Quantum Rhythm : When Information Breathes in Time

This article develops the quantum-coherence sector of the Chronon Field program while keeping standard quantum mechanics and open-system dynamics as the mandatory reference model. The central question is deliberately restricted: after the Hamiltonian dynamics, environmental decoherence, calibration history, control loops, General Relativity and instrumental effects have been modeled, can a reproducible differential phase or coherence-loss residual remain that correlates with an independently defined Chronon exposure? The framework uses the normalized tempo factor Φ̂=Φ/Φ₀ and the weak-field residual χΦ=lnΦ̂−U/c². Because the absolute normalization of Φ is gauge dependent, absolute terms proportional to Φ are excluded from admissible observables. Candidate signatures are instead expressed through residual frequency shifts, phase differences, gradient-sensitive exposures and differential coherence-loss rates. The article explicitly separates phase evolution, coherence loss Γ and the signed balance term Σ. Standard decoherence is therefore not interpreted as evidence for the Chronon Field. Residual models are formulated only after subtraction of the platform-specific standard dynamics, with coefficients allowed to depend on the experimental platform rather than assuming an unjustified universal coupling. The paper also discusses qubits, dynamical decoupling, quantum-error-correction controllers, phase noise, filter functions and the necessity of recording calibration and feedback channels as experimental witnesses. The work remains C0: it provides the operational variables, identifiability conditions, fail-fast criteria and statistical architecture required for a future preregistered quantum test, without claiming a quantum Chronon detection.