Phase estimation in spontaneous nonlinear interferometry for enhanced quantum imaging

Abstract:Bicolor quantum imaging can reach, in principle, phase supersensitivity approaching the Heisenberg limit using squeezed light from high-gain parametric down-conversion, but established quantum-imaging setups typically operate in the low-gain, spontaneous regime, where such scaling is inaccessible. Here, we show experimentally and theoretically that a symmetric nonlinear interferometer, even in the spontaneous regime, retains a phase-sensitivity advantage over configurations where entanglement is not exploited as a quantum-metrological resource, although the achievable phase sensitivity remains shot-noise-limited. This advantage appears as a shift of the optimal working point toward the dark fringe, the low-gain signature of the mechanism underlying high-gain supersensitivity. We derive design choices for phase-optimized nonlinear interferometers accordingly, favoring configurations that exploit entanglement as a metrological resource and specifying their optimal operating point.

Quantum Physics (quant-ph); Optics (physics.optics)

arXiv:2609.07338 [quant-ph]

(or arXiv:2609.07338v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2609.07338 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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