Deprecate BackendV1 and qiskit.providers.models (backport #12629)

qiskit/circuit/add_control.py

@@ -73,7 +73,7 @@ def control(
 ) -> ControlledGate:
     """Return controlled version of gate using controlled rotations. This function
     first checks the name of the operation to see if it knows of a method from which
-    to generate a controlled version. Currently these are `x`, `rx`, `ry`, and `rz`.
+    to generate a controlled version. Currently, these are ``x``, ``rx``, ``ry``, and ``rz``.
     If a method is not directly known, it calls the unroller to convert to `u1`, `u3`,
     and `cx` gates.
 

qiskit/compiler/transpiler.py

@@ -315,10 +315,28 @@ def callback_func(**kwargs):
         optimization_level = config.get("transpile_optimization_level", 1)
 
     if backend is not None and getattr(backend, "version", 0) <= 1:
-        # 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.
-        backend = BackendV2Converter(backend)
+        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

qiskit/providers/backend.py

@@ -23,6 +23,7 @@
 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
 
 
 class Backend:
@@ -43,7 +44,7 @@ class BackendV1(Backend, ABC):
     This abstract class is to be used for Backend objects.
     There are several classes of information contained in a Backend.
     The first are the attributes of the class itself. These should be used to
-    defined the immutable characteristics of the backend. The ``options``
+    define the immutable characteristics of the backend. The ``options``
     attribute of the backend is used to contain the dynamic user configurable
     options of the backend. It should be used more for runtime options
     that configure how the backend is used. For example, something like a
@@ -71,6 +72,14 @@ class BackendV1(Backend, ABC):
 
     version = 1
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="If the backend only encapsulates a hardware description, "
+        "consider constructing a Target directly. If it is part of a provider "
+        "that gives access to execution, consider using Primitives instead. "
+        "Alternatively, consider moving to BackendV2 (see https://qisk.it/backendV1-to-V2).",
+    )
     def __init__(self, configuration, provider=None, **fields):
         """Initialize a backend class
 

qiskit/providers/backend_compat.py

@@ -390,10 +390,13 @@ def __init__(
         self._properties = None
         self._defaults = None
 
-        if hasattr(self._backend, "properties"):
-            self._properties = self._backend.properties()
-        if hasattr(self._backend, "defaults"):
-            self._defaults = self._backend.defaults()
+        with warnings.catch_warnings():
+            # The class QobjExperimentHeader is deprecated
+            warnings.filterwarnings("ignore", category=DeprecationWarning, module="qiskit")
+            if hasattr(self._backend, "properties"):
+                self._properties = self._backend.properties()
+            if hasattr(self._backend, "defaults"):
+                self._defaults = self._backend.defaults()
 
         self._target = None
         self._name_mapping = name_mapping

qiskit/providers/basic_provider/basic_simulator.py

@@ -236,24 +236,32 @@ def configuration(self) -> BackendConfiguration:
             for name in self.target.operation_names
         ]
 
-        self._configuration = BackendConfiguration(
-            backend_name=self.name,
-            backend_version=self.backend_version,
-            n_qubits=self.num_qubits,
-            basis_gates=self.target.operation_names,
-            gates=gates,
-            local=True,
-            simulator=True,
-            conditional=True,
-            open_pulse=False,
-            memory=True,
-            # This max_shots is used by the assembler, setting it to 0
-            # to maintain the behavior from the previous implementation.
-            # Not related to the actual shots set in the backend options
-            max_shots=0,
-            coupling_map=None,
-            description="A python simulator for quantum experiments",
-        )
+        with warnings.catch_warnings():
+            # TODO Provider models are deprecated
+            #   https://github.com/Qiskit/qiskit/issues/12843
+            warnings.filterwarnings(
+                "ignore",
+                category=DeprecationWarning,
+                message=r".+qiskit\.providers\.models\.backendconfiguration\..+",
+            )
+            self._configuration = BackendConfiguration(
+                backend_name=self.name,
+                backend_version=self.backend_version,
+                n_qubits=self.num_qubits,
+                basis_gates=self.target.operation_names,
+                gates=gates,
+                local=True,
+                simulator=True,
+                conditional=True,
+                open_pulse=False,
+                memory=True,
+                # This max_shots is used by the assembler, setting it to 0
+                # to maintain the behavior from the previous implementation.
+                # Not related to the actual shots set in the backend options
+                max_shots=0,
+                coupling_map=None,
+                description="A python simulator for quantum experiments",
+            )
         return self._configuration
 
     @classmethod

qiskit/providers/fake_provider/fake_qasm_backend.py

@@ -16,6 +16,7 @@
 
 import json
 import os
+import warnings
 
 from qiskit.exceptions import QiskitError
 from qiskit.providers.models import BackendProperties, QasmBackendConfiguration
@@ -61,7 +62,10 @@ def _set_props_from_json(self):
             raise QiskitError("No properties file has been defined")
         props = self._load_json(self.props_filename)
         decode_backend_properties(props)
-        self._properties = BackendProperties.from_dict(props)
+        with warnings.catch_warnings():
+            # This raises the BackendProperties deprecation warning internally
+            warnings.filterwarnings("ignore", category=DeprecationWarning, module="qiskit")
+            self._properties = BackendProperties.from_dict(props)
 
     def _load_json(self, filename):
         with open(os.path.join(self.dirname, filename)) as f_json:

qiskit/providers/models/__init__.py

@@ -38,6 +38,7 @@
    GateProperties
    Nduv
 """
+import warnings
 
 from .backendconfiguration import (
     BackendConfiguration,
@@ -50,3 +51,13 @@
 from .backendstatus import BackendStatus
 from .jobstatus import JobStatus
 from .pulsedefaults import PulseDefaults, Command
+
+
+warnings.warn(
+    "qiskit.providers.models is deprecated since Qiskit 1.2 and will be removed in Qiskit 2.0."
+    "With the removal of Qobj, there is no need for these schema-conformant objects. If you still need"
+    "to use them, it could be because you are using a BackendV1, which is also deprecated in favor"
+    "of BackendV2",
+    DeprecationWarning,
+    2,
+)

qiskit/providers/models/backendconfiguration.py

@@ -26,6 +26,7 @@
     DriveChannel,
     MeasureChannel,
 )
+from qiskit.utils import deprecate_func
 
 
 class GateConfig:
@@ -38,6 +39,15 @@ class GateConfig:
                   and CX.
     """
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` are part "
+        "of the deprecated `BackendV1` workflow  and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+        stacklevel=3,
+    )
     def __init__(
         self,
         name,
@@ -141,6 +151,14 @@ class UchannelLO:
         scale: Scale factor for qubit frequency.
     """
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` are part "
+        "of the deprecated `BackendV1` workflow  and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+    )
     def __init__(self, q, scale):
         """Initialize a UchannelLOSchema object
 
@@ -211,6 +229,15 @@ class QasmBackendConfiguration:
 
     _data = {}
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` are part "
+        "of the deprecated `BackendV1` workflow and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+        stacklevel=3,
+    )
     def __init__(
         self,
         backend_name,
@@ -491,16 +518,35 @@ def __contains__(self, item):
 
 
 class BackendConfiguration(QasmBackendConfiguration):
-    """Backwards compat shim representing an abstract backend configuration."""
+    """Backwards compatibility shim representing an abstract backend configuration."""
 
-    pass
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` are part "
+        "of the deprecated `BackendV1` workflow and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+        stacklevel=3,
+    )
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
 
 
 class PulseBackendConfiguration(QasmBackendConfiguration):
     """Static configuration state for an OpenPulse enabled backend. This contains information
     about the set up of the device which can be useful for building Pulse programs.
     """
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` are part "
+        "of the deprecated `BackendV1` workflow  and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+        stacklevel=3,
+    )
     def __init__(
         self,
         backend_name: str,

qiskit/providers/models/backendproperties.py

@@ -18,6 +18,7 @@
 import dateutil.parser
 
 from qiskit.providers.exceptions import BackendPropertyError
+from qiskit.utils import deprecate_func
 from qiskit.utils.units import apply_prefix
 
 PropertyT = Tuple[Any, datetime.datetime]
@@ -172,6 +173,15 @@ class BackendProperties:
 
     _data = {}
 
+    @deprecate_func(
+        since="1.2",
+        removal_timeline="in the 2.0 release",
+        additional_msg="The models in ``qiskit.providers.models`` and related objects are part "
+        "of the deprecated `BackendV1` workflow,  and no longer necessary for `BackendV2`. If a user "
+        "workflow requires these representations it likely relies on deprecated functionality and "
+        "should be updated to use `BackendV2`.",
+        stacklevel=3,
+    )
     def __init__(
         self, backend_name, backend_version, last_update_date, qubits, gates, general, **kwargs
     ):
@@ -248,6 +258,7 @@ def from_dict(cls, data):
             qubits.append(nduvs)
         gates = [GateProperties.from_dict(x) for x in in_data.pop("gates")]
         general = [Nduv.from_dict(x) for x in in_data.pop("general")]
+
         return cls(
             backend_name, backend_version, last_update_date, qubits, gates, general, **in_data
         )

qiskit/transpiler/preset_passmanagers/__init__.py

@@ -57,12 +57,12 @@
 .. autofunction:: generate_scheduling
 .. currentmodule:: qiskit.transpiler.preset_passmanagers
 """
-
+from .generate_preset_pass_manager import generate_preset_pass_manager
 from .level0 import level_0_pass_manager
 from .level1 import level_1_pass_manager
 from .level2 import level_2_pass_manager
 from .level3 import level_3_pass_manager
-from .generate_preset_pass_manager import generate_preset_pass_manager
+
 
 __all__ = [
     "level_0_pass_manager",

qiskit/transpiler/preset_passmanagers/generate_preset_pass_manager.py

@@ -15,6 +15,7 @@
 """
 
 import copy
+import warnings
 
 from qiskit.circuit.controlflow import CONTROL_FLOW_OP_NAMES
 from qiskit.circuit.library.standard_gates import get_standard_gate_name_mapping
@@ -242,6 +243,14 @@ def generate_preset_pass_manager(
         # 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.
+        warnings.warn(
+            "The `generate_preset_pass_manager` 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,
+        )
         backend = BackendV2Converter(backend)
 
     # Check if a custom inst_map was specified before overwriting inst_map
@@ -319,7 +328,17 @@ def generate_preset_pass_manager(
         if timing_constraints is None:
             timing_constraints = target.timing_constraints()
         if backend_properties is None:
-            backend_properties = target_to_backend_properties(target)
+            with warnings.catch_warnings():
+                # TODO this approach (target-to-properties) is going to be removed soon (1.3) in favor
+                #   of backend-to-target approach
+                #   https://github.com/Qiskit/qiskit/pull/12850
+                warnings.filterwarnings(
+                    "ignore",
+                    category=DeprecationWarning,
+                    message=r".+qiskit\.transpiler\.target\.target_to_backend_properties.+",
+                    module="qiskit",
+                )
+                backend_properties = target_to_backend_properties(target)
 
     # Parse non-target dependent pm options
     initial_layout = _parse_initial_layout(initial_layout)