Remove Provider ABC (deprecated in 1.1)

qiskit/providers/__init__.py

@@ -75,15 +75,6 @@
 Abstract Classes
 ================
 
-Provider
---------
-
-.. autosummary::
-   :toctree: ../stubs/
-
-   Provider
-   ProviderV1
-
 Backend
 -------
 
@@ -672,7 +663,7 @@ def status(self):
 enable algorithms to get the best results with
 mitigation applied directly from your backends. You can refer to the
 documentation in :mod:`qiskit.primitives` on how to write custom
-implementations. Also the built-in implementations: :class:`~.Sampler`,
+implementations. Also, the built-in implementations: :class:`~.Sampler`,
 :class:`~.Estimator`, :class:`~.BackendSampler`, and :class:`~.BackendEstimator`
 can serve as references/models on how to implement these as well.
 
@@ -781,8 +772,6 @@ def status(self):
 """
 
 # Providers interface
-from qiskit.providers.provider import Provider
-from qiskit.providers.provider import ProviderV1
 from qiskit.providers.backend import Backend
 from qiskit.providers.backend import BackendV1
 from qiskit.providers.backend import BackendV2

qiskit/providers/backend.py

@@ -20,7 +20,6 @@
 import datetime
 from typing import List, Union, Iterable, Tuple
 
-from qiskit.providers.provider import Provider
 from qiskit.providers.models.backendstatus import BackendStatus
 from qiskit.circuit.gate import Instruction
 from qiskit.utils import deprecate_func
@@ -87,7 +86,7 @@ def __init__(self, configuration, provider=None, **fields):
         Args:
             configuration (BackendConfiguration): A backend configuration
                 object for the backend object.
-            provider (qiskit.providers.Provider): Optionally, the provider
+            provider: Optionally, the provider
                 object that this Backend comes from.
             fields: kwargs for the values to use to override the default
                 options.
@@ -160,10 +159,10 @@ def properties(self):
         return None
 
     def provider(self):
-        """Return the backend Provider.
+        """Return the backend provider.
 
         Returns:
-            Provider: the Provider responsible for the backend.
+            provider: the provider responsible for the backend.
         """
         return self._provider
 
@@ -327,7 +326,7 @@ class BackendV2(Backend, ABC):
 
     def __init__(
         self,
-        provider: Provider = None,
+        provider=None,
         name: str = None,
         description: str = None,
         online_date: datetime.datetime = None,
@@ -337,9 +336,8 @@ def __init__(
         """Initialize a BackendV2 based backend
 
         Args:
-            provider: An optional backwards reference to the
-                :class:`~qiskit.providers.Provider` object that the backend
-                is from
+            provider: An optional backwards reference to the provider
+                object that the backend is from
             name: An optional name for the backend
             description: An optional description of the backend
             online_date: An optional datetime the backend was brought online
@@ -633,10 +631,10 @@ def options(self):
 
     @property
     def provider(self):
-        """Return the backend Provider.
+        """Return the backend provider.
 
         Returns:
-            Provider: the Provider responsible for the backend.
+            provider: the provider responsible for the backend.
         """
         return self._provider
 

qiskit/providers/basic_provider/basic_provider.py

@@ -23,7 +23,6 @@
 
 from qiskit.exceptions import QiskitError
 from qiskit.providers.backend import Backend
-from qiskit.providers.provider import ProviderV1
 from qiskit.providers.exceptions import QiskitBackendNotFoundError
 from qiskit.providers.providerutils import filter_backends
 
@@ -35,7 +34,7 @@
 SIMULATORS = [BasicSimulator]
 
 
-class BasicProvider(ProviderV1):
+class BasicProvider:
     """Provider for test simulators."""
 
     def __init__(self) -> None:
@@ -44,12 +43,33 @@ def __init__(self) -> None:
         # Populate the list of test backends (simulators)
         self._backends = self._verify_backends()
 
-    def get_backend(self, name: str | None = None, **kwargs) -> Backend:
-        return super().get_backend(name=name, **kwargs)
-
-    def backends(
-        self, name: str | None = None, filters: Callable | None = None, **kwargs
-    ) -> list[Backend]:
+    def get_backend(self, name=None, **kwargs):
+        """Return a single backend matching the specified filtering.
+        Args:
+            name (str): name of the backend.
+            **kwargs: dict used for filtering.
+        Returns:
+            Backend: a backend matching the filtering.
+        Raises:
+            QiskitBackendNotFoundError: if no backend could be found or
+                more than one backend matches the filtering criteria.
+        """
+        backends = self.backends(name, **kwargs)
+        if len(backends) > 1:
+            raise QiskitBackendNotFoundError("More than one backend matches the criteria")
+        if not backends:
+            raise QiskitBackendNotFoundError("No backend matches the criteria")
+        return backends[0]
+
+    def backends(self, name: str | None = None, filters: Callable | None = None) -> list[Backend]:
+        """Return a list of backends matching the specified filtering.
+        Args:
+            name: name of the backend.
+            filters: callable for filtering.
+        Returns:
+            list[Backend]: a list of Backends that match the filtering
+                criteria.
+        """
         backends = self._backends.values()
         if name:
             available = [
@@ -59,7 +79,7 @@ def backends(
                 raise QiskitBackendNotFoundError(
                     f"The '{name}' backend is not installed in your system."
                 )
-        return filter_backends(backends, filters=filters, **kwargs)
+        return filter_backends(backends, filters=filters)
 
