Compact structures for single-beam magneto-optical trapping of ytterbium

Abstract

The ongoing improvement of measurement resolution and measurement capabilities in metrology, including frequency metrology, inertial sensing, and gravimetry, enables applications that require field deployable systems operating reliably outside of a well-controlled environment of a laboratory. Transportable systems demand a miniaturization of key components, including magneto-optical traps (MOTs). Such a miniaturization can be achieved by substituting the standard six-beam MOT configuration with in-vacuum optics that reflect or diffract a single incident beam into multiple beams that provide trapping and cooling forces along all spatial directions. Here, we report a direct comparison between a quasi-monolithic pyramid-shaped reflector and an achromatic Fresnel reflector that are suitable to generate a MOT with a single-beam input. Both reflectors rely on aluminum mirror surfaces to generate secondary beams for three-dimensional trapping and cooling. The use of reflective elements provides achromaticity, preventing a beam overlapping mismatch that arises in diffractive grating structures. We investigate the properties of the corresponding MOT platform by trapping and cooling various isotopes of neutral ytterbium. The comparison encompasses the structures' performance in loading atoms into a first MOT stage operating on the 1S0-1P1 transition. Furthermore, we investigate the transfer efficiency of bosonic 174Yb and fermionic 171Yb into the second MOT stage operating on the narrow 1S0-3P1 transition. The demonstrated trapping and cooling geometries are compact and robust, and provide a reliable atom source for future compact and spaceborne optical lattice clocks.