% Hawk07-A.tex
% Standalone pdfLaTeX source; no external bibliography or figures.
% Suggested build:
%   pdflatex -interaction=nonstopmode Hawk07-A.tex
%   pdflatex -interaction=nonstopmode Hawk07-A.tex
%
% Compilation, numerical optimization, and machine verification
% have not been executed here.

\documentclass[11pt]{article}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[margin=1in]{geometry}
\usepackage{amsmath,amssymb,amsthm,mathtools}
\usepackage{booktabs,array,tabularx,longtable}
\usepackage{enumitem}
\usepackage{microtype}
\usepackage{xurl}
\usepackage[hidelinks]{hyperref}

\setlength{\emergencystretch}{3em}
\setlist[enumerate]{itemsep=3pt,topsep=5pt}
\setlist[itemize]{itemsep=3pt,topsep=5pt}
\numberwithin{equation}{section}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{corollary}[theorem]{Corollary}
\theoremstyle{definition}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{example}[theorem]{Example}
\theoremstyle{remark}
\newtheorem{remark}[theorem]{Remark}

\newcommand{\HH}{\mathcal H}
\newcommand{\BB}{\mathcal B}
\newcommand{\States}{\mathcal S}
\newcommand{\Nchan}{\mathcal N}
\newcommand{\Cchan}{\mathcal C}
\newcommand{\Dchan}{\mathcal D}
\newcommand{\Vchan}{\mathcal V}
\newcommand{\Mchan}{\mathcal M}
\newcommand{\id}{\operatorname{id}}
\newcommand{\Tr}{\operatorname{Tr}}
\newcommand{\rank}{\operatorname{rank}}
\newcommand{\supp}{\operatorname{supp}}
\newcommand{\Ad}{\operatorname{Ad}}
\newcommand{\Enter}{\mathsf{Enter}}
\newcommand{\Drop}{\mathsf{dropBit}}
\newcommand{\Return}{\mathsf{Return}}
\newcommand{\rep}[1]{\mathcal T_{#1}}
\newcommand{\ddiam}{d_\diamond}
\newcommand{\dtr}{d_{\mathrm{tr}}}
\newcommand{\erec}{\varepsilon_{\mathrm{rec}}}
\newcommand{\dleak}{\delta_{\mathrm{full}}}
\newcommand{\Jnorm}{J_{\mathrm n}}
\newcommand{\ket}[1]{\lvert #1\rangle}
\newcommand{\bra}[1]{\langle #1\rvert}
\newcommand{\kb}[2]{\lvert #1\rangle\!\langle #2\rvert}
\newcommand{\norm}[1]{\left\lVert #1\right\rVert}
\newcommand{\Expectation}{\mathbb E}
\newcommand{\Probability}{\mathbb P}
\newcommand{\Fswap}{\mathsf F}
\newcommand{\Harm}[1]{\mathsf H_{#1}}

\title{\textbf{Hawk07-A}\\[4pt]
Existence of Operational Wormhole Certificates\\[3pt]
\large A finite Enter model with a fixed receiver,
nested access, and a positive-residual cutoff}
\author{Ngo Cheung}
\date{15 October 2026}

\begin{document}
\maketitle

\begin{abstract}
We define and prove existence of operational wormhole certificates:
complete finite encodings whose unknown logical input can be returned
through one declared accessible interface, with a deterministic decoder
and a worst-case reference-preserving error allowance. This terminology
describes a recovery contract, not a spacetime wormhole.

The model has an unknown diary, an old-vault register maximally
entangled with accessible early memory, and one input-independent
scrambling unitary. A nested schedule hands over vault cells while
retaining a positive-dimensional physical residual. We prove the exact
complete-complement criterion, derive the finite Haar decoupling moment,
and specify a deterministic decoder by a semidefinite program.
One threshold supplies the same decoder core at every subsequent
retained cut.

For every prescribed full-diamond tolerance \(0<\varepsilon<1\),
an explicit finite parameter family has Haar measure at least \(1/64\)
on which three consecutive retained cuts admit the operational
certificate. On the same devices and for one fixed pure diary input,
late-radiation entropy rises and then falls within that window;
the last cut retains one physical qubit. Append-only Enter records
remain nondecreasing.

We correct two essential claims in the proposed analogy.
Nested-access recovery error and complete residual leakage cannot
peak at an intermediate Page cut: both are nonincreasing.
Furthermore, measuring late radiation does not imply a record-only
obstruction if an early quantum register survives; teleportation
provides an exact counterexample. Terminal readout and forgetting
equal partial trace on the returned interface, not physical
annihilation or disappearance of the complete complement.

No metric, Einstein--Rosen bridge, Morris--Thorne throat,
geometric ER \(=\) EPR identification, or gravitational
signal-crossing theorem is constructed.
\end{abstract}

\paragraph{Meaning of the title.}
The existence result concerns the operational objects defined below.
It is not a proof that physical spacetime wormholes exist.
Calling a recovery certificate a wormhole adds no geometry to it.

\tableofcontents

%=====================================================================
\section{Background, terminology, and debugging}
\label{sec:background}
%=====================================================================

\subsection{The Enter philosophy}

Cheung's Philosophy of Enter distinguishes four questions:
what is the input, what is accessible, what is returned, and what
additional identification is being claimed. Destructive readout,
quantum return, thermodynamic implementation, and geometric
interpretation are separate interfaces
\cite{CheungPhilosophy}.

The Enter calculus treats runtime qubit names as access rights.
Enter consumes measured quantum names and returns classical outcomes;
it is not the identity channel on the consumed quantum factor.
Cheung's operational characterization fixes Born probabilities and
projective residual rays within its specified strategy class, rather
than deriving gravitational dynamics from measurement syntax
\cite{CheungEnter,CheungI}.

We work with ordinary finite-dimensional quantum channels and explicitly
declared Born instruments. Enter supplies the access and return-type
discipline. Haar scrambling, the entangled resource, the release
schedule, and the receiver are additional model declarations.

\subsection{Operational and geometric meanings}

Einstein--Rosen bridges, Morris--Thorne wormholes, and the
ER \(=\) EPR proposal concern geometric or gravitational structures
\cite{EinsteinRosen,MorrisThorne,MaldacenaSusskind}.
Gravitational traversability constructions also specify interactions,
matter stress, and backreaction
\cite{GaoJafferisWall,MaldacenaStanfordYang}.
Those structures are not specified by an isometry
\(L\to R\otimes B\).

Here ``mouth'' is an overlay label for an output factor.
``Throat'' is an overlay label for the complete complementary
channel and its input dependence. The complement is a channel,
not a third tensor factor, a tunnel, or a proper-length quantity.
``Operational traversability'' means successful quantum return
through the declared receiver. It is directional and does not
claim a causal curve from one spatial mouth to another.

\subsection{Corrections required by the proposed plan}

\begingroup
\small
\renewcommand{\arraystretch}{1.12}
\begin{longtable}{@{}p{.35\linewidth}p{.60\linewidth}@{}}
\caption{Corrections used throughout Hawk07-A.}
\label{tab:debug}\\
\toprule
Proposed statement & Correct statement\\
\midrule
\endfirsthead
\toprule
Proposed statement & Correct statement\\
\midrule
\endhead
\bottomrule
\endfoot

A large, nonconstant complement implies high leakage and a nearly
constant accessible channel.
&
Residual dimension alone proves neither assertion. Nonconstancy
obstructs exact full-code recovery, but can be arbitrarily small.
An accessible replacement comparison needs its own estimate.
\\[5pt]

Leakage and recovery error peak at the Page cut.
&
For the nested release used here, both optimal recovery error and
complete leakage are nonincreasing. An intermediate entropy maximum
cannot be identified with their maximum.
\\[5pt]

The dimension of the accumulated record defines the neck.
&
A classical outcome alphabet is not coherent quantum storage.
The entropy comparison uses the dimensions of the unmeasured factors.
\\[5pt]

The receiver is late radiation \(R\), while the recovery theorem
uses late radiation and early memory.
&
We write late radiation as \(P_k\), early memory as \(E\), and the
entire accessible interface as \(R_k=P_kE\). There is no hidden grant
of \(E\).
\\[5pt]

An early reference entangled with the diary is accessible.
&
The diary's untouched test reference is \(Q\), never accessible to
the decoder. Accessible \(E\) purifies an independent old-vault
register \(H\).
\\[5pt]

The pure Page--Sen mean applies to the early-entangled preparation.
&
After tracing \(E\), the vault is a random rank-\(h\) projector
divided by \(h\), not generally a Haar pure state.
\\[5pt]

Enter on late radiation permanently blocks recovery even if \(E\)
remains quantum.
&
The permanent entanglement-breaking bound concerns a purely
classical returned interface. A classical record plus surviving
quantum \(E\) can recover, as teleportation demonstrates.
\\[5pt]

There is no second commuting representation of the logical matrix
algebra anywhere on the joint space.
&
Independent matrix algebras may commute. What is excluded is two
commuting, code-preserving representations that both implement
the same unknown logical input.
\\[5pt]

A half-diamond bound is a full-diamond bound.
&
We use \(d_\diamond=\tfrac12\|\cdot\|_\diamond\). The full-diamond
error is twice the half-diamond error.
\\[5pt]

Readout and \(\mathsf{dropBit}\) remove the physical complete
complement.
&
They remove returned names. A complete realization retains
unreturned record stores and measurement environments.
\\[5pt]

Fixed residual constancy reconstructs every independently variable
residual state.
&
Constancy removes logical input dependence. Recovery of a new,
independently variable \(\BB(B)\) is a different task.
\\[5pt]

A successful postselected branch is a deterministic decoder.
&
Its success probability and failure branch must be retained.
An input-dependent normalized branch is not a linear CPTP channel.
\\
\end{longtable}
\endgroup

These are mathematical corrections, not changes in physical
interpretation alone.

%=====================================================================
\section{The finite model and the certificate}
\label{sec:model}
%=====================================================================

\subsection{Complete preparation}

Fix
\[
 L\simeq\mathbb C^d,\quad
 H\simeq\mathbb C^h,\quad
 F\simeq\mathbb C^f,\quad
 E\simeq\mathbb C^h,
 \qquad d\ge2.
\]
The variable input is the whole diary \(L\).
An arbitrary external reference is untouched.
For Choi tests use \(Q\simeq L\).

Before the unknown input is used, prepare
\[
 \ket{\Phi_h}_{HE}
 =
 \frac1{\sqrt h}\sum_{a=1}^h\ket a_H\ket a_E,
 \qquad
 \ket0_F.
\]
The preparation is independent of \(L\) and its references.
The vault is \(LHF\), of dimension
\[
 D=dhf.
\]
Every purifier is retained: \(E\) is accessible, and \(Q\) belongs
to the reference side of the test, not to either receiver mouth.

A fixed encoding unitary can be absorbed into a known,
input-independent vault unitary \(U\).
For the random model, \(U\) is one Haar sample on \(\mathbb C^D\).
It is sampled once, not independently at every cut.

