def test_krauss_channel_errors(backend):
# bad Kraus matrix shape
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
with pytest.raises(ValueError):
gate = gates.KrausChannel([((0, 1), a1)])
# Using KrausChannel on state vectors
channel = gates.KrausChannel([((0, ), np.eye(2))])
with pytest.raises(ValueError):
channel._state_vector_call(np.random.random(4))
# Attempt to construct unitary for KrausChannel
with pytest.raises(ValueError):
channel._construct_unitary()
def test_krauss_channel_errors(backend):
"""Test errors raised by `gates.KrausChannel`."""
original_backend = qibo.get_backend()
qibo.set_backend(backend)
# bad Kraus matrix shape
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
with pytest.raises(ValueError):
gate = gates.KrausChannel([((0, 1), a1)])
# Using KrausChannel on state vectors
channel = gates.KrausChannel([((0, ), np.eye(2))])
with pytest.raises(ValueError):
channel.state_vector_call(np.random.random(4))
# Attempt to construct unitary for KrausChannel
with pytest.raises(ValueError):
channel.construct_unitary()
qibo.set_backend(original_backend)
def test_general_channel(backend, tfmatrices, oncircuit):
"""Test `gates.KrausChannel`."""
original_backend = qibo.get_backend()
qibo.set_backend(backend)
initial_rho = utils.random_density_matrix(2)
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1],
[0, 0, 1, 0]])
if tfmatrices:
from qibo import K
a1, a2 = K.cast(a1), K.cast(a2)
gate = gates.KrausChannel([((1, ), a1), ((0, 1), a2)])
assert gate.target_qubits == (0, 1)
if oncircuit:
c = models.Circuit(2, density_matrix=True)
c.add(gate)
final_rho = c(np.copy(initial_rho))
else:
final_rho = gate(np.copy(initial_rho))
m1 = np.kron(np.eye(2), np.array(a1))
m2 = np.array(a2)
target_rho = (m1.dot(initial_rho).dot(m1.conj().T) +
m2.dot(initial_rho).dot(m2.conj().T))
np.testing.assert_allclose(final_rho, target_rho)
qibo.set_backend(original_backend)
def test_general_channel(backend, tfmatrices, oncircuit):
"""Test `gates.KrausChannel`."""
original_backend = qibo.get_backend()
qibo.set_backend(backend)
initial_rho = utils.random_density_matrix(2)
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1],
[0, 0, 1, 0]])
if tfmatrices:
import tensorflow as tf
from qibo.config import DTYPES
a1 = tf.cast(a1, dtype=DTYPES.get('DTYPECPX'))
a2 = tf.cast(a2, dtype=DTYPES.get('DTYPECPX'))
gate = gates.KrausChannel([((1, ), a1), ((0, 1), a2)])
assert gate.target_qubits == (0, 1)
if oncircuit:
c = models.Circuit(2, density_matrix=True)
c.add(gate)
final_rho = c(np.copy(initial_rho)).numpy()
else:
if backend == "custom":
final_rho = gate(np.copy(initial_rho))
else:
final_rho = gate(np.copy(initial_rho).reshape(4 * (2, )))
final_rho = final_rho.numpy().reshape((4, 4))
m1 = np.kron(np.eye(2), np.array(a1))
m2 = np.array(a2)
target_rho = (m1.dot(initial_rho).dot(m1.conj().T) +
m2.dot(initial_rho).dot(m2.conj().T))
np.testing.assert_allclose(final_rho, target_rho)
qibo.set_backend(original_backend)
def test_density_matrix_circuit_errors():
"""Check errors of circuits that simulate density matrices."""
# Attempt to distribute density matrix circuit
with pytest.raises(NotImplementedError):
c = models.Circuit(5, accelerators={"/GPU:0": 2}, density_matrix=True)
# Attempt to add Kraus channel to non-density matrix circuit
c = models.Circuit(5)
with pytest.raises(ValueError):
c.add(gates.KrausChannel([((0, ), np.eye(2))]))
def test_controlled_by_channel_error():
with pytest.raises(ValueError):
gates.PauliNoiseChannel(0, px=0.5).controlled_by(1)
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1],
[0, 0, 1, 0]])
config = [((1, ), a1), ((0, 1), a2)]
with pytest.raises(ValueError):
gates.KrausChannel(config).controlled_by(1)
def test_controlled_by_channel():
"""Test that attempting to control channels raises error."""
c = models.Circuit(2, density_matrix=True)
with pytest.raises(ValueError):
c.add(gates.PauliNoiseChannel(0, px=0.5).controlled_by(1))
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1],
[0, 0, 1, 0]])
config = [((1, ), a1), ((0, 1), a2)]
with pytest.raises(ValueError):
gates.KrausChannel(config).controlled_by(1)
def test_density_matrix_circuit_errors():
"""Check errors of circuits that simulate density matrices."""
# Switch `gate.density_matrix` to `True` after setting `nqubits`
gate = gates.X(0)
gate.nqubits = 2
with pytest.raises(RuntimeError):
gate.density_matrix = True
# Attempt to distribute density matrix circuit
with pytest.raises(NotImplementedError):
c = models.Circuit(5, accelerators={"/GPU:0": 2}, density_matrix=True)
# Attempt to add Kraus channel to non-density matrix circuit
c = models.Circuit(5)
with pytest.raises(ValueError):
c.add(gates.KrausChannel([((0, ), np.eye(2))]))
def test_general_channel(backend):
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1],
[0, 0, 1, 0]])
a1, a2 = K.cast(a1), K.cast(a2)
initial_rho = random_density_matrix(2)
gate = gates.KrausChannel([((1, ), a1), ((0, 1), a2)])
assert gate.target_qubits == (0, 1)
final_rho = gate(np.copy(initial_rho))
m1 = np.kron(np.eye(2), K.to_numpy(a1))
m2 = K.to_numpy(a2)
target_rho = (m1.dot(initial_rho).dot(m1.conj().T) +
m2.dot(initial_rho).dot(m2.conj().T))
K.assert_allclose(final_rho, target_rho)
def test_channel_gate_setters(backend):
a1 = np.sqrt(0.4) * np.array([[0, 1], [1, 0]])
a2 = np.sqrt(0.6) * np.array([[1, 0, 0, 0], [0, 1, 0, 0],
[0, 0, 0, 1], [0, 0, 1, 0]])
channel = gates.KrausChannel([((1,), a1), ((0, 1), a2)])
_ = channel.inverse_gates # create inverse gates
channel.nqubits = 5
channel.density_matrix = True
for gate in channel.gates:
assert gate.nqubits == 5
assert gate.density_matrix
for gate in channel.inverse_gates:
if gate is not None:
assert gate.nqubits == 5
assert gate.density_matrix