Cavity-Enhanced Microscope for Cold Atoms : towards Resolved-Sideband Cavity-Cooling of Neutral Atoms.

We have set up a novel type of atom microscope, consisting of ultra-cold Lithium 6 atoms in a high-finesse cavity, combined with high-numerical-aperture optics (0.37). This combined system allows to trap the atoms in a micro-tweezer at 780nm and an intra-cavity optical dipole-trap at 1342nm, inside the near-concentric cavity mode at 671nm addressing the D2 transition of Li6. A beam at 460nm addressing the 2P → 4D transition of Li6, tightly-focused through the high-NA optics, will allow to tune the atom-cavity coupling, temporally and spatially. The dependance of the atom-cavity coupling with detuning will provide a super-resolution effect to this "microscope".

The combination of our narrow linewidth cavity (451 kHz) and strongly confining dipole traps (600 kHz to 2 MHz trapping frequencies) is an ideal setup for realizing sideband-resolved cavity-cooling close to quantum-degeneracy : the atoms scatter photons from a pump beam into the cavity mode at a detuning corresponding to the trapping frequencies and release a quantum of kinetic energy in the process.

Currently, Li6 atoms can be trapped and imaged inside the intra-cavity dipole trap at 1342nm. Dispersive interaction of the atomic cloud with the cavity mode has been verified and we have the first evidence of scattering from a side pump into the cavity mode. I will summarize the important ideas and technical developments behind the design,

present the current status of our experiment and the next steps towards sideband-resolved cavity cooling.