Remove deprecated BackendV1 elements, including base class, providers.models and qobj modules

docs/apidoc/index.rst

@@ -50,7 +50,6 @@ Primitives and providers:
    providers
    providers_basic_provider
    providers_fake_provider
-   providers_models
 
 Results and visualizations:
 
@@ -83,5 +82,4 @@ Other:
 
    compiler
    exceptions
-   qobj
    utils

qiskit/compiler/transpiler.py

@@ -22,7 +22,6 @@
 from qiskit.circuit.quantumcircuit import QuantumCircuit
 from qiskit.dagcircuit import DAGCircuit
 from qiskit.providers.backend import Backend
-from qiskit.providers.backend_compat import BackendV2Converter
 from qiskit.pulse import Schedule
 from qiskit.transpiler import Layout, CouplingMap, PropertySet
 from qiskit.transpiler.basepasses import BasePass
@@ -95,21 +94,20 @@ def transpile(  # pylint: disable=too-many-return-statements
     (``basis_gates``, ``coupling_map``, ``instruction_durations``,
     ``dt`` or ``timing_constraints``). If a ``backend`` is provided together with any loose constraint
     from the list above, the loose constraint will take priority over the corresponding backend
-    constraint. This behavior is independent of whether the ``backend`` instance is of type
-    :class:`.BackendV1` or :class:`.BackendV2`, as summarized in the table below. The first column
+    constraint. This behavior is summarized in the table below. The first column
     in the table summarizes the potential user-provided constraints, and each cell shows whether
     the priority is assigned to that specific constraint input or another input
-    (`target`/`backend(V1)`/`backend(V2)`).
-
-    ============================ ========= ======================== =======================
-    User Provided                target    backend(V1)              backend(V2)
-    ============================ ========= ======================== =======================
-    **basis_gates**              target    basis_gates              basis_gates
-    **coupling_map**             target    coupling_map             coupling_map
-    **instruction_durations**    target    instruction_durations    instruction_durations
-    **dt**                       target    dt                       dt
-    **timing_constraints**       target    timing_constraints       timing_constraints
-    ============================ ========= ======================== =======================
+    (`target`/`backend(V2)`).
+
+    ============================ ========= ========================
+    User Provided                target    backend(V2)
+    ============================ ========= ========================
+    **basis_gates**              target    basis_gates
+    **coupling_map**             target    coupling_map
+    **instruction_durations**    target    instruction_durations
+    **dt**                       target    dt
+    **timing_constraints**       target    timing_constraints
+    ============================ ========= ========================
 
     Args:
         circuits: Circuit(s) to transpile
@@ -320,30 +318,6 @@ def callback_func(**kwargs):
         config = user_config.get_config()
         optimization_level = config.get("transpile_optimization_level", 2)
 
-    if backend is not None and getattr(backend, "version", 0) <= 1:
-        warnings.warn(
-            "The `transpile` function will stop supporting inputs of "
-            f"type `BackendV1` ( {backend} ) in the `backend` parameter in a future "
-            "release no earlier than 2.0. `BackendV1` is deprecated and implementations "
-            "should move to `BackendV2`.",
-            category=DeprecationWarning,
-            stacklevel=2,
-        )
-        with warnings.catch_warnings():
-            # This is a temporary conversion step to allow for a smoother transition
-            # to a fully target-based transpiler pipeline while maintaining the behavior
-            # of `transpile` with BackendV1 inputs.
-            # TODO BackendV1 is deprecated and this path can be
-            #   removed once it gets removed:
-            #   https://github.com/Qiskit/qiskit/pull/12850
-            warnings.filterwarnings(
-                "ignore",
-                category=DeprecationWarning,
-                message=r".+qiskit\.providers\.backend_compat\.BackendV2Converter.+",
-                module="qiskit",
-            )
-            backend = BackendV2Converter(backend)
-
     if (
         scheduling_method is not None
         and backend is None

qiskit/primitives/backend_estimator.py

@@ -22,7 +22,7 @@
 from qiskit.circuit import ClassicalRegister, QuantumCircuit, QuantumRegister
 from qiskit.compiler import transpile
 from qiskit.exceptions import QiskitError
-from qiskit.providers import BackendV1, BackendV2, Options
+from qiskit.providers import BackendV2, Options
 from qiskit.quantum_info import Pauli, PauliList
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 from qiskit.result import Counts, Result
@@ -43,7 +43,7 @@
 
 def _run_circuits(
     circuits: QuantumCircuit | list[QuantumCircuit],
-    backend: BackendV1 | BackendV2,
+    backend: BackendV2,
     clear_metadata: bool = True,
     **run_options,
 ) -> tuple[list[Result], list[dict]]:
@@ -64,9 +64,7 @@ def _run_circuits(
         metadata.append(circ.metadata)
         if clear_metadata:
             circ.metadata = {}
-    if isinstance(backend, BackendV1):
-        max_circuits = getattr(backend.configuration(), "max_experiments", None)
-    elif isinstance(backend, BackendV2):
+    if isinstance(backend, BackendV2):
         max_circuits = backend.max_circuits
     else:
         raise RuntimeError("Backend version not supported")
@@ -96,7 +94,7 @@ class BackendEstimator(BaseEstimator[PrimitiveJob[EstimatorResult]]):
 
