def test_swap_between_qregs(self):
""" Adding a swap affecting different qregs
qr0_0:-------
qr1_0:--(+)--
|
qr1_1:---.---
Coupling map: [1]--[0]--[2]
qr0_0:--X--.---
| |
qr1_0:--|-(+)--
|
qr1_1:--X------
"""
coupling = Coupling({0: [1, 2]})
qr0 = QuantumRegister(1, 'qr0')
qr1 = QuantumRegister(2, 'qr1')
circuit = QuantumCircuit(qr0, qr1)
circuit.cx(qr1[0], qr1[1])
dag = circuit_to_dag(circuit)
expected = QuantumCircuit(qr0, qr1)
expected.swap(qr1[1], qr0[0])
expected.cx(qr1[1], qr0[0])
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(circuit_to_dag(expected), after)
def test_a_single_swap(self):
""" Adding a swap
q0:-------
q1:--(+)--
|
q2:---.---
Coupling map: [1]--[0]--[2]
q0:--X---.---
| |
q1:--X---|---
|
q2:-----(+)--
"""
coupling = Coupling({0: [1, 2]})
qr = QuantumRegister(3, 'q')
circuit = QuantumCircuit(qr)
circuit.cx(qr[1], qr[2])
dag = circuit_to_dag(circuit)
expected = QuantumCircuit(qr)
expected.swap(qr[1], qr[0])
expected.cx(qr[0], qr[2])
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(circuit_to_dag(expected), after)
def test_keep_layout(self):
"""After a swap, the following gates also change the wires.
qr0:---.---[H]--
|
qr1:---|--------
|
qr2:--(+)-------
Coupling map: [0]--[1]--[2]
qr0:--X-----------
|
qr1:--X---.--[H]--
|
qr2:-----(+)------
"""
coupling = Coupling({1: [0, 2]})
qr = QuantumRegister(3, 'q')
circuit = QuantumCircuit(qr)
circuit.cx(qr[0], qr[2])
circuit.h(qr[0])
dag = circuit_to_dag(circuit)
expected = QuantumCircuit(qr)
expected.swap(qr[0], qr[1])
expected.cx(qr[1], qr[2])
expected.h(qr[1])
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(circuit_to_dag(expected), after)
def test_far_swap_with_gate_the_middle(self):
""" A far swap with a gate in the middle.
qr0:--(+)-------.--
| |
qr1:---|--------|--
|
qr2:---|--------|--
| |
qr3:---.--[H]--(+)-
Coupling map: [0]--[1]--[2]--[3]
qr0:-------(+)-------.---
| |
qr1:-----X--.--[H]--(+)--
|
qr2:--X--X---------------
|
qr3:--X------------------
"""
coupling = Coupling({0: [1], 1: [2], 2: [3]})
qr = QuantumRegister(4, 'qr')
circuit = QuantumCircuit(qr)
circuit.cx(qr[3], qr[0])
circuit.h(qr[3])
circuit.cx(qr[0], qr[3])
dag = circuit_to_dag(circuit)
expected = QuantumCircuit(qr)
expected.swap(qr[3], qr[2])
expected.swap(qr[2], qr[1])
expected.cx(qr[1], qr[0])
expected.h(qr[1])
expected.cx(qr[0], qr[1])
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(circuit_to_dag(expected), after)
def test_far_swap(self):
""" A far swap that affects coming CXs.
qr0:--(+)---.--
| |
qr1:---|----|--
| |
qr2:---|----|--
| |
qr3:---.---(+)-
Coupling map: [0]--[1]--[2]--[3]
qr0:--X--------------
|
qr1:--X--X-----------
|
qr2:-----X--(+)---.--
| |
qr3:---------.---(+)-
"""
coupling = Coupling({0: [1], 1: [2], 2: [3]})
qr = QuantumRegister(4, 'q')
circuit = QuantumCircuit(qr)
circuit.cx(qr[0], qr[3])
circuit.cx(qr[3], qr[0])
dag = circuit_to_dag(circuit)
expected = QuantumCircuit(qr)
expected.swap(qr[0], qr[1])
expected.swap(qr[1], qr[2])
expected.cx(qr[2], qr[3])
expected.cx(qr[3], qr[2])
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(circuit_to_dag(expected), after)
def test_trivial_case(self):
"""No need to have any swap, the CX are distance 1 to each other
q0:--(+)-[U]-(+)-
| |
q1:---.-------|--
|
q2:-----------.--
Coupling map: [1]--[0]--[2]
"""
coupling = Coupling({0: [1, 2]})
qr = QuantumRegister(3, 'q')
circuit = QuantumCircuit(qr)
circuit.cx(qr[0], qr[1])
circuit.h(qr[0])
circuit.cx(qr[0], qr[2])
dag = circuit_to_dag(circuit)
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(dag, after)
def test_trivial_in_same_layer(self):
""" No need to have any swap, two CXs distance 1 to each other, in the same layer
q0:--(+)--
|
q1:---.---
q2:--(+)--
|
q3:---.---
Coupling map: [0]--[1]--[2]--[3]
"""
coupling = Coupling({0: [1], 1: [2], 2: [3]})
qr = QuantumRegister(4, 'q')
circuit = QuantumCircuit(qr)
circuit.cx(qr[2], qr[3])
circuit.cx(qr[0], qr[1])
dag = circuit_to_dag(circuit)
pass_ = BasicMapper(coupling)
after = pass_.run(dag)
self.assertEqual(dag, after)