Study of optical clocks based on ultracold ¹⁷¹Yb atoms*

Abstract

The optical atomic clocks have the potential to transform global timekeeping, relying on the state-of-the-art accuracy and stability, and greatly improve the measurement precision for a wide range of scientific and technological applications. Herein we report on the development of the optical clock based on 171Yb atoms confined in an optical lattice. A minimum width of 1.92-Hz Rabi spectra has been obtained with a new 578-nm clock interrogation laser. The in-loop fractional instability of the 171Yb clock reaches 9.1 × 10−18 after an averaging over a time of 2.0 × 104 s. By synchronous comparison between two clocks, we demonstrate that our 171Yb optical lattice clock achieves a fractional instability of 4.60 × 10 − 16 / τ .

Analytical determination of non-local parameter value to investigate the axial buckling of nanoshells affected by the passing nanofluids and their velocities considering various modified cylindrical shell theories

“…The yielded results are listed in Tables 5 and 6, respectively. It should be noted that these results are obtained for a CNT (5,5) with a length of 16.09 nm. For a better visibility, these results are shown in Figs.…”

“…It means the bigger values of the nonlocal parameter should be considered for the longer CNTs with the same radius. Moreover, Hu et al studied the flexural wave propagation in armchair (5,5) and (10,10) SWCNTs for a wide range of wave numbers by using the nonlocal beam models and the MD simulations. [38] They proposed the scale coefficient e = 0.288 for a wide range of wavelengths from ∼ 0.2 nm to ∼ 70 nm.…”

“…Plates and shells are the most widely used tools in industrial and manufacturing applications. With the advancement of technology, applications of these devices in various fields, especially in micro and nano scales of such as micro/nano-electromechanical systems, [1][2][3][4][5] nano-mechanical and biological sensors, [6,7] fluidic transfer devices in medical laboratories, [8,9] are indisputable. Therefore, the studies of mechanical behaviors such as bending, [10] buckling, [11] vibration, [12] and wave propagation, [13] have been highly regarded by researchers in various fields.…”

All polarization-maintaining Er:fiber-based optical frequency comb for frequency comparison of optical clocks

“…Optical atomic clocks have both relative frequency instability and uncertainty at the 10 −18 level or even better, [1][2][3][4][5][6] while state-of-the-art prime Cs fountain clocks have the uncertainty only at the level of 10 −16 . [7][8][9] Consequently, optical clocks are considered as candidates to redefine the seconds unit in the International System of Units (SI), [10,11] and the comparisons among at least three different types of optical clocks with uncertainties below 5×10 −18 have been taken as a mandatory step.…”

Viewing the noise propagation mechanism in a unidirectional transition cascade from the perspective of stability*

“…In the mathematical model of physical processes, only its stable solutions correspond to the motions that are observed in nature. [26] The high stability of physical properties of the equipment is the goal we have been pursuing, such as thin-film photonic devices, [27] optical atomic clocks, [28] and perovskite thermoelectric devices. [29] However, sometimes instability is also very important.…”