Membrane MOT: Trapping Dense Cold Atoms in a Sub-Millimeter Diameter Hole of a Microfabricated Membrane Device

We present a demonstration of keeping a cold-atom ensemble within a sub-millimeter diameter hole in a transparent membrane.Based on the effective beam diameter of the magneto-optical trap (MOT) given by the hole diameter (d = 400 μm), we measurean atom number that is 105 times higher than the predicted value using the conventional d6 scaling rule. Atoms trapped bythe membrane MOT are cooled down to 10 μK with sub-Doppler cooling. Such a device can be potentially coupled to thephotonic/electronic integrated circuits that can be fabricated in the membrane device representing a step toward the atom trapintegrated platform.