_sparse_tools.py 文件源码

def get_ground_state(sparse_operator):
    """Compute lowest eigenvalue and eigenstate.

    Returns:
        eigenvalue: The lowest eigenvalue, a float.
        eigenstate: The lowest eigenstate in scipy.sparse csc format.
    """
    if not is_hermitian(sparse_operator):
        raise ValueError('sparse_operator must be Hermitian.')

    values, vectors = scipy.sparse.linalg.eigsh(
        sparse_operator, 2, which='SA', maxiter=1e7)

    eigenstate = scipy.sparse.csc_matrix(vectors[:, 0])
    eigenvalue = values[0]
    return eigenvalue, eigenstate.getH()