cross-sectional study

Objectives: Sports related aneurysmal degeneration and thrombosis of the Posterior Circumflex Humeral Artery (PCHA) has been known to cause symptoms of digital ischemia (DI) in elite volleyball players. Studies have reported symptoms of DI in as much as 28% of the elite indoor volleyball players. The purpose of this study was to determine the diagnostic value of the Shoulder PCHA Pathology and digital Ischemia-Questionnaire (SPI-Q) for detection of sports related PCHA disease using ultrasound data as the standard of reference. Methods: The SPI-Q was completed by elite indoor volleyball players from the highest and single highest Dutch volleyball division and by elite beach volleyball players participating in the 2014 Grand Slam Beach Tournament The Hague (GSBTH). Ultrasound assessment of the dominant shoulder was performed on-site using the SPI-US protocol. The SPI-Q sensitivity, specificity, positive-and negative predictive value and positive-and negative likelihood ratios, and the diagnostic odds ratio were calculated for detection of sports related PCHA disease, using ultrasound as the standard of reference. Results: Two hundred twenty-four elite male indoor volleyball players from the Dutch division were included in this study and 62 elite male and female beach volleyball players participating in the GSBTH: a total of 278 players. Thirty-five percent of the players reported symptoms of DI. The prevalence of PCHA disease was 6.1%. For the SPI-Q we found a sensitivity of 18% (95% CI 4-43), specificity of 64% (95% CI 58-70), positive predictive value of 3% (95% CI 0.7-8.9) and negative predictive value of 92% (95% CI 87-96), positive likelihood ratio of 0.50 (95% CI 0.18-1.40), negative likelihood ratio of 1.28 (95% CI 1.01-1.62) and a diagnostic odds ratio of 0.39 (95% CI 0.11-1.38). Conclusion: The diagnostic value of the SPI-Q to detect PCHA disease in elite volleyball players is poor, which makes it unsuitable as a diagnostic instrument for sports related PCHA disease specifically. However, it can be used to assess all-cause symptoms of DI and raise awareness within athletes and sports physicians, which is important for preventing ischemic complication