Entropic Reciprocity in Time-Reversed Young Interferometry

Jianming Wen

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arXiv · 2605.01052

Entropic Reciprocity in Time-Reversed Young Interferometry

Jianming Wen

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Abstract

We show that time-reversed Young interferometry reorganizes, rather than reverses, optical entropy. A fixed detector conditions the reciprocal source--detector Green function and produces a source-label probability distribution. Marginal entropies in the standard and time-reversed geometries are generally unequal; the reciprocal invariant is instead the mutual information between source and detector coordinates. Near a destructive response, the conditioned source-label entropy can decrease while Fisher information for small phase, tilt, or defocus perturbations increases. The result identifies time-reversed Young interferometry as a source-space information processor with no analogue in ordinary detector-plane fringe readout.

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Jianming Wen. 2026-05-01. Entropic Reciprocity in Time-Reversed Young Interferometry. https://arxiv.org/abs/2605.01052

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