Nonlinear optical higher-order effects in an optical lattice clock

The development of optical frequency standards with a relative uncertainty of reproducing the time and frequency units at a level as low as 10^-17 – 10^-18 calls for an unprecedented accuracy in estimating the role of higher orders of optical nonlinearity, caused by the influence of the optical lattice on the frequency shift of the 'clock transition'. This paper presents a systematic calculation of the contributions of multipole nonlinear anharmonic effects to the error of clocks based on optical lattices for alkaline-earth-like Sr, Yb, and Hg atoms.