\subsection{Nested release and positive cutoff}

Choose a tensor-cell presentation in advance.
At cut \(k\), regroup the vault as
\[
 P_k\otimes B_k,\qquad
 r_k=\dim P_k,\quad b_k=\dim B_k,\quad r_kb_k=D.
\]
The accessible receiver is
\[
 R_k=P_kE,\qquad \dim R_k=r_kh.
\]
Previously released cells and \(E\) are not subsequently acted on
by the vault.

Release means handing over control of named tensor factors.
It can also be implemented by SWAPs into reserved blank registers.
That implementation adds fixed source placeholders, which must
remain in the complete bookkeeping. The primary model needs no
such additional placeholders: it changes control over existing
laboratory cells. No qubit leaves the laboratory.

The complete prepared isometry is
\begin{equation}
 V_k^U\ket\psi
 =
 (U\otimes I_E)
 \bigl(\ket\psi_L\ket{\Phi_h}_{HE}\ket0_F\bigr),
 \label{eq:V}
\end{equation}
regrouped as \(R_kB_k\).
Set
\begin{align}
 \Nchan_k^U(X)
 &=\Tr_{B_k}\bigl(V_k^UX(V_k^U)^\dagger\bigr),\\
 \Cchan_k^U(X)
 &=\Tr_{R_k}\bigl(V_k^UX(V_k^U)^\dagger\bigr).
 \label{eq:channels}
\end{align}

For qubits,
\[
 d=2^\ell,\quad h=2^m,\quad f=2^a,\quad
 n=\ell+m+a,\quad
 r_k=2^k,\quad b_k=2^{n-k}.
\]
A positive-residual cutoff is a predeclared \(K<n\).
The physical factor \(B_K\) remains present.

\subsection{Norms, leakage, and quantum return}

For states and channels use
\[
 \dtr(\rho,\sigma)=\frac12\norm{\rho-\sigma}_1,
 \qquad
 \ddiam(\Phi,\Psi)=\frac12\norm{\Phi-\Psi}_\diamond.
\]
The diamond norm includes external references
\cite{WatrousBook}.
Write
\[
 \rep{\tau}(X)=\Tr(X)\tau,
\]
\[
 \erec(\Nchan)
 =
 \inf_{\Dchan\ {\rm CPTP}}
 \ddiam(\Dchan\Nchan,\id_L),
 \qquad
 \dleak(\Cchan)
 =
 \inf_{\tau\in\States(B)}
 \ddiam(\Cchan,\rep{\tau}).
\]
Set
\[
 a_d=1-d^{-2},\qquad b_d=1-d^{-1}.
\]
Entropies are in bits.

\begin{definition}[Operational wormhole certificate]
\label{def:wormhole}
A certificate for the whole logical diary is a tuple
\[
 (V,R,B,\Dchan,\varepsilon)
\]
such that:
\begin{enumerate}[label=\textup{(\roman*)}]
\item \(V:L\to R\otimes B\) is a complete isometry;
\item the receiver accesses \(R\), not physical \(B\);
\item \(\Dchan:\BB(R)\to\BB(L_{\rm out})\) is a specified,
deterministic CPTP quantum-return map;
\item
\[
 \norm{\Dchan\Nchan-\id_L}_\diamond\le\varepsilon;
\]
\item \(B\) remains the declared physical residual;
\item no two commuting, code-preserving star representations
both intertwine \(V\) with the same algebra \(\BB(L)\).
\end{enumerate}
We call the certificate nonclassical when
\(\varepsilon<2b_d\), below the record-only lower bound.
The mouth and throat terminology is an overlay on this contract.
\end{definition}

The definition introduces no metric or state trajectory through
a tunnel. It does not define two-way communication.

\begin{remark}[Strength and breadth of the definition]
This definition is a recovery certificate with an additional
terminological overlay. It does not distinguish error-correcting
encodings from geometric wormholes.

For example, with \(U=I\), release all diary cells and retain \(H\).
Then
\[
 V\ket\psi=\ket\psi_{P}\ket{\Phi_h}_{HE},\qquad
 R=PE,\qquad B=H,
\]
and \(\Dchan=\Tr_E\) is exact.
For \(h\ge2\), this has a positive residual and entangled output
mouths, but no spacetime bridge has been constructed.
The Haar theorem below adds a quantitative, nontrivially scrambled
existence statement, not a gravitational identification.
\end{remark}

%=====================================================================
\section{Complete restoration and the complement criterion}
\label{sec:exact}
%=====================================================================

\begin{proposition}[Complete restoration]
\label{prop:global}
For every complete isometry \(V:L\to RB\),
\[
 \mathcal L_V(Y)
 =
 V^\dagger YV+
 \Tr((I-VV^\dagger)Y)\omega_L
\]
is CPTP and left-inverts \(\Ad_V\), for any fixed diary state
\(\omega_L\).
The complete isometry preserves the trace norm of every operator,
also with an external reference.
\end{proposition}

\begin{proof}
Both terms are CP. Their traces sum to \(\Tr Y\), and substitution
gives \(\mathcal L_V(VXV^\dagger)=X\).
An isometric embedding preserves all nonzero singular values,
including after tensoring with a reference identity.
\end{proof}

This is complete-output restoration, not a decoder restricted to \(R\).
It does not relocate the diary into \(B\)
\cite{CheungHawk04AB,CheungEn07B}.

\begin{theorem}[Exact whole-code recovery]
\label{thm:exact}
For \(V:L\to RB\),
\[
 \Dchan\Nchan=\id_L
 \quad\text{for some CPTP }\Dchan
 \quad\Longleftrightarrow\quad
 \Cchan=\rep{\tau_B}
 \quad\text{for some state }\tau_B.
\]
If \(s=\rank\tau_B\), then
\[
 \dim R\ge ds.
\]
There are an isometry \(T:L\otimes\mathbb C^s\to R\) and a state
\(\sigma\) such that
\begin{equation}
 \Nchan(X)=T(X\otimes\sigma)T^\dagger.
 \label{eq:normalform}
\end{equation}
An exact decoder on the entire accessible space is
\begin{equation}
 \Dchan(Y)
 =
 \Tr_{\mathbb C^s}(T^\dagger YT)
 +
 \Tr((I-TT^\dagger)Y)\omega_L.
 \label{eq:exactdecoder}
\end{equation}
\end{theorem}

\begin{proof}
Suppose a decoder is exact and dilate it by \(W:R\to LG\).
The isometry \((W\otimes I_B)V\) dilates the identity.
Its Choi operator has rank one, so every Kraus operator is proportional
to identity. Therefore
\[
 (W\otimes I_B)V\ket\psi
 =
 \ket\psi_L\ket\chi_{GB}
\]
with fixed \(\chi\). Tracing \(LG\) proves complement constancy.

Conversely, diagonalize
\[
 \tau_B=\sum_{\alpha=1}^s\lambda_\alpha\kb\alpha\alpha,
 \qquad \lambda_\alpha>0,
\]
and write
\[
 V\ket i
 =
 \sum_\alpha\sqrt{\lambda_\alpha}
       \ket{u_{i\alpha}}_R\ket\alpha_B.
\]
The identities
\(\Cchan(\kb i j)=\delta_{ij}\tau_B\) give
\[
 \langle u_{j\beta}\mid u_{i\alpha}\rangle
 =
 \delta_{ij}\delta_{\alpha\beta}.
\]
These \(ds\) orthonormal vectors define \(T\).
Equations~\eqref{eq:normalform} and \eqref{eq:exactdecoder}
follow. The decoder is CP, its two trace contributions sum to
\(\Tr Y\), and it recovers every matrix unit.
\end{proof}

This is the established quantum error-correction criterion
\cite{KnillLaflamme}. Cheung's supplied full-code and
observable-target discussions retain the same distinction
\cite{CheungOai280290,Hawk06A}. The proof above does not import
their model-specific channels.

\begin{example}[One observable is not the diary]
The isometry
\[
 V\ket i=\ket i_R\ket i_B
\]
gives computational dephasing on both outputs.
The \(Z\) observable is readable, but the full qubit cannot be
recovered from either factor. The complement is nonconstant.
A successful \(Z\) record does not establish the identity channel.
\end{example}

\begin{lemma}[Approximate correction and replacement benchmarks]
\label{lem:KSW}
Every accessible channel has \(\erec\le a_d\).
A replacement accessible channel has \(\erec=a_d\).
Moreover,
\begin{align}
 \ddiam(\Nchan,\rep{\omega})\le\eta
 &\Longrightarrow
 \erec(\Nchan)\ge\max\{0,a_d-\eta\},
 \label{eq:lower}\\
 \erec(\Nchan)
 &\le\min\{a_d,\sqrt{2\dleak(\Cchan)}\}.
 \label{eq:KSW}
\end{align}
\end{lemma}

\begin{proof}
A decoded replacement channel sends a Bell input to
\(I_Q/d\otimes\sigma_L\), with Bell overlap \(d^{-2}\).
Testing the Bell projector gives error at least \(a_d\).
Preparing \(I_L/d\) attains it, since depolarization is the uniform
average of \(d^2\) Weyl conjugations, one being identity.
This constant decoder also gives the universal upper bound.
Equation~\eqref{eq:lower} follows by contraction and the reverse
triangle inequality.

The finite information--disturbance theorem, stated in full diamond
normalization, gives
\[
 \frac14
 \left(
 \inf_{\Dchan}\norm{\Dchan\Nchan-\id_L}_\diamond
 \right)^2
 \le
 \inf_\tau\norm{\Cchan-\rep{\tau}}_\diamond
 \cite{KSW}.
\]
Substituting the half-diamond convention proves
\eqref{eq:KSW}.
\end{proof}

A nearly constant complement gives an upper recovery bound.
A nearly constant accessible channel gives a lower recovery bound.
The two directions cannot be interchanged.

%=====================================================================
\section{The unavailable phase and the false Page-cut peak}
\label{sec:early}
%=====================================================================

\begin{proposition}[The initial inaccessible diary]
\label{prop:initial}
At cut zero in the declared model, for every \(U\),
\[
 \Nchan_0^U=\rep{I_E/h},
 \qquad
 \erec(\Nchan_0^U)=a_d,
 \qquad
 \dleak(\Cchan_0^U)=a_d.
\]
The initial complement is reversible when completely accessible.
\end{proposition}

\begin{proof}
A unitary on the vault does not change the early marginal:
\[
 \Nchan_0^U(X)=\Tr(X)I_E/h.
\]
The recovery benchmark follows from Lemma~\ref{lem:KSW}.
The complement is
\[
 \Cchan_0^U(X)
 =
 U\bigl(X\otimes I_H/h\otimes\kb0 0_F\bigr)U^\dagger.
\]
Undoing \(U\) and tracing \(HF\) left-inverts it.

