Integrate qiskit-toqm as an optional package for layout and routing.

qiskit/compiler/transpiler.py

@@ -138,7 +138,8 @@ def transpile(
                     [qr[0], None, None, qr[1], None, qr[2]]
 
         layout_method: Name of layout selection pass ('trivial', 'dense', 'noise_adaptive', 'sabre')
-        routing_method: Name of routing pass ('basic', 'lookahead', 'stochastic', 'sabre', 'none')
+        routing_method: Name of routing pass
+            ('basic', 'lookahead', 'stochastic', 'sabre', 'toqm', 'none')
         translation_method: Name of translation pass ('unroller', 'translator', 'synthesis')
         scheduling_method: Name of scheduling pass.
             * ``'as_soon_as_possible'``: Schedule instructions greedily, as early as possible

qiskit/transpiler/preset_passmanagers/level0.py

@@ -55,6 +55,7 @@
 from qiskit.transpiler.passes import ContainsInstruction
 
 from qiskit.transpiler import TranspilerError
+from qiskit.utils.optionals import HAS_TOQM
 
 
 def level_0_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
@@ -137,6 +138,9 @@ def _choose_layout_condition(property_set):
     def _swap_condition(property_set):
         return not property_set["is_swap_mapped"]
 
+    def _swap_needs_basis(property_set):
+        return _swap_condition(property_set) and routing_method == "toqm"
+
     _swap = [BarrierBeforeFinalMeasurements()]
     if routing_method == "basic":
         _swap += [BasicSwap(coupling_map)]
@@ -146,6 +150,25 @@ def _swap_condition(property_set):
         _swap += [LookaheadSwap(coupling_map, search_depth=2, search_width=2)]
     elif routing_method == "sabre":
         _swap += [SabreSwap(coupling_map, heuristic="basic", seed=seed_transpiler)]
+    elif routing_method == "toqm":
+        HAS_TOQM.require_now("TOQM-based routing")
+        from qiskit_toqm import ToqmSwap, ToqmStrategyO0, latencies_from_target
+
+        if initial_layout:
+            raise TranspilerError("Initial layouts are not supported with TOQM-based routing.")
+
+        # Note: BarrierBeforeFinalMeasurements is skipped intentionally since ToqmSwap
+        #       does not yet support barriers.
+        _swap = [
+            ToqmSwap(
+                coupling_map,
+                strategy=ToqmStrategyO0(
+                    latencies_from_target(
+                        coupling_map, instruction_durations, basis_gates, backend_properties
+                    )
+                ),
+            )
+        ]
     elif routing_method == "none":
         _swap += [
             Error(
@@ -223,6 +246,7 @@ def _direction_condition(property_set):
         pm0.append(_choose_layout, condition=_choose_layout_condition)
         pm0.append(_embed)
         pm0.append(_swap_check)
+        pm0.append(_unroll, condition=_swap_needs_basis)
         pm0.append(_swap, condition=_swap_condition)
     pm0.append(_unroll)
     if (coupling_map and not coupling_map.is_symmetric) or (

qiskit/transpiler/preset_passmanagers/level1.py

@@ -63,6 +63,7 @@
 from qiskit.transpiler.passes.layout.vf2_layout import VF2LayoutStopReason
 
 from qiskit.transpiler import TranspilerError
+from qiskit.utils.optionals import HAS_TOQM
 
 
 def level_1_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
@@ -194,6 +195,9 @@ def _vf2_match_not_found(property_set):
     def _swap_condition(property_set):
         return not property_set["is_swap_mapped"]
 
+    def _swap_needs_basis(property_set):
+        return _swap_condition(property_set) and routing_method == "toqm"
+
     _swap = [BarrierBeforeFinalMeasurements()]
     if routing_method == "basic":
         _swap += [BasicSwap(coupling_map)]
@@ -203,6 +207,25 @@ def _swap_condition(property_set):
         _swap += [LookaheadSwap(coupling_map, search_depth=4, search_width=4)]
     elif routing_method == "sabre":
         _swap += [SabreSwap(coupling_map, heuristic="lookahead", seed=seed_transpiler)]
+    elif routing_method == "toqm":
+        HAS_TOQM.require_now("TOQM-based routing")
+        from qiskit_toqm import ToqmSwap, ToqmStrategyO1, latencies_from_target
+
+        if initial_layout:
+            raise TranspilerError("Initial layouts are not supported with TOQM-based routing.")
+
+        # Note: BarrierBeforeFinalMeasurements is skipped intentionally since ToqmSwap
+        #       does not yet support barriers.
+        _swap = [
+            ToqmSwap(
+                coupling_map,
+                strategy=ToqmStrategyO1(
+                    latencies_from_target(
+                        coupling_map, instruction_durations, basis_gates, backend_properties
+                    )
+                ),
+            )
+        ]
     elif routing_method == "none":
         _swap += [
             Error(
@@ -297,6 +320,7 @@ def _opt_control(property_set):
         pm1.append(_improve_layout, condition=_vf2_match_not_found)
         pm1.append(_embed)
         pm1.append(_swap_check)
+        pm1.append(_unroll, condition=_swap_needs_basis)
         pm1.append(_swap, condition=_swap_condition)
     pm1.append(_unroll)
     if (coupling_map and not coupling_map.is_symmetric) or (

