Patent ID: 6363091
Filing Date: 2002-03-26
Classification: G04F

Abstract:
A method for generating a frequency standard, the method comprising:providing a quantum absorber having transitions including 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 having energies that correspond to frequencies of &ohgr;1 and &ohgr;2, respectively, the lower quantum states differing in energy by an energy difference subject to a total a.c. Stark shift having a magnitude; generating incident electro-magnetic radiation, the incident electro-magnetic radiation including: main frequency components at frequencies of &OHgr;1 and &OHgr;2, equal to &ohgr;1 and &ohgr;2, respectively, and differing in frequency by a frequency difference, and additional frequency components collectively having a spectrum; irradiating the quantum absorber with the incident electro-magnetic radiation; detecting electro-magnetic radiation from the quantum absorber to generate a detection signal; controlling the frequency difference to obtain an extremum in the detection signal, the extremum indicating that the frequency difference corresponds to the energy difference between the lower quantum states; setting the spectrum of the additional frequency components to reduce the magnitude of the total a.c. Stark shift; and providing a frequency standard signal related in frequency to the frequency difference.