For any replacement state, this left inverse maps its comparison
to an identity-versus-replacement comparison, whose distance is
at least \(a_d\). Conversely, comparing with
\(\Cchan_0^U(I_L/d)\) and using contraction gives distance at
most \(\ddiam(\id_L,\rep{I_L/d})=a_d\).
\end{proof}

This supplies one rigorously unavailable phase.
It does not show that every nonzero early cut is featureless.

\begin{proposition}[Nested monotonicity]
\label{prop:nested}
In the release schedule of Section~\ref{sec:model},
\[
 \erec(\Nchan_{k+1}^U)\le\erec(\Nchan_k^U),
 \qquad
 \dleak(\Cchan_{k+1}^U)\le\dleak(\Cchan_k^U).
\]
If
\[
 \sigma_{B_k}^U=\Cchan_k^U(I_L/d),
 \qquad
 z_k(U)=\ddiam(\Cchan_k^U,\rep{\sigma_{B_k}^U}),
\]
then \(z_{k+1}(U)\le z_k(U)\).
\end{proposition}

\begin{proof}
Discarding the newly received cells maps \(\Nchan_{k+1}^U\)
to \(\Nchan_k^U\). Any earlier decoder can be used later.

The later complement is a partial trace of the earlier complement.
Partial trace takes a replacement channel to replacement, so
contractivity proves the optimized leakage inequality.
It also maps \(\sigma_{B_k}^U\) to
\(\sigma_{B_{k+1}}^U\), proving the named-center inequality.
\end{proof}

Thus an intermediate ``neck'' cannot be a new maximum of these
quantities. Their initial values are already maximal in this model.
This directly corrects Steps 2--3 of the proposed overlay.

\begin{example}[Nonconstant need not mean large leakage]
For a qubit define
\[
 V_\theta\ket0=\ket0_R\ket0_B,\qquad
 V_\theta\ket1
 =
 \ket1_R(\cos\theta\ket0_B+\sin\theta\ket1_B).
\]
For \(0<\theta<\pi/2\), the complement is nonconstant, but
\[
 \dleak(\Cchan_\theta)=\frac12\sin\theta.
\]
The accessible channel tends to identity as \(\theta\to0\).

Indeed, the complement is a measurement in the logical basis
followed by preparation of two pure states whose trace distance is
\(\sin\theta\). Their average gives the stated upper bound;
the triangle inequality applied to the two outputs gives the
matching lower bound. Appending arbitrarily large fixed residual
spectators changes neither conclusion.
\end{example}

Residual size, complementary nonconstancy, accessible privacy, and
decoder error are separate statements.

%=====================================================================
\section{The Haar decoupling calculation}
\label{sec:haar}
%=====================================================================

Use the Bell test
\[
 \ket{\Phi_d}_{QL}
 =
 \frac1{\sqrt d}\sum_{i=1}^d\ket i_Q\ket i_L.
\]
At a cut \(D=rb\), set
\[
 \omega_{QB}^U
 =
 (\id_Q\otimes\Cchan^U)(\kb{\Phi_d}{\Phi_d}),
 \qquad
 \sigma_B^U=\Cchan^U(I_L/d),
\]
\[
 X_{QB}^U
 =
 \omega_{QB}^U-\frac{I_Q}{d}\otimes\sigma_B^U.
\]

\begin{lemma}[Two-copy twirl]
\label{lem:twirl}
For \(D\ge2\),
\[
 \Expectation_U U^{\dagger\otimes2}OU^{\otimes2}
 =
 \alpha I+\beta\Fswap,
\]
where
\[
 \alpha=
 \frac{\Tr O-\Tr(O\Fswap)/D}{D^2-1},
 \qquad
 \beta=
 \frac{\Tr(O\Fswap)-\Tr O/D}{D^2-1}.
\]
For \(O=I_{PP'}\otimes\Fswap_{BB'}\),
\begin{equation}
 \alpha=\frac{b(r^2-1)}{D^2-1},
 \qquad
 \beta=\frac{r(b^2-1)}{D^2-1}.
 \label{eq:twirl}
\end{equation}
\end{lemma}

\begin{proof}
The averaged operator commutes with every \(U\otimes U\).
The symmetric and antisymmetric subspaces give its expression
as a linear combination of identity and swap.
Preservation of \(\Tr O\) and \(\Tr(O\Fswap)\) fixes the coefficients.
For the specified \(O\), those traces are \(r^2b\) and \(rb^2\).
\end{proof}

\begin{theorem}[Exact complementary Choi moment]
\label{thm:moment}
For the complete entangled preparation,
\begin{equation}
 \boxed{
 \Expectation_U\norm{X_{QB}^U}_2^2
 =
 \frac{r(b^2-1)(d^2-1)}
      {d^2h(D^2-1)}.
 }
 \label{eq:moment}
\end{equation}
\end{theorem}

\begin{proof}
After tracing \(E\), the initial reference--vault state is
\[
 \rho_{Q,\mathrm{vault}}
 =
 \kb{\Phi_d}{\Phi_d}_{QL}
 \otimes I_H/h\otimes\kb0 0_F.
\]
Its purity is \(1/h\), its vault marginal has purity \(1/(dh)\),
and its reference marginal has purity \(1/d\).

The swap identity and Lemma~\ref{lem:twirl} give
\[
 \Expectation\Tr[(\omega_{QB}^U)^2]
 =
 \alpha/d+\beta/h,
\]
\[
 \Expectation\Tr[(\sigma_B^U)^2]
 =
 \alpha+\beta/(dh).
\]
Since \(\Tr_Q\omega_{QB}^U=\sigma_B^U\),
\[
 \norm{X_{QB}^U}_2^2
 =
 \Tr[(\omega_{QB}^U)^2]
 -\frac1d\Tr[(\sigma_B^U)^2].
\]
The \(\alpha\) terms cancel. Insert \(\beta\) from
\eqref{eq:twirl}.
\end{proof}

\begin{lemma}[Choi conversion with its dimension factor]
\label{lem:choi}
For channels with input dimension \(d\),
\[
 \frac12\norm{\Jnorm(\Phi)-\Jnorm(\Psi)}_1
 \le\ddiam(\Phi,\Psi)
 \le
 \frac d2\norm{\Jnorm(\Phi)-\Jnorm(\Psi)}_1.
\]
Consequently,
\begin{equation}
 \Expectation_U z(U)^2
 \le
 \mathsf K(r,b)
 :=
 \frac{dD(b^2-1)(d^2-1)}
      {4h(D^2-1)}
 \le\frac{d^4f}{4r^2},
 \label{eq:K}
\end{equation}
where \(z(U)=\ddiam(\Cchan^U,\rep{\sigma_B^U})\).
\end{lemma}

\begin{proof}
The Bell input gives the lower inequality.
Every pure referenced input with a sufficient reference dimension
can be written as
\((T\otimes I)\ket{\Phi_d}\), with
\(\Tr(T^\dagger T)=d\), hence \(\norm T_\infty^2\le d\).
Multiplying the Choi difference by \(T\otimes I\) on both sides
gives the upper inequality; convexity handles mixed inputs.
This is the usual normalized Choi-to-diamond conversion
\cite{WatrousBook}.

The Choi difference acts on dimension \(db\), so
\[
 z(U)^2
 \le\frac{d^2}{4}\norm{X_{QB}^U}_1^2
 \le\frac{d^3b}{4}\norm{X_{QB}^U}_2^2.
\]
Take expectations and use \eqref{eq:moment}.
Finally,
\[
 \frac{b^2-1}{D^2-1}\le\frac{b^2}{D^2},
 \quad d^2-1\le d^2,\quad D=dhf,\quad b=D/r,
\]
which gives the last bound.
\end{proof}

Discarding the factor \(d\) would incorrectly promote a Bell-input
estimate to a whole-code diamond estimate.

\begin{theorem}[One threshold for all later retained cuts]
\label{thm:threshold}
Fix \(0<p<1\), \(\zeta>0\), and a cutoff \(K\).
If a retained cut \(k_*\le K\) satisfies
\begin{equation}
 \mathsf K(r_{k_*},b_{k_*})\le p\zeta^2,
 \label{eq:threshold}
\end{equation}
then, with Haar probability at least \(1-p\), the same sampled
unitary satisfies, for every \(k_*\le k\le K\),
\[
 \ddiam(\Cchan_k^U,\rep{\sigma_{B_k}^U})\le\zeta,
 \qquad
 \erec(\Nchan_k^U)\le\min\{a_d,\sqrt{2\zeta}\}.
\]
A sufficient threshold is
\begin{equation}
 r_{k_*}\ge
 \frac{d^2\sqrt f}{2\zeta\sqrt p}.
 \label{eq:simplethreshold}
\end{equation}
\end{theorem}

\begin{proof}
Markov's inequality gives
\[
 \Probability\{z_{k_*}(U)>\zeta\}
 \le
 \mathsf K(r_{k_*},b_{k_*})/\zeta^2
 \le p.
\]
Proposition~\ref{prop:nested} propagates this single event to all
later retained cuts. Lemma~\ref{lem:KSW} supplies recovery.
Equation~\eqref{eq:simplethreshold} follows from \eqref{eq:K}.
\end{proof}

The preparation and access resemble the finite information task
studied by Hayden and Preskill \cite{HaydenPreskill}.
The displayed moment is proved here.
Hawk06-A is a predecessor comparison, not a substitute for this
calculation \cite{Hawk06A}.

The theorem does not certify every \(U\), or guarantee a threshold
before an arbitrary chosen cutoff. It applies only when its
dimensional inequality is satisfied.

%=====================================================================
\section{One specified decoder core}
\label{sec:decoder}
%=====================================================================

\subsection{A deterministic finite prescription}

For a map \(\Phi\), use the unnormalized input-first Choi operator
\[
 J(\Phi)
 =
 \sum_{i,j}\kb i j\otimes\Phi(\kb i j).
\]
At \(k_*\), let \(R=R_{k_*}\), \(q_R=\dim R\).
A decoder Choi matrix \(C_{\Dchan}\) on \(R'\otimes L_{\rm out}\)
defines
\[
 \Dchan_C(Y)
 =
 \Tr_{R'}[(Y^{\mathsf T}\otimes I_L)C_{\Dchan}].
\]
Set
\[
 J_\Delta(C)
 =
 J(\Dchan_C\Nchan_{k_*}^U-\id_L).
\]

\begin{definition}[Decoder program]
\label{def:decoder}
Choose a minimizing solution of
\begin{equation}
 \begin{array}{ll}
 \text{minimize} & t/2\\
 \text{subject to}
 & C_{\Dchan}\ge0,\quad \Tr_L C_{\Dchan}=I_{R'},\\
 & Z\ge J_\Delta(C),\quad Z\ge-J_\Delta(C),\\
 & \Tr_L Z\le tI_{L'},\quad t\ge0.
 \end{array}
 \label{eq:SDP}
\end{equation}
Among optimal decoder Choi matrices, choose the one minimizing
the squared Frobenius norm. Call the resulting map \(\Dchan_*\).
\end{definition}

\begin{theorem}[Decoder contract and fixed later policy]
\label{thm:decoder}
The program defines a deterministic CPTP decoder on all of \(R_{k_*}\).
Its optimal value is \(\erec(\Nchan_{k_*}^U)\).
On the success event of Theorem~\ref{thm:threshold},
\[
 \ddiam(\Dchan_*\Nchan_{k_*}^U,\id_L)
 \le e:=\min\{a_d,\sqrt{2\zeta}\}.
\]

For a later cut, let \(\Pi_{k\to k_*}\) discard the additional
received cells and retain the same early memory. Then the one
fixed decoder core with policy
\begin{equation}
 \Dchan_k=\Dchan_*\Pi_{k\to k_*}
 \label{eq:fixedpolicy}
\end{equation}
has
\[
 \Dchan_k\Nchan_k^U
 =
 \Dchan_*\Nchan_{k_*}^U
\]
for every \(k_*\le k\le K\).
Thus the full-diamond error is at most \(2e\) at every retained cut.
\end{theorem}

\begin{proof}
The decoder Choi constraints are exactly complete positivity and
trace preservation. Composition with the fixed channel is linear
in the decoder Choi matrix.

