Remove use of opflow in Estimator (#1996)

Author: ElePT

qiskit_aer/primitives/estimator.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2022.
+# (C) Copyright IBM 2022, 2023.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -23,7 +23,6 @@
 import numpy as np
 from qiskit.circuit import ParameterExpression, QuantumCircuit
 from qiskit.compiler import transpile
-from qiskit.opflow import PauliSumOp
 from qiskit.primitives import BaseEstimator, EstimatorResult
 from qiskit.primitives.primitive_job import PrimitiveJob
 from qiskit.primitives.utils import _circuit_key, _observable_key, init_observable
@@ -174,7 +173,7 @@ def _call(
     def _run(
         self,
         circuits: Sequence[QuantumCircuit],
-        observables: Sequence[BaseOperator | PauliSumOp],
+        observables: Sequence[BaseOperator],
         parameter_values: Sequence[Sequence[float]],
         **run_options,
     ) -> PrimitiveJob:

releasenotes/notes/remove-opflow-estimator-a3b64cfe8a4fd6b3.yaml

@@ -0,0 +1,8 @@
+---
+upgrade:
+  - |
+    The :meth:`qiskit_aer.primitives.Estimator.run` method no longer supports
+    ``observables`` input arguments of type ``PauliSumOp``. The ``PauliSumOp``
+    class was deprecated in Qiskit 0.44 and will be removed in Qiskit 1.0.
+    Alternative types that you can use instead of ``PauliSumOp`` are
+    :class:`qiskit.quantum_info.SparsePauliOp` or :class:`qiskit.quantum_info.Pauli`.

test/terra/primitives/test_estimator.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2022.
+# (C) Copyright IBM 2022, 2023.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -23,7 +23,6 @@
 from qiskit.circuit import Parameter, QuantumCircuit
 from qiskit.circuit.library import RealAmplitudes
 from qiskit.exceptions import QiskitError
-from qiskit.opflow import PauliSumOp
 from qiskit.primitives import EstimatorResult
 from qiskit.quantum_info import Operator, SparsePauliOp
 
@@ -53,19 +52,6 @@ def setUp(self):
     def test_estimator(self, abelian_grouping):
         """test for a simple use case"""
         lst = [("XX", 1), ("YY", 2), ("ZZ", 3)]
-        with self.assertWarns(DeprecationWarning):
-            with self.subTest("PauliSumOp"):
-                observable = PauliSumOp.from_list(lst)
-                ansatz = RealAmplitudes(num_qubits=2, reps=2)
-                est = Estimator(
-                    backend_options={"method": "statevector"}, abelian_grouping=abelian_grouping
-                )
-                result = est.run(
-                    ansatz, observable, parameter_values=[[0, 1, 1, 2, 3, 5]], seed=15
-                ).result()
-                self.assertIsInstance(result, EstimatorResult)
-                np.testing.assert_allclose(result.values, [1.728515625])
-
         with self.subTest("SparsePauliOp"):
             observable = SparsePauliOp.from_list(lst)
             ansatz = RealAmplitudes(num_qubits=2, reps=2)