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Source code for qiskit.transpiler.passes.optimization.remove_diagonal_gates_before_measure

# This code is part of Qiskit.
# (C) Copyright IBM 2017, 2019.
# 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.

"""Remove diagonal gates (including diagonal 2Q gates) before a measurement."""

from qiskit.circuit import Measure
from qiskit.circuit.library.standard_gates import RZGate, ZGate, TGate, SGate, TdgGate, SdgGate, \
    U1Gate, CZGate, CRZGate, CU1Gate, RZZGate
from qiskit.transpiler.basepasses import TransformationPass

[docs]class RemoveDiagonalGatesBeforeMeasure(TransformationPass): """Remove diagonal gates (including diagonal 2Q gates) before a measurement. Transpiler pass to remove diagonal gates (like RZ, T, Z, etc) before a measurement. Including diagonal 2Q gates. """
[docs] def run(self, dag): """Run the RemoveDiagonalGatesBeforeMeasure pass on `dag`. Args: dag (DAGCircuit): the DAG to be optimized. Returns: DAGCircuit: the optimized DAG. """ diagonal_1q_gates = (RZGate, ZGate, TGate, SGate, TdgGate, SdgGate, U1Gate) diagonal_2q_gates = (CZGate, CRZGate, CU1Gate, RZZGate) nodes_to_remove = set() for measure in dag.op_nodes(Measure): predecessor = next(dag.quantum_predecessors(measure)) if predecessor.type == 'op' and isinstance(predecessor.op, diagonal_1q_gates): nodes_to_remove.add(predecessor) if predecessor.type == 'op' and isinstance(predecessor.op, diagonal_2q_gates): successors = dag.quantum_successors(predecessor) if all([s.type == 'op' and isinstance(s.op, Measure) for s in successors]): nodes_to_remove.add(predecessor) for node_to_remove in nodes_to_remove: dag.remove_op_node(node_to_remove) return dag

© Copyright 2020, Qiskit Development Team. Last updated on 2021/03/04.

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