For a Hermiticity-preserving map \(\Delta\), the diamond-norm dual
is
\[
 \norm{\Delta}_\diamond
 =
 \min\{t:Z\ge J(\Delta),\ Z\ge-J(\Delta),\
                \Tr_{\rm out}Z\le tI_{\rm in}\}
 \cite{WatrousSDP}.
\]
This follows as the Hermitian specialization of the two-block
dual: symmetrizing the two diagonal blocks gives \(Z\), and
diagonalizing the block matrix gives \(Z\pm J(\Delta)\ge0\).
It proves the optimal-value assertion.

Decoder Choi matrices form a compact convex set. The continuous
diamond error attains its minimum.
The secondary squared-norm minimization is strictly convex and
therefore selects a unique decoder matrix.
The error estimate follows from Lemma~\ref{lem:KSW}.

Finally,
\(\Pi_{k\to k_*}\Nchan_k^U=\Nchan_{k_*}^U\)
by the nested schedule. This proves the fixed-policy identity.
\end{proof}

The decoder depends on the declared device matrix \(U\), not on
the unknown diary or its test reference.
The optimization is a mathematical prescription, not a reported
execution or an efficiency theorem.

\subsection{Workspace and permissible operations}

\begin{proposition}[A finite batch realization]
\label{prop:workspace}
The decoder Choi rank obeys
\[
 g\le d q_R.
\]
It has a Stinespring isometry
\[
 W_{\Dchan}:R_{k_*}\to L_{\rm out}G,\qquad \dim G=g.
\]
With qubit spaces, a conservative realization at cut \(k\ge k_*\)
uses peak live quantum occupancy at most
\begin{equation}
 \log_2\dim R_k+\log_2d+\lceil\log_2g\rceil
 \le
 \log_2\dim R_k+\log_2q_R+2\log_2d.
 \label{eq:workspace}
\end{equation}
This count includes early memory, all received cells, output, and
allocated decoder environment. It excludes inaccessible \(B_k\)
and the untouched external reference.
\end{proposition}

\begin{proof}
Diagonalize the decoder Choi matrix to obtain at most \(dq_R\)
Kraus operators and stack them into \(W_{\Dchan}\).
Allocate output and environment registers, then extend the
isometry from its prepared subspace to a unitary.
The displayed register count prices a nonoptimal implementation.

Arbitrary finite unitaries admit elementary decompositions when
continuous one-qubit gates and CNOT are permitted
\cite{Barenco}. No efficient gate count or executed compilation
is asserted.
\end{proof}

There is no one-live-qubit or restricted streaming claim.
Cheung's En02-B and En02-C distinguish batch availability from
memory-constrained execution in their specified benchmarks
\cite{CheungEn02BC}.

A completed Petz map is a CPTP candidate, but its formula alone
does not certify \eqref{eq:SDP}'s error.
Similarly, a postselected map satisfying
\[
 \Phi_{\rm succ}\Nchan=p_{\rm succ}\id_L
\]
is trace decreasing when \(p_{\rm succ}<1\).
A completed decoder with a failure output has unconditional
error at most \(1-p_{\rm succ}\) in half-diamond normalization,
but not automatically zero.
The success probability, reflections, failure flag, and resources
in an amplitude-amplified implementation must be declared
\cite{CheungEn02BC,YoshidaKitaev}.

\subsection{Compatible transfer and finite precision}

\begin{proposition}[The same receiver survives compatible errors]
\label{prop:transfer}
Suppose proxy and actual complete channels, after access-preserving
identifications, differ by at most \(\eta\) in half-diamond distance.
Suppose the implemented receiver differs from the specified receiver
by at most \(\iota\).
If the specified proxy decoder has half-diamond error \(e\), then
\[
 \ddiam(\Dchan_{\rm imp}\Nchan_{\rm act},\id_L)
 \le\min\{1,e+\eta+\iota\}.
\]
A proxy complementary replacement allowance \(\zeta\) gives actual
leakage at most \(\min\{1,\zeta+\eta\}\).
\end{proposition}

\begin{proof}
Partial trace contracts the complete comparison.
Insert the same decoder and apply CPTP contraction and the triangle
inequality. Do the same with the proxy replacement state.
\end{proof}

Thus channel closeness \emph{can} transfer a fixed decoder on a
correctly identified common interface. It does not install the decoder,
grant forbidden access, or prove its laboratory calibration.
Comparisons mixing physical \(B\) into the receiver are not
access preserving \cite{CheungHawk04D}.

Haar matrices and the ideal decoder may have arbitrary real
coefficients. Exact finite-alphabet compilation is not presumed.
Finite-precision implementations belong to the allowance
\(\eta+\iota\).

%=====================================================================
\section{Coherent entropy, classical records, and the dimension neck}
\label{sec:entropy}
%=====================================================================

Fix one pure diary input \(\ket\psi\), independent of \(U\).
After tracing \(E\), the vault state is
\[
 \rho_{\rm vault}^U
 =
 \frac1h UP_\psi U^\dagger,\qquad \rank P_\psi=h.
\]
Its late marginal is \(\rho_{P_k}^U\).
It is this late-radiation entropy, not necessarily the entropy of
the entire receiver \(P_kE\), that we plot.

\begin{theorem}[Entropy estimates for the declared preparation]
\label{thm:entropy}
At \(D=rb\), define
\begin{align}
 p_{\rm q}(r,b,h)
 &=
 \frac{r(b^2-1)+b(r^2-1)/h}{D^2-1},\\
 p_{\rm c}(r,b,h)
 &=
 \frac{Db+(D-b)/h-1}{D^2-1}.
 \label{eq:purities}
\end{align}
Then
\[
 \Expectation_U\Tr[(\rho_P^U)^2]=p_{\rm q}(r,b,h).
\]
For computational-basis Enter on the released cells, with prefix
probabilities \(p_y^U\),
\[
 \Expectation_U\sum_y(p_y^U)^2=p_{\rm c}(r,b,h).
\]
Writing \(t=\min(r,bh)\), one has
\begin{align}
 -\log_2p_{\rm q}
 &\le\Expectation_U S(P)\le\log_2t,\\
 -\log_2p_{\rm c}
 &\le\Expectation_U H(Y)\le\log_2r,\\
 0\le\log_2t-\Expectation_U S(P)
 &\le
 \log_2\left(1+\frac{\min(r,bh)}{\max(r,bh)}\right)
 \le1.
 \label{eq:entropybound}
\end{align}
\end{theorem}

\begin{proof}
Twirl \(\Fswap_P\otimes I_{BB'}\).
Its identity and swap coefficients are
\[
 \frac{r(b^2-1)}{D^2-1},
 \qquad
 \frac{b(r^2-1)}{D^2-1}.
\]
The initial vault purity is \(1/h\), giving \(p_{\rm q}\).

For record probabilities, use
\(\Pi_y=\kb y y_P\otimes I_B\), of rank \(b\).
The averaged two-copy vault state is
\[
 \Expectation_U(\rho_{\rm vault}^U)^{\otimes2}
 =
 \frac{1-1/(hD)}{D^2-1}I
 +
 \frac{1/h-1/D}{D^2-1}\Fswap.
\]
Since \(p_y^U=\Tr(\Pi_y\rho_{\rm vault}^U)\),
\[
 \Expectation(p_y^U)^2
 =
 \frac{b^2[1-1/(hD)]+b[1/h-1/D]}{D^2-1}.
\]
Sum over \(r\) outcomes.

The late marginal has rank at most \(\min(r,bh)\), and the
record has at most \(r\) outcomes. These prove the upper bounds.
Entropy is at least minus the logarithm of purity; Jensen's
inequality proves the lower bounds.
Direct comparison gives
\(p_{\rm q}\le1/r+1/(bh)\), proving the final estimate.
\end{proof}

The coherent rank envelope is
\[
 \min\{\log_2r,\log_2b+\log_2h\}.
\]
Its balancing cut is \(r=bh\), when that cut is retained.
It is not generally \(r=b\).
Nor is it a balance between the augmented receiver dimension \(rh\)
and the residual dimension \(b\).

These dimension comparisons are not throat area, proper length,
or quantum extremal surfaces.

\subsection{The pure-state Page--Sen comparison}

Only when \(h=1\) does the declared fixed pure input become a
Haar pure-state ensemble on the vault.
Let \(m_0=\min(r,b)\), \(n_0=\max(r,b)\), and
\(\Harm j=\sum_{u=1}^j u^{-1}\). Then
\[
 \Expectation_U S(P)
 =
 \frac{\Harm D-\Harm{n_0}-(m_0-1)/(2n_0)}{\ln2},
\]
\[
 \Expectation_U H(Y)
 =
 \frac{\Harm D-\Harm b}{\ln2}.
\]
The first is the established Page--Sen evaluation
\cite{PageAverage,Sen}. The second follows by differentiating
the Dirichlet moment
\[
 \Expectation p_y^s
 =
 \frac{\Gamma(b+s)\Gamma(D)}
      {\Gamma(b)\Gamma(D+s)}
\]
and summing over the \(r\) outcomes.
These pure-ensemble comparisons do not replace
Theorem~\ref{thm:entropy}'s early-entangled calculation
\cite{CheungHawk05BC,Hawk06A}.

\subsection{Enter records cannot turn over}

For a measured factor \(A\) in a declared basis, define
\[
 \Enter_A(X)
 =
 \sum_y\bra yX\ket y\,\kb y y_Y.
\]
With surviving quantum factors \(E\), use
\[
 (\Enter_A\otimes\id_E)(X)
 =
 \sum_y\kb y y_Y\otimes
 (\bra y_A\otimes I_E)X(\ket y_A\otimes I_E).
\]
The name \(A\) is consumed. The surviving \(E\) is not.

\begin{proposition}[Append-only entropy]
\label{prop:record}
For every fixed prescribed process whose complete record is append
only,
\[
 H(Y_{\le k+1})
 =
 H(Y_{\le k})+H(Y_{k+1}\mid Y_{\le k})
 \ge H(Y_{\le k}).
\]
The statement permits adaptive readout and does not require Haar
scrambling.

