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themathqueen committed Jun 24, 2024
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4 changes: 2 additions & 2 deletions blueprint/src/chapters/ips.tex
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Expand Up @@ -197,11 +197,11 @@ \section{The modular automorphism}
\begin{proof}\uses{modAut_real_apply, dual_eq_trace}\leanok
Let $x,y\in{B}$. Then we compute
\begin{align*}
\ip{x}{\sigma_{t}^*(y)} &= \ip{\sigma_{t}(x)}{y}=\psi({\sigma_{t}(x)}^*y)=\psi(\sigma_{-t}(x^*)y) &\text{by \ref{modAut_real_apply}}\\
\ip{x}{\sigma_{t}^*(y)} &= \ip{\sigma_{t}(x)}{y}=\psi({\sigma_{t}(x)}^*y)=\psi(\sigma_{-t}(x^*)y)\\
&=\Tr(Q\sigma_{-t}(x^*)y)=\Tr(QQ^tx^*Q^{-t}y)\\
&= \Tr(Q x^*Q^{-t}yQ^t)=\ip{x}{\sigma_{t}(y)}.
\end{align*}
Thus $\sigma_{t}$ is self-adjoint. Note that we used the fact $\psi\colon x\mapsto\Tr(Q x)$ (Proposition \ref{dual_eq_trace}).
Thus $\sigma_{t}$ is self-adjoint.
\end{proof}

\begin{corollary}\label{modAut_isCoalgHom}\uses{modAut}
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57 changes: 55 additions & 2 deletions blueprint/src/chapters/quantumset.tex
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Expand Up @@ -4,7 +4,7 @@ \chapter{Quantum sets}
\uses{LinearMap.real, FiniteDimensionalCoAlgebra_isFrobeniusAlgebra_of, isAlgHom_iff_adjoint_isCoalgHom}
\lean{QuantumSet}\leanok
Given a $^*$-algebra $(\mathcal{A},m,\eta)$ that is also a finite-dimensional Hilbert space,
we say it is a \textit{quantum set} when there is a modular automorphism $\sigma_t\colon\mathcal{A}\cong\mathcal{A}$, which is an algebra automorphism for each $t\in\RR$, and that the following properties are satisfied:
we say it is a \textit{quantum set} when there is a modular automorphism $\sigma_t\colon\mathcal{A}\cong\mathcal{A}$, which is an algebra automorphism for each $t\in\mathbb{R}$, and that the following properties are satisfied:
\begin{enumerate}
\item $\sigma_t\circ\sigma_s=\sigma_{t+s}$,
\item $\sigma_0=\id$,
Expand All @@ -15,9 +15,62 @@ \chapter{Quantum sets}
\end{enumerate}
By Proposition \ref{FiniteDimensionalCoAlgebra_isFrobeniusAlgebra_of}, we see that $(\mathcal{A},m,\eta)$ is a Frobenius algebra.

And by Proposition \ref{isAlgHom_iff_adjoint_isCoalgHom}, we can see that for any $t\in\RR$, we get $\sigma_t$ is also a co-algebra homomorphism.
And by Proposition \ref{isAlgHom_iff_adjoint_isCoalgHom}, we can see that for any $t\in\mathbb{R}$, we get $\sigma_t$ is also a co-algebra homomorphism.

We can easily see that we get $\ip{x}{y}=\eta^*(x^*y)$ for all $x,y\in\mathcal{A}$.
\end{definition}

Clearly, the Hilbert space of $\bigoplus_iM_{n_i}$ given by a positive and faithful linear functional $\psi$ (Definition \ref{PiMat.InnerProductSpace}) is a quantum set with modular automorphism defined in Definition \ref{modAut}.

