Readability and Recoverability of Decohered Information

Under unitary quantum mechanics, decoherence redistributes information into systemenvironment correlations but does not destroy it. The statement that information remains "in the environment" is operationally incomplete: it may be globally present without being locally readable or actively recoverable under realistic constraints. We distinguish three notions-presence, readability, and recoverability-and show that they are operationally distinct. In controlled simulations of four decoherence models (random circuits, Trotterized Ising, isotropic Heisenberg, CNOT fan-out), we find that recovery is inverse-specific: the correct inverse of the decoherence process succeeds while generic circuits of com parable depth fail. Coupling geometry further shapes accessibility: anisotropic Ising and isotropic Heisenberg dynamics exhibit sharply different local capture structure despite comparable scalar decoherence indicators. On superconducting (Rigetti Ankaa-3) and trapped-ion (IonQ Forte) hardware, exact inverse recovery remains observable on both platforms. On IonQ, the geometry-depen dent capture separation between Ising and Heisenberg dynamics reappears (∼ 10 × in capture efficiency), while on Rigetti it is suppressed to the noise floor by routing overhead—indicating that local accessibility is more hardware-sensitive than global recoverability. The central empirical result is not that exact inversion can restore decohered correla tions—a consequence expected under unitary control—but that decoherence models with comparable scalar indicators and identical global recoverability can produce sharply different local accessibility structures, and that this difference is selectively visible depending on hardware compilation overhead. These results do not establish asymptotic hardness barriers or distinguish between interpretations of quantum mechanics. They support a narrower conclusion: the operational accessibility of decohered information is determined by coupling geometry, not merely by the degree of decoherence, and whether it remains readable or recoverable depends jointly on interaction structure, observer access, and available control operations.