Material Registration in Quantum Measurement: A Carrier-Access Factorization

Quantum instruments, open-system dynamics, and decoherence describe microscopic interaction and outcome statistics, but a completed physical measurement also requires a persistent material record. We formulate an effective registration framework in which this material requirement defines the admissible domain of the theory. The framework separates stable material support, microscopic access, detector-conditioned signal formation, stochastic activation, and persistent registration.As one explicit representation-theoretic realization, we decompose the Dirac field into charge-conjugation-even and charge-conjugation-odd components. In this basis, the electromagnetic vector current is entirely off-diagonal, providing a separation between the assigned carrier representation and the electromagnetic access operator without modifying the electromagnetic interaction. For detectors admitting an overdamped weak-noise reduction, we represent registration by a Kramers escape process and derive an inverse rate-compatibility criterion relating the effective ensemble hazard to independently specified quantum-instrument rates. We also show that the exponential hazard form alone does not select the linear Born response. The resulting framework separates algebraic accessibility from material registration while remaining fully compatible with the ordinary gauge-invariant Dirac interaction.