qiskit/transpiler/preset_passmanagers/level2.py

@@ -63,6 +63,7 @@
 from qiskit.transpiler.passes.layout.vf2_layout import VF2LayoutStopReason
 
 from qiskit.transpiler import TranspilerError
+from qiskit.utils.optionals import HAS_TOQM
 
 
 def level_2_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
@@ -178,6 +179,9 @@ def _vf2_match_not_found(property_set):
     def _swap_condition(property_set):
         return not property_set["is_swap_mapped"]
 
+    def _swap_needs_basis(property_set):
+        return _swap_condition(property_set) and routing_method == "toqm"
+
     _swap = [BarrierBeforeFinalMeasurements()]
     if routing_method == "basic":
         _swap += [BasicSwap(coupling_map)]
@@ -187,6 +191,25 @@ def _swap_condition(property_set):
         _swap += [LookaheadSwap(coupling_map, search_depth=5, search_width=5)]
     elif routing_method == "sabre":
         _swap += [SabreSwap(coupling_map, heuristic="decay", seed=seed_transpiler)]
+    elif routing_method == "toqm":
+        HAS_TOQM.require_now("TOQM-based routing")
+        from qiskit_toqm import ToqmSwap, ToqmStrategyO2, latencies_from_target
+
+        if initial_layout:
+            raise TranspilerError("Initial layouts are not supported with TOQM-based routing.")
+
+        # Note: BarrierBeforeFinalMeasurements is skipped intentionally since ToqmSwap
+        #       does not yet support barriers.
+        _swap = [
+            ToqmSwap(
+                coupling_map,
+                strategy=ToqmStrategyO2(
+                    latencies_from_target(
+                        coupling_map, instruction_durations, basis_gates, backend_properties
+                    )
+                ),
+            )
+        ]
     elif routing_method == "none":
         _swap += [
             Error(
@@ -284,6 +307,7 @@ def _opt_control(property_set):
         pm2.append(_choose_layout_1, condition=_vf2_match_not_found)
         pm2.append(_embed)
         pm2.append(_swap_check)
+        pm2.append(_unroll, condition=_swap_needs_basis)
         pm2.append(_swap, condition=_swap_condition)
     pm2.append(_unroll)
     if (coupling_map and not coupling_map.is_symmetric) or (

qiskit/transpiler/preset_passmanagers/level3.py

@@ -66,6 +66,7 @@
 from qiskit.transpiler.passes.layout.vf2_layout import VF2LayoutStopReason
 
 from qiskit.transpiler import TranspilerError
+from qiskit.utils.optionals import HAS_TOQM
 
 
 def level_3_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
@@ -180,6 +181,9 @@ def _vf2_match_not_found(property_set):
     def _swap_condition(property_set):
         return not property_set["is_swap_mapped"]
 
+    def _swap_needs_basis(property_set):
+        return _swap_condition(property_set) and routing_method == "toqm"
+
     _swap = [BarrierBeforeFinalMeasurements()]
     if routing_method == "basic":
         _swap += [BasicSwap(coupling_map)]
@@ -189,6 +193,25 @@ def _swap_condition(property_set):
         _swap += [LookaheadSwap(coupling_map, search_depth=5, search_width=6)]
     elif routing_method == "sabre":
         _swap += [SabreSwap(coupling_map, heuristic="decay", seed=seed_transpiler)]
+    elif routing_method == "toqm":
+        HAS_TOQM.require_now("TOQM-based routing")
+        from qiskit_toqm import ToqmSwap, ToqmStrategyO3, latencies_from_target
+
+        if initial_layout:
+            raise TranspilerError("Initial layouts are not supported with TOQM-based routing.")
+
+        # Note: BarrierBeforeFinalMeasurements is skipped intentionally since ToqmSwap
+        #       does not yet support barriers.
+        _swap = [
+            ToqmSwap(
+                coupling_map,
+                strategy=ToqmStrategyO3(
+                    latencies_from_target(
+                        coupling_map, instruction_durations, basis_gates, backend_properties
+                    )
+                ),
+            )
+        ]
     elif routing_method == "none":
         _swap += [
             Error(
@@ -295,6 +318,7 @@ def _opt_control(property_set):
         pm3.append(_choose_layout_1, condition=_vf2_match_not_found)
         pm3.append(_embed)
         pm3.append(_swap_check)
+        pm3.append(_unroll, condition=_swap_needs_basis)
         pm3.append(_swap, condition=_swap_condition)
     pm3.append(_unroll)
     if (coupling_map and not coupling_map.is_symmetric) or (

qiskit/utils/optionals.py

@@ -40,6 +40,10 @@
       - :mod:`Qiskit Ignis <qiskit.ignis>` provides tools for quantum hardware verification, noise
         characterization, and error correction.
 
