Library of Unparameterizable Standard Gates Commutations

qiskit/circuit/commutation_library.py

@@ -0,0 +1,20 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017, 2023.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Provides a commutation checker that caches the determined commutation results during this session """
+
+from qiskit.circuit import CommutationChecker
+
+from qiskit.circuit._standard_gates_commutations import standard_gates_commutations
+
+StandardGateCommutations = standard_gates_commutations
+SessionCommutationChecker = CommutationChecker(StandardGateCommutations)

qiskit/dagcircuit/dagdependency.py

@@ -19,12 +19,12 @@
 
 import rustworkx as rx
 
+from qiskit.circuit.commutation_library import SessionCommutationChecker as scc
 from qiskit.circuit.controlflow import condition_resources
 from qiskit.circuit.quantumregister import QuantumRegister, Qubit
 from qiskit.circuit.classicalregister import ClassicalRegister, Clbit
 from qiskit.dagcircuit.exceptions import DAGDependencyError
 from qiskit.dagcircuit.dagdepnode import DAGDepNode
-from qiskit.circuit.commutation_checker import CommutationChecker
 
 
 # ToDo: DagDependency needs to be refactored:
@@ -112,7 +112,7 @@ def __init__(self):
         self.duration = None
         self.unit = "dt"
 
-        self.comm_checker = CommutationChecker()
+        self.comm_checker = scc
 
     @property
     def global_phase(self):

qiskit/transpiler/passes/optimization/commutation_analysis.py

@@ -14,9 +14,9 @@
 
 from collections import defaultdict
 
+from qiskit.circuit.commutation_library import SessionCommutationChecker as scc
 from qiskit.dagcircuit import DAGOpNode
 from qiskit.transpiler.basepasses import AnalysisPass
-from qiskit.circuit.commutation_checker import CommutationChecker
 
 
 class CommutationAnalysis(AnalysisPass):
@@ -29,7 +29,7 @@ class CommutationAnalysis(AnalysisPass):
 
     def __init__(self):
         super().__init__()
-        self.comm_checker = CommutationChecker()
+        self.comm_checker = scc
 
     def run(self, dag):
         """Run the CommutationAnalysis pass on `dag`.

qiskit/transpiler/passes/optimization/commutative_inverse_cancellation.py

@@ -11,13 +11,11 @@
 # that they have been altered from the originals.
 
 """Cancel pairs of inverse gates exploiting commutation relations."""
-
-
+from qiskit.circuit.commutation_library import SessionCommutationChecker as scc
 from qiskit.dagcircuit import DAGCircuit, DAGOpNode
 from qiskit.quantum_info import Operator
 from qiskit.quantum_info.operators.predicates import matrix_equal
 from qiskit.transpiler.basepasses import TransformationPass
-from qiskit.circuit.commutation_checker import CommutationChecker
 
 
 class CommutativeInverseCancellation(TransformationPass):
@@ -94,8 +92,8 @@ def run(self, dag: DAGCircuit):
 
         removed = [False for _ in range(circ_size)]
 
+        cc = scc
         phase_update = 0
-        cc = CommutationChecker()
 
         for idx1 in range(0, circ_size):
             if self._skip_node(topo_sorted_nodes[idx1]):

releasenotes/notes/add-commutation-library-88b7ff65b3d35f9a.yaml

@@ -0,0 +1,13 @@
+---
+features:
+  - |
+    Adds a commutation library to the :class:`.CommutationChecker`. The commutation library stores all
+    commutation relations of unparameterizable standard gates into a dictionary that allows for efficient
+    lookup at runtime. Furthermore, the :class:`.CommutationChecker` was refactored and an upper limit was
+    set to the number of cached commutation relations that are not in the commutation library. A session
+    commutation checker was added, that can be used to cache commutations computed during one qiskit
+    execution. Addresses `#8020 <https://github.com/Qiskit/qiskit-terra/issues/8020>_` and
+    `#7101 <https://github.com/Qiskit/qiskit-terra/issues/7101>_`
+  - |
+    Adds a `SessionCommutationChecker`, i.e. a commutation checker with commutations that are cached
+    consistently during the runtime of a python execution.