Deprecate qiskit.Aer and qiskit.providers.aer

qiskit/__init__.py

@@ -102,34 +102,34 @@ def __init__(self):
 
     def __bool__(self):
         if self.aer is None:
+            warnings.warn(
+                "The qiskit.Aer entry point will be deprecated in a future release and "
+                "subsequently removed. Instead you should use this "
+                "directly from the root of the qiskit-aer package.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
             try:
-                from qiskit.providers import aer
-
-                self.aer = aer.Aer
-                warnings.warn(
-                    "The qiskit.Aer entry point will be deprecated in a future release and "
-                    "subsequently removed. Instead you should use this "
-                    "directly from the root of the qiskit-aer package.",
-                    PendingDeprecationWarning,
-                    stacklevel=2,
-                )
+                import qiskit_aer
+
+                self.aer = qiskit_aer.Aer
             except ImportError:
                 return False
         return True
 
     def __getattr__(self, attr):
         if not self.aer:
+            warnings.warn(
+                "The qiskit.Aer entry point will be deprecated in a future release and "
+                "subsequently removed. Instead you should use this "
+                "directly from the root of the qiskit-aer package.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
             try:
-                from qiskit.providers import aer
-
-                self.aer = aer.Aer
-                warnings.warn(
-                    "The qiskit.Aer entry point will be deprecated in a future release and "
-                    "subsequently removed. Instead you should use this "
-                    "directly from the root of the qiskit-aer package.",
-                    PendingDeprecationWarning,
-                    stacklevel=2,
-                )
+                import qiskit_aer
+
+                self.aer = qiskit_aer.Aer
             except ImportError as ex:
                 raise MissingOptionalLibraryError(
                     "qiskit-aer", "Aer provider", "pip install qiskit-aer"
@@ -145,40 +145,39 @@ def __init__(self):
 
     def __bool__(self):
         if self.ibmq is None:
+            warnings.warn(
+                "The qiskit.IBMQ entrypoint and the qiskit-ibmq-provider package ("
+                "accessible from 'qiskit.providers.ibmq`) are deprecated and will be removed "
+                "in a future release. Instead you should use the qiskit-ibm-provider package "
+                "which is accessible from 'qiskit_ibm_provider'. You can install it with "
+                "'pip install qiskit_ibm_provider'",
+                DeprecationWarning,
+                stacklevel=2,
+            )
             try:
                 from qiskit.providers import ibmq
 
                 self.ibmq = ibmq.IBMQ
-                warnings.warn(
-                    "The qiskit.IBMQ entrypoint and the qiskit-ibmq-provider package ("
-                    "accessible from 'qiskit.providers.ibmq`) are deprecated and will be removed "
-                    "in a future release. Instead you should use the qiskit-ibm-provider package "
-                    "which is accessible from 'qiskit_ibm_provider'. You can install it with "
-                    "'pip install qiskit_ibm_provider'",
-                    DeprecationWarning,
-                    stacklevel=2,
-                )
-
             except ImportError:
                 return False
         return True
 
     def __getattr__(self, attr):
         if not self.ibmq:
+            warnings.warn(
+                "The qiskit.IBMQ entrypoint and the qiskit-ibmq-provider package ("
+                "accessible from 'qiskit.providers.ibmq`) are deprecated and will be removed "
+                "in a future release. Instead you should use the qiskit-ibm-provider package "
+                "which is accessible from 'qiskit_ibm_provider'. You can install it with "
+                "'pip install qiskit_ibm_provider'. Just replace 'qiskit.IBMQ' with "
+                "'qiskit_ibm_provider.IBMProvider'",
+                DeprecationWarning,
+                stacklevel=2,
+            )
             try:
                 from qiskit.providers import ibmq
 
