Introduction

• New portable optical atomic clock offers very accurate timekeeping at sea.
• The clock was tested during a three-week naval exercise on HMNZS Aotearoa.

Significance of Atomic Clocks

• Backbone of GPS: Used for navigation, emergency response, and military operations.
• Need for Improvement: Despite high accuracy, advancements are still being made.
• Optical Atomic Clocks: Push the boundaries of precision timekeeping.

Challenges of Traditional Atomic Clocks

• Bulky and Fragile: Restricted to large research facilities.
• Power-Hungry and Expensive: Limits widespread use.

Development of Portable Optical Atomic Clock

• Nature Study: Introduced a portable version for use onboard ships.
• Trade-offs: Some accuracy traded for size and robustness, but still more accurate than other marine timekeeping devices.

Functioning of Atomic Clocks

• Atomic Timekeeping: Uses atoms like Cs-133 to define seconds.
• Energy Levels: Atoms absorb energy and transition between levels.
• Microwave Radiation: Cs-133 transitions at 9,192,631,770 Hz to measure one second.

Optical Atomic Clocks: Enhanced Accuracy

• Laser Use: Stimulate atomic transitions with coherent light.
• Higher Operating Frequency: More oscillations allow finer time measurements.
• Narrower Linewidths: Enable precise frequency tuning and higher accuracy.
• Strontium Atoms: Commonly used for their stable optical transitions.

Building the Portable Device

• Miniaturization: Spectrometer, laser system, and frequency comb made compact.
• Design: Fits within a 35-liter volume, weighs 26 kg, consumes 85 W power.
• Autonomous Operation: Software control system ensures stability and functionality.

Testing the Portable Atomic Clock

• Initial Tests: Conducted at NIST in April 2022.
• Performance: Outperformed hydrogen maser in short-term accuracy and had lower long-term drift than rubidium clocks.
• Sea Trials: Tested on a boat at Pearl Harbor, stable despite environmental fluctuations.

Accuracy Trade-offs and Applications

• Laboratory vs. Portable: Portable version less accurate than lab counterparts but gains mobility and robustness.
• Potential Applications:
  • Navigation and Maritime Communication: Enhanced precision in marine environments.
  • Scientific Research: Monitoring underwater seismic activity, testing theories of relativity, and reducing satellite navigation costs.