Heidelberg 2015 – wissenschaftliches Programm
A 34.3: Vortrag
Donnerstag, 26. März 2015, 15:00–15:15, P/H2
Double-EIT Cooling: A Quicker Route to the Ground State — Jannes Wübbena1, Nils Scharnhorst1, Stephan Hannig1, •Ian D. Leroux1, and Piet O. Schmidt1,2 — 1QUEST Institute for Experimental Quantum Metrology, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig — 2Leibniz Universität Hannover, 30167 Hannover
Laser cooling using the Lorentzian scattering resonances of (effective) two-level atoms suffers from a fundamental conflict between low equilibrium temperatures, which require narrow cooling resonances, and fast cooling, which requires frequent scattering to remove entropy from the atom’s motion and broad resonances to address multiple motional modes at once. In multi-level atoms, coherences between levels can be used to design non-Lorentzian scattering spectra that selectively suppress heating processes. This allows laser cooling with a speed and bandwidth typical of Doppler cooling to equilibrium temperatures normally only reached through slow sideband cooling on narrow transitions. We demonstrate that so-called double-EIT cooling, based on a tripod level scheme, can be used to cool a 40Ca+ ion to the motional ground state several times faster than optimised sideband cooling. Such fast cooling has important applications in state-of-the-art optical frequency standards, which we briefly discuss.