test_algorithms.py 文件源码

def test_expectation():
    """expectation() routine can take a PauliSum operator on a matrix.  Check
    this functionality and the return of the correct scalar value"""
    X = np.array([[0, 1], [1, 0]])

    def RX_gate(phi):
        return expm(-1j*phi*X)

    def rotation_wavefunction(phi):
        state = np.array([[1], [0]])
        return RX_gate(phi).dot(state)

    prog = Program([RX(-2.5)(0)])
    hamiltonian = PauliTerm("Z", 0, 1.0)

    minimizer = MagicMock()
    fake_result = Mock()
    fake_result.fun = 1.0
    minimizer.return_value = fake_result

    fake_qvm = Mock(spec=['wavefunction', 'expectation', 'run'])
    fake_qvm.wavefunction.return_value = (Wavefunction(rotation_wavefunction(-2.5)))
    fake_qvm.expectation.return_value = [0.28366219]
    # for testing expectation
    fake_qvm.run.return_value = [[0], [0]]

    inst = VQE(minimizer)
    energy = inst.expectation(prog, PauliSum([hamiltonian]), None, fake_qvm)
    assert np.isclose(energy, 0.28366219)

    hamiltonian = np.array([[1, 0], [0, -1]])
    energy = inst.expectation(prog, hamiltonian, None, fake_qvm)
    assert np.isclose(energy, 0.28366219)

    prog = Program(H(0))
    hamiltonian = PauliSum([PauliTerm('X', 0)])
    energy = inst.expectation(prog, hamiltonian, 2, fake_qvm)
    assert np.isclose(energy, 1.0)