Continuous generation of an ultracold atomic beam using crossed moving optical lattices

Using orthogonally crossed moving lattices, we demonstrate the continuous transport of ⁸⁸Sr atoms in the long-lived metastable ³P₀ and ³P₂ states to a region free from scattered laser-cooling light, while two-stage cooling on the ¹S₀--¹P₁ and ³P₂--³D₃ transitions is being conducted. The transfer efficiency between the crossed lattices was close to unity when laser cooling was applied in the crossed region. For a clock laser propagating along the lattice axis, such a lattice-trapped atomic beam enables continuous interrogation of the clock transition free from the Doppler effect arising from the thermal motion of atoms.