Laser frequency stabilisation on narrow resonances of cold magnesium atoms at the 1S0 – 3P1 transition

Experimental studies aimed at developing an optical frequency standard based on ultracold magnesium atoms with a relative uncertainty of Δν/ν < 10^-16 are performed. The frequency of the clock laser system at a wavelength of 457 nm is stabilised to narrow optical resonances (Ramsey fringes) in time-separated laser fields interacting with cold magnesium atoms localised in a magneto-optical trap (MOT). The frequency stability of the laser system is investigated using a femtosecond comb based on a Ti : sapphire laser. Long-term frequency stability (determined by the Allan function) of ~5 × 10^-15 at averaging time τ = 1000 s is obtained.