Detection of the clock transition (1.14 μm) in ultra-cold thulium atoms

Abstract

The magnetic dipole transition between fine structure sublevels of the ground state of thulium atom 4f13(2Fo)6s2 has been directly excited in a cloud of ultra-cold atoms by a frequency-stabilised laser. This transition at the wavelength λ = 1.14 μm is planned to be used as the clock one in an optical frequency reference on laser-cooled thulium atoms.