The physics of Coherent Population Trapped (CPT) atomic clock instability

François Tricot, Peter Yun, Stéphane Guérandel +1 more

S M Ignatovich, Mikhail N Skvortsov, I. S. Mesenzova +4 more

Abstract Experimental parameters of the resonance of coherent population trapping (CTP) on D1 line in 87Rb and light shifts are compared under modulation of the laser pump current at frequencies of 3.4 and 6.8 GHz. Reproducibility of the parameters of a laser with a vertical cavity needed for long-term stability of an atomic clock is considered. The instabilities of atomic CPT-clock obtained for 1 s are 1.2 × 10−11 and 3 × 10−12 for frequencies of 3.4 GHz and 6.8 GHz, respectively.

Weiquan Cai

A brief review about the development of the coherent population trapping (CPT) based atomic clocks is presented. The physics principle of the CPT effect is simply explained, the basic configurations for making the clocks, including their features and the current situation in study and in manufacture, are described, and finally, the applications and the prospects of CPT atomic clocks are predicted.

Jaques Vanier

Vladislav P. Gerginov, Svenja A. Knappe, Vishal Shah +2 more

We present preliminary results showing that some noise sources in vapor cell atomic clocks based on coherent population trapping (CPT) can be suppressed with differential detection. The scheme we propose differs from more conventional differential detection in that both optical fields pass through the alkali vapor cell but have different polarizations, one circular and one linear. Because CPT resonances are only excited by the circularly polarized beam, the linearly polarized beam can be used to reduce several important sources of noise. With this technique, we demonstrate reduction of the short-term frequency instability of a CPT atomic frequency reference by a factor of about 1.5.

Vishal Shah, John E. Kitching