Source code for quantum_launcher.routines.qiskit_routines.backends.qiskit_backend

  1""" Base backend class for Qiskit routines. """
  2from typing import Literal
  3
  4from qiskit.providers import BackendV1, BackendV2
  5from qiskit.primitives import (
  6    BackendSamplerV2,
  7    BackendEstimatorV2,
  8    StatevectorEstimator,
  9    StatevectorSampler,
 10    Sampler
 11)
 12
 13from qiskit_algorithms.optimizers import COBYLA
 14from qiskit_ibm_runtime import Options
 15
 16from quantum_launcher.base import Backend
 17from quantum_launcher.routines.qiskit_routines.v2_wrapper import SamplerV2Adapter
 18
 19from quantum_launcher.routines.qiskit_routines.backends.utils import (
 20    set_estimator_auto_run_behavior, set_sampler_auto_run_behavior,
 21    AUTO_TRANSPILE_ESTIMATOR_TYPE, AUTO_TRANSPILE_SAMPLER_TYPE
 22)
 23
 24from qiskit.providers import BackendV1, BackendV2
 25from qiskit.primitives import (
 26    BackendSamplerV2,
 27    BackendEstimatorV2,
 28    StatevectorEstimator,
 29    StatevectorSampler,
 30    Sampler
 31)
 32from qiskit_algorithms.optimizers import COBYLA, SPSA
 33from qiskit_ibm_runtime import Options
 34
 35

[docs]
 36class QiskitBackend(Backend):
 37    """
 38    Base class for backends compatible with qiskit.
 39
 40    Attributes:
 41        name (str): The name of the backend.
 42        options (Options | None, optional): The options for the backend. Defaults to None.
 43        backendv1v2 (BackendV1 | BackendV2 | None, optional): Predefined backend to use with name 'backendv1v2'. Defaults to None.
 44        sampler (BaseSamplerV2): The sampler used for sampling.
 45        estimator (BaseEstimatorV2): The estimator used for estimation.
 46        optimizer (Optimizer): The optimizer used for optimization.
 47    """
 48
 49    def __init__(
 50        self,
 51        name: Literal['local_simulator', 'backendv1v2'] | str,
 52        options: Options | None = None,
 53        backendv1v2: BackendV1 | BackendV2 | None = None,
 54        auto_transpile_level: Literal[0, 1, 2, 3] | None = None
 55    ) -> None:
 56        """
 57        Args:
 58            **name (Literal[&#39;local_simulator&#39;, &#39;backendv1v2&#39;] | str)**: Name or mode of operation,
 59            'backendv1v2' allows for using a specific backend simulator.
 60            **options (Options | None, optional)**: Defaults to None.
 61            **backendv1v2 (BackendV1 | BackendV2 | None, optional)**: 
 62                Used with name 'backendv1v2', sampler and estimator will use it. Defaults to None.
 63            **auto_transpile_level (Literal[0, 1, 2, 3] | None, optional)**: 
 64                Optimization level for automatic transpilation of circuits.  
 65            - None: Don't transpile.
 66            - 0: No optimization (only transpile to compatible gates).
 67            - 1: Light optimization.
 68            - 2: Heavy optimization.
 69            - 3: Heaviest optimization.
 70            Defaults to None.
 71        """
 72        super().__init__(name)
 73        self.options = options
 74        self.backendv1v2 = backendv1v2
 75        self._auto_transpile_level = auto_transpile_level
 76        self._auto_assign = False
 77        self._samplerV1: Sampler | None = None
 78        self._set_primitives_on_backend_name()
 79
 80    @property
 81    def samplerV1(self) -> Sampler:
 82        if self._samplerV1 is None:
 83            self._samplerV1 = SamplerV2Adapter(self.sampler)
 84        return self._samplerV1
 85
 86    def _set_primitives_on_backend_name(self):
 87        if self.name == 'local_simulator':
 88            self.estimator = StatevectorEstimator()
 89            self.sampler = StatevectorSampler()
 90            self.optimizer = COBYLA()
 91        elif self.name == 'backendv1v2':
 92            if self.backendv1v2 is None:
 93                raise AttributeError(
 94                    'Please indicate a backend when in backendv1v2 mode.')
 95            self.estimator = BackendEstimatorV2(backend=self.backendv1v2)
 96            self.sampler = BackendSamplerV2(backend=self.backendv1v2)
 97            self.optimizer = SPSA() if self.backendv1v2.name.startswith('ibm') else COBYLA()  # set spsa for real backends
 98
 99        else:
100            raise ValueError(f"Unsupported mode for this backend:'{self.name}'")
101
102        self._configure_auto_behavior()
103
104    def _configure_auto_behavior(self):
105        """
106        Set auto transpilation and/or auto assignment if turned on, on estimator and sampler if compatible.
107        """
108        do_transpile, level = self._auto_transpile_level != None, int(
109            self._auto_transpile_level if self._auto_transpile_level != None else 0)
110        if isinstance(self.estimator, AUTO_TRANSPILE_ESTIMATOR_TYPE.__constraints__):
111            self.estimator = set_estimator_auto_run_behavior(
112                self.estimator,
113                auto_transpile=do_transpile,
114                auto_transpile_level=level,
115                auto_assign=self._auto_assign
116            )
117        if isinstance(self.sampler, AUTO_TRANSPILE_SAMPLER_TYPE.__constraints__):
118            self.sampler = set_sampler_auto_run_behavior(
119                self.sampler,
120                auto_transpile=do_transpile,
121                auto_transpile_level=level,
122                auto_assign=self._auto_assign
123            )