def test_Z():
"""Test for the _make_Z function"""
dim = 4
Z_expected = -np.eye(dim)
Z_expected[0, 0] = 1
Z = _make_Z(dim)
assert np.allclose(Z, Z_expected)
def test_apply_controlled_z(n_wires):
"""Test if the _apply_controlled_z performs the correct transformation by reconstructing the
unitary and comparing against the one provided in _make_Z."""
n_all_wires = n_wires + 1
wires = Wires(range(n_wires))
control_wire = n_wires
work_wires = None
circ = lambda: _apply_controlled_z(
wires=wires, control_wire=control_wire, work_wires=work_wires)
u = get_unitary(circ, n_all_wires)
# Note the sign flip in the following. The sign does not matter when performing the Q unitary
# because two Zs are used.
z_ideal = -_make_Z(2**n_wires)
circ = lambda: qml.ControlledQubitUnitary(
z_ideal, wires=wires, control_wires=control_wire)
u_ideal = get_unitary(circ, n_all_wires)
assert np.allclose(u, u_ideal)