Detecting rubidium atoms with a nanofiber on a chip

Abstract

This work describes several measurements made on a atom-cloud of 87Rubidium with a tapered optical fiber. The atoms are loaded in a Magneto-Optical Trap, and detected with a Fabry-Perot cavity inside an optical nanofiber. The nanometer scale waist of the fiber leads to an evanescent light field, allowing the atomic photons to coupled into the fiber. Two Bragg gratings on both sides of the waist form a cavity for the atomic photons, enhancing their signal. The fiber is located just below an Atomchip, which leads to a great control over the cloud and the possibility of a one-dimensional trap matching the geometrical properties of the fiber. In this thesis, the atoms are detected through the cavity, independently from the trap. Furthermore, methods for the confirmation of detection of a single atom at the fiber were analized. An optical dipole force was then implemented in an usual nanofiber to repel the atoms from the fiber surface, by building a barrier of potential with a blue detuned light.