Remove DeprecationWarning when import qiskit.primitives

qiskit/primitives/backend_estimator.py

@@ -18,12 +18,12 @@
 import copy
 from collections.abc import Sequence
 from itertools import accumulate
+from typing import TYPE_CHECKING
 
 import numpy as np
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.compiler import transpile
-from qiskit.opflow import PauliSumOp
 from qiskit.providers import BackendV1, BackendV2, Options
 from qiskit.quantum_info import Pauli, PauliList
 from qiskit.quantum_info.operators.base_operator import BaseOperator
@@ -34,6 +34,9 @@
 from .primitive_job import PrimitiveJob
 from .utils import _circuit_key, _observable_key, init_observable
 
+if TYPE_CHECKING:
+    from qiskit.opflow import PauliSumOp
+
 
 def _run_circuits(
     circuits: QuantumCircuit | list[QuantumCircuit],

qiskit/primitives/base/base_estimator.py

@@ -83,11 +83,10 @@
 from abc import abstractmethod
 from collections.abc import Sequence
 from copy import copy
-from typing import Generic, TypeVar
+from typing import TYPE_CHECKING, Generic, TypeVar
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.circuit.parametertable import ParameterView
-from qiskit.opflow import PauliSumOp
 from qiskit.providers import JobV1 as Job
 from qiskit.quantum_info.operators import SparsePauliOp
 from qiskit.quantum_info.operators.base_operator import BaseOperator
@@ -97,6 +96,9 @@
 
 T = TypeVar("T", bound=Job)
 
+if TYPE_CHECKING:
+    from qiskit.opflow import PauliSumOp
+
 
 class BaseEstimator(BasePrimitive, Generic[T]):
     """Estimator base class.

qiskit/primitives/estimator.py

@@ -16,24 +16,21 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 import numpy as np
 
 from qiskit.circuit import QuantumCircuit
 from qiskit.exceptions import QiskitError
-from qiskit.opflow import PauliSumOp
 from qiskit.quantum_info import Statevector
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 
 from .base import BaseEstimator, EstimatorResult
 from .primitive_job import PrimitiveJob
-from .utils import (
-    _circuit_key,
-    _observable_key,
-    bound_circuit_to_instruction,
-    init_observable,
-)
+from .utils import _circuit_key, _observable_key, bound_circuit_to_instruction, init_observable
+
+if TYPE_CHECKING:
+    from qiskit.opflow import PauliSumOp
 
 
 class Estimator(BaseEstimator[PrimitiveJob[EstimatorResult]]):

qiskit/primitives/utils.py

@@ -15,17 +15,20 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
+from typing import TYPE_CHECKING
 
 import numpy as np
 
 from qiskit.circuit import Instruction, ParameterExpression, QuantumCircuit
 from qiskit.circuit.bit import Bit
 from qiskit.extensions.quantum_initializer.initializer import Initialize
-from qiskit.opflow import PauliSumOp
 from qiskit.quantum_info import SparsePauliOp, Statevector
 from qiskit.quantum_info.operators.base_operator import BaseOperator
 from qiskit.quantum_info.operators.symplectic.base_pauli import BasePauli
 
+if TYPE_CHECKING:
+    from qiskit.opflow import PauliSumOp
+
 
 def init_circuit(state: QuantumCircuit | Statevector) -> QuantumCircuit:
     """Initialize state by converting the input to a quantum circuit.
@@ -60,7 +63,7 @@ def init_observable(observable: BaseOperator | PauliSumOp | str) -> SparsePauliO
     """
     if isinstance(observable, SparsePauliOp):
         return observable
-    elif isinstance(observable, PauliSumOp):
+    elif hasattr(observable, "primitive") and isinstance(observable.primitive, SparsePauliOp):
         if isinstance(observable.coeff, ParameterExpression):
             raise TypeError(
                 f"Observable must have numerical coefficient, not {type(observable.coeff)}."