def test_crx_decomposition_correctness(self, phi, tol):
"""Test that the decomposition of the controlled X
qubit rotation is correct"""
expected = CRotx(phi)
obtained = np.kron(I, Rotz(-np.pi / 2)) @ CNOT @ np.kron(
I, Roty(-phi / 2)) @ CNOT @ np.kron(I, Roty(phi / 2)) @ np.kron(
I, Rotz(np.pi / 2))
assert np.allclose(expected, obtained, atol=tol, rtol=0)
def test_qnode_fanout(self, qubit_device_1_wire, tol):
"""Tests that qnodes can compute the correct function when the same parameter is used in multiple gates."""
@qml.qnode(qubit_device_1_wire, interface='torch')
def circuit(reused_param, other_param):
qml.RX(reused_param, wires=[0])
qml.RZ(other_param, wires=[0])
qml.RX(reused_param, wires=[0])
return qml.expval(qml.PauliZ(0))
thetas = torch.linspace(-2 * np.pi, 2 * np.pi, 7)
for reused_param in thetas:
for theta in thetas:
other_param = theta**2 / 11
y_eval = circuit(reused_param, other_param)
Rx = Rotx(reused_param.numpy())
Rz = Rotz(other_param.numpy())
zero_state = np.array([1., 0.])
final_state = (Rx @ Rz @ Rx @ zero_state)
y_true = expZ(final_state)
assert np.allclose(y_eval, y_true, atol=tol, rtol=0)
def test_multiple_expectation_different_wires(self, qubit_device_2_wires,
tol):
"""Tests that qnodes return multiple expectation values."""
a, b, c = torch.tensor(0.5), torch.tensor(0.54), torch.tensor(0.3)
@qml.qnode(qubit_device_2_wires, interface='torch')
def circuit(x, y, z):
qml.RX(x, wires=[0])
qml.RZ(y, wires=[0])
qml.CNOT(wires=[0, 1])
qml.RY(y, wires=[0])
qml.RX(z, wires=[0])
return qml.expval(qml.PauliY(0)), qml.expval(qml.PauliZ(1))
res = circuit(a, b, c)
out_state = np.kron(Rotx(c.numpy()), I) @ np.kron(Roty(b.numpy()), I) @ CNOT \
@ np.kron(Rotz(b.numpy()), I) @ np.kron(Rotx(a.numpy()), I) @ np.array([1, 0, 0, 0])
ex0 = np.vdot(out_state, np.kron(Y, I) @ out_state)
ex1 = np.vdot(out_state, np.kron(I, Z) @ out_state)
ex = np.array([ex0, ex1])
assert np.allclose(ex, res.numpy(), atol=tol, rtol=0)
