Generalized Ramsey methods in the spectroscopy of coherent-population-trapping resonances

Abstract

We present a rigorous justification for the applicability of the recently developed methods of generalized autobalanced Ramsey spectroscopy (GABRS) [V. I. Yudin et al., Phys. Rev. Appl. 9, 054034 (2018)] and combined error signal in Ramsey spectroscopy (CESRS) [V. I. Yudin et al., New J. Phys. 20, 123016 (2018)] for resonances of coherent population trapping (CPT). A protocol of modified combined error signal for CPT resonances is also proposed, in which two successive interrogations of atoms under different times of free evolution are integrated in one cycle. The implementation of the GABRS and CESRS methods in a compact atomic clock based on the CPT effect allows us to significantly suppress the light shift and its fluctuation, which will lead to an improvement in the long-term stability and accuracy of these devices. Moreover, these spectroscopic schemes are insensitive to various distortions of the pulse shape, relaxation processes, errors in the generation of phase jumps, etc., which provides their high reliability and immunity to perturbations.

Light-shift mitigation in a microcell-based atomic clock with Symmetric Auto-Balanced Ramsey spectroscopy

“…Nevertheless, Ramsey-CPT spectroscopy suffers from a residual sensitivity to light-shifts, experienced by the atoms during the light pulses. Advanced Ramsey-based tailored interrogation protocols, based on two consecutive Ramsey sequences with different dark times, have then been proposed and demonstrated in various types of atomic clocks for enhanced light-shift mitigation [20][21][22][23][24][25][26] . In standard vapor cell clocks, it was demonstrated that the symmetry of the interrogation was of crucial importance to tackle an atomic memory effect, mainly linked to the limited duty cycle of the probing sequence, and then to optimize light-shift mitigation 11,22 .…”