Generation of polarization entanglement from spatially-correlated photons in spontaneous parametric down-conversion

We propose a novel scheme to generate polarization entanglement from spatially-correlated photon pairs. We experimentally realized a scheme by means of a spatial correlation effect in a spontaneous parametric down-conversion and a modified Michelson interferometer. The scheme we propose in this paper can be interpreted as a conversion process from spatial correlation to polarization entanglement.Comment: 4 pages, 4 figure

A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment

KamLAND is a reactor neutrino oscillation experiment with a very long baseline. This experiment successfully measured oscillation phenomena of reactor antineutrinos coming mainly from 53 reactors in Japan. In order to extract the results, it is necessary to accurately calculate time-dependent antineutrino spectra from all the reactors. A simple model of reactor cores and code implementing it were developed for this purpose. This paper describes the model of the reactor cores used in the KamLAND reactor analysis.Comment: 14 pages, 7 figures, submitted to Nuclear Instruments and Methods in Physics Research

Quantum key distribution over 30km of standard fiber using energy-time entangled photon pairs: a comparison of two chromatic dispersion reduction methods

We present a full implementation of a quantum key distribution system using energy-time entangled photon pairs and functioning with a 30km standard telecom fiber quantum channel. Two bases of two orthogonal states are implemented and the setup is quite robust to environmental constraints such as temperature variation. Two different ways to manage chromatic dispersion in the quantum channel are discussed.Comment: 10 pages, 4 figure

Tension-tension testing of a novel mooring rope construction

This is the author accepted manuscript.Synthetic fibre ropes are in widespread use in maritime applications ranging from lifting to temporary and permanent mooring systems for vessels, offshore equipment and platforms. The selection of synthetic ropes over conventional steel components is motivated by several key advantages including selectable axial stiffness, energy absorption (and hence load mitigation), fatigue resistance and low unit cost. The long-term use of ropes as safety critical components in potentially high dynamic loading environments necessitates that new designs are verified using stringent qualification procedures. The International Organization for Standardization (ISO) is one certification body that has produced several guidelines for the testing of synthetic ropes encompassing quasi-static and dynamic loading as well as fatigue cycling. This paper presents the results of tension-tension tests carried out to ISO 2307:2010, ISO 18692:2007(E) and ISO/TS 19336:2015(E) on three different 12-strand rope constructions manufactured by Ashimori Industry Co. Ltd from polyester and Vectran® fibres. The purpose of the tests was to characterise the performance of a novel 12-strand construction and compare this to a conventional 12-strand construction. Utilising the Dynamic Marine Component test facility (DMaC) at the University of Exeter several key performance metrics were determined including; elongation, minimum break load (MBL) and quasi-static and dynamic stiffness. During the ISO 2307:2010(E) test programme the samples were tested dry and during the ISO 18692:2007(E) and ISO/TS 19336:2015(E) test programmes the samples were fully submerged in tap water after being soaked for at least 24 hours. Two methods were used to quantify sample extension: i) an optical tracking system and ii) a draw-wire potentiometer. Axial compression fatigue and cyclic loading endurance tests were also carried out on two Vectran® samples. Further load-to-failure tests and sample analysis were also carried out by Ashimori Industry Co. Ltd. It was found that the MBL of the samples exceeded the values specified by the manufacturer (by 7.7-29.5% for the polyester samples) with failure occurring at the splices in all cases and minor abrasion noted in several locations. The measured MBL of the novel polyester Straight Strand Rope (SSR) construction was up to 16% higher than the conventional construction with increases of quasi-static and dynamic stiffness of up to 6.8%. Differences between the viscoelastic and viscoplastic behaviour of the samples were also noted. The data obtained during these tests will provide insight into the behaviour of these materials and different rope constructions which will be of use to rope manufacturers, mooring system designers in addition to offshore equipment and vessel operators.The authors at the University of Exeter would like to thank their colleagues at Nagasaki University and Ashimori Industry Co. Ltd for being given the opportunity to carry out the interesting work reported in this paper. Through the Peninsula Research Institute for Marine Renewable Energy (PRIMaRE) consortium, the DMaC test facility was funded from the ERDF Convergence programme and South West Regional Development Agenc

Immittance Matching for Multi-dimensional Open-system Photonic Crystals

An electromagnetic (EM) Bloch wave propagating in a photonic crystal (PC) is characterized by the immittance (impedance and admittance) of the wave. The immittance is used to investigate transmission and reflection at a surface or an interface of the PC. In particular, the general properties of immittance are useful for clarifying the wave propagation characteristics. We give a general proof that the immittance of EM Bloch waves on a plane in infinite one- and two-dimensional (2D) PCs is real when the plane is a reflection plane of the PC and the Bloch wavevector is perpendicular to the plane. We also show that the pure-real feature of immittance on a reflection plane for an infinite three-dimensional PC is good approximation based on the numerical calculations. The analytical proof indicates that the method used for immittance matching is extremely simplified since only the real part of the immittance function is needed for analysis without numerical verification. As an application of the proof, we describe a method based on immittance matching for qualitatively evaluating the reflection at the surface of a semi-infinite 2D PC, at the interface between a semi-infinite slab waveguide (WG) and a semi-infinite 2D PC line-defect WG, and at the interface between a semi-infinite channel WG and a semi-infinite 2D PC slab line-defect WG.Comment: 8 pages, 6 figure