def test_unmappable_cnots_in_a_layer(self):
"""Test mapping of a circuit with 2 cnots in a layer into T-shape coupling,
which BIPMapping cannot map."""
qr = QuantumRegister(4, "q")
cr = ClassicalRegister(4, "c")
circuit = QuantumCircuit(qr, cr)
circuit.cx(qr[0], qr[1])
circuit.cx(qr[2], qr[3])
circuit.measure(qr, cr)
coupling = CouplingMap([[0, 1], [1, 2], [1, 3]]) # {0: [1], 1: [2, 3]}
actual = BIPMapping(coupling)(circuit)
# Fails to map and returns the original circuit
self.assertEqual(circuit, actual)
def test_no_swap_multi_layer(self):
"""Can find the best layout for a circuit with multiple layers."""
coupling = CouplingMap([[0, 1], [1, 2], [2, 3]])
qr = QuantumRegister(4, name="qr")
circuit = QuantumCircuit(qr)
circuit.cx(qr[1], qr[0])
circuit.cx(qr[0], qr[3])
property_set = {}
actual = BIPMapping(coupling, objective="depth")(circuit, property_set)
self.assertEqual(2, actual.depth())
CheckMap(coupling)(actual, property_set)
self.assertTrue(property_set["is_swap_mapped"])
def test_ignore_initial_layout(self):
"""Ignoring initial layout even when it is supplied"""
coupling = CouplingMap([[0, 1], [0, 2]])
circuit = QuantumCircuit(3)
circuit.cx(1, 2)
property_set = {
"layout": Layout.generate_trivial_layout(*circuit.qubits)
}
actual = BIPMapping(coupling)(circuit, property_set)
q = QuantumRegister(3, name="q")
expected = QuantumCircuit(q)
expected.cx(q[0], q[1])
self.assertEqual(expected, actual)
def test_qubit_subset(self):
"""Test if `qubit_subset` option works as expected."""
circuit = QuantumCircuit(3)
circuit.cx(0, 1)
circuit.cx(1, 2)
circuit.cx(0, 2)
coupling = CouplingMap([(0, 1), (1, 3), (3, 2)])
qubit_subset = [0, 1, 3]
actual = BIPMapping(coupling, qubit_subset=qubit_subset)(circuit)
# all used qubits are in qubit_subset
bit_indices = {bit: index for index, bit in enumerate(actual.qubits)}
for _, qargs, _ in actual.data:
for q in qargs:
self.assertTrue(bit_indices[q] in qubit_subset)
# ancilla qubits are set in the resulting qubit
idle = QuantumRegister(1, name="ancilla")
self.assertEqual(idle[0], actual._layout[2])
def test_trivial_case(self):
"""No need to have any swap, the CX are distance 1 to each other
q0:--(+)-[H]-(+)-
| |
q1:---.-------|--
|
q2:-----------.--
CouplingMap map: [1]--[0]--[2]
"""
coupling = CouplingMap([[0, 1], [0, 2]])
circuit = QuantumCircuit(3)
circuit.cx(1, 0)
circuit.h(0)
circuit.cx(2, 0)
actual = BIPMapping(coupling)(circuit)
self.assertEqual(3, len(actual))
for inst, _, _ in actual.data: # there are no swaps
self.assertFalse(isinstance(inst, SwapGate))
def test_different_number_of_virtual_and_physical_qubits(self):
"""Test the case when number of virtual and physical qubits are different."""
# q_0: ──■────■───────
# ┌─┴─┐ │
# q_1: ┤ X ├──┼────■──
# └───┘ │ ┌─┴─┐
# q_2: ──■────┼──┤ X ├
# ┌─┴─┐┌─┴─┐└───┘
# q_3: ┤ X ├┤ X ├─────
# └───┘└───┘
circuit = QuantumCircuit(4)
circuit.cx(0, 1)
circuit.cx(2, 3)
circuit.cx(0, 3)
circuit.cx(1, 2)
coupling = CouplingMap.from_line(5)
with self.assertRaises(TranspilerError):
BIPMapping(coupling)(circuit)
def test_can_map_measurements_correctly(self):
"""Verify measurement nodes are updated to map correct cregs to re-mapped qregs."""
coupling = CouplingMap([[0, 1], [0, 2]])
qr = QuantumRegister(3, "qr")
cr = ClassicalRegister(2)
circuit = QuantumCircuit(qr, cr)
circuit.cx(qr[1], qr[2])
circuit.measure(qr[1], cr[0])
circuit.measure(qr[2], cr[1])
actual = BIPMapping(coupling)(circuit)
q = QuantumRegister(3, "q")
expected = QuantumCircuit(q, cr)
expected.cx(q[0], q[1])
expected.measure(q[0], cr[0]) # <- changed due to initial layout change
expected.measure(q[1], cr[1]) # <- changed due to initial layout change
self.assertEqual(expected, actual)
def test_multi_cregs(self):
"""Test for multiple ClassicalRegisters."""