     def _verify_backends(self) -> OrderedDict[str, Backend]:
         """

qiskit/providers/basic_provider/basic_simulator.py

@@ -43,7 +43,6 @@
 from qiskit.circuit import QuantumCircuit
 from qiskit.circuit.library import UnitaryGate
 from qiskit.circuit.library.standard_gates import get_standard_gate_name_mapping, GlobalPhaseGate
-from qiskit.providers import Provider
 from qiskit.providers.backend import BackendV2
 from qiskit.providers.models.backendconfiguration import BackendConfiguration
 from qiskit.providers.options import Options
@@ -76,14 +75,13 @@ class BasicSimulator(BackendV2):
 
     def __init__(
         self,
-        provider: Provider | None = None,
+        provider=None,
         target: Target | None = None,
         **fields,
     ) -> None:
         """
         Args:
-            provider: An optional backwards reference to the
-                :class:`~qiskit.providers.Provider` object that the backend
+            provider: An optional backwards reference to the provider object that the backend
                 is from.
             target: An optional target to configure the simulator.
             fields: kwargs for the values to use to override the default

releasenotes/notes/remove_provider_abc-87b611c223311a40.yaml

@@ -0,0 +1,17 @@
+---
+upgrade_providers:
+  - |
+    The abstract base classes ``Provider`` and ``ProviderV1`` have been deprecated since Qiskit 1.1 and they are now removed.
+    The abstraction provided by these interface definitions were not providing a huge value, solely just the attributes
+    ``name``, ``backends``, and a ``get_backend()``. A _provider_, as a concept, will continue existing as a collection
+    of backends. If you're implementing a provider currently you can adjust your
+    code by simply removing ``ProviderV1`` as the parent class of your
+    implementation. As part of this you probably would want to add an
+    implementation of ``get_backend`` for backwards compatibility. For example::
+        def get_backend(self, name=None, **kwargs):
+          backend = self.backends(name, **kwargs)
+          if len(backends) > 1:
+              raise QiskitBackendNotFoundError("More than one backend matches the criteria")
+          if not backends:
+              raise QiskitBackendNotFoundError("No backend matches the criteria")
+          return backends[0]

test/python/providers/basic_provider/test_basic_provider_backends.py

@@ -22,8 +22,7 @@ class TestBasicProviderBackends(QiskitTestCase):
 
     def setUp(self):
         super().setUp()
-        with self.assertWarns(DeprecationWarning):
-            self.provider = BasicProvider()
+        self.provider = BasicProvider()
         self.backend_name = "basic_simulator"
 
     def test_backends(self):
@@ -33,11 +32,9 @@ def test_backends(self):
 
     def test_get_backend(self):
         """Test getting a backend from the provider."""
-        with self.assertWarns(DeprecationWarning):
-            backend = self.provider.get_backend(name=self.backend_name)
+        backend = self.provider.get_backend(name=self.backend_name)
         self.assertEqual(backend.name, self.backend_name)
 
     def test_aliases_fail(self):
         """Test a failing backend lookup."""
-        with self.assertWarns(DeprecationWarning):
-            self.assertRaises(QiskitBackendNotFoundError, BasicProvider().get_backend, "bad_name")
+        self.assertRaises(QiskitBackendNotFoundError, BasicProvider().get_backend, "bad_name")

test/python/providers/basic_provider/test_multi_registers_convention.py

@@ -36,8 +36,7 @@ def test_circuit_multi(self):
 
         qc = circ.compose(meas)
 
-        with self.assertWarns(DeprecationWarning):
-            backend_sim = BasicProvider().get_backend("basic_simulator")
+        backend_sim = BasicProvider().get_backend("basic_simulator")
 
         result = backend_sim.run(qc).result()
         counts = result.get_counts(qc)

test/utils/base.py

@@ -235,8 +235,7 @@ def tearDown(self):
         # due to importing the instances from the top-level qiskit namespace.
         from qiskit.providers.basic_provider import BasicProvider
 
-        with self.assertWarns(DeprecationWarning):
-            BasicProvider()._backends = BasicProvider()._verify_backends()
+        BasicProvider()._backends = BasicProvider()._verify_backends()
 
     def assertQuantumCircuitEqual(self, qc1, qc2, msg=None):
         """Extra assertion method to give a better error message when two circuits are unequal."""