For fixed-basis Enter on \(P_k\),
\[
 H(Y_{\le k})=S(\Delta_{P_k}\rho_{P_k})\ge S(\rho_{P_k}),
\]
where \(\Delta\) denotes basis dephasing.
\end{proposition}

\begin{proof}
The first identity is the classical chain rule.
Dephasing is an average of diagonal unitary conjugations, so
entropy concavity gives the second inequality.
\end{proof}

Measuring emitted cells affects conditional residual states.
It does not change the unconditional later unmeasured marginals
when subsequent vault operations do not act on the emitted cells.
One must not identify conditional branch entropies with the coherent
history in Theorem~\ref{thm:entropy}.

%=====================================================================
\section{Existence with a nontrivial window and turnover}
\label{sec:existence}
%=====================================================================

\begin{theorem}[Three retained cuts with one fixed receiver]
\label{thm:joint}
Take
\[
 d=16,\qquad f=1,\qquad h=2^m,\qquad D=16h.
\]
Declare
\[
 k_*=m+1,\qquad k_{\rm peak}=m+2,\qquad K=m+3.
\]
The three cuts have
\[
 (r_{k_*},b_{k_*})=(2h,8),\quad
 (r_{k_{\rm peak}},b_{k_{\rm peak}})=(4h,4),\quad
 (r_K,b_K)=(8h,2).
\]
If
\begin{equation}
 h\ge\frac{512}{\zeta},
 \label{eq:size}
\end{equation}
then a set of Haar unitaries of measure at least \(1/64\) satisfies
all of the following:
\begin{enumerate}[label=\textup{(\roman*)}]
\item \(z_k(U)\le\zeta\) for every \(k_*\le k\le K\);
\item the fixed decoder policy \eqref{eq:fixedpolicy} has
half-diamond error at most
\(\min\{a_{16},\sqrt{2\zeta}\}\) at all three cuts;
\item for the fixed pure diary input,
\begin{equation}
 S(P_{k_{\rm peak}}^U)>
 \log_2(2h)\ge
 \max\{S(P_{k_*}^U),S(P_K^U)\};
 \label{eq:riseandfall}
\end{equation}
\item every append-only destructive record is nondecreasing;
\item the cutoff retains one physical vault qubit.
\end{enumerate}
The ensemble mean also rises and falls strictly at these three cuts.
\end{theorem}

\begin{proof}
At \(k_*\), \eqref{eq:K} gives
\[
 \Expectation z_{k_*}(U)^2\le\frac{4096}{h^2}.
\]
Hence, under \eqref{eq:size},
\[
 \Probability\{z_{k_*}(U)>\zeta\}
 \le\frac{4096}{h^2\zeta^2}\le\frac1{64}.
 \label{eq:failure}
\]

At the intermediate cut,
\[
 p_{\rm q}(4h,4,h)
 =
 \frac{124h-4/h}{256h^2-1}.
\]
Markov's inequality gives
\[
 \Probability\left\{
 \Tr[(\rho_{P_{k_{\rm peak}}}^U)^2]\ge\frac1{2h}
 \right\}
 \le
 \frac{248h^2-8}{256h^2-1}
 <\frac{31}{32}.
\]
Therefore an event of probability greater than \(1/32\) has
\[
 S(P_{k_{\rm peak}}^U)>\log_2(2h).
\]
At \(k_*\), rank is at most \(2h\).
At \(K\), rank is at most \(b_Kh=2h\).
Their entropy upper bounds hold for every unitary.

Subtracting the leakage failure set from the turnover event leaves
measure greater than \(1/64\), hence at least \(1/64\).
Nested monotonicity and Theorem~\ref{thm:decoder} prove (i)--(ii).
Proposition~\ref{prop:record} gives (iv), and \(b_K=2\) gives (v).

Finally,
\[
 p_{\rm q}(4h,4,h)<\frac1{2h}.
\]
The mean entropy lower bound in Theorem~\ref{thm:entropy} is therefore
strictly greater than \(\log_2(2h)\) at the intermediate cut,
whereas both neighboring mean entropies are at most that value.
\end{proof}

The turnover is a same-model entropy result. It is not the decoder
proof. In particular, leakage and optimal recovery error remain
nonincreasing through this entropy peak.

\begin{corollary}[Any prescribed nontrivial full-diamond tolerance]
\label{cor:tolerance}
For every \(0<\varepsilon<1\), choose
\[
 \zeta=\frac{\varepsilon^2}{8},
 \qquad
 2^m\ge\frac{4096}{\varepsilon^2}.
\]
There is one finite model and a set of Haar unitaries of measure
at least \(1/64\) on which
\[
 \norm{\Dchan_k\Nchan_k^U-\id_{16}}_\diamond
 \le\varepsilon
 \qquad(k_*\le k\le K),
\]
with the same decoder core, strict coherent rise-and-fall,
and a cutoff retaining one physical qubit.
\end{corollary}

\begin{proof}
The chosen \(h\) satisfies \eqref{eq:size}, and
\(2\sqrt{2\zeta}=\varepsilon\).
Apply Theorem~\ref{thm:joint}.
The nonduplicate condition is proved in Section~\ref{sec:nocopy}.
Since \(\varepsilon<1<2b_{16}\), the receiver is below the
purely classical recovery floor.
\end{proof}

\begin{example}[An analytic numerical certificate]
Let
\[
 \varepsilon=\frac15,\qquad
 \zeta=\frac1{200},\qquad
 m=17,\qquad h=131072.
\]
The size requirement is \(h\ge102400\).
The vault has \(21\) qubits, and the early receiver has \(17\).
The retained cuts are:
\[
\begin{array}{c|c|c|c}
\text{cut}&\text{late qubits}&\text{active residual qubits}
 &\text{total receiver qubits}\\
\hline
k_*=18&18&3&35\\
k_{\rm peak}=19&19&2&36\\
K=20&20&1&37
\end{array}
\]
The full-diamond allowance is \(0.2\), not \(0.1\).
The fixed decoder core has input dimension \(2^{35}\);
its Kraus rank is at most \(2^{39}\).
Equation~\eqref{eq:workspace} gives a conservative batch peak of
\(80\) live decoder qubits at the last cut.

This is an exact parameter calculation.
No Haar sample, decoder optimization, or hardware execution is reported.
\end{example}

\begin{remark}[Finite descriptions and stability]
The Haar existence statement is an ideal-control theorem.
It does not assert that a generic Haar matrix has a finite exact
description in a discrete gate alphabet.

A finite-description approximation can be obtained without changing
the operational interpretation. Apply Theorem~\ref{thm:joint}
with a stricter leakage target, for example \(\zeta/2\).
For a successful unitary, \(z_{k_*}<\zeta\) has a margin,
and the entropy inequalities have a strictly positive gap.
Channels and finite-dimensional entropy are continuous in \(U\);
more explicitly,
\[
 \ddiam(\Ad_U,\Ad_{U'})\le\norm{U-U'}_\infty.
\]
Hence sufficiently accurate finite gate approximations preserve
the leakage target and the strict entropy gap.
Dense finite gate families provide such approximations
\cite{Barenco}, while Proposition~\ref{prop:transfer} prices the
same decoder's return error.

This proves robustness and existence of finite-precision realizations,
not an executed search or an efficient compilation.
\end{remark}

%=====================================================================
\section{The classical obstruction and the surviving quantum mouth}
\label{sec:classical}
%=====================================================================

\begin{proposition}[Purely classical return is insufficient]
\label{prop:classical}
For a purely classical returned channel on a \(d\)-dimensional diary,
every deterministic decoder has
\[
 \ddiam(\Dchan\Mchan,\id_L)\ge b_d=1-\frac1d.
\]
Equivalently, its full-diamond error is at least \(2b_d\).
\end{proposition}

\begin{proof}
Decoding a classical channel is measure-and-prepare, hence
entanglement breaking \cite{EntanglementBreaking}.
Its Bell-input output is separable.
A normalized product vector has squared overlap at most \(1/d\)
with \(\ket{\Phi_d}\), and convexity extends the bound to separable
states. Testing the Bell projector gives error at least \(1-1/d\).
\end{proof}

This applies if the returned interface is an album only, including
the case in which both late cells and early memory are measured.
The packet obstruction in Em03-F is a separately specified instance
\cite{CheungEm03AF}.

\begin{example}[Enter plus surviving quantum memory: teleportation]
\label{ex:teleport}
Take \(d=2^\ell\) and prepare \(\ell\) Bell pairs \(HE\) before the
unknown diary is supplied.
A Bell transform on \(LH\) gives the complete expansion
\[
 V_{\rm tel}\ket\psi
 =
 \frac1d\sum_{z=1}^{d^2}\ket z_TW_z\ket\psi_E
 \otimes\ket0_S,
\]
where \(W_z\) are fixed Pauli corrections and \(S\) is an untouched
two-dimensional spectator.

Enter on \(T\) returns the hybrid channel
\[
 \Mchan(X)
 =
 \frac1{d^2}\sum_z
 \kb z z_Y\otimes W_zXW_z^\dagger.
\]
The CPTP receiver
\[
 \Dchan_{\rm tel}(Z)
 =
 \sum_z W_z^\dagger
   (\bra z_Y\otimes I_E)Z(\ket z_Y\otimes I_E)W_z
\]
satisfies \(\Dchan_{\rm tel}\Mchan=\id_L\), including references.

A complete measurement realization is the isometry
\[
 \ket z_T\longmapsto\ket z_Y\ket z_G.
\]
For the resulting complete channel \(L\to(YE)\otimes(GS)\),
the complement is
\[
 \rep{I_G/d^2\otimes\kb0 0_S}.
\]
Thus its physical residual is positive dimensional, although the
returned classical record alone is input independent.
\end{example}

This is standard teleportation, not recovery from classical data alone
\cite{Teleportation}.
The quantum output is carried by \(E\), and the Bell resource and
communication are part of the contract.

In the main Haar model, entering \(P_k\) and retaining \(E\)
produces a hybrid interface.
We neither assume that it remains recoverable nor apply the
record-only bound to it without further analysis.
Its Shannon record entropy is still append-only and nondecreasing.

%=====================================================================
\section{No duplicate logical exterior}
\label{sec:nocopy}
%=====================================================================

\begin{proposition}[No commuting duplicate action]
\label{prop:noduplicate}
For \(d\ge2\), there cannot be two commuting star representations
\(\pi_1,\pi_2\) of \(\BB(L)\) on the joint output which preserve the
code and satisfy
\[
 \pi_1(X)V=VX,\qquad \pi_2(X)V=VX
\]
for all \(X\in\BB(L)\).
\end{proposition}

\begin{proof}
For arbitrary \(X,Y\),
\[
 VXY=\pi_1(X)\pi_2(Y)V
     =\pi_2(Y)\pi_1(X)V=VYX.
\]
Injectivity of \(V\) would make every logical matrix commute.
This is false for \(d\ge2\).
\end{proof}

The intertwiners and code-preserving hypotheses are essential.
The proposition does not exclude commuting algebras of independent
degrees of freedom \cite{CheungHawk03A,Hawk06A}.

\begin{proposition}[Residual observables and approximate recovery]
\label{prop:residual}
If \(\Cchan=\rep{\tau_B}\), then
\[
 V^\dagger(I_R\otimes Z)V=\Tr(\tau_BZ)I_L
 \qquad(Z\in\BB(B)).
\]
If instead
\(\ddiam(\Cchan,\rep{\tau_B})\le\zeta\), then
\[
 \norm{
 V^\dagger(I_R\otimes Z)V-\Tr(\tau_BZ)I_L}_\infty
 \le2\zeta\norm Z_\infty
\]
for Hermitian \(Z\).

