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Light shifts are known to be an important limitation to the mid- and long-term fractional frequency stability of different types of atomic clocks. In this article, we demonstrate the experimental implementation of an anti-light-shift interrogation protocol onto a continuous-wave (cw) microcell atomic clock based on coherent population trapping (CPT). The method, inspired by the autobalanced Ramsey spectroscopy technique demonstrated in pulsed atomic clocks, consists in the extraction of atomic based information from two successive light-shifted clock frequencies obtained at two different laser-power values. Two error signals, computed from the linear combination of signals acquired along a symmetric sequence, are managed in a dual-loop configuration to generate a clock frequency free from light shift. Using this method, the sensitivity of the clock frequency to both laser-power and microwave-power variations can be reduced by more than an order of magnitude compared to normal operation. In the present experiment, the consideration of the nonlinear light-shift dependence allows enhancement of the light-shift mitigation. The implemented technique allows an improvement of the clock Allan deviation for time scales higher than 1000 s. This method can be applied in various kinds of atomic clocks such as CPT-based atomic clocks, double-resonance $\mathrm{Rb}$ clocks, or cell-stabilized lasers.

We show that the light shift in atomic clocks can be suppressed using time variation of the interrogation field intensity. By measuring the clock output at two intensity levels, error signals can be generated that simultaneously stabilize a local oscillator to an atomic transition and correct for the shift of this transition caused by the interrogating optical field. These methods are suitable for optical clocks using one- and two-photon transitions, as well as for microwave clocks based on coherent population trapping or direct interrogation. The proposed methods can be widely used both for high-precision scientific instruments and for a wide range of commercial clocks, including chip-scale atomic clocks., 7 pages, 6 figures

The use of matter-wave interferometry to detect inertial forces is already a powerful tool in precision measurement, but extending it beyond the lab to navigation applications requires optimization for compact setups. Here researchers characterize point-source atom interferometry (PSI) in a centimeter-scale cell, using an expanding cloud of cold atoms and an optical Raman interaction for simultaneous measurement of the system's acceleration along the Raman laser beams plus its rotation vector projected into the plane perpendicular to the beams. The sensitivity measurements presented here inform the further development of quantum inertial sensing that balances size and performance.

Atomic clocks based on coherent population trapping (CPT) are of great interest for portable applications, due to their high performance, low power requirements, and potential for miniaturization. Slow frequency drift, however, limits their holdover ability on long time scales. This study reports a CPT clock that minimizes long-term drift, with a fractional frequency stability of $3\ifmmode\times\else\texttimes\fi{}{10}^{-13}$ over the span of an hour---ten times as good as previous CPT clocks. After successful shrinking of the laser-cooling apparatus, this clock could see commercial use, as the atoms fall just a few millimeters during a typical probe period.