λEnter Calculus CompanionRegistered manuscripts, kept distinct

Manuscript Em05-A@1 · Em05-A-v1.tex · section · 9cac0def

The question

Scope, prior work, and the diagnostic question › The question · lines 128–148

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The following quantities are often considered together:

  1. excitation transferred to an accessible subsystem;

  2. coherence in a specified occupation basis;

  3. entanglement across a specified partition;

  4. purity of an accessible or residual marginal;

  5. recoverability of an unknown quantum message, including its correlations with an external reference.

They answer different questions.

This manuscript constructs an exact comparison within a specified channel family. In particular, we prove that a pure accessible subsystem can contain no message information, and that a mixed accessible subsystem can carry a perfectly recoverable quantum message. We also construct two experiments with identical Bell-input accessible marginals and identical excitation populations, but different optimal quantum-recovery errors.