We simultaneously measure the gravitationally-induced phase shift in two Raman-type matter-wave interferometers operated with laser-cooled ensembles of $^{87}$Rb and $^{39}$K atoms. Our measurement yields an E\"otv\"os ratio of $\eta_{\text{Rb,K}}=(0.3\pm 5.4)\times 10^{-7}$. We briefly estimate possible bias effects and present strategies for future improvements

The refractive index of silicon oxynitride (SiON), a widely used material for integrated optics devices, can be chosen in a wide range between 1.45-2.0. We describe how the consequent large design freedom can be exploited on the one hand for a "standard" polarization independent optical channel waveguide having a favorable tradeoff between efficient fiberchip coupling and small bend radii (compact devices) and on the other hand for special-purpose and hybrid components where the refractive index should be finely adjusted for obtaining the desired functionality. We illustrate the applicability of SiON by describing a few devices for optical filtering in a new architecture for wavelength multiplexing, modulation, polarization splitting and second-harmonic generation.

Surface roughness is one of the crucial factors in silicon fusion bonding. Due to the enhanced surface roughness, it is almost impossible to bond wafers after KOH etching. This also applies when wafers are heavily doped, have a thick LPCVD silicon nitride layer on top or have a LPCVD polysilicon layer of poor quality. It has been demonstrated that these wafers bond spontaneously after a very brief chemical mechanical polishing step. An adhesion parameter, that comprises of both the mechanical and chemical properties of the surface, is introduced when discussing the influence of surface roughness on the bondability. Fusion bonding, combined with a polishing technique, will broaden the applications of bonding techniques in silicon micromachining.

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We report on an improved test of the Universality of Free Fall using a rubidium-potassium dual-species matter wave interferometer. We describe our apparatus and detail challenges and solutions relevant when operating a potassium interferometer, as well as systematic effects affecting our measurement. Our determination of the Eötvös ratio yields ηRb,K = −1.9 × 10−7 with a combined standard uncertainty of ση = 3.2 × 10−7. Graphical abstract