Nonlinear Interference effect for Optical Clocks in Yb Atoms

TL;DR

This paper investigates two-photon absorption resonance in Yb atoms for optical clocks, demonstrating a noise-insensitive, narrow resonance that can be stabilized with an additional laser for high-precision frequency standards.

Contribution

It introduces a novel approach to enhance optical clock stability using two-photon resonance in Yb atoms, less sensitive to noise and Stark shifts.

Findings

Two-photon resonance exhibits narrow, high-amplitude absorption far from the line center.

The resonance is less sensitive to noise and probing field effects than electromagnetically induced transparency.

Using an additional narrow-line laser can stabilize the optical clock frequency to sub-Hertz precision.

Abstract

In this paper, two-photon absorption resonance has been investigated . We studied this phenomenon in three-level system with common upper level, two lower long-life levels and two quasi-resonant laser fields with different frequency spectrum. It has been shown that, the absorption coefficient in the far distance from absorption line at the frequency of two-photon resonance has considerable amplitude and narrow width. Frequency difference between two lower levels is transition frequency for optical clocks. This resonance is much less sensitive to the effects of noise components and probing fields compared with electromagnetically induced transparency. Stark shift of the two-photon resonance can be offset and reduced by the changes in the probing field amplitude. We recommended to use an additional laser with narrow line to stabilize the frequency at optical clock to get a line in sub-Hertz range.