def test_reset_error(backend, density_matrix):
reset = ResetError(0.8, 0.2)
noise = NoiseModel()
noise.add(reset, gates.X, 1)
noise.add(reset, gates.CNOT)
noise.add(reset, gates.Z, (0,1))
circuit = Circuit(3, density_matrix=density_matrix)
circuit.add(gates.CNOT(0,1))
circuit.add(gates.Z(1))
target_circuit = Circuit(3, density_matrix=density_matrix)
target_circuit.add(gates.CNOT(0,1))
target_circuit.add(gates.ResetChannel(0, 0.8, 0.2))
target_circuit.add(gates.ResetChannel(1, 0.8, 0.2))
target_circuit.add(gates.Z(1))
target_circuit.add(gates.ResetChannel(1, 0.8, 0.2))
initial_psi = random_density_matrix(3) if density_matrix else random_state(3)
np.random.seed(123)
K.set_seed(123)
final_state = noise.apply(circuit)(initial_state=np.copy(initial_psi))
np.random.seed(123)
K.set_seed(123)
target_final_state = target_circuit(initial_state=np.copy(initial_psi))
K.assert_allclose(final_state, target_final_state)
def test_reset_channel(backend):
initial_rho = random_density_matrix(3)
gate = gates.ResetChannel(0, p0=0.2, p1=0.2)
gate.density_matrix = True
final_rho = gate(K.cast(np.copy(initial_rho)))
dtype = initial_rho.dtype
collapsed_rho = np.copy(initial_rho).reshape(6 * (2, ))
collapsed_rho[0, :, :, 1, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho[1, :, :, 0, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho[1, :, :, 1, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho = collapsed_rho.reshape((8, 8))
collapsed_rho /= np.trace(collapsed_rho)
mx = np.kron(np.array([[0, 1], [1, 0]]), np.eye(4))
flipped_rho = mx.dot(collapsed_rho.dot(mx))
target_rho = 0.6 * initial_rho + 0.2 * (collapsed_rho + flipped_rho)
K.assert_allclose(final_rho, target_rho)
def test_reset_channel_repeated(backend):
original_backend = qibo.get_backend()
qibo.set_backend(backend)
initial_state = random_state(5)
c = Circuit(5)
c.add(gates.ResetChannel(2, p0=0.3, p1=0.3, seed=123))
final_state = c(np.copy(initial_state), nshots=30)
np.random.seed(123)
target_state = []
for _ in range(30):
noiseless_c = Circuit(5)
if np.random.random() < 0.3:
noiseless_c.add(gates.Collapse(2))
if np.random.random() < 0.3:
noiseless_c.add(gates.Collapse(2))
noiseless_c.add(gates.X(2))
target_state.append(noiseless_c(np.copy(initial_state)))
np.testing.assert_allclose(final_state, target_state)
qibo.set_backend(original_backend)
def test_reset_channel(backend):
"""Check ``gates.ResetChannel`` on a 3-qubit random density matrix."""
original_backend = qibo.get_backend()
qibo.set_backend(backend)
initial_rho = utils.random_density_matrix(3)
c = models.Circuit(3, density_matrix=True)
c.add(gates.ResetChannel(0, p0=0.2, p1=0.2))
final_rho = c(np.copy(initial_rho))
dtype = initial_rho.dtype
collapsed_rho = np.copy(initial_rho).reshape(6 * (2, ))
collapsed_rho[0, :, :, 1, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho[1, :, :, 0, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho[1, :, :, 1, :, :] = np.zeros(4 * (2, ), dtype=dtype)
collapsed_rho = collapsed_rho.reshape((8, 8))
collapsed_rho /= np.trace(collapsed_rho)
mx = np.kron(np.array([[0, 1], [1, 0]]), np.eye(4))
flipped_rho = mx.dot(collapsed_rho.dot(mx))
target_rho = 0.6 * initial_rho + 0.2 * (collapsed_rho + flipped_rho)
np.testing.assert_allclose(final_rho, target_rho)
qibo.set_backend(original_backend)
def test_reset_channel_repeated(backend):
initial_state = random_state(5)
c = Circuit(5)
c.add(gates.ResetChannel(2, p0=0.3, p1=0.3, seed=123))
final_state = c(K.cast(np.copy(initial_state)), nshots=30)
np.random.seed(123)
target_state = []
collapse = gates.M(2, collapse=True)
collapse.nqubits = 5
xgate = gates.X(2)
for _ in range(30):
state = K.cast(np.copy(initial_state))
if np.random.random() < 0.3:
state = K.state_vector_collapse(collapse, state, [0])
if np.random.random() < 0.3:
state = K.state_vector_collapse(collapse, state, [0])
state = xgate(state)
target_state.append(K.copy(state))
target_state = K.stack(target_state)
K.assert_allclose(final_state, target_state)