def get_grad(self, params: Sequence[float] = []) -> np.ndarray:
"""Returns the gradient for this gate, see Gate for more info."""
self.check_parameters(params)
H = dot_product(params, self.sigmav)
_, dU = dexpmv(H, self.sigmav)
return dU
def get_unitary_and_grad(
self,
params: Sequence[float] = [],
) -> tuple[UnitaryMatrix, np.ndarray]:
"""Returns the unitary and gradient, see Gate for more info."""
self.check_parameters(params)
H = dot_product(params, self.sigmav)
U, dU = dexpmv(H, self.sigmav)
return UnitaryMatrix(U, check_arguments=False), dU
def test_single(self, alpha: np.ndarray) -> None:
paulis = PauliMatrices(2)
H = paulis.dot_product(alpha)
for p in paulis:
F0, dF0 = dexpm_exact(H, p)
F1, dF1 = dexpmv(H, p)
assert np.allclose(F0, F1)
assert np.allclose(dF0, dF1)
def test_vector(self, alpha: np.ndarray) -> None:
paulis = PauliMatrices(2)
H = paulis.dot_product(alpha)
dFs0 = []
for p in paulis:
_, dF = dexpm_exact(H, p)
dFs0.append(dF)
dFs0_np = np.array(dFs0)
_, dFs1 = dexpmv(H, paulis.get_numpy())
assert np.allclose(dFs0_np, dFs1)
def test_invalid(self) -> None:
with pytest.raises(Exception):
dexpmv(0, 0) # type: ignore
with pytest.raises(Exception):
dexpmv(0, [1, 0]) # type: ignore
with pytest.raises(Exception):
dexpmv([1, 0], 0) # type: ignore
with pytest.raises(Exception):
dexpmv([1, 0], [1, 0]) # type: ignore
I = np.identity(2)
with pytest.raises(Exception):
dexpmv(I, 0) # type: ignore
with pytest.raises(Exception):
dexpmv(0, I) # type: ignore
with pytest.raises(Exception):
dexpmv(I, [1, 0]) # type: ignore
with pytest.raises(Exception):
dexpmv([1, 0], I) # type: ignore