MICROWAVE AND SURFACE ELECTROMETRY WITH RYDBERG ATOMS

Abstract

Measurements of microwave electric fields in rubidium vapor cells, and of static electric fields near quartz with cold rubidium are presented. The measurements are performed using electromagnetically induced transparency (EIT) with Rydberg atoms. The theoretical basics of Rydberg atoms and EIT are discussed. An electric field perturbs the energy levels of Rydberg states, and Rydberg atom EIT is used to measure the perturbation. Experimental and theoretical results are presented, demonstrating the ability to measure the amplitude and polarization of microwave electric fields. These measurements are done using room temperature vapor cells, providing a pathway for portable atom based sensing of microwave electric fields. A second set of experiments is done with cold rubidium atoms in a magnetic trap near the (0001) surface of single crystal quartz. The experimental apparatus and lasers used in the experiments are described in detail. Electric fields due to Rb adsorbates on the surface are measured. The thermal desorption of Rb from the surface is characterized and theoretically analyzed using a Langmuir isobar. Blackbody ionization of Rydberg atoms produces electrons with low kinetic energy. The blackbody electrons bind to the surface and reduce the overall electric field. Electric fields as small as 30 mV/cm have been measured 20 µm from the surface. These results open up possibilities for using Rydberg atoms in hybrid quantum systems. Some of these possibilities are discussed.