Optical frequency standard with ultra-cold strontium atoms
N. Poli, Robert E. Drullinger, Marco G. Tarallo, Fiodor Sorrentino, M. Prevedelli
Abstract
We report on our progress toward the realization of an optical frequency standard referenced to strontium intercombination lines. While first frequency measurement of the weakly allowed 1S 0- 3P 1 transition was done with saturation spectroscopy on a thermal beam, we are preparing the experimental setup for high resolution spectroscopy on ultracold atoms of the doubly forbidden 1S 0- 3P 0 line. Our current setup allows the capture more than 10 7 atoms at 1 μK in 500 ms in two stages of magneto-optical trapping. We also demonstrated the dipole trapping of ultracold strontium isotopes for accurate spectroscopy and collisional measurements. A semiconductor laser source at 698 nm has already been locked to a pre-stabilization cavity obtaining a fast linewidth of less than 1 kHz. Second stage stabilization of the clock laser to ultra-high finesse cavity is in development. Recent measurement of elastic and inelastic cross-sections of the two most abundant 88Sr and 86Sr isotopes are also presented.