_sparse_tools_test.py 文件源码

def test_jw_restrict_operator(self):
        """Test the scheme for restricting JW encoded operators to number"""
        # Make a Hamiltonian that cares mostly about number of electrons
        n_qubits = 6
        target_electrons = 3
        penalty_const = 100.
        number_sparse = jordan_wigner_sparse(number_operator(n_qubits))
        bias_sparse = jordan_wigner_sparse(
            sum([FermionOperator(((i, 1), (i, 0)), 1.0) for i
                 in range(n_qubits)], FermionOperator()))
        hamiltonian_sparse = penalty_const * (
            number_sparse - target_electrons *
            scipy.sparse.identity(2**n_qubits)).dot(
            number_sparse - target_electrons *
            scipy.sparse.identity(2**n_qubits)) + bias_sparse

        restricted_hamiltonian = jw_number_restrict_operator(
            hamiltonian_sparse, target_electrons, n_qubits)
        true_eigvals, _ = eigh(hamiltonian_sparse.A)
        test_eigvals, _ = eigh(restricted_hamiltonian.A)

        self.assertAlmostEqual(norm(true_eigvals[:20] - test_eigvals[:20]),
                               0.0)