Single-photon interference over 150-km transmission using silica-based integrated-optic interferometers for quantum cryptography

We have demonstrated single-photon interference over 150 km using time-division interferometers for quantum cryptography, which were composed of two integrated-optic asymmetric Mach-Zehnder interferometers, and balanced gated-mode photon detectors. The observed fringe visibility was more than 80% after 150-km transmission.Comment: 10 pages, 2 figures, submitted to Electronics Letter

Serum free fatty acids levels not associated with normal tension glaucoma

Kenya Yuki, Itaru Kimura, Kazuo TsubotaDepartment of Ophthalmology, Keio University School of Medicine, Tokyo, JapanPurpose: To determine the free fatty acid levels in the sera of patients with normal-tension glaucoma and compare it with that of normal controls.Methods: Forty-four consecutive patients with newly diagnosed normal-tension glaucoma and forty-four age and gender matched controls were evaluated. The type and level of fatty acids in the sera were measured by gas chromatography (Model GC17A; Shimazu, Kyoto, Japan). Twenty-four fatty acids were identified from 12:0 to 24:1. The values were compared between the normal-tension glaucoma and control groups by Mann–Whitney U tests.Results: No statistically significant difference was found in the levels of any free fatty acids between the normal-tension glaucoma group and control group.Conclusion: No significant association was found in the serum free fatty acids levels including docosahexaenoic acid and eicosapentaenoic acid between normal-tension glaucoma patients and controls.Keywords: free fatty acid, docosahexaenoic acid, eicosapentaenoic acid, normal tension glaucom

Precise magnetization measurements of single crystalline Bi2Sr2CaCu2O8+δ

Precise dc-magnetization measurements, using a superconducting quantum interference device magnetometer (SQUID), have been performed on single crystalline Bi2Sr2CaCu2O8+δ in magnetic fields both parallel to the c axis (H∥c) and tilted away from the c axis towards the ab plane to investigate the vortex state at various temperatures between 40 K and Tc=83.0 K. The magnetization curves at a fixed temperature as a function of magnetic field (H∥c) show a clear jump at HM, which corresponds to the flux-line-lattice-melting transition (FLLMT) as observed previously. In the vicinity of Tc=83.0 K, it is shown that the HM(T) line changes its character near T*=79.5 K, below which it can be described well by the FLLMT and above which the change of magnetization, ΔM, and the corresponding change of the entropy, ΔS, at HM, falls sharply as Tc is approached. A simultaneous decoupling of the Josephson coupling and the melting of the flux-line lattice may be an appropriate picture below T*, whereas above T* an additional degree of freedom makes a contribution to the FLLMT due, perhaps, to vortex-antivortex creation and annihilation processes. In a tilted magnetic field, it is found that the angular dependence of HM, as well as ΔM and ΔS, obeys a scaling law up to θ<~80°. The deduced anisotropy parameter γs≃9 is found to be much lower than the value of γl≃150–200 found in the liquid state. We interpret such a discrepancy as due to the difference of the dimensionality of the vortex pancake state above and below HM. Furthermore, from the scaling behavior of ΔS in tilted fields, it is inferred that the FLLMT is predominantly ruled by the number of pancake vortices, n, in the superconducting CuO2 layers and that Josephson vortices do not play an important role for the FLLMT