Geography of Europe

Pauli gate

{wiki=Quantum_logic_gate\#Controlled_gates}

<Controlled quantum gates> are gates that have two types of input qubits:
* control <qubits>
* operand <qubits> (terminology made up by <Ciro Santilli> just now)
These gates can be understood as doing a certain <unitary operation> only if the control qubits are enabled or disabled.

The first example to look at is the <CNOT gate>.

\Image[https://upload.wikimedia.org/wikipedia/commons/d/dc/Controlled_gate.svg]
{title=Generic <controlled quantum gate> symbol}
{description=
The black dot means "control qubit", and "U" means an arbitrary <Unitary operation>.

When the operand has a conventional symbol, e.g. the <image Quantum NOT gate symbol> for the <quantum NOT gate> to form the <CNOT gate>, that symbol is used in the operand instead. 
}


Controlled quantum gate

Evening raga

\Video[https://www.youtube.com/watch?v=jPIl2G88w_A]
{title=Raag Puriya Dhanashri performed on the <Sitar> by Shahid Parvez}


Puriya

Ungulate subclade

Information Engineering group of the University of Oxford

{c}
{wiki=Quantum_logic_gate\#Hadamard_gate}

The <Hadamard gate> takes $\ket{0}$ or $\ket{1}$ (<quantum states> with probability 1.0 of measuring either 0 or 1), and produces states that have equal probability of 0 or 1.

$$
H = \frac{1}{\sqrt{2}} \begin{bmatrix} 1 & 1 \\ 1 & -1 \end{bmatrix}
$$
{title=<Hadamard gate> <matrix>}

\Image[https://upload.wikimedia.org/wikipedia/commons/1/1a/Hadamard_gate.svg]
{title=<Hadamard gate> symbol}


Hadamard gate

Some authors use the convention of:
* filled black circle: conventional <controlled quantum gate>, i.e. operate if control qubit is active
* empty (White) circle: operate if control qubit is inactive


Ciro Santilli @cirosantilli 37