Ultrabright narrow-band telecom two-photon source for long-distance quantum communication

We demonstrate an ultrabright narrow-band two-photon source at the 1.5 -\mu m telecom wavelength for long-distance quantum communication. By utilizing a bow-tie cavity, we obtain a cavity enhancement factor of $4.06\times 10^4$. Our measurement of the second-order correlation function $G^{(2)} ({\tau})$ reveals that the linewidth of $2.4$ MHz has been hitherto unachieved in the 1.5 -\mu m telecom band. This two-photon source is useful for obtaining a high absorption probability close to unity by quantum memories set inside quantum repeater nodes. Furthermore, to the best of our knowledge, the observed spectral brightness of $3.94\times 10^5$ pairs/(s$\cdot$MHz$\cdot$mW) is also the highest reported over all wavelengths.Comment: 11 pages, 4 figures, 2 table

Beam and SKS spectrometers at the K1.8 beam line

High-resolution spectrometers for both incident beams and scattered particles have been constructed at the K1.8 beam line of the Hadron Experimental Facility at J-PARC. A point-to-point optics is realized between the entrance and exit of QQDQQ magnets for the beam spectrometer. Fine-pitch wire chamber trackers and hodoscope counters are installed in the beam spectrometer to accept a high rate beam up to 107 Hz. The superconducting kaon spectrometer for scattered particles was transferred from KEK with modifications to the cryogenic system and detectors. A missing-mass resolution of 1.9 ± 0.1 MeV/c2 (FWHM) was achieved for the ∑ peaks of (π±, K+) reactions on a proton target in the first physics run of E19 in 2010

Making Meaning of Appointed School-Transfer-Experiences for High-School Teachers: An Explorative Inquiry Through Self-Study

In Japan, school teachers are deployed to schools by the local government, so their work place must be changed every several years. This appointed school-transfer-experience should affect school teachers in various aspects of their work life, but a few researches have conducted. This study inquires how high-school teachers assess their own experiences. We shared our individual episodes through group interviews and analyzed the transcript qualitatively by using GTA (Saiki-craighill 2006). Then, we re-interpreted our own experiences in a form of story. Findings showed that high school teachers shared peculiar and implicit sense, i.e. the age equals to years of teaching career which shows their professional ability. We discussed the implicit sense functioned as a “screening test” for the newly appointed teacher, and this test varied according to human relationship within the school. Suggestions are provided for future teachers as well as teacher educators to make school climate collaborative: 1) newly coming teachers mind one’s words and behavior, 2) school teachers treat newly coming teachers as colleagues with caring mind, and 3) the school be equipped a mechanism to capture voiceless opinions, turning school staff ’s efforts to make their work place open to a divergent view

Synergistic effect of 18-crown-6 derivatives on chelate extraction of lanthanoids(III) into an ionic liquid with 2-thenoyltrifluoroacetone

金沢大学理工研究域物質化学系The synergistic effect of 18-crown-6 derivatives, such as 18-crown-6 (18C6), cis-dicyclohexano-18-crown-6 (DC18C6) and dibenzo-18-crown-6 (DB18C6), on the extraction of trivalent lanthanoids (Ln3+) into an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, with 2-thenoyltrifluoroacetone (Htta) was investigated. The extractability of lighter Ln3+ was enhanced by adding 18C6 or DC18C6, whereas no enhancement of the extractability was observed by adding DB18C6. Moreover, the synergistic effect by the crown ether (CE) was increased along with the decrease in the atomic number of Ln. In the synergistic extraction system, Ln3+ was extracted as cationic ternary complexes Ln(tta)2(CE)+ and Ln(tta)(CE)2+, and it was suggested that the formation of the Ln(tta)(CE)2+ complex as an extracted species results in the large synergistic effect. This synergistic effect originated in a size-fitting effect of CE on complexation to Ln3+. 2010 © The Japan Society for Analytical Chemistry