Realisierung eines kompakten Laborsystems zur Durchfuehrung atomoptischer Fallturmexperimente

Abstract

Cold and ultracold ensembles of atoms are increasingly used in different applications in science and technology. In recent years they also have been used as the source of optical atomic clocks or atom interferometers. With the latter it is possible to perform various fundamental physical measurements with very high accuracy, such as measurements of the fine structure constant or the gravitational constant. In addition, tests of fundamental theories, like general relativity, can be realized. This includes tests of the weak equivalence principle. Under weightlessness the sensitivity of a measurement of this kind can be signifcantly increased due to the longer interferometer time. This thesis presents the realization of a miniaturized laboratory system to analyze cold atomic ensembles in microgravity. The system provides, as the first of its kind, a cold 2 species mixture of rubidium and potassium atoms in the drop tower, which forms the starting point for a non classical measurement of the universality of free fall. Adding a second species implies a doubling of the complexity of the experiment compared to existing 1 species experiments in microgravity. In a system, comprising a source chamber and an experiment chamber, 87Rb and 39K atoms are cooled by magneto optical traps. A newly designed 2 species oven for use in a zero gravity environment provides the required steam pressure in the source chamber. A FE simulation confirms the experimentally measured parameters of the source. A combined and miniaturized state of the art laser system allows the preparation and detection of the atoms and also contains additional laser modules to implement the needed laser pulse beam splitter for an atom interferometer in the future. The 2 species laser system is designed in such a way that it takes place on a capsule platform with a diameter of 70 cm. It was tested in a drop tower campaign in terms of stability. In addition, the drop capsule includes an optical dipole trap with a wavelength of 1950 nm to trap atoms with this technology and cool them evaporatively in weightlessness for the first time. The light of a thulium fiber laser with an optical output power of 26 W is guided to the experiment chamber by a free beam setup and generates the dipole trap. An optical dipole trap is a promising alternative to atom chip experiments with magnetic traps. One of the advantages are better starting conditions for an atom interferometer. All in all, the realized laboratory system fulfills pathfinder characteristics and is a technology demonstrator for space projects with atom optical focus. The realization of a cold 2 species ensemble and an optical dipole trap for use in microgravity offer further possibilities for future satellite based atom interferometers.