Prepare for Qiskit 2.0 by addressing removed classes and methods (#1526)

This change prepares for Qiskit 2.0 by guarding or replacing references
to objects removed in Qiskit 2.0.

## Detailed list of changes:

### Compatibility changes:

* Guard references to `BackendV1`. `BackendV1` was removed in Qiskit
2.0. There were only a few remaining references to `BackendV1` after the
previous removal of pulse support, so it was not hard to keep the
remaining support for now but it should be removed when Qiskit 1 is no
longer supported.
* Update usage of `qiskit.result.Result.header` to expect a dict (Qiskit
2) as well as a class (Qiskit 1). `ExperimentData` gets the circuit
metadata from the header (by convention the metadata is copied into the
result and `ExperimentData` relies on this).
* Add classes `MeasLevel` and `MeasReturnType` to enumerate the expected
measurement level (kerneled or classified) and return type (averaged or
not). Previously, private classes of Qiskit were inadvertently used for
these purposes but they were removed in Qiskit 2.0.
* Remove null default `inst_map` transpile options from experiments.
These should have been removed along with the rest of pulse support.
* Update tests to use `GenericBackendV2` or a custom `BackendV2` in
place of removed `FakeOpenPulse2Q` and `Fake5QV1` backends from Qiskit.
* Remove suppression of Qiskit deprecation warnings from the tests.
* Remove stray references to `ProviderV1` in tests.
* Update the saved `QuantumVolume` results for Qiskit 2.0's change in
the quantum volume algorithm.
* Vendor deprecation decorators to prepare for their removal from
Qiskit's public API (see
[here](Qiskit/qiskit#11296 (review))).
At first it appeared that these methods would be changed late in the
Qiskit 2.0 cycle but the change was pushed back in time. Still the plan
is to make the functions private, so we need to stop using them.

### Other changes

* Provide a more specific warning in `LocalReadouMitigator` if it is
used with a backend without a ``properties()`` method or with a backend
that does not the required readout error properties.
* Fix a performance issue in `QuantumVolume`. When Qiskit Aer is
installed, `QuantumVolume` uses `AerSimulator` to simulate the outcomes
of the quantum volume circuits to determine the heavy output
probabilities. In its default instantiation, `AerSimulator` regenerates
its `Target` every time it is accessed and this generation takes an
appreciable amount of time. Because the target was being accessed
separately for every circuit, this overhead could accumulate to over a
minute in the standard 100 circuit experiment. This overhead was reduced
by processing all the circuits in one pass.
* Switch `FineFrequency` tests to use `T2HahnBackend` in place
`MockIQBackend` since it provides a more realistic backend emulation.
* Fix the `stacklevel` on the deprecation warning for `RestlessNode`.

---------

Co-authored-by: Eli Arbel <arbel@il.ibm.com>

Author: wshanks

CONTRIBUTING.md

@@ -424,12 +424,11 @@ release notes.
 
