Get Givens angles and DiagonalHamiltonian to simulate squared one-body.

The goal here will be to prepare to simulate evolution under :math:(\sum_{pq} h_{pq} a^\dagger_p a_q)^2 by decomposing as :math:R e^{-i \sum_{pq} V_{pq} n_p n_q} R^\dagger' where :math:R` is a basis transformation matrix.

one_body_matrix (ndarray of floats): an N by N array storing the coefficients of a one-body operator to be squared. For instance, in the above the elements of this matrix are :math:h_{pq}. spin_basis (bool): Whether the matrix is passed in the spin orbital basis.

density_density_matrix(ndarray of floats) an N by N array storing the diagonal two-body coefficeints :math:V_{pq} above. basis_transformation_matrix (ndarray of floats) an N by N array storing the values of the basis transformation.

ValueError one_body_matrix is not Hermitian.