Abstract

Alkali-earth atoms have an electronic level structure particularly suited for applications in matter-wave interferometry and high-precision laser spectroscopy. Recently atomic strontium was the subject of active research in several fields such as all-optical cooling towards quantum degeneracy¹ and detection of ultra-narrow optical transitions². Because of its small elastic cross-section³, we show that ultra-cold ⁸⁸Sr in presence of a lattice potential is also particularly well suited for the realization of inertial sensors to accurately measure forces with micro-metric spatial resolution. By loading the sample into a vertical lattice potential we observe persistent Bloch oscillations with a damping time longer than 10 seconds⁴, and from the measured Bloch frequency we determine the local gravity with a sensitivity of 5 × 10⁻⁶g. Our result has direct implications in force measurements at small distances from surfaces such as tests of possible deviations form the Newtonian gravity potential at sub-millimetre distances. We will present the status of a force measurement at distances below 20 μm from dielectric and metallic surfaces, which based on ultra-cold atoms undergoing Bloch oscillations.

© 2007 IEEE