Coherent population trapping-based method for generating a frequency standard having a reduced magnitude of total a.c. stark shift

摘要

A quantum absorber is provided having transitions that include a first transition between a first lower quantum state and an upper quantum state, and a second transition between a second lower quantum state and the upper quantum state. The first transition and the second transition have energies that correspond to frequencies of omega1 and omega2, respectively. The lower quantum states differ in energy by an energy difference subject to a total a.c. Stark shift. Incident electro-magnetic radiation is generated. The incident electro-magnetic radiation includes main frequency components and additional frequency components. The main frequency components are at frequencies of OMEGA1 and OMEGA2, equal to omega1 and omega2, respectively, and differ in frequency by a frequency difference. The additional frequency components collectively have a spectrum. The quantum absorber is irradiated with the incident electro-magnetic radiation. Electro-magnetic radiation from the quantum absorber is detected to generate a detection signal. The frequency difference is controlled to obtain an extremum in the detection signal. The extremum indicates that the frequency difference corresponds to the energy difference between the lower quantum states. The spectrum of the additional frequency components is set to reduce the magnitude of the total a.c. Stark shift, and a frequency standard signal related in frequency to the frequency difference is provided.