Symmetry-Driven Coherence Restoration in Open Quantum Systems: Generator Deformations, Geometric Phase Control, and Non-Hermitian Spectral Signatures

Decoherence in open quantum systems is commonly associated with irreversible loss of phase information governed by non-Hermitian effective generators. However, the spectral structure of these generators is not invariant under all symmetry-preserving dynamical embeddings. In this work, we introduce a symmetry-driven coherence restoration (SDCR) mechanism in which structured geometric and temporal alignments induce controlled deformations of the effective Liouvillian spectrum. Within a conservative extension of open-system theory, SDCR does not modify the microscopic Hamiltonian, particle content, or fundamental interactions. Instead, it operates at the level of the reduced generator Leff, producing small but systematic redistributions of its complex eigenvalues while preserving complete positivity, trace preservation, and global unitarity of the total system. We formulate the mechanism consistently across Lindblad, Redfield, and influence-functional descriptions and show that the resulting generator deformations can be compactly organized using an internal octonionic embedding without introducing additional physical degrees of freedom. From a spectral perspective, SDCR selectively suppresses decay channels associated with specific eigenmodes rather than introducing explicit gain–loss terms, placing it naturally within the modern framework of non-Hermitian many-body dynamics. Phenomenological implications are discussed for neutrino oscillations, interferometric phase measurements, and precision gravimetry, where SDCR predicts small, symmetry-correlated phase deviations within current or near-future experimental reach. The framework is explicitly falsifiable and reduces to standard decoherence in the absence of symmetry alignment. SDCR therefore provides a conservative and testable geometric mechanism for spectral control in open quantum systems.