For the receiver \(R\), an \(e\)-accurate decoder has a unital CP
adjoint \(\Dchan^*\) satisfying
\[
 \norm{
 V^\dagger(\Dchan^*(X)\otimes I_B)V-X}_\infty
 \le2e\norm X_\infty
\]
for Hermitian logical \(X\).
This map need not be a star representation at nonzero error.
\end{proposition}

\begin{proof}
Apply channel trace/operator-norm duality to the complementary
comparison and to \(\Dchan\Nchan-\id_L\).
The exact formula is the zero-error specialization.
\end{proof}

Complement constancy therefore does not reconstruct an independently
variable \(\BB(B)\) from \(R\). It says that residual observables act
as scalars on the fixed logical task.

Moreover, if the residual is within \(\zeta\) of replacement, then
a receiver restricted to that residual has optimal recovery error
at least \(\max\{0,a_d-\zeta\}\), by \eqref{eq:lower}.
The recovered diary does not simultaneously become an independently
recoverable diary at the other mouth.

\begin{proposition}[No-cloning channel form]
No CPTP map clones every pure state of a nontrivial diary.
\end{proposition}

\begin{proof}
Dilate a proposed cloner. Pure clone marginals force
\[
 W\ket\psi=\ket\psi\ket\psi\ket{\chi_\psi}.
\]
For two input states with overlap modulus \(0<c<1\), isometry gives
\[
 c=c^2|\langle\chi_\phi\mid\chi_\psi\rangle|\le c^2,
\]
a contradiction.
\end{proof}

This is the standard semantic obstruction
\cite{WoottersZurek,CheungEnter}.
The accessible early memory is a resource correlated with \(H\),
not an additional copy of the unknown diary.
The only EPR-like structure used here is a declared Bell preparation;
no ER \(=\) EPR geometric consequence is inferred.

%=====================================================================
\section{The causal overlay and its communication ledger}
\label{sec:causal}
%=====================================================================

The release clock counts interface events, not spacetime distance.
An optional local implementation must add a site architecture,
a metric or graph-length convention, and charged operation times.

\begin{proposition}[Finite snapshot--support equivalence]
\label{prop:snapshot}
Let \(\Phi\) be a channel on a finite tensor-product system.
Let \(\mathcal A(I)\) and \(\mathcal A(Y)\) be the input and output
local algebras. The following are equivalent:
\begin{enumerate}[label=\textup{(\roman*)}]
\item the output reduction on \(Y\) factors through input reduction
on \(I\) by a CPTP map;
\item equal input reductions on \(I\) give equal output reductions
on \(Y\);
\item \(\Phi^*(\mathcal A(Y))\subseteq\mathcal A(I)\).
\end{enumerate}
The resulting equality of channels preserves external references.
\end{proposition}

\begin{proof}
Factorization gives equal-snapshot dependence and the adjoint
containment.

For the converse from equal snapshots, let \(A=A^\dagger\) be a
pulled-back output observable. If \(A\notin\mathcal A(I)\),
orthogonal projection in the Hilbert--Schmidt inner product gives
a nonzero Hermitian component \(F\) orthogonal to \(\mathcal A(I)\).
Then \(\Tr_{I^c}F=0\) and \(\Tr F=0\).
For sufficiently small \(t>0\), the states
\(I/\dim\HH\pm tF\) are positive, have equal \(I\)-reductions,
and distinguish \(A\), a contradiction.

Under containment, define the adjoint local map by restricting
\(\Phi^*\) to the embedded output algebra.
It is unital and completely positive because the inclusions
preserve matrix positivity. Its dual is CPTP and yields
factorization. Equality of linear maps is stable under reference
extension.
\end{proof}

This is the finite tensor version of the comparison discipline in
En05-A and En05-C \cite{CheungEn05AC}.

\begin{theorem}[Scheduled ancestry is an influence upper bound]
\label{thm:cone}
Let \((X,\mathrm{dist})\) be a supplied finite metric space.
At tick \(j\), let the channel be a product over partition blocks
of diameter at most \(\Delta\):
\[
 \Phi_j=\bigotimes_{B\in\mathcal P_j}\Phi_{j,B}.
\]
Define backward sets
\[
 N_{t,t}(Y)=Y,\qquad
 N_{s,t}(Y)
 =
 \bigcup\{B\in\mathcal P_{s+1}:B\cap N_{s+1,t}(Y)\ne\varnothing\}.
\]
Then
\[
 (\Phi_{s+1}^*\circ\cdots\circ\Phi_t^*)(\mathcal A(Y))
 \subseteq\mathcal A(N_{s,t}(Y)),
\]
\[
 N_{s,t}(Y)
 \subseteq\{x:\mathrm{dist}(x,Y)\le(t-s)\Delta\}.
\]
The result includes initially entangled states.
Unreported operations outside this ancestry cannot change the
terminal reduced output.
\end{theorem}

\begin{proof}
A block disjoint from the current observable support acts on identity,
which a channel adjoint preserves.
Backward induction gives the support inclusion.
Each backward step adds at most one block diameter, so the triangle
inequality gives the metric envelope.
Proposition~\ref{prop:snapshot} supplies reduced-channel dependence.
The proof uses no assumption of initial product states.
\end{proof}

If a tick has supplied duration \(\tau\), then
\(\Delta/\tau\) is the schedule-speed envelope.
It is not extracted from entanglement, and its upper-bound support
need not equal the actual influence region
\cite{CheungEn05AC,CheungEn06B}.

A logical wire routed by SWAPs with reserved blanks is the identity
channel on its payload, including references.
Following a topological order of a fixed routed circuit therefore
preserves its complete instrument. If the payloads have compatible
half-diamond allowances \(\eta_v\), replacing them one at a time
gives total error at most \(\sum_v\eta_v\) by contraction.
These are channel-routing statements, not metric reconstruction.

\subsection{Entanglement does not provide free signaling}

\begin{proposition}[No signaling by an unreported local operation]
\label{prop:nosignal}
For every bipartite state \(\rho_{AB}\) and TP local channel
\(\Lambda_A\),
\[
 \Tr_A[(\Lambda_A\otimes\id_B)(\rho_{AB})]=\Tr_A\rho_{AB}.
\]
Thus a Bell resource alone cannot signal a later choice at \(A\)
to \(B\).
\end{proposition}

\begin{proof}
For every \(B\)-observable \(Z\), the pulled-back observable is
\[
 \Lambda_A^*(I_A)\otimes Z=I_A\otimes Z.
\]
Expectations and hence reduced states agree.
\end{proof}

In Example~\ref{ex:teleport}, before the classical label \(z\)
arrives, the receiver's state is
\[
 \frac1{d^2}\sum_zW_zXW_z^\dagger
 =
 \Tr(X)I_E/d.
\]
Only communication of \(z\), followed by the declared correction,
returns the diary. For \(\ell\) qubits, the label has \(2\ell\)
classical bits. Resource preparation, measurement, message
transport, and correction have to be placed in the schedule
\cite{Teleportation,CheungEn05AC}.
A constant local overhead is not super-cone transport.

In the main Haar model, released quantum cells themselves cross
a declared control interface. Their transfer is the communication
resource. No signaling without that transfer is claimed.

\subsection{Scheduler consistency does not determine a Lorentz metric}

A finite dependency graph can terminate, admit order-independent
evaluation of independent vertices, and preserve causal ancestry
without determining a metric. The same graph can be equipped with
arbitrarily rescaled supplied edge lengths and tick durations,
with no change to its channel contractions or records.

Consequently neither a proper throat length nor a Lorentzian metric
follows from the schedule alone. Additional representation hypotheses
are required for a Lorentz-cone theorem
\cite{CheungEn08A}.
No such reconstruction is attempted here.

%=====================================================================
\section{Terminal discard, the endpoint, and three separate ledgers}
\label{sec:endpoint}
%=====================================================================

\begin{proposition}[Residual readout and forgetting]
\label{prop:drop}
For the declared residual interface,
\[
 \Drop\circ\Enter_B=\Tr_B,
\]
including untouched references and all surviving receiver factors.
Thus residual readout and forgetting leave \(\Nchan\) unchanged.
The same is true for any unreported TP local residual operation.
\end{proposition}

\begin{proof}
Expand an operator as
\[
 X=\sum_{i,j}X_{ij}\otimes\kb i j_B.
\]
Readout and forgetting return \(\sum_iX_{ii}=\Tr_BX\).
The general TP assertion follows from the adjoint identity
\(\Lambda_B^*(I_B)=I_B\).
\end{proof}

Here Enter consumes a quantum name; \(\Drop\) subsequently forgets
a classical record. Neither notation specifies physical annihilation.

\begin{proposition}[The complete complement cannot be deleted
by changing returned names]
\label{prop:physicaldiscard}
Suppose the terminal residual operation is realized completely by
an isometry \(W_B:B\to B'\), including every unreturned record store
and measurement environment. Then
\[
 \Cchan'=\Ad_{W_B}\Cchan,
 \qquad
 \dleak(\Cchan')=\dleak(\Cchan).
\]
Its accessible channel is the same \(\Nchan\).
\end{proposition}

\begin{proof}
Tracing \(B'\) after the isometry is tracing \(B\), so the accessible
channel is unchanged.

For any comparison state \(\tau_B\), the isometry maps it to a
comparison state on \(B'\) and preserves trace norm with references.
This gives \(\dleak(\Cchan')\le\dleak(\Cchan)\).
A CPTP left inverse of the isometric channel exists by
Proposition~\ref{prop:global}. Applying it to any replacement
comparison on \(B'\) gives the reverse inequality.
\end{proof}

Operational discard can remove the residual from the returned address
space without making the physical complete complement trivial.
Its bookkeeping cannot be used to force leakage to zero.

\subsection{The four endpoint obligations}

The following table adapts En07-B's endpoint discipline to the
objects actually supplied here \cite{CheungEn07B}.

\begin{center}
\small
\renewcommand{\arraystretch}{1.12}
\begin{tabularx}{\linewidth}{@{}p{.29\linewidth}X@{}}
\toprule
Obligation & Status in Hawk07-A\\
\midrule
Complete preparation &
Supplied: independent \(HE\) Bell resource, variable diary,
fixed \(F\), and untouched references.\\
Complete evolution &
Supplied in the ideal finite model: one \(U\), named factor
regroupings, and any explicitly included terminal dilations.\\
Outgoing access and access-preserving comparison &
Supplied: \(R_k=P_kE\), excluding \(B_k\).
The exact finite comparison is identity on those named interfaces.
Physical approximations remain conditional on their declared
allowances.\\
Endpoint map &
Supplied on the successful devices: the fixed receiver
\(\Dchan_*\Pi_{K\to k_*}\), with its displayed error.\\
\bottomrule
\end{tabularx}
\end{center}

For the gravitational interpretation, all corresponding microscopic,
geometric, collection, and receiver identifications remain
unsupplied. The finite table does not discharge those physical
obligations.

