Pauli-X gate

The Pauli-X gate is a single-qubit rotation through $\pi$ radians around the x-axis.

$\ X = \sigma_x = \sigma_1 = \begin{pmatrix} 0 & 1 \ 1 & 0 \end{pmatrix}$

Examples:

        
          X q[0] # execute x-gate on qubit 0
X q[1:3] # execute x-gate on qubits 1,2 and 3