Nonlinear Interferometry for Quantum-Enhanced Measurements of Multiphoton Absorption

Area of Science:

• Quantum optics
• Nonlinear optics
• Spectroscopy

Background:

• Multiphoton absorption is crucial for spectroscopy, microscopy, and lithography.
• The inherent weakness of multiphoton absorption necessitates high field intensities, limiting practical applications.

Purpose of the Study:

• To enhance the precision of multiphoton cross-section estimation.
• To overcome the limitations of high field intensity requirements in multiphoton absorption detection.

Main Methods:

• Utilizing an imbalanced nonlinear interferometer with a multiphoton absorbent.
• Comparing precision with strategies based on photon-number measurements using coherent or squeezed light.

Main Results:

• The nonlinear interferometer significantly enhances measurement precision for multiphoton cross-section estimation.
• Achieved a 1-order increase in sensitivity power scaling with photon flux compared to coherent light transmission measurements.
• Demonstrated robustness of enhanced precision against photon losses and experimental imperfections.

Conclusions:

• Employing a nonlinear SU(1,1) interferometer offers a superior method for detecting weak multiphoton absorption signals.
• The enhanced sensitivity and robustness open new possibilities for applications requiring precise multiphoton absorption measurements at lower intensities.