qiskit/opflow/evolutions/trotterizations/trotterization_factory.py

# This code is part of Qiskit.
#
# (C) Copyright IBM 2020, 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.

"""TrotterizationFactory Class"""

from qiskit.opflow.evolutions.trotterizations.qdrift import QDrift
from qiskit.opflow.evolutions.trotterizations.suzuki import Suzuki
from qiskit.opflow.evolutions.trotterizations.trotter import Trotter
from qiskit.opflow.evolutions.trotterizations.trotterization_base import TrotterizationBase
from qiskit.utils.deprecation import deprecate_func


class TrotterizationFactory:
    """Deprecated: A factory for conveniently creating TrotterizationBase instances."""

    @staticmethod
    @deprecate_func(
        since="0.24.0",
        additional_msg="For code migration guidelines, visit https://qisk.it/opflow_migration.",
    )
    def build(mode: str = "trotter", reps: int = 1) -> TrotterizationBase:
        """A factory for conveniently creating TrotterizationBase instances.

        Args:
            mode: One of 'trotter', 'suzuki', 'qdrift'
            reps: The number of times to repeat the Trotterization circuit.

        Returns:
            The desired TrotterizationBase instance.

        Raises:
            ValueError: A string not in ['trotter', 'suzuki', 'qdrift'] is given for mode.
        """
        if mode == "trotter":
            return Trotter(reps=reps)

        elif mode == "suzuki":
            return Suzuki(reps=reps)

        elif mode == "qdrift":
            return QDrift(reps=reps)

        raise ValueError(f"Trotter mode {mode} not supported")