Magnetometer and frequency standard based on coherently prepared thermal alkali atomic vapors

Summary form only given. We have experimentally investigated the potential of narrow coherent population trapping resonances for precision applications like magnetometry or atomic frequency standards. CPT can be observed in /spl Lambda/ systems where two ground states are coupled to a common excited state by two near-resonant light fields. Effective formation of ground state coherences takes place when the frequency difference of the light fields precisely matches the ground state splitting. This process leads to reduced absorption in the medium ("electromagnetically induced transparency") and thus reduced fluorescence intensity ("dark resonance") at the optical resonance frequency. Extremely narrow dark resonances can be observed when the two light fields have fixed phase and frequency difference and time-of-flight broadening is suppressed by the use of a buffer gas, making this type of system a promising candidate for precision applications. The /spl Lambda/ systems under study here are the D/sub 2/ lines of Cs, /sup 87/Rb and /sup 85/Rb where the ground state hyperfine splittings are 9.2 GHz, 6.8 GHz, and 3.0 GHz, respectively. Thus in a magnetic field the CPT resonance splits into several Zeeman components whose frequency positions are determined by the Breit-Rabi formula.