GisinState

GisinState is a function that produces a two-qubit "Gisin state", as defined in, which has the following standard basis representation:
 * $$\rho_{\lambda,\theta} := \lambda\begin{bmatrix}0 & 0 & 0 & 0 \\ 0 & \sin^2(\theta) & -\sin(\theta)\cos(\theta) & 0 \\ 0 & -\sin(\theta)\cos(\theta) & \cos^2(\theta) & 0 \\ 0 & 0 & 0 & 0\end{bmatrix} + \frac{1-\lambda}{2}\begin{bmatrix}1 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1\end{bmatrix}.$$

Syntax

 * GISIN_STATE = GisinState(LAMBDA,THETA)

Argument descriptions

 * LAMBDA: A real number between 0 and 1.
 * THETA: A real number.

Examples
The following code generates the Gisin state $\rho_{0.5,1}$: