Optical Frequency Standard with Ultra-cold Strontium Atoms for Earth and Space Applications

Quessada, Courtillot, Kovacich +6 more

Lucas Béguin, Mathieu Bertrand, Torben Pöpplau +1 more

Audrey Quessada, Philip A. Tuckey

Andrew D. Ludlow, T. Ido, Martin M. Boyd +5 more

As a key component of a strontium based optical clock, we have developed an apparatus which allows laser cooling and trapping of more than 10/sup 7/ /sup 88/Sr atoms to temperatures below 1 /spl mu/K. Using this system, we have performed the first high accuracy measurement of the /sup 88/Sr /sup 1/S/sub 0/-/sup 3/P/sub 1/ clock transition using an ultra-cold sample. Detailed descriptions of both the measurement technique and corresponding systematic uncertainties is provided. In addition, by varying the density of the ultra-cold /sup 88/Sr sample over a range of three orders of magnitude we obtain the first definitive measurement of a density-related frequency shift and linewidth broadening of an optical clock transition in an ultra-cold alkaline earth system. Spectroscopy of the /sub 1/S/sub 0/-/sup 3/P/sub 0/ transition is currently underway using this narrow probe laser and an octave spanning femtosecond laser. Our most recent results are presented. The proposed measurement technique, accuracy, and stability of an optical clock based on the EIT (electromagnetically-induced-transparency) measurement in /sup 88/Sr are described.

G. Ferrari, Andrea Alberti, Robert E. Drullinger +5 more

Summary form only given. 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 degeneracy and detection of ultra-narrow optical transitions. Because of its small elastic cross-section, we show that ultra-cold88Sr 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 seconds, and from the measured Bloch frequency we determine the local gravity with a sensitivity of 5 x 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 mum from dielectric and metallic surfaces, which based on ultra-cold atoms undergoing Bloch oscillations. We will also report on the progress towards the realization of an optical frequency standard based on the highly forbidden1S0-3Po 88Sr intercombination line at 698 nm as well as the realization of a laser suited for precision spectroscopy on this transition.

Pottie, Binnewies, Stoehr +3 more