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arXiv · 2308.13267

Supersensitive phase estimation by thermal light in a Kerr-nonlinear interferometric setup

Nilakantha Meher·Eilon Poem·Tomáš Opatrný·Ofer Firstenberg·Gershon Kurizki
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Abstract

Estimation of the phase delay between interferometer arms is the core of transmission phase microscopy. Such phase estimation may exhibit an error below the standard quantum (shot-noise) limit, if the input is an entangled two-mode state, e.g., a N00N state. We show, by contrast, that such supersensitive phase estimation (SSPE) is achievable by \textit{incoherent}, e.g., \textit{thermal}, light that is injected into a Mach-Zehnder interferometer via a Kerr-nonlinear two-mode coupler. Phase error is shown to be reduced below $1/\bar{n}$, $\bar{n}$ being the mean photon number, by thermal input in such interferometric setups, even for small nonlinear phase-shifts per photon pair or for significant photon loss. Remarkably, the phase accuracy achievable in such setups by thermal input surpasses that of coherent light with the same $\bar{n}$. Available mode couplers with giant Kerr nonlinearity that stems either from dipole-dipole interactions of Rydberg polaritons in a cold atomic gas, or from cavity-enhanced dispersive atom-field interactions, may exploit such effects to substantially advance interferometric phase microscopy using incoherent, faint light sources.

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Nilakantha Meher, Eilon Poem, Tomáš Opatrný, Ofer Firstenberg, Gershon Kurizki. 2023-08-25. Supersensitive phase estimation by thermal light in a Kerr-nonlinear interferometric setup. https://arxiv.org/abs/2308.13267

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