Velocity-selective optical ramsey fringes by optical pumping in a Ca atomic beam

Abstract

Velocity-selective optical Ramsey fringes have been observed at the ¹ S ₀−³ P ₁ intercombination line of Ca, utilizing the optical pumping of one narrow velocity group of atoms from the ³ P ₁ state to the ³ S ₁ state. The width of velocity selection of about 60 m/s was achieved with a pump power of 1 mW. Velocity distribution of atoms in the excited state of ³ P ₁ and velocity-selective optical Ramsey fringes were measured as a function of atomic velocity. The velocity-slective Ramsey fringes will be an attractive reference for future wavelength/frequency standards, because the fractional width of the second order Doppler shift is reduced to the 10⁻¹³ level.