def test_correct_method_non_gaussian_observable(self, operable_mock_CV_device_2_wires):
"""Tests that a non-Gaussian observable one parameter fallsback to finite-diff"""
par = [0.4, -2.3]
def qf(x, y):
qml.Displacement(x, 0, wires=[0]) # followed by nongaussian observable
qml.Beamsplitter(0.2, 1.7, wires=[0, 1])
qml.Displacement(y, 0, wires=[1]) # followed by order-2 observable
return qml.expval(qml.FockStateProjector(np.array([2]), 0)), qml.expval(qml.NumberOperator(1))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: "F", 1: "A"}
def test_correct_method_non_gaussian_preceeding_one_param(self, operable_mock_CV_device_2_wires):
"""Tests that a non-Gaussian preceeding one parameter fallsback to finite-diff"""
par = [0.4, -2.3]
def qf(x, y):
qml.Kerr(y, wires=[1])
qml.Displacement(x, 0, wires=[0])
qml.Beamsplitter(0.2, 1.7, wires=[0, 1])
return qml.expval(qml.X(0)), qml.expval(qml.X(1))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: "A", 1: "F"}
def test_param_no_observables(self, operable_mock_CV_device_2_wires):
"""Tests that a parameter has 0 gradient if it is not followed by any observables"""
par = [0.4]
def qf(x):
qml.Displacement(x, 0, wires=[0])
qml.Squeezing(0.3, x, wires=[0])
qml.Rotation(1.3, wires=[1])
return qml.expval(qml.X(1))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: "0"}
def test_param_not_differentiable(self, operable_mock_CV_device_2_wires):
"""Tests that a parameter is not differentiable if used in an operation
where grad_method=None"""
par = [0.4]
def qf(x):
qml.FockState(x, wires=[0])
qml.Rotation(1.3, wires=[0])
return qml.expval(qml.X(0))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: None}
def test_correct_method_non_gaussian_successor_all_params(self, operable_mock_CV_device_2_wires):
"""Tests that a non-Gaussian succeeding all parameters fallsback to finite-diff"""
par = [0.4, -2.3]
def qf(x, y):
qml.Displacement(x, 0, wires=[0])
qml.Displacement(1.2, y, wires=[1])
qml.Beamsplitter(0.2, 1.7, wires=[0, 1])
qml.Rotation(1.9, wires=[0])
qml.Kerr(0.3, wires=[1]) # nongaussian succeeding both x and y due to the beamsplitter
return qml.expval(qml.X(0)), qml.expval(qml.X(1))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: "F", 1: "F"}
def test_correct_method_non_gaussian_successor_unused_param(self, operable_mock_CV_device_2_wires):
"""Tests that a non-Gaussian succeeding a parameter fallsback to finite-diff
alongside an unused parameter"""
par = [0.4, -2.3]
def qf(x, y):
qml.Displacement(x, 0, wires=[0])
qml.CubicPhase(0.2, wires=[0]) # nongaussian succeeding x
qml.Squeezing(0.3, x, wires=[1]) # x affects gates on both wires, y unused
qml.Rotation(1.3, wires=[1])
return qml.expval(qml.X(0)), qml.expval(qml.X(1))
q = CVQNode(qf, operable_mock_CV_device_2_wires)
q._construct(par, {})
assert q.par_to_grad_method == {0: "F", 1: "0"}