Multimode optical parametric amplification in the phase-sensitive regime.

Area of Science:

• Quantum optics
• Nonlinear optics
• Quantum sensing

Background:

• Sub-shot-noise sensing techniques improve measurement precision by overcoming classical noise limits.
• Phase-sensitive optical parametric amplification (PSA) is crucial for enhancing the robustness of these quantum sensing methods.
• Multimode light is often employed in quantum sensing applications like imaging and spectroscopy, necessitating multimode amplification.

Purpose of the Study:

• To determine optimal methods for multimode phase-sensitive amplification.
• To experimentally verify these optimal methods for quantum-enhanced sensing.
• To provide guidelines for implementing phase-sensitive amplification in near-field and time-frequency domains.

Main Methods:

• Theoretical investigation of optimal multimode phase-sensitive amplification.
• Experimental setup using a pumped second-order nonlinear crystal seeded with a Gaussian coherent beam.
• Focusing the seed tightly into the crystal to achieve phase-sensitive amplification.

Main Results:

• Optimal phase-sensitive amplification was achieved by tightly focusing the seed beam into the nonlinear crystal.
• This method contrasts with traditional seeding using close-to-plane waves.
• The experimental verification confirmed the effectiveness of the proposed near-field amplification technique.

Conclusions:

• Phase-sensitive amplification of sub-shot-noise images should be performed in the near field.
• A similar approach is applicable to time and frequency domains, benefiting quantum-enhanced spectroscopy.
• This work provides a practical framework for advancing quantum-enhanced sensing technologies.