PT quantum mechanics

-symmetric quantum mechanics (PTQM) has become a hot area of research and investigation. Since its beginnings in 1998, there have been over 1000 published papers and more than 15 international conferences entirely devoted to this research topic. Originally, PTQM was studied at a highly mathematical level and the techniques of complex variables, asymptotics, differential equations and perturbation theory were used to understand the subtleties associated with the analytic continuation of eigenvalue problems. However, as experiments on -symmetric physical systems have been performed, a simple and beautiful physical picture has emerged, and a -symmetric system can be understood as one that has a balanced loss and gain. Furthermore, the phase transition can now be understood intuitively without resorting to sophisticated mathe- matics. Research on PTQM is following two different paths: at a fundamental level, physicists are attempting to understand the underlying mathematical structure of these theories with the long-range objective of applying the techniques of PTQM to understanding some of the outstanding problems in physics today, such as the nature of the Higgs particle, the properties of dark matter, the matter–antimatter asymmetry in the universe, neutrino oscillations and the cosmological constant; at an applied level, new kinds of -synthetic materials are being developed, and the phase transition is being observed in many physical contexts, such as lasers, optical wave guides, microwave cavities, superconducting wires and electronic circuits. The purpose of this Theme Issue is to acquaint the reader with the latest developments in PTQM. The articles in this volume are written in the style of mini-reviews and address diverse areas of the emerging and exciting new area of -symmetric quantum mechanics.

3-D Woven Composites Instrumented With EFPI Fiber Optic Sensors

A novel approach to continuous health monitoring of polymeric composite materials and structural elements using embedded Extrinsic Fabry-Perot Interferometers (EFPI) is proposed and validated. The proof of concept includes several consecutive steps. First, it is verified that simple optical wave guides survived a regular 3-D weaving process. Then EFPI sensor assemblies are manually incorporated into the preforms and it is verified that they are functional. Next step is resin infusion of instrumented preforms using VARTM method, followed by investigation of possible mechanical damage to sensor leads. Finally, test specimens are fabricated, and four-point bending tests are performed. The internal strain monitoring results provided by the embedded fiber optic sensors are compared to the data from surface foil gages. The developed approach validates, particularly, the possibility of continuous through-thickness strain monitoring, which is crucial for composite bonded and bolted joints, components with holes, openings, stiffeners, and other cases of high strain gradients.

Damage profile and mode observation in LiTaO3 by low-energy H+ ions

LiTaO3 samples were implanted with 50, 80, 120, and 150 keV H + ions. The damage profiles in LiTaO3 induced by H+ ions were investigated using the Rutherford backscattering/channeling technique. We used TRIM (transport of ions in matter) to simulate it. It was found that the shape of the experimental damage profile was similar to one predicted by TRIM'98, but the experimental damage ratio (NDN) was higher than the calculated damage ratio based on TRIM'98. The modes in LiTaO3 were measured by a prism-coupling method for all samples. The modes were observed only for LiTaO3 implanted with 80, 120, and 150 keV H+ ions. The present result shows that optical wave guides in LiTaO3 can be formed by lower energy H+ ions. PACS Nos.: 61.72-y, 61.82-d, 61.85+p, 78.20Ci

Glass-sandwich structure for one-step writing of optical wave guides in photopolymers

By squeezing a few drops of UV-curing optical adhesive between two glass plates, a planar wave-guide sandwich structure is formed. Strip wave guides can then be written in one step by focussing a computer-controlled UV laser beam into the liquid adhesive layer and thereby solidifying it along a narrow path. Measured optical losses at 633 nm fall in the range 0.4–1.1 dB cm−1 for 12 μm wide wave guides.