@@ -56,68 +56,92 @@ The Pauli matrices (and gate operations following therefrom) are defined as
5656
5757!split
5858===== Pauli-$X$ gate =====
59+
5960The Pauli-$X$ gate is also known as the _NOT_ gate, which flips the state of the qubit.
6061!bt
6162\begin{align}
6263 X\ket{0} &= \ket{1}, \\
6364 X\ket{1} &= \ket{0}.
6465\end{align}
6566!et
66- The Pauli-Y gate flips the bit and multiplies the phase by $ i $.
67+ The Pauli-$Y$ gate flips the bit and multiplies the phase by $ i $.
68+ !bt
6769\begin{align}
6870 Y\ket{0} &= i\ket{1}, \\
6971 Y\ket{1} &= -i\ket{0}.
7072\end{align}
71- The Pauli-Z gate multiplies only the phase of $\ket{1}$ by $ -1 $.
73+ !et
74+ The Pauli-$Z$ gate multiplies only the phase of $\ket{1}$ by $ -1 $.
75+ !bt
7276\begin{align}
7377 Z\ket{0} &= \ket{0}, \\
7478 Z\ket{1} &= -\ket{1}.
7579\end{align}
80+ !et
81+ !split
82+ ===== Hadamard gate =====
7683
77- \subsubsection{Hadamard Gate}
7884The Hadamard gate is defined as
79- \begin{equation}
85+ !bt
86+ \[
8087 H = \frac{1}{\sqrt{2}} \begin{pmatrix}
8188 1 & 1 \\
8289 1 & -1
8390 \end{pmatrix}.
84- \end{equation}
91+ \]
92+ !et
93+
8594It creates a superposition of the $ \ket{0} $ and $ \ket{1} $ states.
95+ !bt
8696\begin{align}
8797 H\ket{0} &= \frac{1}{\sqrt{2}} \left( \ket{0} + \ket{1} \right), \\
8898 H\ket{1} &= \frac{1}{\sqrt{2}} \left( \ket{0} - \ket{1} \right).
8999\end{align}
100+ !et
90101
91- \subsubsection{Phase Gates}
92- The S-phase gate is usually denoted as $ S $ and is defined as
102+ !split
103+ ===== Phase Gates =====
104+ The phase gate is usually denoted as $S$ and is defined as
105+ !bt
93106\begin{equation}
94107 S = \begin{pmatrix}
95108 1 & 0 \\
96109 0 & i
97110 \end{pmatrix}.
98111\end{equation}
112+ !et
99113It multiplies only the phase of the $ \ket{1} $ state by $ i $.
114+ !bt
100115\begin{align}
101116 S\ket{0} &= \ket{0}, \\
102117 S\ket{1} &= i\ket{1}.
103118\end{align}
104- Its inverse
119+ !et
120+
121+ !split
122+ ===== The inverse of the $S$-gate =====
123+
124+ The inverse
125+ !bt
105126\begin{equation}
106127 S^\dagger = \begin{pmatrix}
107128 1 & 0 \\
108129 0 & -i
109130 \end{pmatrix}
110131\end{equation}
111- is known as the $ S^\dagger $ gate which applies a $ -i $ phase shift to \ $ \ket{1}$.
132+ !et
133+ is known as the $ S^\dagger $ gate which applies an $\imath$ phase shift to $\ket{1}$.
134+ !bt
112135\begin{align}
113136 S^\dagger\ket{0} &= \ket{0}, \\
114137 S^\dagger\ket{1} &= -i\ket{1}.
115138\end{align}
139+ !et
140+ !split
141+ ===== Two-qubit gates =====
116142
117- \subsection{Two Qubit Gates}
118- \subsubsection{CNOT Gate}
119- \label{ssub:cnot_gate}
120143The CNOT gate is a two-qubit gate which acts on two qubits, a control qubit and a target qubit. The CNOT gate is defined as
144+ !bt
121145\begin{equation}
122146 \text{CNOT} = \begin{pmatrix}
123147 1 & 0 & 0 & 0 \\
@@ -126,17 +150,22 @@ The CNOT gate is a two-qubit gate which acts on two qubits, a control qubit and
126150 0 & 0 & 1 & 0
127151 \end{pmatrix}.
128152\end{equation}
153+ !et
129154It is often used to perform linear entanglement on qubits.
155+ !bt
130156\begin{align*}
131157 \label{eq:cnot-behaviour}
132158 \cnot \ket{00} &= \ket{00}, \\
133159 \cnot \ket{01} &= \ket{01}, \\
134160 \cnot \ket{10} &= \ket{11}, \\
135161 \cnot \ket{11} &= \ket{10}.
136162\end{align*}
137- \subsubsection{SWAP gate}%
138- \label{ssub:swap_gate}
163+ !et
164+
165+ !split
166+ ===== The SWAP gate =====
139167The SWAP gate is a two-qubit gate which swaps the state of two qubits. It is defined as
168+ !bt
140169\begin{equation}
141170 \text{SWAP} = \begin{pmatrix}
142171 1 & 0 & 0 & 0 \\
@@ -145,13 +174,14 @@ The SWAP gate is a two-qubit gate which swaps the state of two qubits. It is def
145174 0 & 0 & 0 & 1
146175 \end{pmatrix}.
147176\end{equation}
177+ !et
148178\begin{align*}
149- \swp \ket{00} &= \ket{00}, \\
150- \swp \ket{01} &= \ket{10}, \\
151- \swp \ket{10} &= \ket{01}, \\
152- \swp \ket{11} &= \ket{11}.
179+ \text{SWAP} \ket{00} &= \ket{00}, \\
180+ \text{SWAP} \ket{01} &= \ket{10}, \\
181+ \text{SWAP} \ket{10} &= \ket{01}, \\
182+ \text{SWAP} \ket{11} &= \ket{11}.
153183\end{align*}
154-
184+ !et
155185
156186!split
157187===== Pauli Strings =====
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