High stability multiple-frequency cavity locking based on Doppler-free optogalvanic Calcium ion spectroscopy

Area of Science:

• Atomic Physics
• Laser Spectroscopy
• Quantum Information Science

Background:

• Precise laser frequency control is crucial for atomic clocks and quantum computing.
• Calcium ions (Ca+) are widely used in trapped-ion systems for these applications.
• Doppler-free spectroscopy provides high-resolution atomic transition measurements.

Purpose of the Study:

• To perform Doppler-free spectroscopy on the 3D3/2 → 4P1/2 transition of 40Ca+.
• To utilize this transition as a frequency standard for laser stabilization.
• To demonstrate a simple setup for dual-color laser frequency locking.

Main Methods:

• Optogalvanic detection was employed for Doppler-free spectroscopy of 40Ca+.
• A laser was locked to the resonance of an ultra-low expansion (ULE) glass cavity.
• Lamb dip spectrum fitting was used to analyze laser frequency stability.

Main Results:

• The long-term drift of the laser system was measured to be below 2 MHz per hour.
• A frequency locking setup for dual lasers at 866 nm and 780 nm was successfully demonstrated.
• The frequency difference between the two stabilized lasers showed consistency within 2 MHz over an hour.

Conclusions:

• Doppler-free spectroscopy of 40Ca+ provides a reliable method for laser frequency stabilization.
• The demonstrated laser system exhibits excellent long-term frequency stability.
• The dual-color laser locking technique is robust and suitable for applications requiring precise frequency control.