Remove use of deprecated objects in BasicSimulator (#13743)

* Refactor BasicSimulator not to rely on assemble or qobj. Drop support for c_if (deprecated) and providing parameter bounds to the "run" method.

* Code cleanup and style fixing

* Add reno

* Address small oversights

* Apply suggestions from Eli's code review

Co-authored-by: Eli Arbel <[email protected]>

* Fix handling of backend options in both BasicSimulator and BackendV2. Add unit tests. Rename kwargs to unify use of options with aer simulator and update documentation to reflect actual usage.

* Document header in docstring

* Fix lint

* Apply suggestions from Eli's code review

Co-authored-by: Eli Arbel <[email protected]>

---------

Co-authored-by: Eli Arbel <[email protected]>

qiskit/providers/backend.py

@@ -361,9 +361,9 @@ def __init__(
         self._provider = provider
         if fields:
             for field in fields:
-                if field not in self._options.data:
+                if field not in self._options:
                     raise AttributeError(f"Options field {field} is not valid for this backend")
-            self._options.update_config(**fields)
+            self._options.update_options(**fields)
         self.name = name
         """Name of the backend."""
         self.description = description

releasenotes/notes/remove-backend-configuration-basic-simulator-cac1c2783a5a4e25.yaml

@@ -0,0 +1,11 @@
+---
+upgrade_providers:
+  - |
+    The ``configuration`` method of :class:`.BasicSimulator` has been removed following its deprecation
+    in Qiskit 1.3. This method returned a ``BackendConfiguration`` instance, and this class was
+    part of the deprecated :class:`.BackendV1` workflow. The individual configuration elements 
+    can be retrieved directly from the backend or from the contained :class:`.Target` instance ``(backend.target)``.
+
+  - |
+    The ``run_experiment`` method of :class:`.BasicSimulator` has also been removed. This method took an instance
+    of the ``QasmQobjExperiment`` class as an input argument, and the class has been deprecated since Qiskit 1.2.

test/python/circuit/test_parameters.py

@@ -1084,46 +1084,6 @@ def test_parameter_equality_to_expression(self, ptype):
         self.assertEqual(hash(x1), hash(x1_expr))
         self.assertEqual(hash(x2), hash(x2_expr))
 
-    def test_binding_parameterized_circuits_built_in_multiproc_(self):
-        """Verify subcircuits built in a subprocess can still be bound.
-        REMOVE this test once assemble is REMOVED"""
-        # ref: https://github.com/Qiskit/qiskit-terra/issues/2429
-
-        num_processes = 4
-
-        qr = QuantumRegister(3)
-        cr = ClassicalRegister(3)
-
-        circuit = QuantumCircuit(qr, cr)
-        parameters = [Parameter(f"x{i}") for i in range(num_processes)]
-
-        results = parallel_map(
-            _construct_circuit, parameters, task_args=(qr,), num_processes=num_processes
-        )
-
-        for qc in results:
-            circuit.compose(qc, inplace=True)
-
-        parameter_values = [{x: 1.0 for x in parameters}]
-
-        with self.assertWarns(DeprecationWarning):
-            qobj = assemble(
-                circuit,
-                backend=BasicSimulator(),
-                parameter_binds=parameter_values,
-            )
-
-        self.assertEqual(len(qobj.experiments), 1)
-        self.assertEqual(len(qobj.experiments[0].instructions), 4)
-        self.assertTrue(
-            all(
-                len(inst.params) == 1
-                and isinstance(inst.params[0], float)
-                and float(inst.params[0]) == 1
-                for inst in qobj.experiments[0].instructions
-            )
-        )
-
     def test_binding_parameterized_circuits_built_in_multiproc(self):
         """Verify subcircuits built in a subprocess can still be bound."""
         # ref: https://github.com/Qiskit/qiskit-terra/issues/2429
@@ -1170,10 +1130,13 @@ def test_transpiling_multiple_parameterized_circuits(self):
         qc1.u(theta, 0, 0, qr[0])
         qc2.u(theta, 3.14, 0, qr[0])
 
