def test_prob_hess(self, method):
"""Test the probability Hessian using linear combination of unitaries method
d^2p0/da^2 = - sin(a)sin(b) / 2
d^2p1/da^2 = sin(a)sin(b) / 2
d^2p0/dadb = cos(a)cos(b) / 2
d^2p1/dadb = - cos(a)cos(b) / 2
"""
a = Parameter('a')
b = Parameter('b')
params = [(a, a), (a, b)]
q = QuantumRegister(1)
qc = QuantumCircuit(q)
qc.h(q)
qc.rz(a, q[0])
qc.rx(b, q[0])
op = CircuitStateFn(primitive=qc, coeff=1.)
prob_hess = Hessian(hess_method=method).convert(operator=op, params=params)
values_dict = [{a: np.pi / 4, b: 0}, {a: np.pi / 4, b: np.pi / 4},
{a: np.pi / 2, b: np.pi}]
correct_values = [[[0, 0], [1 / (2 * np.sqrt(2)), - 1 / (2 * np.sqrt(2))]],
[[- 1 / 4, 1 / 4], [1 / 4, - 1 / 4]],
[[0, 0], [0, 0]]]
for i, value_dict in enumerate(values_dict):
for j, prob_hess_result in enumerate(prob_hess.assign_parameters(value_dict).eval()):
np.testing.assert_array_almost_equal(prob_hess_result,
correct_values[i][j], decimal=1)
def test_operator_coefficient_hessian(self, method):
"""Test the operator coefficient hessian
<Z> = Tr( | psi > < psi | Z) = sin(a)sin(b)
<X> = Tr( | psi > < psi | X) = cos(a)
d<H>/dc_0 = 2 * c_0 * <X> + c_1 * <Z>
d<H>/dc_1 = c_0 * <Z>
d^2<H>/dc_0^2 = 2 * <X>
d^2<H>/dc_0dc_1 = <Z>
d^2<H>/dc_1dc_0 = <Z>
d^2<H>/dc_1^2 = 0
"""
a = Parameter('a')
b = Parameter('b')
q = QuantumRegister(1)
qc = QuantumCircuit(q)
qc.h(q)
qc.rz(a, q[0])
qc.rx(b, q[0])
coeff_0 = Parameter('c_0')
coeff_1 = Parameter('c_1')
ham = coeff_0 * coeff_0 * X + coeff_1 * coeff_0 * Z
op = ~StateFn(ham) @ CircuitStateFn(primitive=qc, coeff=1.)
gradient_coeffs = [(coeff_0, coeff_0), (coeff_0, coeff_1), (coeff_1, coeff_1)]
coeff_grad = Hessian(hess_method=method).convert(op, gradient_coeffs)
values_dict = [{coeff_0: 0.5, coeff_1: -1, a: np.pi / 4, b: np.pi},
{coeff_0: 0.5, coeff_1: -1, a: np.pi / 4, b: np.pi / 4}]
correct_values = [[2 / np.sqrt(2), 0, 0], [2 / np.sqrt(2), 1 / 2, 0]]
for i, value_dict in enumerate(values_dict):
np.testing.assert_array_almost_equal(coeff_grad.assign_parameters(value_dict).eval(),
correct_values[i],
decimal=1)
def test_state_hessian(self, method):
"""Test the state Hessian
Tr(|psi><psi|Z) = sin(a)sin(b)
Tr(|psi><psi|X) = cos(a)
d^2<H>/da^2 = - 0.5 cos(a) + 1 sin(a)sin(b)
d^2<H>/dbda = - 1 cos(a)cos(b)
d^2<H>/dbda = - 1 cos(a)cos(b)
d^2<H>/db^2 = + 1 sin(a)sin(b)
"""
ham = 0.5 * X - 1 * Z
a = Parameter('a')
b = Parameter('b')
params = [(a, a), (a, b), (b, b)]
q = QuantumRegister(1)
qc = QuantumCircuit(q)
qc.h(q)
qc.rz(a, q[0])
qc.rx(b, q[0])
op = ~StateFn(ham) @ CircuitStateFn(primitive=qc, coeff=1.)
state_hess = Hessian(hess_method=method).convert(operator=op, params=params)
values_dict = [{a: np.pi / 4, b: np.pi}, {a: np.pi / 4, b: np.pi / 4},
{a: np.pi / 2, b: np.pi / 4}]
correct_values = [[-0.5 / np.sqrt(2), 1 / np.sqrt(2), 0],
[-0.5 / np.sqrt(2) + 0.5, -1 / 2., 0.5],
[1 / np.sqrt(2), 0, 1 / np.sqrt(2)]]
for i, value_dict in enumerate(values_dict):
np.testing.assert_array_almost_equal(state_hess.assign_parameters(value_dict).eval(),
correct_values[i], decimal=1)
def test_state_hessian_custom_combo_fn(self, method):
"""Test the state Hessian with on an operator which includes
a user-defined combo_fn.
Tr(|psi><psi|Z) = sin(a)sin(b)
Tr(|psi><psi|X) = cos(a)
d^2<H>/da^2 = - 0.5 cos(a) + 1 sin(a)sin(b)
d^2<H>/dbda = - 1 cos(a)cos(b)
d^2<H>/dbda = - 1 cos(a)cos(b)
d^2<H>/db^2 = + 1 sin(a)sin(b)
"""
ham = 0.5 * X - 1 * Z
a = Parameter('a')
b = Parameter('b')
params = [(a, a), (a, b), (b, b)]
q = QuantumRegister(1)
qc = QuantumCircuit(q)
qc.h(q)
qc.rz(a, q[0])
qc.rx(b, q[0])
op = ListOp([~StateFn(ham) @ CircuitStateFn(primitive=qc, coeff=1.)],
combo_fn=lambda x: x[0]**3 + 4 * x[0])
state_hess = Hessian(hess_method=method).convert(operator=op,
params=params)
values_dict = [{
a: np.pi / 4,
b: np.pi
}, {
a: np.pi / 4,
b: np.pi / 4
}, {
a: np.pi / 2,
b: np.pi / 4
}]
correct_values = [[-1.28163104, 2.56326208, 1.06066017],
[-0.04495626, -2.40716991, 1.8125],
[2.82842712, -1.5, 1.76776695]]
for i, value_dict in enumerate(values_dict):
np.testing.assert_array_almost_equal(
state_hess.assign_parameters(value_dict).eval(),
correct_values[i],
decimal=1)