Add backend method (#1995)

* add backend method

* release note

---------

Co-authored-by: Kevin Tian <[email protected]>

qiskit_ibm_runtime/base_primitive.py

@@ -234,6 +234,10 @@ def options(self) -> OptionsT:
         """Return options"""
         return self._options
 
+    def backend(self) -> BackendV1 | BackendV2:
+        """Return the backend the primitive query will be run on."""
+        return self._backend
+
     def _set_options(self, options: Optional[Union[Dict, OptionsT]] = None) -> None:
         """Set options."""
         if options is None:

qiskit_ibm_runtime/noise_learner/noise_learner.py

@@ -221,6 +221,10 @@ def _program_id(cls) -> str:
         """Return the program ID."""
         return "noise-learner"
 
+    def backend(self) -> BackendV2:
+        """Return the backend the primitive query will be run on."""
+        return self._backend
+
     def _set_options(
         self, options: Optional[Union[Dict, NoiseLearnerOptions, EstimatorOptions]] = None
     ) -> None:

release-notes/unreleased/1995.feat.rst

@@ -0,0 +1,2 @@
+:class:`.SamplerV2`, :class:`.EstimatorV2`, and :class:`.noise_learner.NoiseLearner` now each has
+a ``backend()`` method that returns the backend the class is configured with.

test/unit/test_ibm_primitives_v2.py

@@ -23,13 +23,12 @@
 from qiskit.circuit.library import RealAmplitudes
 from qiskit.quantum_info import SparsePauliOp
 
-from qiskit_ibm_runtime import Session
+from qiskit_ibm_runtime import Session, Batch
 from qiskit_ibm_runtime.utils.default_session import _DEFAULT_SESSION
 from qiskit_ibm_runtime import EstimatorV2, SamplerV2
 from qiskit_ibm_runtime.estimator import Estimator as IBMBaseEstimator
 from qiskit_ibm_runtime.fake_provider import FakeManilaV2
 from qiskit_ibm_runtime.exceptions import IBMInputValueError
-from qiskit_ibm_runtime.options.utils import Unset
 
 from ..ibm_test_case import IBMTestCase
 from ..utils import (
@@ -630,6 +629,21 @@ def test_abstract_circuits(self, primitive):
         with self.assertRaisesRegex(IBMInputValueError, "target hardware"):
             inst.run(pubs=[tuple(pub)])
 
+    @data(EstimatorV2, SamplerV2)
+    def test_get_backend_primitive(self, primitive):
+        """Test getting the backend used in the primitive."""
+        backend = get_mocked_backend()
+        inst = primitive(mode=backend)
+        self.assertEqual(inst.backend().name, backend.name)
+
+    @combine(primitive=[EstimatorV2, SamplerV2], session=[Session, Batch])
+    def test_get_backend_session(self, primitive, session):
+        """Test getting the backend used in the primitive when session is used."""
+        backend = FakeManilaV2()
+        with session(backend=backend):
+            inst = primitive()
+            self.assertEqual(inst.backend().name, backend.name)
+
     def _update_dict(self, dict1, dict2):
         for key, val in dict1.items():
             if isinstance(val, dict):
@@ -643,40 +657,3 @@ def _assert_dict_partially_equal(self, dict1, dict2):
             dict_paritally_equal(dict1, dict2),
             f"{dict1} and {dict2} not partially equal.",
         )
-
-    def test_qctrl_supported_values_for_options_estimator(self):
-        """Test exception when options levels not supported for Estimator V2."""
-        no_resilience_options = {
-            "measure_mitigation": Unset,
-            "measure_noise_learning": {},
-            "zne_mitigation": Unset,
-            "zne": {},
-            "pec_mitigation": Unset,
-            "pec": {},
-            "layer_noise_learning": {},
-        }
-
-        options_good = [
-            # Minimum working settings
-            {},
-            # No warnings, we need resilience options here because by default they are getting populated.
-            {"resilience": no_resilience_options},
-            # Arbitrary resilience options(issue warning)
-            {
-                "resilience_level": 1,
-                "resilience": {"measure_mitigation": True},
-            },
-            # Resilience level > 1 (issue warning)
-            {"resilience_level": 2},
-            # Twirling (issue warning)
-            {"twirling": {"strategy": "active"}},
-            # Dynamical_decoupling (issue warning)
-            {"dynamical_decoupling": {"sequence_type": "XY4"}},
-        ]
-        session = get_mocked_session()
-        session.service.backend().configuration().simulator = False
-        for options in options_good:
-            with self.subTest(msg=f"EstimatorV2, {options}"):
-                print(options)
-                inst = EstimatorV2(mode=session, options=options)
-                _ = inst.run(**get_primitive_inputs(inst))

test/unit/test_noise_learner.py

@@ -125,3 +125,9 @@ def test_not_supported_in_local_mode(self):
         """Test exception when circuits is not ISA."""
         with self.assertRaisesRegex(ValueError, "not currently supported in local mode"):
             NoiseLearner(FakeSherbrooke())
+
+    def test_get_backend(self):
+        """Test getting the backend used."""
+        backend = get_mocked_backend()
+        inst = NoiseLearner(backend)
+        self.assertEqual(inst.backend().name, backend.name)