+        qc1 = qc1.assign_parameters({theta: 1})
+        qc2 = qc2.assign_parameters({theta: 1})
+
         circuits = [qc1, qc2]
 
         backend = BasicSimulator()
-        job = backend.run(transpile(circuits, backend), shots=512, parameter_binds=[{theta: 1}])
+        job = backend.run(transpile(circuits, backend), shots=512)
 
         self.assertTrue(len(job.result().results), 2)
 
@@ -1435,20 +1398,6 @@ def test_num_parameters(self):
             qc.x(0)
             self.assertEqual(qc.num_parameters, 0)
 
-    def test_execute_result_names(self):
-        """Test unique names for list of parameter binds."""
-        theta = Parameter("θ")
-        reps = 5
-        qc = QuantumCircuit(1, 1)
-        qc.rx(theta, 0)
-        qc.measure(0, 0)
-
-        plist = [{theta: i} for i in range(reps)]
-        simulator = BasicSimulator()
-        result = simulator.run(transpile(qc, simulator), parameter_binds=plist).result()
-        result_names = {res.name for res in result.results}
-        self.assertEqual(reps, len(result_names))
-
     def test_to_instruction_after_inverse(self):
         """Verify converting an inverse generates a valid ParameterTable"""
         # ref: https://github.com/Qiskit/qiskit-terra/issues/4235

test/python/circuit/test_scheduled_circuit.py

@@ -518,32 +518,7 @@ def test_duration_on_same_instruction_instance(self, scheduling_method):
         cxs = [inst.operation for inst in sc.data if inst.operation.name == "cx"]
         self.assertNotEqual(cxs[0].duration, cxs[1].duration)
 
-    def test_transpile_and_assemble_delay_circuit_for_simulator(self):
-        """See: https://github.com/Qiskit/qiskit-terra/issues/5962"""
-        qc = QuantumCircuit(1)
-        qc.delay(100, 0, "ns")
-        circ = transpile(qc, self.simulator_backend)
-        self.assertEqual(circ.duration, None)  # not scheduled
-        with self.assertWarns(DeprecationWarning):
-            qobj = assemble(circ, self.simulator_backend)
-        self.assertEqual(qobj.experiments[0].instructions[0].name, "delay")
-        self.assertEqual(qobj.experiments[0].instructions[0].params[0], 1e-7)
-
-    def test_transpile_and_assemble_t1_circuit_for_simulator(self):
-        """Check if no scheduling is done in transpiling for simulator backends"""
-        qc = QuantumCircuit(1, 1)
-        qc.x(0)
-        qc.delay(0.1, 0, "us")
-        qc.measure(0, 0)
-        circ = transpile(qc, self.simulator_backend)
-        self.assertEqual(circ.duration, None)  # not scheduled
-        with self.assertWarns(DeprecationWarning):
-            qobj = assemble(circ, self.simulator_backend)
-        self.assertEqual(qobj.experiments[0].instructions[1].name, "delay")
-        self.assertAlmostEqual(qobj.experiments[0].instructions[1].params[0], 1e-7)
-
     # Tests for circuits with parameterized delays
-
     def test_can_transpile_circuits_after_assigning_parameters(self):
         """Check if not scheduled but duration is converted in dt"""
         idle_dur = Parameter("t")

test/python/providers/basic_provider/__init__.py

@@ -18,13 +18,6 @@
 class BasicProviderBackendTestMixin:
     """Test mixins for BasicProvider backend tests."""
 
-    def test_configuration(self):
-        """Test backend.configuration()."""
-        with self.assertWarns(DeprecationWarning):
-            # The method is deprecated
-            configuration = self.backend.configuration()
-        return configuration
-
     def test_run_circuit(self):
         """Test running a single circuit."""
         transpiled_qc = transpile(self.circuit, self.backend)