                 self.ibmq = ibmq.IBMQ
-                warnings.warn(
-                    "The qiskit.IBMQ entrypoint and the qiskit-ibmq-provider package ("
-                    "accessible from 'qiskit.providers.ibmq`) are deprecated and will be removed "
-                    "in a future release. Instead you should use the qiskit-ibm-provider package "
-                    "which is accessible from 'qiskit_ibm_provider'. You can install it with "
-                    "'pip install qiskit_ibm_provider'. Just replace 'qiskit.IBMQ' with "
-                    "'qiskit_ibm_provider.IBMProvider'",
-                    DeprecationWarning,
-                    stacklevel=2,
-                )
             except ImportError as ex:
                 raise MissingOptionalLibraryError(
                     "qiskit-ibmq-provider", "IBMQ provider", "pip install qiskit-ibmq-provider"

qiskit/algorithms/optimizers/umda.py

@@ -73,7 +73,7 @@ class UMDA(Optimizer):
         .. code-block:: python
 
             from qiskit.opflow import X, Z, I
-            from qiskit import Aer
+            from qiskit_aer import Aer
             from qiskit.algorithms.optimizers import UMDA
             from qiskit.algorithms import QAOA
             from qiskit.utils import QuantumInstance

qiskit/namespace.py

@@ -17,6 +17,7 @@
 import sys
 from importlib.abc import MetaPathFinder, Loader
 import importlib
+import warnings
 
 
 def _new_namespace(fullname, old_namespace, new_package):
@@ -34,6 +35,12 @@ def __init__(self, new_package, old_namespace):
         super().__init__()
         self.new_package = new_package
         self.old_namespace = old_namespace
+        warnings.warn(
+            f"Importing from '{self.old_namespace}' is deprecated."
+            f" Import from '{self.new_package}' instead, which should work identically.",
+            category=DeprecationWarning,
+            stacklevel=3,
+        )
 
     def module_repr(self, module):
         return repr(module)

qiskit/opflow/expectations/aer_pauli_expectation.py

@@ -90,7 +90,7 @@ def convert(self, operator: OperatorBase) -> OperatorBase:
     @classmethod
     def _replace_pauli_sums(cls, operator):
         try:
-            from qiskit.providers.aer.library import SaveExpectationValue
+            from qiskit_aer.library import SaveExpectationValue
         except ImportError as ex:
             raise MissingOptionalLibraryError(
                 libname="qiskit-aer",

qiskit/providers/fake_provider/__init__.py

@@ -71,7 +71,7 @@
     .. code-block:: python
 
         from qiskit.providers.ibmq import IBMQ
-        from qiskit.providers.aer import AerSimulator
+        from qiskit_aer import AerSimulator
 
         # get a real backend from a real provider
         provider = IBMQ.load_account()

qiskit/providers/fake_provider/fake_backend.py

@@ -118,9 +118,9 @@ def _parse_channels(self, channels):
 
     def _setup_sim(self):
         if _optionals.HAS_AER:
-            from qiskit.providers import aer
+            import qiskit_aer
 
-            self.sim = aer.AerSimulator()
+            self.sim = qiskit_aer.AerSimulator()
             if self.target and self._props_dict:
                 noise_model = self._get_noise_model_from_backend_v2()
                 self.sim.set_options(noise_model=noise_model)
@@ -200,9 +200,9 @@ def _default_options(cls):
                 default values set
         """
         if _optionals.HAS_AER:
-            from qiskit.providers import aer
+            import qiskit_aer
 
-            return aer.AerSimulator._default_options()
+            return qiskit_aer.AerSimulator._default_options()
         else:
             return basicaer.QasmSimulatorPy._default_options()
 
