Configuration-Dependent Complex Time in Delayed-Choice Interferometry

We introduce a configuration‑dependent parametrisation of coherence in Wheeler’s delayed‑choice experiment based on the complex quantity T=t−iτ. The real component t retains its usual causal role, while the imaginary component τ encodes coherence attenuation without representing a physical time coordinate or an additional degree of freedom. Different interferometric configurations correspond to different decompositions of T, effectively acting as an internal rotation that modifies the imaginary‑time difference between paths and therefore the visibility. This mechanism alters coherence without affecting causal evolution and does not require retrocausality. The construction remains fully compatible with standard quantum mechanics: it preserves unitary evolution, the Born rule, and the structure of completely positive trace‑preserving maps, and is equivalent to a standard dephasing channel written in a compact parametrised form. The framework yields experimentally testable predictions for visibility modulation and temporal correlations, including a temporal CHSH protocol in which the departure from classical bounds arises from the configuration dependence of Δτ rather than from any modification of the underlying dynamics.