Ramsey-Bordé Matter-Wave Interferometry for Laser Frequency Stabilization at 10^{-16} Frequency Instability and Below

Area of Science:

• Atomic Physics
• Laser Spectroscopy
• Quantum Metrology

Background:

• Laser stabilization is crucial for precision measurements.
• Atomic spectroscopy offers high-resolution frequency references.
• Ramsey-Bordé (RB) interferometry provides a sensitive probe for atomic transitions.

Purpose of the Study:

• To demonstrate high-performance laser stabilization using RB atom interferometry.
• To achieve fractional frequency instability below 2×10⁻¹⁶.
• To evaluate the performance of RB spectroscopy on the ⁴⁰Ca ⁶⁵⁷ nm transition.

Main Methods:

• Utilizing RB atom interferometry with two counterpropagating ⁴⁰Ca atomic beams.
• Interrogating the ¹S₀-³P₁ transition at 657 nm.
• Employing fluorescence detection on the ³P₁-³P₀ transition at 431 nm.

Main Results:

• Achieved fractional frequency instability <2×10⁻¹⁶ for timescales of 10–1000 s.
• Observed 1.6 kHz linewidth interference fringes.
• Demonstrated superior stability compared to other atomic/molecular systems.

Conclusions:

• RB atom interferometry is a highly effective technique for laser stabilization.
• The demonstrated stability surpasses existing methods by 1–2 orders of magnitude.
• Further improvements in laser stability are anticipated with this technique.