@@ -376,13 +376,13 @@ def _get_noise_model_from_backend_v2(
 
         from qiskit.circuit import Delay
         from qiskit.providers.exceptions import BackendPropertyError
-        from qiskit.providers.aer.noise import NoiseModel
-        from qiskit.providers.aer.noise.device.models import (
+        from qiskit_aer.noise import NoiseModel
+        from qiskit_aer.noise.device.models import (
             _excited_population,
             basic_device_gate_errors,
             basic_device_readout_errors,
         )
-        from qiskit.providers.aer.noise.passes import RelaxationNoisePass
+        from qiskit_aer.noise.passes import RelaxationNoisePass
 
         if self._props_dict is None:
             self._set_props_dict_from_json()
@@ -403,7 +403,7 @@ def _get_noise_model_from_backend_v2(
         with warnings.catch_warnings():
             warnings.filterwarnings(
                 "ignore",
-                module="qiskit.providers.aer.noise.device.models",
+                module="qiskit_aer.noise.device.models",
             )
             gate_errors = basic_device_gate_errors(
                 properties,
@@ -459,10 +459,10 @@ def __init__(self, configuration, time_alive=10):
 
     def _setup_sim(self):
         if _optionals.HAS_AER:
-            from qiskit.providers import aer
-            from qiskit.providers.aer.noise import NoiseModel
+            import qiskit_aer
+            from qiskit_aer.noise import NoiseModel
 
-            self.sim = aer.AerSimulator()
+            self.sim = qiskit_aer.AerSimulator()
             if self.properties():
                 noise_model = NoiseModel.from_backend(self)
                 self.sim.set_options(noise_model=noise_model)
@@ -527,9 +527,9 @@ def properties(self):
     @classmethod
     def _default_options(cls):
         if _optionals.HAS_AER:
-            from qiskit.providers import aer
+            from qiskit_aer import QasmSimulator
 
-            return aer.QasmSimulator._default_options()
+            return QasmSimulator._default_options()
         else:
             return basicaer.QasmSimulatorPy._default_options()
 
@@ -553,12 +553,20 @@ def run(self, run_input, **kwargs):
                 "QuantumCircuit, Schedule, or a list of either" % circuits
             )
         if pulse_job:
+            warnings.warn(
+                "Simulating pulse jobs on fake backends is deprecated as of Qiskit 0.46,"
+                " and the functionality will be removed in Qiskit 1.0, due to Qiskit Aer removing"
+                " its pulse-simulation capabilities in its most recent versions."
+                " You can try using Qiskit Dynamics instead.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
             if _optionals.HAS_AER:
-                from qiskit.providers import aer
-                from qiskit.providers.aer.pulse import PulseSystemModel
+                import qiskit_aer
+                from qiskit_aer.pulse import PulseSystemModel
 
                 system_model = PulseSystemModel.from_backend(self)
-                sim = aer.Aer.get_backend("pulse_simulator")
+                sim = qiskit_aer.Aer.get_backend("pulse_simulator")
                 job = sim.run(circuits, system_model=system_model, **kwargs)
             else:
                 raise QiskitError("Unable to run pulse schedules without qiskit-aer installed")

qiskit/test/decorators.py

@@ -17,11 +17,10 @@
 import functools
 import os
 import socket
-import sys
 from typing import Union, Callable, Type, Iterable
 import unittest
 
-from qiskit.utils import wrap_method
+from qiskit.utils import wrap_method, optionals
 from .testing_options import get_test_options
 
 HAS_NET_CONNECTION = None
@@ -55,14 +54,7 @@ def is_aer_provider_available():
     Returns:
         bool: True if simulator executable is available
     """
-    # TODO: HACK FROM THE DEPTHS OF DESPAIR AS AER DOES NOT WORK ON MAC
-    if sys.platform == "darwin":
-        return False
-    try:
-        import qiskit.providers.aer  # pylint: disable=unused-import
-    except ImportError:
-        return False
-    return True
+    return bool(optionals.HAS_AER)
 
 
 def requires_aer_provider(test_item):

qiskit/utils/backend_utils.py

@@ -14,6 +14,7 @@
 
 import logging
 from qiskit.utils.deprecation import deprecate_func
+from qiskit.utils import optionals
 
 logger = logging.getLogger(__name__)
 
