Primordial Magnetic Field from Gravitationally Coupled Electrodynamics in Bouncing Scenario

We in this paper study the generation of primordial magnetic field (PMF) in the non-singular bouncing scenario, through the coupling of the electromagnetic field to gravity. We adopt an electrodynamic model with a coupling coefficient as a function of the scale factor $a$, i.e. $f=1+(a/a_\star)^{-n}$, with $a_\star$ and $n>0$ being constants. The result implies that in this mechanism, the power spectrum of PMF today is always blue tilted on large scales from $1$ Mpc to the Hubble length, and the observational constraints favor the ekpyrotic-bounce scenario. Furthermore, the back reaction of the energy density of PMF at the bouncing point yields theoretical constraints on the bouncing model

2D InP photonic crystal fabrication process development

We have developed a reliable process to fabricate high quality 2D air-hole and dielectric column InP photonic crystals with a high aspect ratio on a STS production tool using ICP N2+Cl2 plasma. The photonic crystals have a triangular lattice with lattice constant of 400 nm and air-hole and dielectric column radius of 120 nm. Large efforts have been devoted on developing a proper mask. We obtained a perfect, clean and vertical profiled SiNx mask. The next main effort is InP pattern transfer in Cl 2+N2 plasma. Etching selectivity, smooth sidewall and etch profile are directly related to plasma process condition, besides the quality of SiNx mask. We have optimized the N2+Cl2 plasma condition to obtain high aspect ratio, vertical profile and smooth sidewall InP structures. Cylindrical holes (2 micron depth) and rodlike pillars (2.4 micron height) are uniformly fabricated. An aspect ratio of 18 for 100nm trench lines has been obtained. AFM measurement evidences that etched surfaces are smooth. The root mean square roughness of pillar and hole is 0.7 nm and 0.8 nm, respectively. The optical transmission characterization of ridge waveguides has been carried out. Transmission spectrum of 1 micron wide waveguide has been obtained

Generation and control of ultrashort-wavelength two-dimensional surface acoustic waves at nanoscale interfaces

In this work, we generate and probe the shortest wavelength surface acoustic waves to date, at 45 nm, by diffracting coherent extreme ultraviolet beams from a suboptical phononic crystal. The short acoustic wavelengths correspond to penetration depths of approximately 10 nm. We also measure the acoustic dispersion in two-dimensional nanostructured phononic crystals down to this wavelength for the first time, showing that it is strongly influenced by the ultrashort acoustic penetration depth, and that advanced finite-element analysis is required to model the dispersion. Finally, we use pulse sequences to control surface acoustic wave generation in one-dimensional nanostructured gratings, to preferentially enhance higher-order surface waves, while suppressing lower frequency waves. This allows us to reduce the generated surface acoustic wavelength by a factor of two for a defined nanostructure period

Diamondoid Coating Enables Disruptive Approach for Chemical and Magnetic Imaging with 10 nm Spatial Resolution

Diamondoids are unique molecular nano-materials with diamond structure and fascinating properties such as negative electron affinity and short electron mean free paths. A thin layer of diamondoids deposited on a cathode is able to act as an electron monochromator, reducing the energy spread of photo-emitted electrons from a surface. This property can be applied effectively to improve the spatial resolution in x-ray photoemission electron microscopy (X-PEEM), which is limited by chromatic aberration of the electron optics. In this paper, we present X-PEEM measurements reaching the technological relevant spatial resolution of 10?nm without the need of expensive and complex corrective optics. Our results provide a simple approach to image surface chemical and magnetic information at nanometer scales by employing diamondoids