\begin{lemma}\label{ket_real}\uses{LinearMap.real, ket}\lean{ket_real}\leanok
Given a Hilbert space $\Hcal$ that is also a $^*$-algebra, and $x\in\Hcal$, we get $\ket{x}^{\operatorname{r}}=\ket{x^*}$.
\end{lemma}
\begin{proof}\leanok
\[{\ket{x}(1^*)}^*=\ket{x^*}(1).\]
\end{proof}

\begin{lemma}\label{bra_real}\uses{LinearMap.real, bra, QuantumSet}\lean{bra_real}\leanok
Given a quantum set $(\mathcal{A},m,\eta,\sigma_r)$ and $x\in\mathcal{A}$, we get $\bra{x}^{\operatorname{r}}=\bra{\sigma_{-1}(x^*)}$.
\end{lemma}
\begin{proof}\leanok
\[{\bra{x}(y^*)}^*=\ip{y^*}{x}=\ip{\sigma_{-1}(x^*)}{y}=\bra{\sigma_{-1}(x^*)}(y).\]
\end{proof}
\begin{corollary}\label{rankOne_real}
\uses{QuantumSet, LinearMap.real}
\lean{rankOne_real}\leanok
Given quantum sets $(\mathcal{A}_1,m_1,\eta_1,\sigma_r)$ and $(\mathcal{A}_2,m_2,\eta_2,\vartheta_r)$, and elements $a\in\mathcal{A}_1$ and $b\in\mathcal{A}_2$, we get
\[\ketbra{a}{b}^{\operatorname{r}}=\ketbra{a^*}{\theta_{-1}(b^*)}.\]
\end{corollary}
\begin{proof}\uses{ket_real, bra_real, LinearMap.real_comp}\leanok
Use Lemmas \ref{ket_real}, \ref{bra_real}, and \ref{LinearMap.real.comp}.
\end{proof}

\begin{proposition}\label{LinearMap.adjoint_real_eq}
\uses{LinearMap.real, QuantumSet}
\lean{LinearMap.adjoint_real_eq}\leanok
Given quantum sets $(\mathcal{A}_1,m_1,\eta_1,\sigma_r)$ and $(\mathcal{A}_2,m_2,\eta_2,\vartheta_r)$, and $f\colon\mathcal{A}_1\to\mathcal{A}_2$, we get
\[ f^{*\operatorname{r}}=\vartheta_1f^{\operatorname{r}*}\sigma_{-1}.\]
\end{proposition}
\begin{proof}\leanok
Let $x\in{\mathcal{A}_2}$ and $y\in \mathcal{A}_1$, and compute,
\begin{align*}
\ip{{A^{*\operatorname{r}}}(x)}{y} &= \ip{{A^*(x^*)}^*}{y} =\ip{y^*}{\sigma_{-1}(A^*(x^*))}\\
&= \ip{A(\sigma_{-1}(y^*))}{x^*}\\
&= \ip{A({\sigma_{1}(y)}^*)}{x^*}
= \ip{x}{\vartheta_{-1}A^{\operatorname{r}}\sigma_{1}(y)}\\
&= \ip{\sigma_{1}A^{\operatorname{r}*}\vartheta_{-1}(x)}{y}
\end{align*}
Thus, $A^{*\operatorname{r}}=\sigma_{1}A^{\operatorname{r}*}\vartheta_{-1}$.
\end{proof}


\begin{definition}\label{QuantumSet.Psi}
\uses{QuantumSet}
\lean{QuantumSet.Psi}\leanok
Given quantum sets $(\mathcal{A}_1,m_1,\eta_1,\sigma_r)$ and $(\mathcal{A}_2,m_2,\eta_2,\vartheta_r)$, then for each $t,r\in\mathbb{R}$, we define $\Psi_{t,r}$ to be the linear isomorphism from $\Bcal(\mathcal{A}_1,\mathcal{A}_2)$ to $\mathcal{A}_2\otimes\mathcal{A}_1^{\operatorname{op}}$ given by
\[\Psi_{t,r}(\ketbra{a}{b})=\vartheta_t(a)\otimes{\sigma_r(b)}^{*\operatorname{op}},\]
with inverse given by
\[\Psi_{t,r}^{-1}(a\otimes b^{\operatorname{op}})=\ketbra{\sigma_{-t}(a)}{\vartheta_{-r}(b^*)}.\]
\end{definition}


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