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We demonstrate a simple stacked scheme that enables absorption imaging through a hole in the surface of a grating magneto-optical trap (GMOT) chip, placed immediately below a micro-fabricated vacuum cell. The imaging scheme is capable of overcoming the reduced optical access and surface scatter that is associated with this chip-scale platform, while further permitting both trapping and imaging of the atoms from a single incident laser beam. The through-hole imaging is used to characterise the impact of the reduced optical overlap volume of the GMOT in the chip-scale cell, with an outlook to an optimised atom number in low volume systems., 5 pages, 3 figures

International audience; 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- andtwo-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.

International audience; Point source atom interferometry, employing optical Raman pulses and a cold atom source, enables measurements of rotation and acceleration in a compact experimental package. This system is uniquely sensitive to rotations in the plane perpendicular to the Raman beamline. Here we discuss our experiment’s sensitivity, stability, systematic errors, and other performance-limiting factors both fundamentaland technical. Our current measurements for the sensitivity to the magnitude and direction of the rotation vector are 0.6 mrad/s and 5 mrad, respectively.

International audience; We present a brief review of the rapidly growing field of autobalanced Ramsey spectroscopy followed by a detailed discussion and review of two novel techniques that were developed and tested in our laboratory: displaced frequency-jump Ramsey spectroscopy and combined error signal spectroscopy. These two techniques are related to, yet different from autobalanced Ramsey spectroscopy. The use of these techniques in a cold-atom clock based on coherent population trapping has reduced instabilities from variations in light-shift parameters by at least one order of magnitude. In each of these techniques the Ramsey sequence adapts to cancel light shifts and drifts.

International audience; In point source atom interferometry (PSI), a cloud of laser-cooled atom expands within a pair of counterpropagatingRaman laser beams and, after a beamsplitter-mirror-beamsplitter Raman pulse sequence, asingle snapshot of the expanded cloud allows simultaneous measurements of one axis of acceleration and two axes of rotation. In PSI, the thermal expansion of the cold-atom cloud, which is undesirable in other atom interferometry methods, is used to establish a position-velocity correlation in the expanded atom cloud. This correlation is employed to map the velocity dependence of the interferometric phaseshift onto a two-dimensional spatial image plane. As a result, the thermal velocity spread of the cloud of laser-cooled atoms facilitates the parallel operation of many atom interferometers, which yields the simultaneous multi-axis sensitivity. PSI provides a new approach to applications of atom interferometers in navigation and space science. For example, the 2D rotation measurement with PSI can be used to find geographic north or to measure the precession of a rotation vector. We have developed a scheme using PSI that is amenable to portable applications and we have demonstrated the measurement of a rotation vector in a plane [1]. We will present our recent results on evaluating the performance and systematic errors in a compact setup and discuss our proposals to address the challenges toward implementing ahigh-precision and portable PSI system.

International audience; Sophisticated Ramsey-based interrogation protocols using composite laser pulse sequences have been recently proposed to provide next-generation high-precision atomic clocks with a near perfect elimination of frequency shifts induced during the atom-probing field interaction.We propose here a simple alternative approach to the autobalanced Ramsey interrogation protocol and demonstrate its application to a cold-atom microwave clock based on coherent population trapping (CPT). The main originality of the method, based on two consecutive Ramsey sequences with different dark periods, is to sample the central Ramsey fringes with frequency jumps finely adjusted by an additional frequency-displacement concomitant parameter, scaling as the inverse of the dark period. The advantage of this displaced frequency-jump Ramsey method is that the local oscillator (LO) frequency is used as a single physical variable to control both servo loops of the sequence, simplifying its implementation and avoiding noise associated with controlling the LO phase. When tested using a CPT cold-atom clock, the DFJR scheme reduces the sensitivity of the clock frequency to variations of the light shifts by more than an order of magnitude compared with the standard Ramsey interrogation. This simple method can be applied in a wide variety of Ramsey-spectroscopy based applications including frequency metrology with CPT-based and optical atomic clocks, mass spectrometry, and precision spectroscopy.

We have developed a universal method to form the reference signal for the stabilization of arbitrary atomic clocks based on Ramsey spectroscopy. Our approach uses an interrogation scheme of the atomic system with two different Ramsey periods and a specially constructed combined error signal (CES) computed by subtracting two error signals with the appropriate calibration factor. CES spectroscopy allows for perfect elimination of probe-induced light shifts and does not suffer from the effects of relaxation, time-dependent pulse fluctuations and phase-jump modulation errors and other imperfections of the interrogation procedure. The method is simpler than recently developed auto-balanced Ramsey spectroscopy techniques [Ch. Sanner, et al., Phys. Rev. Lett. 120, 053602 (2018); V. I. Yudin, et al., Phys. Rev. Appl. 9, 054034 (2018)], because it uses a single error signal that feeds back on the clock frequency. CES universal technique can be applied to many applications of precision spectroscopy., 12 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1712.03365