@ -497,7 +497,7 @@ A quantum gate is just a unitary operator on a select set of qubits. Because the
\label{def:gate_nbit_extension}
Let $\ket{\mathbf{x}}=\ket{x_1, \dots, x_n}$ be the $n$ qubits of a quantum system and let $U$ be a $k$-qubit quantum gate, with $k < n$. The $k$-tuple $I =(i_1, \dots, i_k)$ with $i_l, i_g \in[1,n]$ and $i_l \neq i_g$ for all $l,g$ maps $k$ qubits from $\ket{\mathbf{x}}$ to the inputs of $U$. Then,
\begin{equation*}
G_n(U,I) \coloneqq V_{\pi_I} (U \otimes\idmat_{n-k})
G_n(U,I) \coloneqq V_{\pi_I} (U \otimes\idmat_{n-k}) V_{\pi_I}^\dagger
\end{equation*}
is the $n$-qubit extension of $U$, with $V_{\pi_I}$ being a permutation matrix that satisfies
\begin{equation*}
@ -509,7 +509,7 @@ A quantum gate is just a unitary operator on a select set of qubits. Because the
\begin{remark}
Two gates $U_1\in\C^{2^{k_1}}$ and $U_2\in\C^{2^{k_2}}$ acting on $I_1=(i_1^1,\dots,i_{k_1}^1)$ and $I_2=(i_1^2,\dots,i_{k_2}^2)$ respectively can be computed in parallel iff $I_1\cap I_2=\emptyset$ and thus
with $I_1I_2$ being the concatenation of $I_1$ and $I_2$ and
\begin{equation*}
@ -525,4 +525,4 @@ A quantum gate is just a unitary operator on a select set of qubits. Because the
The circuit $C$ is said to be maximally parallelized if all neighboring gate extensions $G_n(U_l,I_l)$ and $G_n(U_{l+1}, I_{l+1})$ with $I_l \cap I_{l+1}=\emptyset$ are reduced to $G_n(U_l \otimes U_{l+1}, I_l I_{l+1})$.
\end{definition}
\contentsketch{Circuit example Deutsch's algorithm}