\subsection{Purity, thermodynamics, and leakage}

The complete prepared evolution preserves the purity of a pure
diary--reference input with its retained preparation purifiers.
This is not a theorem of energy conservation or heat production.

Readout-and-forgetting equality does not determine heat, work, or
cyclic memory-reset cost. As a direct example, SWAP with a blank qubit
implements the same reset channel for every common excitation gap
\(\epsilon_{\rm gap}>0\), while transferring energy
\(\epsilon_{\rm gap}p\) for input excitation probability \(p\).
The blank resource is consumed and the information moves to its
unreturned carrier; a cyclic reset would also have to restore that
resource \cite{CheungEn07A}.

Complete purity, thermodynamic reset, and input-dependent residual
leakage are therefore separate ledgers.
No \(k_{\rm B}T\ln2\) conclusion follows from channel notation alone.

An externally supplied luminosity
\[
 \dot M=-\lambda/M^2,\qquad M_{\rm cut}>0
\]
would give
\[
 t_{\rm cut}-t_0
 =
 \frac{M_0^3-M_{\rm cut}^3}{3\lambda}.
\]
This elementary integration does not identify the cell clock with
mass evolution, establish an energy condition, or prove a
below-cutoff endpoint \cite{CheungHawk04D}.
No such luminosity or temperature schedule is needed here.

\subsection{The finite endpoint is not permanent evaporation}

The cutoff in Corollary~\ref{cor:tolerance} retains one physical
qubit before any terminal readout.
A stopped program can then remove its name from the returned
interface, but its physical state and complete environment have
not been annihilated.

A fixed finite autonomous Hamiltonian with a fixed access partition
can have arbitrarily late recurrences of its complete channel.
This follows by simultaneous recurrence of its finitely many
eigenvalue phases. It is a different model from a terminated,
isolated-output schedule \cite{CheungHawk04AB}.
Neither finite termination nor recurrence proves a gravitational
pinch-off or disappearance of a universe.

%=====================================================================
\section{The corrected laboratory analogy}
\label{sec:analogy}
%=====================================================================

\paragraph{Before the receiver is available.}
An unknown diary enters a finite vault.
A Bell resource between old-vault cells and early receiver memory
has already been prepared. The inaccessible test reference remains
outside the receiver's control.
At cut zero, the early receiver is exactly independent of the diary.
There is global restoration, but no outgoing diary decoder.

\paragraph{Two mouths and a channel called a throat.}
The control system names an accessible register and a complete
residual. They can be drawn as two mouths.
The inaccessible channel can be drawn as a throat.
These drawings add no third system or spatial connection.
The physical residual is not a second exterior universe.

\paragraph{The transfers are the communication.}
The declared schedule hands over cells.
That handover, or its SWAP implementation, is an actual resource.
It is not traversal generated by looking at the diagram.
A Haar hypothesis is an added assumption about the device,
not a consequence of the name ``wormhole.''

\paragraph{The neck does not diagnose a recovery maximum.}
An entropy envelope compares \(r_k\) with \(b_kh\).
The recovery calculation compares the complete complementary channel
with a replacement channel.
These are different calculations.
In this model recovery error and leakage decrease under nested
access, even when coherent entropy rises to a peak.

\paragraph{Operationally traversable.}
After the certified threshold, one declared decoder core returns
the diary with its untouched reference correlations within the
stated allowance.
This is operational traversability.
The residual still exists and is not operated on by the decoder.
No independently variable residual diary is reconstructed.

\paragraph{Film and album.}
The coherent receiver stores a quantum film.
An Enter-only receiver has an album.
The album's cumulative Shannon entropy cannot fall.
If a genuine early quantum register survives, however, the return
type is hybrid rather than album-only. Teleportation can use that
quantum resource and a communicated label; it does not restore an
unknown state from photographs alone.

\paragraph{Termination is not pinch-off.}
Residual Enter followed by forgetting is partial trace on the returned
interface. The program reaches its last instruction.
No gravitational region shrinks to zero by that instruction,
and no final explosion or remnant-free endpoint has been proved.

The wormhole is the overlay. The complete encoding, the access
restriction, and the specified receiver are the mathematical result.

%=====================================================================
\section{The Hawk07-A existence theorem}
\label{sec:main}
%=====================================================================

\begin{theorem}[Existence of finite operational wormhole certificates]
\label{thm:main}
For every \(0<\varepsilon<1\), there is a declared finite Enter model
with a diary of dimension \(16\), an independent entangled
preparation, one Haar unitary, a threshold \(k_*\), and a
positive-residual cutoff \(K\), such that a set of sampled unitaries
of Haar measure at least \(1/64\) has the following properties:
\begin{enumerate}[label=\textup{(\roman*)}]
\item for every retained cut \(k_*\le k\le K\),
\[
 (V_k^U,R_k,B_k,\Dchan_k,\varepsilon)
\]
is an operational wormhole certificate;
\item \(\Dchan_k\) uses one fixed decoder core and the nested discard
policy, never physical \(B_k\) or the test reference;
\item for one fixed pure input independent of the sampled unitary,
late-radiation entropy rises and falls strictly within the
three-cut retained window;
\item every append-only destructive Enter record has nondecreasing
Shannon entropy;
\item the cutoff retains one physical vault qubit;
\item no second commuting, code-preserving representation of the
same noncommutative diary algebra is produced;
\item terminal residual readout and forgetting leave the already
returned accessible channel unchanged.
\end{enumerate}

This is not a gravitational island, a quantum extremal surface,
a replica wormhole, an Einstein--Rosen bridge, a Morris--Thorne
throat, a gravitational evaporation Page curve, or spacetime
emergence. The separately inherited analytic admission gates are
not opened or discharged by this theorem.
\end{theorem}

\begin{proof}
Use the parameter choice in Corollary~\ref{cor:tolerance}.
The complete prepared isometry is \eqref{eq:V}, the accessible
interface is \(R_k=P_kE\), and the residual is \(B_k\).
The exact Haar calculation, single-cut probability estimate, and
nested monotonicity give the complementary certificate.

Theorem~\ref{thm:decoder} supplies one fixed receiver core and
full-diamond error at most \(\varepsilon\) throughout the window.
Theorem~\ref{thm:joint} gives strict same-device entropy turnover
and the positive cutoff.
Proposition~\ref{prop:record} gives record monotonicity.
Propositions~\ref{prop:noduplicate} and \ref{prop:drop} give the
last two assertions.

None of the declared data contains a spacetime metric, geometric
throat, gravitational stress tensor, or causal crossing through
such a throat. The excluded identifications are therefore not
conclusions of the construction.
\end{proof}

\subsection{What a gravitational successor would still need}

A gravitational wormhole claim would have to identify, in one model:
\begin{enumerate}
\item the metric or justified effective geometry and the regions
called mouths and throat;
\item its gravitational equations and the matter or quantum stress
assumptions appropriate to the claim;
\item the relevant causal structure and boundary conditions;
\item an injection, propagation, and extraction experiment supporting
a signal-crossing claim;
\item the microscopic input, all inaccessible outputs, and a physical
receiver or collection interface;
\item quantitative comparisons between those objects and any finite
channel proxy.
\end{enumerate}

An energy-condition statement must be supplied rather than inferred
from entanglement. Different wormhole constructions have different
physical assumptions; the finite certificate proves no universal
gravitational energy-condition theorem
\cite{MorrisThorne,GaoJafferisWall}.

Em03-A's supplied calculation uses a prescribed Schwarzschild
background and horizon. It does not generate a new horizon or
wormhole from this schedule \cite{CheungEm03AF}.
The ER \(=\) EPR proposal and gravitational teleportation accounts
remain external comparisons
\cite{MaldacenaSusskind,MaldacenaStanfordYang}.
They are not a geometric dictionary for the finite certificate.

%=====================================================================
\appendix
\section{Independent inherited analytic stops}
\label{app:stops}
%=====================================================================

The supplied XIV-I and XIV-J passages concern a different,
characteristic-distribution problem. Constructed internal amplitudes
at I2 do not supply the full joint characteristic map at I3/J2.
The supported-sector reference is not the complete six-branch
construction \cite{CheungXIVIJ}.

The supplied XV-B version 2 establishes abstract lifting and extension
interfaces while retaining an unresolved graph-specific map.
It is not absent as a manuscript; rather, the downstream
quantum-admission exit remains unopened.
XVI-N's stated special-family obstruction and its remaining universal
obligation are also different from this finite channel problem
\cite{CheungXVBXVIN}.

In the supplied documentary scope:
\[
 \boxed{
 \text{XV-B admission exit not opened},\qquad
 \text{XVI-N not discharged},\qquad
 O.1=\texttt{NOT\_CLOSED}.
 }
\]
Hawk07-A admits no inherited characteristic quantum coefficient.
These are scoped provenance statements, not new universal
nonexistence theorems \cite{CheungXVIO,CheungPhilosophy}.

The OpenAI catalogue and Family 265 are documentary comparisons,
not premises. A static area-law record does not supply a temporal
radiation channel or throat area \cite{CheungOai265}.
No catalogue verification or characteristic-map completion is asserted.

%=====================================================================
\section*{Declarations}
\addcontentsline{toc}{section}{Declarations}
%=====================================================================

\paragraph{Mathematical scope.}
The new term ``operational wormhole certificate'' denotes a
reference-preserving recovery contract.
The exact correction criterion, information--disturbance theorem,
teleportation mechanism, and diamond-norm optimization are established
quantum-information theory. No priority claim is made for those results.

\paragraph{Local contribution.}
The manuscript assembles one complete finite model, proves its
displayed Haar moment and probability constants, gives one fixed
decoder policy over a nontrivial retained window, and proves coexistence
of that certificate with a strict three-cut entropy peak.
The false intermediate leakage/recovery peak and the overextended
classical-record obstruction are explicitly removed.

\paragraph{Source provenance.}
Cheung's philosophy essay and journal article are cited separately
from internal manuscript records supplied in the request.
Hawk06-A is a supplied predecessor; its attribution follows the
request's source record and is not an independent publication
verification. Internal identifiers do not establish publication,
acceptance, or proof checking.

\paragraph{Physical scope.}
No gravitational wormhole, spacetime emergence, exotic matter,
null-energy violation, new horizon, thermal machine, or gravitational
signal crossing is constructed. Entanglement is a declared resource,
not a metric.

\paragraph{Implementation scope.}
The ideal receiver has a finite-dimensional prescription and priced
batch realization under stated controls. No efficient optimization,
finite-alphabet exact Haar compilation, laboratory calibration,
or experiment has been executed.

\paragraph{Verification.}
This is standalone source intended for \texttt{pdflatex}.
No successful compilation, proof-assistant verification, numerical
execution, independent referee approval, or journal acceptance of
Hawk07-A is asserted.

