Function SXGate 

pub fn SXGate() -> UnitaryExpression

The single-qubit SX gate (square-root of X / square-root of Pauli-X).

$$ SX = \sqrt{X} = \frac{1}{2}\begin{pmatrix} 1+i & 1-i \\ 1-i & 1+i \end{pmatrix} $$

Note: a qudit generalization of this gate as $X^{1/2}$ is mathematically well-defined but its matrix entries involve geometric sums with non-integer exponents that do not reduce to a simple closed-form expression in QGL.