Abstract

We construct a two-packet operational interface for the stationary free-scalar Hawking model. The inherited outgoing quasifree prescription determines a normal joint Gaussian density, its joint count generating function, and its interpacket number covariance. Orthogonal packet modes are independent precisely when their off-diagonal occupation covariance vanishes.

The apparatus construction uses two memories coupled to one effective temporal port. Compact temporal tests are corrected at zero frequency, jointly orthonormalized, and compared with the desired packet plane. An explicit matrix-valued passive interaction captures both tests during the same switching interval. This avoids treating overlapping windows as independent apparatuses. Joint preparation errors, memory and register coupling, and correlated assignment noise enter one complete, reference-stable budget.

After coherent extraction, bounded single-qubit rotations and destructive pointer readout implement an informationally complete Pauli measurement family. We prove its effects, its complete-record implementation bound, an independent-trial statistical estimate, and a trace-distance reconstruction certificate. Destructive count tails and coherent state-approximation tails are distinguished.

A bounded-effect discrimination theorem translates a specified state departure into a certifiable record departure. A separate input-information theorem proves that an input-independent radiation channel cannot recover an unknown microscopic label or preserve its reference entanglement. The results concern a declared effective apparatus and a fixed-background baseline. They do not construct a local Schwarzschild detector, a collapse packet limit, a quantum-gravity correction, or microscopic evaporation dynamics.