Coherent local reception remains a separate gate

The decoder (eq:decoder) acts on an identified outgoing packet and a fresh qubit. Its CPTP definition is complete. Its physical implementation has not been supplied.

A coherent local receiver would require a specified compact field–probe interaction, independent receiver preparation, a retained quantum memory output, and a comparison on the source input including its reference. The general local system–probe framework provides scattering and induced observables FewsterVerch,FewsterJubbRuep; it does not identify the above decoder with a local receiver.

Two valid future interfaces are:

1. Packet factorization: prove that the receiver acts through the named packets with a fixed environmental channel or preparation;

2. Direct source-to-memory calculation: derive the composed source–field–receiver channel without assuming a packet/environment product state.

The second option is especially relevant when unselected background modes are correlated with the selected packet.