# ┌───┐ ░ ┌─┐
# qr_0: ──■────────────┤ X ├─░─┤M├─────────
# ┌─┴─┐ ┌───┐└─┬─┘ ░ └╥┘┌─┐
# qr_1: ┤ X ├──■──┤ H ├──■───░──╫─┤M├──────
# └───┘┌─┴─┐└───┘ ░ ║ └╥┘┌─┐
# qr_2: ──■──┤ X ├───────────░──╫──╫─┤M├───
# ┌─┴─┐└───┘ ░ ║ ║ └╥┘┌─┐
# qr_3: ┤ X ├────────────────░──╫──╫──╫─┤M├
# └───┘ ░ ║ ║ ║ └╥┘
# c: 2/════════════════════════╩══╬══╩══╬═
# 0 ║ 1 ║
# ║ ║
# d: 2/═══════════════════════════╩═════╩═
# 0 1
qr = QuantumRegister(4, "qr")
cr1 = ClassicalRegister(2, "c")
cr2 = ClassicalRegister(2, "d")
circuit = QuantumCircuit(qr, cr1, cr2)
circuit.cx(qr[0], qr[1])
circuit.cx(qr[2], qr[3])
circuit.cx(qr[1], qr[2])
circuit.h(qr[1])
circuit.cx(qr[1], qr[0])
circuit.barrier(qr)
circuit.measure(qr[0], cr1[0])
circuit.measure(qr[1], cr2[0])
circuit.measure(qr[2], cr1[1])
circuit.measure(qr[3], cr2[1])
coupling = CouplingMap([[0, 1], [0, 2], [2, 3]]) # linear [1, 0, 2, 3]
property_set = {}
actual = BIPMapping(coupling, objective="depth")(circuit, property_set)
self.assertEqual(5, actual.depth())
CheckMap(coupling)(actual, property_set)
self.assertTrue(property_set["is_swap_mapped"])
def test_multi_cregs(self):
"""Test for multiple ClassicalRegisters."""
qr = QuantumRegister(4, "qr")
cr1 = ClassicalRegister(2, "c")
cr2 = ClassicalRegister(2, "d")
circuit = QuantumCircuit(qr, cr1, cr2)
circuit.cx(qr[0], qr[1])
circuit.cx(qr[2], qr[3])
circuit.cx(qr[1], qr[2])
circuit.h(qr[1])
circuit.cx(qr[1], qr[0])
circuit.barrier(qr)
circuit.measure(qr[0], cr1[0])
circuit.measure(qr[1], cr2[0])
circuit.measure(qr[2], cr1[1])
circuit.measure(qr[3], cr2[1])
coupling = CouplingMap([[0, 1], [0, 2], [2, 3]]) # linear [1, 0, 2, 3]
property_set = {}
actual = BIPMapping(coupling, objective="depth")(circuit, property_set)
self.assertEqual(5, actual.depth())
CheckMap(coupling)(actual, property_set)
self.assertTrue(property_set["is_swap_mapped"])
def test_swaps_in_dummy_steps(self):
"""Test the case when swaps are inserted in dummy steps."""
# ┌───┐ ░ ░
# q_0: ──■──┤ H ├─░───■────────░───■───────
# ┌─┴─┐├───┤ ░ │ ░ │
# q_1: ┤ X ├┤ H ├─░───┼────■───░───┼────■──
# └───┘├───┤ ░ │ ┌─┴─┐ ░ ┌─┴─┐ │
# q_2: ──■──┤ H ├─░───┼──┤ X ├─░─┤ X ├──┼──
# ┌─┴─┐├───┤ ░ ┌─┴─┐└───┘ ░ └───┘┌─┴─┐
# q_3: ┤ X ├┤ H ├─░─┤ X ├──────░──────┤ X ├
# └───┘└───┘ ░ └───┘ ░ └───┘
circuit = QuantumCircuit(4)
circuit.cx(0, 1)
circuit.cx(2, 3)
circuit.h([0, 1, 2, 3])
circuit.barrier()
circuit.cx(0, 3)
circuit.cx(1, 2)
circuit.barrier()
circuit.cx(0, 2)
circuit.cx(1, 3)
coupling = CouplingMap.from_line(4)
property_set = {}
actual = BIPMapping(coupling, objective="depth")(circuit, property_set)
self.assertEqual(7, actual.depth())
CheckMap(coupling)(actual, property_set)
self.assertTrue(property_set["is_swap_mapped"])
# no swaps before the first barrier
for inst, _, _ in actual.data:
if isinstance(inst, Barrier):
break
self.assertFalse(isinstance(inst, SwapGate))
def test_empty(self):
"""Returns the original circuit if the circuit is empty."""
coupling = CouplingMap([[0, 1]])
circuit = QuantumCircuit(2)
actual = BIPMapping(coupling)(circuit)
self.assertEqual(circuit, actual)
def test_initialize_gate_error_objective_without_backend_prop(self):
"""Fails if ``objective`` that requires ``backend_prop`` is specified but it is not supplied."""
with self.assertRaises(TranspilerError):
BIPMapping(coupling_map=CouplingMap.from_line(3),
objective="gate_error")