 #### Adding deprecation warnings
 
-We use the deprecation wrappers in [Qiskit
-Utilities](https://docs.quantum.ibm.com/api/qiskit/utils) to add warnings:
+We use deprecation wrappers in `qiskit_experiments.framework.deprecation` to add warnings:
 
 ```python
 
-  from qiskit.utils.deprecation import deprecate_func
+  from qiskit_experiments.framework.deprecation import deprecate_func
 
   @deprecate_func(
       since="0.5",

docs/conf.py

@@ -211,9 +211,12 @@ def setup(app):
 # Should come up with better way to address this
 
 from qiskit_experiments.curve_analysis import ParameterRepr
+from qiskit_experiments.framework import MeasLevel, MeasReturnType
 
 
 def maybe_skip_member(app, what, name, obj, skip, options):
+    if skip:
+        return True
     skip_names = [
         "analysis",
         "set_run_options",
@@ -234,6 +237,11 @@ def maybe_skip_member(app, what, name, obj, skip, options):
         ParameterRepr.repr,
         ParameterRepr.unit,
     ]
+    if (
+        not name.isupper() and
+        (getattr(MeasLevel, name, None) == obj or getattr(MeasReturnType, name, None) == obj)
+    ):
+        return True
     if not skip:
         return (name in skip_names or obj in skip_members) and what == "attribute"
     return skip

docs/manuals/characterization/t1.rst

@@ -37,8 +37,7 @@ for qubit 0.
 .. jupyter-execute::
 
     import numpy as np
-    from qiskit.qobj.utils import MeasLevel
-    from qiskit_experiments.framework import ParallelExperiment
+    from qiskit_experiments.framework import MeasLevel, ParallelExperiment
     from qiskit_experiments.library import T1
     from qiskit_experiments.library.characterization.analysis.t1_analysis import T1KerneledAnalysis
 

docs/tutorials/custom_experiment.rst

@@ -601,7 +601,7 @@ perfect symmetrical results between :math:`|0000\rangle` and :math:`|1111\rangle
 
 .. jupyter-execute::
 
-    expdata_ideal = exp.run(AerSimulator(), shots=shots)
+    expdata_ideal = exp.run(backend_ideal, shots=shots)
     counts_ideal = expdata_ideal.analysis_results("counts").value
     print(counts_ideal)
 

docs/tutorials/getting_started.rst

@@ -297,7 +297,7 @@ supports can be set:
 
 .. jupyter-execute::
 
-  from qiskit.qobj.utils import MeasLevel
+  from qiskit_experiments.framework import MeasLevel
 
   exp.set_run_options(shots=1000,
                       meas_level=MeasLevel.CLASSIFIED)

qiskit_experiments/curve_analysis/utils.py

@@ -19,14 +19,14 @@
 import lmfit
 import numpy as np
 import pandas as pd
-from qiskit.utils.deprecation import deprecate_func
 from qiskit.utils import detach_prefix
 from uncertainties import UFloat, wrap as wrap_function
 from uncertainties import unumpy
 
 from qiskit_experiments.curve_analysis.curve_data import CurveFitResult
 from qiskit_experiments.exceptions import AnalysisError, QiskitError
 from qiskit_experiments.framework import AnalysisResultData
+from qiskit_experiments.framework.deprecation import deprecate_func
 
 
 UNUMPY_FUNCS = {fn: getattr(unumpy, fn) for fn in unumpy.__all__}

qiskit_experiments/data_processing/mitigation/local_readout_mitigator.py

@@ -15,6 +15,7 @@
 
 
 import math
+import warnings
 from typing import Optional, List, Tuple, Iterable, Callable, Union, Dict
 import numpy as np
 
@@ -53,6 +54,8 @@ def __init__(
         Raises:
             QiskitError: matrices sizes do not agree with number of qubits
         """
+        if assignment_matrices is None and backend is None:
+            raise QiskitError("Either assignment_matrices or backend must be provided.")
         if assignment_matrices is None:
             assignment_matrices = self._from_backend(backend, qubits)
         else:
@@ -293,7 +296,14 @@ def stddev_upper_bound(self, shots: int, qubits: List[int] = None):
 
     def _from_backend(self, backend, qubits):
         """Calculates amats from backend properties readout_error"""
-        backend_qubits = backend.properties().qubits
+        try:
+            backend_qubits = backend.properties().qubits
+        except AttributeError as exc:
+            raise QiskitError(
+                "Either assignment_matrices must be passed or a backend "
+                "supporting backend.properties().qubits"
+            ) from exc
+
         if qubits is not None:
             if any(qubit >= len(backend_qubits) for qubit in qubits):
                 raise QiskitError("The chosen backend does not contain the specified qubits.")
@@ -304,13 +314,20 @@ def _from_backend(self, backend, qubits):
         amats = np.zeros([num_qubits, 2, 2], dtype=float)
 
         for qubit_idx, qubit_prop in enumerate(backend_qubits):
+            props_to_find = {"prob_meas0_prep1", "prob_meas1_prep0"}
             for prop in qubit_prop:
                 if prop.name == "prob_meas0_prep1":
+                    props_to_find.discard(prop.name)
                     (amats[qubit_idx])[0, 1] = prop.value
                     (amats[qubit_idx])[1, 1] = 1 - prop.value
                 if prop.name == "prob_meas1_prep0":
+                    props_to_find.discard(prop.name)
                     (amats[qubit_idx])[1, 0] = prop.value
                     (amats[qubit_idx])[0, 0] = 1 - prop.value
+            if props_to_find:
+                warnings.warn(
+                    f"Expected readout error properties were missing: {','.join(props_to_find)}"
+                )
 
         return amats
 

qiskit_experiments/data_processing/nodes.py

@@ -23,7 +23,7 @@
 from uncertainties import unumpy as unp, ufloat
 
 from qiskit.result.postprocess import format_counts_memory
-from qiskit.utils import deprecate_func
+from qiskit_experiments.framework.deprecation import deprecate_func
 from qiskit_experiments.data_processing.data_action import DataAction, TrainableDataAction
 from qiskit_experiments.data_processing.exceptions import DataProcessorError
 from qiskit_experiments.data_processing.discriminator import BaseDiscriminator
@@ -921,6 +921,7 @@ class RestlessNode(DataAction, ABC):
             "processor on an experiment."
         ),
         package_name="qiskit-experiments",
+        stacklevel=3,
     )
     def __init__(
         self, validate: bool = True, memory_allocation: ShotOrder = ShotOrder.circuit_first

qiskit_experiments/data_processing/processor_library.py

@@ -14,9 +14,8 @@
 
 import warnings
 from typing import Union, Optional, List
-from qiskit.qobj.utils import MeasLevel, MeasReturnType
 
-from qiskit_experiments.framework import ExperimentData, Options
+from qiskit_experiments.framework import ExperimentData, MeasLevel, MeasReturnType, Options
 from qiskit_experiments.data_processing.exceptions import DataProcessorError
 from qiskit_experiments.data_processing.data_action import DataAction
 from qiskit_experiments.data_processing.data_processor import DataProcessor

qiskit_experiments/framework/__init__.py

@@ -99,6 +99,8 @@
     Job
     BaseJob
     ExtendedJob
+    MeasLevel
+    MeasReturnType
 
 .. _composite-experiment:
 
@@ -145,6 +147,17 @@
     FigureData,
     FigureType,
 )
+from .provider_interfaces import (
+    BaseJob,
+    BaseProvider,
+    ExtendedJob,
+    IBMProvider,
+    Job,
+    MeasLevel,
+    MeasReturnType,
+    Provider,
+)
+
 from .base_analysis import BaseAnalysis
 from .base_experiment import BaseExperiment
 from .backend_timing import BackendTiming
@@ -159,4 +172,3 @@
     CompositeAnalysis,
 )
 from .json import ExperimentEncoder, ExperimentDecoder
-from .provider_interfaces import BaseJob, BaseProvider, ExtendedJob, IBMProvider, Job, Provider