Atomic clock performance enabling geodesy below the centimetre level

Area of Science:

• Atomic Physics
• Metrology
• Geophysics

Background:

• Atomic clocks measure time by counting oscillations of frequency standards.
• Optical atomic clocks offer superior precision, reaching fractional performance below 10⁻¹⁷.
• Relativity theory dictates time passage is relative, affected by velocity, acceleration, and gravity.

Purpose of the Study:

• To demonstrate optical clock measurements exceeding current abilities to account for Earth's gravitational spacetime distortion.
• To establish new benchmarks in systematic uncertainty, measurement instability, and reproducibility for optical clocks.

Main Methods:

• Utilized two independent ytterbium optical lattice clocks.
• Performed local clock measurements to assess performance benchmarks.
• Conducted ten blinded frequency comparisons for reproducibility analysis.

Main Results:

• Achieved systematic uncertainty of 1.4 × 10⁻¹⁸ (in units of clock frequency).
• Reported measurement instability of 3.2 × 10⁻¹⁹.
• Demonstrated reproducibility with a frequency difference of [-7 ± 5(stat) ± 8(sys)] × 10⁻¹⁹.

Conclusions:

• The demonstrated optical clocks surpass current capabilities in measuring gravitational distortion of spacetime.
• Their sensitivity to geopotential enables advanced geodesy with centimeter-level resolution.
• These clocks can be applied to explore geophysical phenomena, test general relativity, and search for dark matter.