%=====================================================================
\begin{thebibliography}{99}
\addcontentsline{toc}{section}{References}
%=====================================================================

\bibitem{CheungPhilosophy}
N.~Cheung,
\emph{The Philosophy of Enter: Destructive Readout, Quantum Recovery,
and the Refusal of Identification}.
EntPhil, version 2, Enter Calculus Companion.
Introductory essay, not a registered theorem premise.
\url{https://enter.grok.me/enter}.

\bibitem{CheungEnter}
N.~Cheung,
``The Enter Calculus: A Linear Quantum Lambda Calculus with an
Operational Characterization of Measurement.''
\emph{Frontiers in Physics}, volume 14 (2026).
DOI: \url{https://doi.org/10.3389/fphy.2026.1954943}.
Publisher author name: Ngo Cheung.
Publisher record identifies an accepted article; no independent
verification of its proofs is claimed here.

\bibitem{CheungI}
N.~Cheung,
\emph{Manuscript I}, version 2.
Enter Calculus Companion.
Supplied measurement-characterization and no-cloning passages.
No external publication date is inferred.

\bibitem{Hawk06A}
N.~Cheung, as attributed in the supplied source record,
\emph{Hawk06-A: Existence of Operational Islands in a Finite Enter Model},
version 1.
Supplied predecessor manuscript.
The local recovery and entropy calculations are reproduced and
adapted here; publication status is not assumed.

\bibitem{CheungHawk04AB}
N.~Cheung,
\emph{Hawk04-A}, version 1, and
\emph{Hawk04-B}, version 2.
Enter Calculus Companion.
Supplied complete restoration, full-code correction, classical-return,
discard, and finite-recurrence passages.

\bibitem{CheungEn07B}
N.~Cheung,
\emph{En07-B}, version 1.
Enter Calculus Companion.
Supplied four same-model endpoint obligations,
complete-complement criterion, and endpoint certificate.

\bibitem{CheungOai280290}
N.~Cheung,
\emph{Oai280-C}, version 1, and
\emph{Oai290-A}, version 1.
Enter Calculus Companion.
Supplied distinctions among whole-code recovery, subsystem recovery,
finite algebra, and named-observable tasks.

\bibitem{CheungHawk05BC}
N.~Cheung, attribution in the supplied manuscript records,
\emph{Hawk05-B}, version 1, and
\emph{Hawk05-C}, version 1.
Enter Calculus Companion.
Supplied Haar Page--Sen, record-entropy, capacity-clock, and
separate recovery-certificate passages.

\bibitem{CheungEn02BC}
N.~Cheung,
\emph{En02-B}, version 1, and
\emph{En02-C}, version 1.
Enter Calculus Companion.
Supplied batch decoder, streaming-memory obstruction, postselected
Hayden--Preskill identity, and decoder-resource passages.
Benchmark-specific statements are not imported as unrestricted optima.

\bibitem{CheungHawk03A}
N.~Cheung,
\emph{Hawk03-A}, version 1.
Enter Calculus Companion.
Supplied encoded-partner algebra and no commuting duplicate
logical-action comparisons.

\bibitem{CheungHawk04D}
N.~Cheung,
\emph{Hawk04-D}, version 1.
Enter Calculus Companion.
Supplied access-preserving transfer, positive-cutoff luminosity,
and conditional endpoint comparisons.

\bibitem{CheungEn05AC}
N.~Cheung,
\emph{En05-A}, version 1, and
\emph{En05-C}, version 1.
Enter Calculus Companion.
Supplied schedule locality, entanglement-assisted communication,
and snapshot--adjoint factorization passages.

\bibitem{CheungEn06B}
N.~Cheung,
\emph{En06-B}, version 1.
Enter Calculus Companion.
Supplied complete instrument preservation under declared routing
and compatible payload-error budgets.

\bibitem{CheungEn08A}
N.~Cheung,
\emph{En08-A}, version 1.
Enter Calculus Companion.
Supplied failure of metric reconstruction from scheduler consistency
and separately hypothesized cone-representation theorem.

\bibitem{CheungEn07A}
N.~Cheung,
\emph{En07-A}, version 1.
Enter Calculus Companion.
Supplied readout-and-forgetting identity and
\texttt{prop:no-landauer-from-channel}.

\bibitem{CheungEm03AF}
N.~Cheung,
\emph{Em03-A}, version 1, and
\emph{Em03-F}, version 1.
Enter Calculus Companion.
Supplied fixed-background scalar emission law and separately declared
entanglement-breaking packet obstruction.
Not a complete microscopic wormhole or evaporation channel.

\bibitem{CheungOai265}
N.~Cheung,
\emph{Oai265-A}, version 2.
Enter Calculus Companion.
Supplied static area-law record and separation from recovery and
radiation history. Family 265 is not verified here.

\bibitem{CheungXIVIJ}
N.~Cheung,
\emph{XIV-I}, version 1, and
\emph{XIV-J}, version 1.
Enter Calculus Companion.
Supplied constructed internal-amplitude gate and unresolved
full-characteristic-map and quantum-admission boundaries.

\bibitem{CheungXVBXVIN}
N.~Cheung,
\emph{XV-B}, version 2, and
\emph{XVI-N}, version r12.
Enter Calculus Companion.
Supplied lifting-interface, graph-specific unresolved map,
conditional massless obstruction, and remaining universal-obligation
records.

\bibitem{CheungXVIO}
N.~Cheung,
\emph{XVI-O}, revision o70-sync.
Enter Calculus Companion.
Supplied separation of kernel-subsector progress from
bulk \(O.1=\texttt{NOT\_CLOSED}\).

\bibitem{KnillLaflamme}
E.~Knill and R.~Laflamme,
``Theory of quantum error-correcting codes.''
\emph{Physical Review A} \textbf{55} (1997), 900--911.
DOI: \url{https://doi.org/10.1103/PhysRevA.55.900}.

\bibitem{KSW}
D.~Kretschmann, D.~Schlingemann, and R.~F.~Werner,
``The information-disturbance tradeoff and the continuity of
Stinespring's representation.''
\emph{IEEE Transactions on Information Theory}
\textbf{54} (2008), 1708--1717.
DOI: \url{https://doi.org/10.1109/TIT.2008.917696}.
\url{https://arxiv.org/abs/quant-ph/0605009}.

\bibitem{WatrousBook}
J.~Watrous,
\emph{The Theory of Quantum Information}.
Cambridge University Press, 2018.
Author's manuscript:
\url{https://cs.uwaterloo.ca/~watrous/TQI/TQI.pdf}.

\bibitem{WatrousSDP}
J.~Watrous,
``Simpler semidefinite programs for completely bounded norms.''
\emph{Chicago Journal of Theoretical Computer Science}
\textbf{2013}, article 8.
\url{https://arxiv.org/abs/1207.5726}.

\bibitem{Barenco}
A.~Barenco, C.~H.~Bennett, R.~Cleve, D.~P.~DiVincenzo,
N.~Margolus, P.~Shor, T.~Sleator, J.~A.~Smolin, and H.~Weinfurter,
``Elementary gates for quantum computation.''
\emph{Physical Review A} \textbf{52} (1995), 3457--3467.
DOI: \url{https://doi.org/10.1103/PhysRevA.52.3457}.

\bibitem{HaydenPreskill}
P.~Hayden and J.~Preskill,
``Black holes as mirrors: quantum information in random subsystems.''
\emph{Journal of High Energy Physics}
\textbf{2007}(09), 120.
DOI: \url{https://doi.org/10.1088/1126-6708/2007/09/120}.
\url{https://arxiv.org/abs/0708.4025}.

\bibitem{YoshidaKitaev}
B.~Yoshida and A.~Kitaev,
\emph{Efficient decoding for the Hayden--Preskill protocol}.
arXiv:1710.03363.
\url{https://arxiv.org/abs/1710.03363}.

\bibitem{PageAverage}
D.~N.~Page,
``Average entropy of a subsystem.''
\emph{Physical Review Letters} \textbf{71} (1993), 1291--1294.
DOI: \url{https://doi.org/10.1103/PhysRevLett.71.1291}.
\url{https://arxiv.org/abs/gr-qc/9305007}.

\bibitem{Sen}
S.~Sen,
``Average entropy of a subsystem.''
\emph{Physical Review Letters} \textbf{77} (1996), 1--3.
DOI: \url{https://doi.org/10.1103/PhysRevLett.77.1}.
\url{https://arxiv.org/abs/hep-th/9601132}.

\bibitem{EntanglementBreaking}
M.~Horodecki, P.~W.~Shor, and M.~B.~Ruskai,
``Entanglement breaking channels.''
\emph{Reviews in Mathematical Physics}
\textbf{15} (2003), 629--641.
DOI: \url{https://doi.org/10.1142/S0129055X03001709}.
\url{https://arxiv.org/abs/quant-ph/0302031}.

\bibitem{Teleportation}
C.~H.~Bennett, G.~Brassard, C.~Cr\'epeau, R.~Jozsa,
A.~Peres, and W.~K.~Wootters,
``Teleporting an unknown quantum state via dual classical and
Einstein--Podolsky--Rosen channels.''
\emph{Physical Review Letters} \textbf{70} (1993), 1895--1899.
DOI: \url{https://doi.org/10.1103/PhysRevLett.70.1895}.

\bibitem{WoottersZurek}
W.~K.~Wootters and W.~H.~Zurek,
``A single quantum cannot be cloned.''
\emph{Nature} \textbf{299} (1982), 802--803.
DOI: \url{https://doi.org/10.1038/299802a0}.

\bibitem{EinsteinRosen}
A.~Einstein and N.~Rosen,
``The particle problem in the general theory of relativity.''
\emph{Physical Review} \textbf{48} (1935), 73--77.
DOI: \url{https://doi.org/10.1103/PhysRev.48.73}.

\bibitem{MorrisThorne}
M.~S.~Morris and K.~S.~Thorne,
``Wormholes in spacetime and their use for interstellar travel:
A tool for teaching general relativity.''
\emph{American Journal of Physics} \textbf{56} (1988), 395--412.
DOI: \url{https://doi.org/10.1119/1.15620}.

\bibitem{MaldacenaSusskind}
J.~Maldacena and L.~Susskind,
``Cool horizons for entangled black holes.''
\emph{Fortschritte der Physik} \textbf{61} (2013), 781--811.
DOI: \url{https://doi.org/10.1002/prop.201300020}.
\url{https://arxiv.org/abs/1306.0533}.

\bibitem{GaoJafferisWall}
P.~Gao, D.~L.~Jafferis, and A.~C.~Wall,
``Traversable wormholes via a double trace deformation.''
\emph{Journal of High Energy Physics}
\textbf{2017}(12), 151.
\url{https://arxiv.org/abs/1608.05687}.

\bibitem{MaldacenaStanfordYang}
J.~Maldacena, D.~Stanford, and Z.~Yang,
``Diving into traversable wormholes.''
\emph{Fortschritte der Physik} \textbf{65} (2017), 1700034.
DOI: \url{https://doi.org/10.1002/prop.201700034}.
\url{https://arxiv.org/abs/1704.05333}.

\end{thebibliography}

\end{document}