Magic wavelengths near 800 nm for precision spectroscopy of an inner-shell transition in thulium atoms

Abstract

Differential dynamic polarisability of the inner-shell clock transition at a wavelength of 1.14 μm in the thulium atom is measured by the method of precision laser spectroscopy in the spectral range of 800 – 860 nm. Experimental data approximated by a theoretical model yield the probability of the transition at λ = 809.5 nm: A809.5 = 460(70) s−1. The values of two magic wavelengths are obtained experimentally, namely, λm1 = 807.727(18) nm and λm2 = 813.3(2) nm, the wavelength of λm1 being determined for the first time. Main parameters of an optical lattice at these wavelengths are compared and a conclusion is made that trapping thulium atoms in an optical lattice at λm2 is preferable for optical clock operation.