some tests

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Daniel Knüttel 2019-11-05 11:21:26 +01:00
parent c2a01d0c19
commit 3853290d42
2 changed files with 38 additions and 7 deletions

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@ -37,21 +37,21 @@ Where $X = \left(\begin{array}{cc} 0 & 1 \\ 1 & 0\end{array}\right)$,
C_n := \{U \in SU(2) | UpU^\dagger \in P_n \forall p \in P_n\}
\end{equation}
is called the Clifford group on $n$ qbits.
$C_1 =: C_L$ is called the local Clifford group.
$C_1$ is called the local Clifford group.
\end{definition}
One can show that the Clifford group $C_n$ can be generated using the elements of $C_L$ acting on all qbits and
One can show that the Clifford group $C_n$ can be generated using the elements of $C_1$ acting on all qbits and
the controlled phase gate $CZ$ between all qbits\cite{andersbriegel2005}. It is worth noting that the $CX$ gate can be
generated using $CZ$ and $C_L$ gates.
generated using $CZ$ and $C_1$ gates.
\begin{lemma}
Let $a \in C_L$ then $\forall \phi \in [0, 2\pi)$ also $\exp(i\phi)a \in C_L$.
Let $a \in C_1$ then $\forall \phi \in [0, 2\pi)$ also $\exp(i\phi)a \in C_1$.
\textbf{Note}: This is also true for $C_n \forall n >= 1$.
\end{lemma}
\begin{proof}
Let $a' := \exp(i\phi)a$. $a' \in C_L$ iff $a'pa^{\prime\dagger} \in P \forall p \in P$.
Let $a' := \exp(i\phi)a$. $a' \in C_1$ iff $a'pa^{\prime\dagger} \in P \forall p \in P$.
\begin{equation}
\begin{aligned}
@ -115,16 +115,40 @@ generated using $CZ$ and $C_L$ gates.
\end{proof}
\begin{corrolary}
One can disregard global phases of elements of the $C_L$ group.
One can disregard global phases of elements of the $C_1$ group.
\end{corrolary}
\begin{proof}
As it has been shown above a quantum computer cannot measure global phases. Also
the entanglement gates $CX, CZ$ map qbit-global phases to multi-qbit-global phases which cannot
be measured. It has been shown above that one can choose the $C_L$ operators such that they do not yield
be measured. It has been shown above that one can choose the $C_1$ operators such that they do not yield
a phase.
\end{proof}
\begin{definition}
\begin{equation}
C_L := \{a \in C_1 | \nexists \phi \in [0, 2\pi), b \in C_L : a = \exp(i\phi)b\}
\end{equation}
Is called the non-trivial local Clifford group.
\end{definition}
\textbf{Remark.} When computing the elements of $C_L$ and their products one will realize that $C_L$ is not a group.
If one however disregards a global phase the product of two $C_L$ elements will be in $C_L$ again. Because the global phases
can be disregarded as discussed above $C_L$ will be used from now on instead of $C_1$.
\begin{theorem}
\begin{equation}
| C_L | = 24
\end{equation}
\end{theorem}
\begin{proof}
It is clear that $\forall a \in C_L$ a is a group isomorphism $P \circlearrowleft$: $apa^\dagger a p' a^\dagger = a pp'a^\dagger$.
Therefore $a$ will preserve the (anti-)commutator relations of $P$. Also $P$ is generated by $X,Z$ when disregarding a phase wich
does not matter for anticommutator relations.
This means that $X$ can be mapped to any $p \in P$ which are six elements disregarding
\end{proof}
\subsection{Graph Storage}

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@ -17,6 +17,7 @@
\newtheorem{postulate}{Postulate}
\newtheorem{corrolary}{Corrolary}
\newtheorem{lemma}{Lemma}
\newtheorem{theorem}{Theorem}
\numberwithin{equation}{section}
@ -48,6 +49,12 @@ Simulator with a Focus on Simulation in the Graph Formalism }
\include{chapters/graph_simulator}
\section{Appendix}
\subsection{Computing the Local Clifford Group and the Products of its Elements}
%\include{chapters/C_L_elements_and_products}
%\backmatter
\bibliographystyle{unsrt}