Quantum Probes for the Characterization of Nonlinear Media

Area of Science:

• Quantum optics
• Nonlinear optics
• Quantum metrology

Background:

• Active optical media with Hamiltonians H=λ˜(a+a†)ζ are vital for quantum optical technologies.
• Characterizing these nonlinear media is essential for advancing quantum technology.

Purpose of the Study:

• To investigate the use of quantum probes, specifically squeezed probes, for characterizing nonlinear optical media.
• To compare the precision of quantum probes against semiclassical probes for estimating nonlinear parameters.

Main Methods:

• Utilizing tools from quantum estimation theory.
• Analyzing the joint and individual estimation of nonlinear coupling (λ˜) and nonlinearity order (ζ).
• Comparing the performance of squeezed probes with varying energy levels against semiclassical coherent probes.

Main Results:

• Nonlinear parameters (λ˜ and ζ) are compatible and can be jointly estimated without additional quantum noise.
• Squeezed probes improve estimation precision at a fixed probe energy.
• Squeezed vacuum is optimal for low energies; an optimal squeezing fraction exists for higher energies.
• Optimized quantum probes offer improved precision scaling with energy compared to semiclassical probes.

Conclusions:

• Quantum probes are a valuable resource for enhancing the precision of nonlinear media characterization.
• The findings suggest potential applications in current quantum optical technologies.