     The :class:`~.BackendEstimator` class is a generic implementation of the
     :class:`~.BaseEstimator` (V1) interface that is used to wrap a :class:`~.BackendV2`
-    (or :class:`~.BackendV1`) object in the :class:`~.BaseEstimator` V1 API. It
+    object in the :class:`~.BaseEstimator` V1 API. It
     facilitates using backends that do not provide a native
     :class:`~.BaseEstimator` V1 implementation in places that work with
     :class:`~.BaseEstimator` V1.
@@ -117,7 +115,7 @@ class BackendEstimator(BaseEstimator[PrimitiveJob[EstimatorResult]]):
     )
     def __init__(
         self,
-        backend: BackendV1 | BackendV2,
+        backend: BackendV2,
         options: dict | None = None,
         abelian_grouping: bool = True,
         bound_pass_manager: PassManager | None = None,
@@ -195,7 +193,7 @@ def transpiled_circuits(self) -> list[QuantumCircuit]:
         return self._transpiled_circuits
 
     @property
-    def backend(self) -> BackendV1 | BackendV2:
+    def backend(self) -> BackendV2:
         """
         Returns:
             The backend which this estimator object based on
@@ -478,9 +476,5 @@ def _passmanager_for_measurement_circuits(layout, backend) -> PassManager:
         coupling_map = backend.coupling_map
         passmanager.append(FullAncillaAllocation(coupling_map))
         passmanager.append(EnlargeWithAncilla())
-    elif isinstance(backend, BackendV1) and backend.configuration().coupling_map is not None:
-        coupling_map = CouplingMap(backend.configuration().coupling_map)
-        passmanager.append(FullAncillaAllocation(coupling_map))
-        passmanager.append(EnlargeWithAncilla())
     passmanager.append(ApplyLayout())
     return passmanager

qiskit/primitives/backend_estimator_v2.py

@@ -23,7 +23,7 @@
 
 from qiskit.circuit import ClassicalRegister, QuantumCircuit, QuantumRegister
 from qiskit.exceptions import QiskitError
-from qiskit.providers import BackendV1, BackendV2
+from qiskit.providers import BackendV2
 from qiskit.quantum_info import Pauli, PauliList
 from qiskit.result import Counts
 from qiskit.transpiler import PassManager, PassManagerConfig
@@ -76,7 +76,7 @@ class BackendEstimatorV2(BaseEstimatorV2):
 
     The :class:`~.BackendEstimatorV2` class is a generic implementation of the
     :class:`~.BaseEstimatorV2` interface that is used to wrap a :class:`~.BackendV2`
-    (or :class:`~.BackendV1`) object in the :class:`~.BaseEstimatorV2` API. It
+    object in the :class:`~.BaseEstimatorV2` API. It
     facilitates using backends that do not provide a native
     :class:`~.BaseEstimatorV2` implementation in places that work with
     :class:`~.BaseEstimatorV2`. However,
@@ -127,7 +127,7 @@ class BackendEstimatorV2(BaseEstimatorV2):
     def __init__(
         self,
         *,
-        backend: BackendV1 | BackendV2,
+        backend: BackendV2,
         options: dict | None = None,
     ):
         """
@@ -153,7 +153,7 @@ def options(self) -> Options:
         return self._options
 
     @property
-    def backend(self) -> BackendV1 | BackendV2:
+    def backend(self) -> BackendV2:
         """Returns the backend which this sampler object based on."""
         return self._backend
 

qiskit/primitives/backend_sampler.py

@@ -19,7 +19,7 @@
 from typing import Any
 
 from qiskit.circuit.quantumcircuit import QuantumCircuit
-from qiskit.providers.backend import BackendV1, BackendV2
+from qiskit.providers.backend import BackendV2
 from qiskit.providers.options import Options
 from qiskit.result import QuasiDistribution, Result
 from qiskit.transpiler.passmanager import PassManager
@@ -57,7 +57,7 @@ class BackendSampler(BaseSampler[PrimitiveJob[SamplerResult]]):
     )
     def __init__(
         self,
-        backend: BackendV1 | BackendV2,
+        backend: BackendV2,
         options: dict | None = None,
         bound_pass_manager: PassManager | None = None,
         skip_transpilation: bool = False,
@@ -115,7 +115,7 @@ def transpiled_circuits(self) -> list[QuantumCircuit]:
         return self._transpiled_circuits
 
     @property
-    def backend(self) -> BackendV1 | BackendV2:
+    def backend(self) -> BackendV2:
         """
         Returns:
             The backend which this sampler object based on

qiskit/primitives/backend_sampler_v2.py

@@ -36,7 +36,7 @@
 from qiskit.primitives.containers.bit_array import _min_num_bytes
 from qiskit.primitives.containers.sampler_pub import SamplerPub
 from qiskit.primitives.primitive_job import PrimitiveJob
-from qiskit.providers.backend import BackendV1, BackendV2
+from qiskit.providers.backend import BackendV2
 from qiskit.result import Result
 
 
@@ -83,7 +83,7 @@ class BackendSamplerV2(BaseSamplerV2):
 
     The :class:`~.BackendSamplerV2` class is a generic implementation of the
     :class:`~.BaseSamplerV2` interface that is used to wrap a :class:`~.BackendV2`
-    (or :class:`~.BackendV1`) object in the class :class:`~.BaseSamplerV2` API. It
+    object in the class :class:`~.BaseSamplerV2` API. It
     facilitates using backends that do not provide a native
     :class:`~.BaseSamplerV2` implementation in places that work with
     :class:`~.BaseSamplerV2`. However,
@@ -119,7 +119,7 @@ class BackendSamplerV2(BaseSamplerV2):
     def __init__(
         self,
         *,
-        backend: BackendV1 | BackendV2,
+        backend: BackendV2,
         options: dict | None = None,
     ):
         """
@@ -132,7 +132,7 @@ def __init__(
         self._options = Options(**options) if options else Options()
 
     @property
-    def backend(self) -> BackendV1 | BackendV2:
+    def backend(self) -> BackendV2:
         """Returns the backend which this sampler object based on."""
         return self._backend