Extended the from_backend method of InstructionDurations to suppo…

…rt both `BackendV1` and `BackendV2` (#12941)

* Extended the `from_backend` method of `InstructionDurations` to support `GenericBackendV2`

* Simplified the `from_backend` method to allow using `BackendV2`. Added a test and a releasenote.

* Made changes to the releasenote.

(cherry picked from commit 6107799)

qiskit/transpiler/instruction_durations.py

@@ -18,6 +18,7 @@
 from qiskit.circuit import Barrier, Delay, Instruction, ParameterExpression
 from qiskit.circuit.duration import duration_in_dt
 from qiskit.providers import Backend
+from qiskit.providers.backend import BackendV2
 from qiskit.transpiler.exceptions import TranspilerError
 from qiskit.utils.units import apply_prefix
 
@@ -75,6 +76,9 @@ def from_backend(cls, backend: Backend):
             TranspilerError: If dt and dtm is different in the backend.
         """
         # All durations in seconds in gate_length
+        if isinstance(backend, BackendV2):
+            return backend.target.durations()
+
         instruction_durations = []
         backend_properties = backend.properties()
         if hasattr(backend_properties, "_gates"):

releasenotes/notes/fix-InstructionDurations-b47a9770b424d7a0.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixed a bug where :meth:`.InstructionDurations.from_backend` did not work for :class:`.BackendV2` backends.
+    Fixed `#12760 <https://github.com/Qiskit/qiskit/issues/12760>`.

test/python/transpiler/test_instruction_durations.py

@@ -16,6 +16,7 @@
 
 from qiskit.circuit import Delay, Parameter
 from qiskit.providers.fake_provider import Fake27QPulseV1
+from qiskit.providers.fake_provider import GenericBackendV2
 from qiskit.transpiler.exceptions import TranspilerError
 from qiskit.transpiler.instruction_durations import InstructionDurations
 from test import QiskitTestCase  # pylint: disable=wrong-import-order
@@ -92,3 +93,10 @@ def test_fail_if_get_unbounded_duration_with_unit_conversion_when_dt_is_not_prov
         parameterized_delay = Delay(param, "s")
         with self.assertRaises(TranspilerError):
             InstructionDurations().get(parameterized_delay, 0)
+
+    def test_from_backend_with_backendv2(self):
+        """Test if `from_backend()` method allows using BackendV2"""
+        backend = GenericBackendV2(num_qubits=4, calibrate_instructions=True, seed=42)
+        inst_durations = InstructionDurations.from_backend(backend)
+        self.assertEqual(inst_durations, backend.target.durations())
+        self.assertIsInstance(inst_durations, InstructionDurations)