def test_param_unused(self, operable_mock_device_2_wires):
"""Test that the gradient is 0 of an unused parameter"""
def circuit(x, y):
qml.RX(x, wires=[0])
return qml.expval(qml.PauliZ(0))
q = QubitQNode(circuit, operable_mock_device_2_wires)
q._construct([1.0, 1.0], {})
assert q.par_to_grad_method == {0: "A", 1: "0"}
def test_no_following_observable(self, operable_mock_device_2_wires):
"""Test that the gradient is 0 if no observables succeed"""
def circuit(x):
qml.RX(x, wires=[1])
return qml.expval(qml.PauliZ(0))
q = QubitQNode(circuit, operable_mock_device_2_wires)
q._construct([1.0], {})
assert q.par_to_grad_method == {0: "0"}
def test_not_differentiable(self, operable_mock_device_2_wires):
"""Test that an operation with grad_method=None is marked as
non-differentiable"""
def circuit(x):
qml.BasisState(x, wires=[1])
return qml.expval(qml.PauliZ(0))
q = QubitQNode(circuit, operable_mock_device_2_wires)
q._construct([np.array([1.0])], {})
assert q.par_to_grad_method == {0: None}