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single_qubit_gates_merger

SingleQubitGatesMerger

Bases: Merger

Source code in opensquirrel/passes/merger/single_qubit_gates_merger.py 
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class SingleQubitGatesMerger(Merger):
    def merge(self, ir: IR, qubit_register_size: int) -> None:
        """Merge all consecutive 1-qubit gates in the circuit.
        Gates obtained from merging other gates become anonymous gates.

        Args:
            ir: Intermediate representation of the circuit.
            qubit_register_size: Size of the qubit register

        """
        accumulators_per_qubit: dict[Qubit, BlochSphereRotation] = {
            Qubit(qubit_index): I(qubit_index) for qubit_index in range(qubit_register_size)
        }

        statement_index = 0
        while statement_index < len(ir.statements):
            statement = ir.statements[statement_index]

            # Accumulate consecutive Bloch sphere rotations
            instruction: Instruction = cast("Instruction", statement)
            if isinstance(instruction, BlochSphereRotation):
                already_accumulated = accumulators_per_qubit[instruction.qubit]
                composed = compose_bloch_sphere_rotations(already_accumulated, instruction)
                accumulators_per_qubit[instruction.qubit] = composed
                del ir.statements[statement_index]
                continue

            def insert_accumulated_bloch_sphere_rotations(qubits: list[Qubit]) -> None:
                nonlocal statement_index
                for qubit in qubits:
                    if not accumulators_per_qubit[qubit].is_identity():
                        ir.statements.insert(statement_index, accumulators_per_qubit[qubit])
                        accumulators_per_qubit[qubit] = I(qubit)
                        statement_index += 1

            # For barrier directives, insert all accumulated Bloch sphere rotations
            # For other instructions, insert accumulated Bloch sphere rotations on qubits used by those instructions
            # In any case, reset the dictionary entry for the inserted accumulated Bloch sphere rotations
            if isinstance(instruction, Barrier) or isinstance(statement, AsmDeclaration):
                insert_accumulated_bloch_sphere_rotations([Qubit(i) for i in range(qubit_register_size)])
            else:
                insert_accumulated_bloch_sphere_rotations(instruction.get_qubit_operands())
            statement_index += 1

        for accumulated_bloch_sphere_rotation in accumulators_per_qubit.values():
            if not accumulated_bloch_sphere_rotation.is_identity():
                ir.statements.append(accumulated_bloch_sphere_rotation)

merge(ir, qubit_register_size)

Merge all consecutive 1-qubit gates in the circuit. Gates obtained from merging other gates become anonymous gates.

Parameters:

Name Type Description Default
ir IR

Intermediate representation of the circuit.

 required
qubit_register_size int

Size of the qubit register

 required
Source code in opensquirrel/passes/merger/single_qubit_gates_merger.py 
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def merge(self, ir: IR, qubit_register_size: int) -> None:
    """Merge all consecutive 1-qubit gates in the circuit.
    Gates obtained from merging other gates become anonymous gates.

    Args:
        ir: Intermediate representation of the circuit.
        qubit_register_size: Size of the qubit register

    """
    accumulators_per_qubit: dict[Qubit, BlochSphereRotation] = {
        Qubit(qubit_index): I(qubit_index) for qubit_index in range(qubit_register_size)
    }

    statement_index = 0
    while statement_index < len(ir.statements):
        statement = ir.statements[statement_index]

        # Accumulate consecutive Bloch sphere rotations
        instruction: Instruction = cast("Instruction", statement)
        if isinstance(instruction, BlochSphereRotation):
            already_accumulated = accumulators_per_qubit[instruction.qubit]
            composed = compose_bloch_sphere_rotations(already_accumulated, instruction)
            accumulators_per_qubit[instruction.qubit] = composed
            del ir.statements[statement_index]
            continue

        def insert_accumulated_bloch_sphere_rotations(qubits: list[Qubit]) -> None:
            nonlocal statement_index
            for qubit in qubits:
                if not accumulators_per_qubit[qubit].is_identity():
                    ir.statements.insert(statement_index, accumulators_per_qubit[qubit])
                    accumulators_per_qubit[qubit] = I(qubit)
                    statement_index += 1

        # For barrier directives, insert all accumulated Bloch sphere rotations
        # For other instructions, insert accumulated Bloch sphere rotations on qubits used by those instructions
        # In any case, reset the dictionary entry for the inserted accumulated Bloch sphere rotations
        if isinstance(instruction, Barrier) or isinstance(statement, AsmDeclaration):
            insert_accumulated_bloch_sphere_rotations([Qubit(i) for i in range(qubit_register_size)])
        else:
            insert_accumulated_bloch_sphere_rotations(instruction.get_qubit_operands())
        statement_index += 1

    for accumulated_bloch_sphere_rotation in accumulators_per_qubit.values():
        if not accumulated_bloch_sphere_rotation.is_identity():
            ir.statements.append(accumulated_bloch_sphere_rotation)