Conditions for realizing high-parametric-gain sensitivity enhancement with experimental losses

Determine under what conditions the potential beyond-shot-noise sensitivity advantage of the high-parametric-gain SU(1,1) interferometer can be realized in actual Fourier-domain optical coherence tomography experiments when optical losses are present and not known precisely.

Background

The paper notes that operating an SU(1,1) interferometer in the high-parametric-gain regime can, from a fundamental perspective, potentially surpass the shot-noise limit. However, the attainable advantage depends on losses in the interferometer, sample, and detection paths.

Because losses are often not known precisely in real experimental setups, the conditions under which the theoretical sensitivity advantage survives experimentally remain unresolved. Establishing these conditions would clarify when high-parametric-gain operation offers a genuine metrological benefit over seeded low-gain operation.

References

From a fundamental perspective, this regime can potentially allow going beyond the Shot-noise limit of sensitivity, although losses, most of the times unknown with precision in {\it real} experimental setups, should be considered to determine under what conditions this potential advantage can be actually realized in experiments~.

— Seeded SU(1,1) interferometry for Fourier-domain optical coherence tomography  (2608.18750 - Padilla et al., 19 Aug 2026) in Section Conclusions