Intercombination line frequencies in ¹⁷¹Yb validated with the clock transition

Area of Science:

• Atomic Physics
• Spectroscopy
• Quantum Metrology

Background:

• Precise frequency measurements are essential for advancing atomic clocks and fundamental physics tests.
• The Ytterbium-171 isotope (¹⁷¹Yb) offers unique properties for high-precision spectroscopy due to its nuclear spin.

Purpose of the Study:

• To conduct absolute frequency measurements of the (6s² ) ¹S₀-(6s6p) ³P₁ intercombination transition in ¹⁷¹Yb.
• To determine the hyperfine constant of the ³P₁ state using high-resolution spectroscopic techniques.

Main Methods:

• Sub-Doppler spectroscopy was employed to achieve high-resolution measurements of the ¹⁷¹Yb intercombination line.
• A stabilized 556 nm laser was locked to a frequency reference derived from a quartz oscillator steered to the Global Navigation Satellite System (GNSS) time scale via a frequency comb.
• Spectroscopy on the ¹S₀-³P₀ clock line in laser-cooled ¹⁷¹Yb atoms was used to validate the frequency reference to approximately 3×10⁻¹².

Main Results:

• Absolute frequency measurements of the (6s² ) ¹S₀-(6s6p) ³P₁ transition were successfully performed.
• The hyperfine separation between the F=1/2 and F=3/2 levels of the ³P₁ state was accurately determined.
• The hyperfine constant for the ³P₁ state was calculated as A(³P₁) = 3957833(28) kHz.

Conclusions:

• The determined hyperfine constant provides critical data for theoretical models and applications in atomic physics.
• The high precision achieved validates the employed spectroscopic methods and frequency referencing techniques for future metrology applications.