code: def covariance_mtx_to_superop(self, mtx):
          
          M = self.flat()
          return qt.Qobj(
              np.dot(np.dot(M.conj().T, mtx), M),
              dims=[[self.dims] * 2] * 2
          )
docs: Converts a covariance matrix to the corresponding
          superoperator, represented as a QuTiP Qobj
          with ``type="super"``.