+    * - .. py:data:: HAS_TOQM
+      - `Qiskit TOQM <https://github.com/qiskit-toqm/qiskit-toqm>`__ provides transpiler passes
+        for the `Time-optimal Qubit mapping algorithm <https://doi.org/10.1145/3445814.3446706>`__.
+
 
 External Python Libraries
 -------------------------
@@ -206,6 +210,7 @@
     name="Qiskit Ignis",
     install="pip install qiskit-ignis",
 )
+HAS_TOQM = _LazyImportTester("qiskit_toqm", name="Qiskit TOQM", install="pip install qiskit-toqm")
 
 HAS_CPLEX = _LazyImportTester(
     "cplex",

releasenotes/notes/qiskit-toqm-41bd0f3b6760df6f.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Adds new layout and routing methods based on paper
+    `Time-optimal Qubit mapping` <https://dl.acm.org/doi/10.1145/3445814.3446706>`__
+    to :func:`~qiskit.compiler.transpile`. To use them, optional package
+    `Qiskit TOQM <https://github.com/qiskit-toqm/qiskit-toqm>`__ must be
+    installed. The ``layout_method`` and ``routing_method`` kwargs of 
+    :func:`~qiskit.compiler.transpile` support an additional value, ``'toqm'``
+    which is used to enable layout and or routing via TOQM.

requirements-dev.txt

@@ -20,6 +20,7 @@ seaborn>=0.9.0
 reno>=3.4.0
 Sphinx>=3.0.0
 qiskit-sphinx-theme>=1.6
+qiskit-toqm>=0.0.1;platform_machine != 'aarch64' or platform_system != 'Linux'
 sphinx-autodoc-typehints<1.14.0
 jupyter-sphinx
 sphinx-panels

test/python/transpiler/test_preset_passmanagers.py

@@ -22,7 +22,7 @@
 from qiskit import QuantumCircuit, ClassicalRegister, QuantumRegister
 from qiskit.circuit import Qubit
 from qiskit.compiler import transpile, assemble
-from qiskit.transpiler import CouplingMap, Layout
+from qiskit.transpiler import CouplingMap, Layout, TranspilerError
 from qiskit.circuit.library import U2Gate, U3Gate
 from qiskit.test import QiskitTestCase
 from qiskit.test.mock import (
@@ -32,11 +32,15 @@
     FakeRueschlikon,
     FakeTokyo,
     FakePoughkeepsie,
+    FakeWashington,
+    FakeLima,
 )
 from qiskit.converters import circuit_to_dag
 from qiskit.circuit.library import GraphState
 from qiskit.quantum_info import random_unitary
 
+from qiskit.utils.optionals import HAS_TOQM
+
 
 def emptycircuit():
     """Empty circuit"""
@@ -203,6 +207,51 @@ def test_alignment_constraints_called_with_delay_in_circuit(self, level):
         mock.assert_called_once()
 
 
+@ddt
+@unittest.skipUnless(HAS_TOQM, "qiskit-toqm needs to be installed")
+class TestToqmIntegration(QiskitTestCase):
+    """Test transpiler with TOQM-based routing"""
+
+    @combine(
+        level=[0, 1, 2, 3],
+        layout_method=[None, "trivial", "dense", "noise_adaptive", "sabre"],
+        backend_vbits_pair=[(FakeWashington(), 10), (FakeLima(), 5)],
+        dsc="TOQM-based routing with '{layout_method}' layout"
+        + "method on '{backend_vbits_pair[0]}' backend at level '{level}'",
+        name="TOQM_{layout_method}_{backend_vbits_pair[0]}_level{level}",
+    )
+    def test_basic_circuit(self, level, layout_method, backend_vbits_pair):
+        """
+        Basic circuits transpile across all opt levels and layout
+        methods when using TOQM-based routing.
+        """
+        backend, circuit_size = backend_vbits_pair
+        qr = QuantumRegister(circuit_size, "q")
+        qc = QuantumCircuit(qr)
+
+        # Generate a circuit that should need swaps.
+        for i in range(1, qr.size):
+            qc.cx(0, i)
+
+        result = transpile(
+            qc,
+            layout_method=layout_method,
+            routing_method="toqm",
+            backend=backend,
+            optimization_level=level,
+            seed_transpiler=4222022,
+        )
+
+        self.assertIsInstance(result, QuantumCircuit)
+
+    def test_initial_layout_is_rejected(self):
+        """Initial layout is rejected when using TOQM-based routing"""
+        with self.assertRaisesRegex(
+            TranspilerError, "Initial layouts are not supported with TOQM-based routing."
+        ):
+            transpile(QuantumCircuit(2), initial_layout=[1, 0], routing_method="toqm")
+
+
 @ddt
 class TestTranspileLevels(QiskitTestCase):
     """Test transpiler on fake backend"""