Enhancing Measurement Precision of Non-Degenerate Two-Photon Absorption

TL;DR

This paper investigates how different measurement strategies using two-mode squeezed light affect the precision of non-degenerate two-photon absorption measurements, highlighting a trade-off between robustness to losses and quantum enhancement.

Contribution

It compares measurement strategies for two-photon absorption with squeezed light, identifying the most effective approach and analyzing robustness to experimental imperfections.

Findings

Intensity correlation measurements outperform others in ideal conditions.

Normalized intensity correlation is more robust to photon losses.

Quantum enhancements are diminished by linear photon losses.

Abstract

Recent theoretical and experimental studies have shown that squeezed states of light can be engineered to enhance the resolution of nonlinear optical measurements. Here, we analyze non-degenerate two-photon absorption signals obtained from transmission measurements using two-mode squeezed light and compare different measurement strategies. In particular, we investigate how correlations between the light modes may be used to improve the achievable precision. We find that intensity correlation measurements offer the best performance compared to normalized intensity correlation and noise reduction factor approaches. Under experimental imperfections modeled as linear photon losses, the enhancements from intensity and noise reduction measurements are reduced. In contrast, the normalized intensity correlation remains robust to loss, though this comes at the cost of losing the enhancement from non-classical light fields. This establishes a trade-off between robustness to loss and the achievable quantum advantage.