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

Abstract

Velocity-selective optical Ramsey fringes have been observed at the 1S0−3P1 intercombination line of Ca, utilizing the optical pumping of one narrow velocity group of atoms from the 3P1 state to the 3S1 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 3P1 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.