Optical atomic clocks are currently one of the most sensitive tools making it possible to precisely test the fundamental symmetry properties of spacetime and Einstein’s theory of relativity. At the same time, the extremely high stability and accuracy of compact transportable optical clocks open new perspectives in important fields, such as satellite navigation, relativistic geodesy, and the global time and frequency network. Our project aimed to develop a compact transportable optical clock based on a single ytterbium ion. We present the first prototype of the Yb${}^{+}$ clock (298 kg in 1 m${}^3$) and present several solutions aimed to improve the clock’s robustness to approach the demands of a space-qualified system. We present spectroscopic studies of a 435.5 nm quadrupole clock transition with Fourier-limited spectra of 25 Hz. The estimated instability of the output frequency at 1 GHz, which was down-converted with an optical frequency comb (OFC), is at the level of $9\times {10}^{-15}/\sqrt{\tau }$, and the long-term instability and inaccuracy are at the level of $5\times {10}^{-16}$. As the next steps, we present a new design for the clock laser and the OFC.

Deep laser cooling of atoms, ions, and molecules facilitates the study of fundamental physics as well as applied research. In this work, we report on the narrow-line laser cooling of thulium atoms at the wavelength of $506.2\mathrm{nm}$ with the natural linewidth of $7.8\mathrm{kHz}$, which widens the limits of atomic cloud parameters control. Temperatures of about $400\mathrm{nK}$, phase-space density of up to $3.5\times {10}^{-4}$ and $2\times {10}^6$ number of trapped atoms were achieved. We have also demonstrated formation of double cloud structure in an optical lattice by adjusting parameters of the $506.2\mathrm{nm}$ magneto-optical trap. These results can be used to improve experiments with BEC, atomic interferometers, and optical clocks.

EPJ Web of Conferences, open-access proceedings in physics and astronomy