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The metrology of time
1Bureau International des Poids et Mesures, Observatoire de Paris, Paris. farias@bipm.org
Summary
Accurate timekeeping relies on international collaboration and advanced atomic clocks. Researchers are developing new methods to improve the precision of the second, aiming for greater accuracy in global time measurement.
Area of Science:
- Metrology
- Atomic Physics
- Timekeeping Science
Background:
- International timekeeping is coordinated by the Bureau International des Poids et Mesures.
- Current atomic clocks achieve stability of 10⁻¹⁴, necessitating advanced remote comparison techniques.
- The second is realized with an uncertainty of 10⁻¹⁵ using caesium fountains.
Purpose of the Study:
- To explore the evolution of time measurement.
- To detail current state-of-the-art timekeeping methods.
- To identify future challenges and advancements in realizing the second.
Main Methods:
- Utilizing world-class atomic clocks for a stable reference time-scale.
- Developing highly performing remote clock comparison techniques.
- Investigating femtosecond comb technology and optical clocks.
Main Results:
- Commercial atomic clocks demonstrate stability up to 10⁻¹⁴.
- Caesium fountains realize the SI second with an uncertainty around 10⁻¹⁵.
- Efforts are underway to reduce uncertainty by an order of magnitude.
Conclusions:
- Enhanced time and frequency transfer techniques are crucial for progress.
- Femtosecond comb technology and optical clocks are expected to improve the definition of the second.
- Continuous innovation is vital for advancing the precision of time measurement.