def test_lookahead_swap_maps_barriers(self):
"""Verify barrier nodes are updated to re-mapped qregs.
Create a circuit with a barrier on q0 and q2, following a swap between q0 and q2.
Since that swap is not in the coupling, one of the two will be required to move.
Verify that the mapped barrier corresponds to one of the two possible layouts following
the swap.
"""
qr = QuantumRegister(3, "q")
cr = ClassicalRegister(2)
circuit = QuantumCircuit(qr, cr)
circuit.cx(qr[0], qr[2])
circuit.barrier(qr[0], qr[2])
dag_circuit = circuit_to_dag(circuit)
coupling_map = CouplingMap([[0, 1], [1, 2]])
mapped_dag = LookaheadSwap(coupling_map).run(dag_circuit)
mapped_barrier_qargs = [set(op.qargs) for op in mapped_dag.named_nodes("barrier")][0]
self.assertIn(mapped_barrier_qargs, [{qr[0], qr[1]}, {qr[1], qr[2]}])
def test_lookahead_swap_maps_measurements(self):
"""Verify measurement nodes are updated to map correct cregs to re-mapped qregs.
Create a circuit with measures on q0 and q2, following a swap between q0 and q2.
Since that swap is not in the coupling, one of the two will be required to move.
Verify that the mapped measure corresponds to one of the two possible layouts following
the swap.
"""
qr = QuantumRegister(3, "q")
cr = ClassicalRegister(2)
circuit = QuantumCircuit(qr, cr)
circuit.cx(qr[0], qr[2])
circuit.measure(qr[0], cr[0])
circuit.measure(qr[2], cr[1])
dag_circuit = circuit_to_dag(circuit)
coupling_map = CouplingMap([[0, 1], [1, 2]])
mapped_dag = LookaheadSwap(coupling_map).run(dag_circuit)
mapped_measure_qargs = {op.qargs[0] for op in mapped_dag.named_nodes("measure")}
self.assertIn(mapped_measure_qargs, [{qr[0], qr[1]}, {qr[1], qr[2]}])
def test_lookahead_swap_maps_measurements(self):
"""Verify measurement nodes are updated to map correct cregs to re-mapped qregs.
Create a circuit with measures on q0 and q2, following a swap between q0 and q2.
Since that swap is not in the coupling, one of the two will be required to move.
Verify that the mapped measure corresponds to one of the two possible layouts following
the swap.
"""
qr = QuantumRegister(3)
cr = ClassicalRegister(2)
circuit = QuantumCircuit(qr, cr)
circuit.cx(qr[0], qr[2])
circuit.measure(qr[0], cr[0])
circuit.measure(qr[2], cr[1])
dag_circuit = circuit_to_dag(circuit)
coupling_map = CouplingMap([[0, 1], [1, 2]])
mapped_dag = LookaheadSwap(coupling_map).run(dag_circuit)
mapped_measure_qargs = set(
mapped_dag.multi_graph.nodes(data=True)[op]['qargs'][0]
for op in mapped_dag.named_nodes('measure'))
self.assertIn(mapped_measure_qargs, [
set(((QuantumRegister(3, 'q'), 0), (QuantumRegister(3, 'q'), 1))),
set(((QuantumRegister(3, 'q'), 1), (QuantumRegister(3, 'q'), 2)))
])
