def test_dephase():
q0, q1 = cirq.LineQubit.range(2)
circuit = cirq.Circuit(
cirq.CircuitOperation(
cirq.FrozenCircuit(
cirq.CX(q1, q0),
cirq.measure(q0, key='a'),
cirq.CX(q0, q1),
cirq.measure(q1, key='b'),
)))
assert_equivalent_to_dephased(circuit)
dephased = cirq.dephase_measurements(circuit)
cirq.testing.assert_same_circuits(
dephased,
cirq.Circuit(
cirq.CircuitOperation(
cirq.FrozenCircuit(
cirq.CX(q1, q0),
cirq.KrausChannel.from_channel(cirq.phase_damp(1),
key='a')(q0),
cirq.CX(q0, q1),
cirq.KrausChannel.from_channel(cirq.phase_damp(1),
key='b')(q1),
))),
)
def test_dephase_nocompile_context():
q0, q1 = cirq.LineQubit.range(2)
circuit = cirq.Circuit(
cirq.CircuitOperation(
cirq.FrozenCircuit(
cirq.CX(q1, q0),
cirq.measure(q0, key='a').with_tags('nocompile'),
cirq.CX(q0, q1),
cirq.measure(q1, key='b'),
)))
dephased = cirq.dephase_measurements(
circuit,
context=cirq.TransformerContext(tags_to_ignore=('nocompile', )))
cirq.testing.assert_same_circuits(
dephased,
cirq.Circuit(
cirq.CircuitOperation(
cirq.FrozenCircuit(
cirq.CX(q1, q0),
cirq.measure(q0, key='a').with_tags('nocompile'),
cirq.CX(q0, q1),
cirq.KrausChannel.from_channel(cirq.phase_damp(1),
key='b')(q1),
))),
)
def test_dephase_classical_conditions():
q0, q1 = cirq.LineQubit.range(2)
circuit = cirq.Circuit(
cirq.measure(q0, key='a'),
cirq.X(q1).with_classical_controls('a'),
cirq.measure(q1, key='b'),
)
with pytest.raises(ValueError, match='defer_measurements first to remove classical controls'):
_ = cirq.dephase_measurements(circuit)
def assert_equivalent_to_dephased(circuit: cirq.Circuit):
qubits = list(circuit.all_qubits())
with cirq.testing.assert_deprecated('ignore_measurement_results',
deadline='v0.15',
count=14):
sim = cirq.DensityMatrixSimulator(ignore_measurement_results=True)
num_qubits = len(qubits)
backwards = list(circuit.all_operations())[::-1]
for j in range(num_qubits):
backwards.append(cirq.H(qubits[j])**np.random.rand())
modified = cirq.Circuit(backwards[::-1])
for j in range(num_qubits):
modified.append(cirq.H(qubits[j])**np.random.rand())
dephased = cirq.dephase_measurements(modified)
result = sim.simulate(modified)
result1 = sim.simulate(dephased)
np.testing.assert_almost_equal(result.final_density_matrix,
result1.final_density_matrix)