The present invention provides a method and system to simultaneously use the
microwave and Zeeman end resonances associated with the same sublevel of maximum
(or minimum) azimuthal quantum number m to lock both the atomic clock frequency
and the magnetic field to definite values. This eliminates the concern about the
field dependence of the end-resonance frequency. In an embodiment of the system
of the present invention, alkali metal vapor is pumped with circularly-polarized
D1 laser light that is intensity-modulated at appropriate resonance
frequencies, thereby providing coherent population trapping (CPT) resonances. In
another embodiment, pumping with constant-intensity circularly-polarized D1
laser light enhances magnetic resonances that are excited by alternating
magnetic fields oscillating at appropriate resonance frequencies. In both embodiments,
the resonances are greatly enhanced by concentrating most of the atoms in the initial
state of the resonances, and by diminishing the spin-exchange broadening of the
resonances. This leads to greater stability of optically pumped atomic clocks.
This invention can also be used to operate an atomic magnetometer, where the feedback
signal used to stabilize the magnetic field at the alkali-vapor cell can serve
as a sensitive measure of the ambient magnetic field.
