A CPT-based Cs cell clock using the auto-balanced Ramsey interrogation protocol

International audienceWe propose a preliminary theoretical investigation and demonstrate experimentally the application of the autobalanced Ramsey (ABR) interrogation protocol onto a pulsed hot vapor Cs cell microwave atomic clock based on coherent population trapping (CPT). This approach, based on the alternation of two successive Ramsey-CPT sequences with unequal free-evolution times and the subsequent management oftwo interconnected phase and frequency servo loops, is found to allow a reduction of the clock frequency sensitivity to laser power variations. This approach, combined with the implementation of advanced electronics laser power stabilization systems, yields the demonstration of a CPT-based Cs cell clock with a fractional frequency stability at the level of 3.1 × 10−13 τ−1/2 and averaging down to the level of 7 ×10−15 at 2000 s integration time