Coherent frequency transfer with < 5*10^-21 stability via a multi-branch comb with noise cancellation

Area of Science:

• Physics
• Optical Engineering
• Metrology

Background:

• Frequency combs are crucial for precise frequency measurements.
• Achieving high spectral purity transfer is essential for advanced applications.
• Existing methods often require complex reference cavities.

Purpose of the Study:

• To demonstrate a novel multi-branch frequency comb system.
• To enable hardware-based noise cancellation for enhanced spectral purity.
• To achieve high-stability coherent frequency transfer without a reference cavity.

Main Methods:

• Utilizing a multi-branch frequency comb architecture.
• Implementing hardware-enabled noise cancellation with a continuous-wave (cw) noise transfer laser.
• Verifying frequency transfer stability over time.

Main Results:

• Successful demonstration of a multi-branch frequency comb.
• Coherent frequency transfer achieved with stabilities of approximately 2×10^-18 within 1 second.
• Exceptional long-term stability below 5×10^-21 demonstrated over 10,000 seconds.
• Validation of performance without the need for a reference cavity.

Conclusions:

• The developed frequency comb system effectively transfers spectral purity.
• Hardware-based noise cancellation significantly enhances frequency transfer stability.
• This cavity-free approach offers a more robust and potentially simpler solution for high-precision frequency metrology.