Because of the low sensitivity of a thulium optical clock to black-body radiation and good accuracy and stability estimations, it is considered as a promising transportable optical clock. One of the leading systematic effects for Tm clock transition, i.e., the second-order Zeeman effect, can be canceled by probing two clock transitions between different hyperfine levels of ground and metastable states during clock operation. Herein, we demonstrate efficient optical pumping into the $m_F=0$ state of both ground hyperfine levels using single-frequency radiation at 418.8 nm. We prepared the atoms in both target states simultaneously and excited two clock transitions alternately. The resulting population of $m_F=0$ states of ground hyperfine levels was 36% and 3.8% of the initial number of atoms with less than 4% and 0.4% on nonzero magnetic sublevels, respectively. We performed numerical simulations of the optical pumping process, which is able to explain experimental results well.

This paper presents a detailed analysis of the effect of the optical lattice field on clock transition spectroscopy, as exemplified by thulium atoms. We consider the applicability of the sifting of atoms in an optical lattice by ramping down the power of the laser light that produces it. This method allows the number of filled vibrational sublevels to be reduced down to a single vibrational state, without changing the inner state of the atoms. The effectiveness of the method is illustrated by the example of the spectroscopy of a clock transition in thulium atoms in the resolved sideband regime.

We discuss extension of a recently proposed method based on continuous spectroscopy of ⁸⁸Sr atoms trapped into a moving optical lattice [Appl. Phys. Express,14(7),072006(2021)] to operation of bicolor thulium optical clocks. Simultaneous interrogation of two clock transitions at 1.14μm and building up a synthetic frequency provides a straightforward way to significantly suppress the first-order Doppler shift and cancel out the second-order Zeeman shift, the latter being one of the major uncertainty sources in the originally proposed ⁸⁸Sr setup. In our configuration, the total systematic frequency shift is 4×10⁻¹⁶ and instability at or lower than 10⁻¹⁸ after 1 hour of integration.

Hyperfine-encoded qubits in alkali atoms have established themselves as robust platforms for quantum computing, while alkaline-earth-like elements expand the state manipulation toolbox through their rich spectrum of optical transitions and metastable states. In this work, we demonstrate that thulium is a viable candidate for quantum computing, combining advantages of hyperfine qubit encoding with a rich energy-level structure of alkaline-earth-like atoms. We describe protocols for the initial state preparation and state-selective readout, and show single-qubit operations on the microwave transition at 1497 MHz. We demonstrate ground-state hyperfine qubit coherence times up to T 2 ∗ = 22 − 2 + 2 s and T 2 = 55 − 14 + 59 s, representing record-scale performance for neutral-atom systems. Furthermore, we show operations involving metastable optical states, including shelving for the state-selective readout as well as coherent population transfer of the ground-state qubit with coherence time primarily limited by the metastable level natural lifetime of 112 ms. These results mark the first step toward using thulium for quantum computing applications and highlight its promising characteristics.

We present refined values of the hyperfine splitting frequencies of the ground $|g\rangle =|4f^{13}{(}^2{F}^o)6s^2,J=7/2\rangle$ and clock $|c\rangle =|4f^{13}{(}^2{F}^o)6s^2,J=5/2\rangle$ states of thulium atoms, $f_g^{\text{HFS}}=1496550658.23\left(3\right)$ Hz and $f_c^{\text{HFS}}=2113946873.08\left(9\right)$ Hz, respectively. The measurements are performed on an ultracold atomic ensemble in an optical lattice using combined microwave and optical transition spectroscopy. The achieved measurement accuracy of less than 0.1 ppb represents an improvement of 2 and 7 orders of magnitude for $f_g^{\text{HFS}}$ and $f_c^{\text{HFS}}$, respectively, compared to the previously published values. We also refine the value of the Landé $g$-factor of the clock level to $g_c=0.854786\left(12\right)$. The results of this work can be used in the frequency standards and quantum simulators based on thulium atoms being developed today, as well as in a number of fundamental studies that require precise knowledge of the hyperfine structure characteristics of various elements.

We report on building a pulsed source of cold Tm atoms and loading of the narrow-line magneto-optical trap (MOT) from the cold atomic beam. We achieve the loading rate of the first-stage MOT in the primary chamber up to 108 atoms/s and obtain a cold atomic beam with the mean longitudinal velocity ∼10 m/s and an angular spread of 18 mrad in a pulsed mode. In this regime, we can form a cold atomic beam with up to 5 × 106 atoms at a 5 Hz repetition rate. We also introduce a novel method to enhance the capture velocity of the narrow-line MOT by incorporating an additional axial cooling beam and achieve loading efficiency η = 10% of the second-stage MOT in the science chamber. Our approach could be extended to other atomic species with similar properties, such as Sr, Yb, Dy, and Er, serving as a convenient alternative for the traditional 2D-MOT schemes. Providing rapid loading of the MOT in the science chamber, it would reduce preparation time of the atomic ensemble leading to a shorter dead time in spectroscopy experiments and a higher repetition rate.