Sideband-Enhanced Cold Atomic Source for Optical Clocks

We demonstrate the enhancement and optimization of a cold strontium atomic beam from a two-dimensional magneto-optical trap (2D MOT) transversely loaded from a collimated atomic beam by adding a sideband frequency to the cooling laser. The parameters of the cooling and sideband beams are scanned to achieve the maximum atomic beam flux and are compared with Monte Carlo simulations. We obtain a 2.3 times larger total atomic flux and a brightness increase of a factor 4 compared with a conventional, single-frequency 2D MOT for a given total power of 200 mW. We show that the sideband-enhanced 2D MOT can reach the loading-rate performances of space-demanding Zeeman-slower-based systems, while it can overcome systematic effects due to thermal-beam collisions and hot-black-body-radiation shift, making it suitable for both transportable and accurate optical lattice clocks. Finally, we numerically study possible extensions of the sideband-enhanced 2D MOT to other alkaline-earth species.