Hamburg 2009 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 15: Poster I

A 15.11: Poster

Dienstag, 3. März 2009, 16:30–19:00, VMP 9 Poster

Towards an optical lattice clock with ⁸⁸Sr — •Thomas Middelmann, Joseph Sundar Raaj Vellore Winfred, Christian Lisdat, Thomas Legero, Fritz Riehle, and Uwe Sterr — Physikalisch-Technische Bundesanstalt and Centre for Quantum Engineering and Space-Time Research QUEST, Bundesallee 100, 38116 Braunschweig, Germany

Optical clocks achieve a higher stability and lower systematic uncertainty than the current microwave clocks using a hyperfine transition of ¹³³Cs, that defines the SI second. Thus optical clocks might be used to redefine the SI second. A very promising candidate is strontium. The doubly forbidden ¹S₀−³P₀ clock transition is weakly allowed in ⁸⁷Sr (linewidth ≈ 1.2 mHz) and can be induced by a magnetic field in ⁸⁸Sr. We trap ⁸⁸Sr atoms in a horizontal 1-D optical lattice, where the atoms are confined in the Lamb-Dicke regime to suppress motional effects. At present the highest contributions to the uncertainty of strontium lattice clocks are frequency shifts due to the environmental black body radiation and especially for bosonic ⁸⁸Sr collisional shifts. We have measured the influence of collisions on the clock transition and discuss implications for the operation of a clock. To precisely evaluate the black body shift, atoms will be transferred to a cryogenic environment. First tests of the mechanical setup will be presented.