Phase-Dependent Squeezing in Dual-Comb Interferometry

Area of Science:

• Quantum optics
• Laser physics
• Optical metrology

Background:

• Squeezing quantum noise in continuous-wave lasers has advanced optical interferometry.
• Optical frequency comb interferometry with pulsed squeezed sources has lagged despite the importance of frequency combs in metrology.

Purpose of the Study:

• To introduce a novel time-domain approach for characterizing squeezed femtosecond light pulses.
• To enable quantum-enhanced applications in dual-comb interferometry.

Main Methods:

• Utilizing dual-comb interferometry to generate time-domain interferograms.
• Employing multiheterodyne beating between a Kerr soliton-squeezed frequency comb and a coherent state comb.
• Analyzing interferogram noise to reveal phase-dependent squeezing and antisqueezing.

Main Results:

• Demonstrated quantum noise dipping below the shot noise level by up to 3.8±0.2 dB.
• Observed phase-dependent squeezing and antisqueezing at alternating zero crossings.
• Modeled the nonstationary quantum noise as a periodic optical displacement.

Conclusions:

• The developed time-domain method effectively characterizes squeezed femtosecond light pulses.
• Results pave the way for quantum-enhanced dual-comb timing applications.
• Supports advancements in high-speed quantum state tomography using dual-comb interferometers.