Readability and Recoverability of Decohered Information

Abstract

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.