@@ -79,18 +80,7 @@ def has_ibmq():
 )
 def has_aer():
     """Check if Aer is installed."""
-    if not _PROVIDER_CHECK.checked_aer:
-        try:
-            from qiskit.providers.aer import AerProvider
-
-            _PROVIDER_CHECK.has_aer = True
-        except Exception as ex:  # pylint: disable=broad-except
-            _PROVIDER_CHECK.has_aer = False
-            logger.debug("AerProvider not loaded: '%s'", str(ex))
-
-        _PROVIDER_CHECK.checked_aer = True
-
-    return _PROVIDER_CHECK.has_aer
+    return bool(optionals.HAS_AER)
 
 
 @deprecate_func(
@@ -107,11 +97,11 @@ def is_aer_provider(backend):
         bool: True is AerProvider
     """
     if has_aer():
-        from qiskit.providers.aer import AerProvider
+        from qiskit_aer import AerProvider
 
         if isinstance(_get_backend_provider(backend), AerProvider):
             return True
-        from qiskit.providers.aer.backends.aerbackend import AerBackend
+        from qiskit_aer.backends.aerbackend import AerBackend
 
         return isinstance(backend, AerBackend)
 
@@ -192,7 +182,7 @@ def is_statevector_backend(backend):
         return False
     backend_interface_version = _get_backend_interface_version(backend)
     if has_aer():
-        from qiskit.providers.aer.backends import AerSimulator, StatevectorSimulator
+        from qiskit_aer.backends import AerSimulator, StatevectorSimulator
 
         if isinstance(backend, StatevectorSimulator):
             return True

qiskit/utils/optionals.py

@@ -29,16 +29,16 @@
     :widths: 25 75
 
     * - .. py:data:: HAS_AER
-      - :mod:`Qiskit Aer <qiskit.providers.aer>` provides high-performance simulators for the
-        quantum circuits constructed within Qiskit.
+      - `Qiskit Aer <https://qiskit.org/ecosystem/aer/>`__ provides high-performance simulators for
+        the quantum circuits constructed within Qiskit.
 
     * - .. py:data:: HAS_IBMQ
-      - The :mod:`Qiskit IBMQ Provider <qiskit.providers.ibmq>` is used for accessing IBM Quantum
-        hardware in the IBM cloud.
+      - The Qiskit IBMQ Provider was historically used for accessing IBM Quantum hardware in the IBM
+        cloud, but is now deprecated.
 
     * - .. py:data:: HAS_IGNIS
-      - :mod:`Qiskit Ignis <qiskit.ignis>` provides tools for quantum hardware verification, noise
-        characterization, and error correction.
+      - Qiskit Ignis provided tools for quantum hardware verification, noise characterization, and
+        error correction, but is now deprecated.
 
     * - .. py:data:: HAS_TOQM
       - `Qiskit TOQM <https://github.com/qiskit-toqm/qiskit-toqm>`__ provides transpiler passes
@@ -224,7 +224,7 @@
 _logger = _logging.getLogger(__name__)
 
 HAS_AER = _LazyImportTester(
-    "qiskit.providers.aer",
+    "qiskit_aer",
     name="Qiskit Aer",
     install="pip install qiskit-aer",
 )

qiskit/utils/quantum_instance.py

@@ -502,7 +502,7 @@ def execute(self, circuits, had_transpiled: bool = False):
 
         if self.is_statevector and "aer_simulator_statevector" in self.backend_name:
             try:
-                from qiskit.providers.aer.library import SaveStatevector
+                from qiskit_aer.library import SaveStatevector
 
                 def _find_save_state(data):
                     for instruction in reversed(data):

qiskit/version.py

@@ -109,11 +109,9 @@ def _load_versions(self):
             stacklevel=3,
         )
         try:
-            # TODO: Update to use qiskit_aer instead when we remove the
-            # namespace redirect
-            from qiskit.providers import aer
+            import qiskit_aer
 
-            self._version_dict["qiskit-aer"] = aer.__version__
+            self._version_dict["qiskit-aer"] = qiskit_aer.__version__
         except Exception:
             self._version_dict["qiskit-aer"] = None
         try: