dq.spost

spost(x: QArrayLike) -> QArray

Returns the superoperator formed from post-multiplication by an operator.

Post-multiplication by matrix \(A\) is defined by the superoperator \(A^\mathrm{T} \otimes I_n\) in vectorized form: $$ XA \to (A^\mathrm{T} \otimes I_n) \kett{X}. $$

Parameters:

• x (qarray-like of shape (..., n, n)) –

  Operator.

Returns:

• (qarray of shape (..., n^2, n^2)) –

  Post-multiplication superoperator.

Examples:

>>> dq.spost(dq.destroy(3)).shape
(9, 9)