From 341386144d6093f8765d08b695d1c2d2c56eac6f Mon Sep 17 00:00:00 2001
From: "mergify[bot]" <37929162+mergify[bot]@users.noreply.github.com>
Date: Wed, 21 Aug 2024 13:20:15 +0000
Subject: [PATCH] Extended the `from_backend` method of `InstructionDurations`
 to support both `BackendV1` and `BackendV2` (#12941) (#13009)

* 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 6107799ce19996ed125cb3f01663ad394e4eadbc)

Co-authored-by: Shravan Patel <78003234+shravanpatel30@users.noreply.github.com>
---
 qiskit/transpiler/instruction_durations.py                | 4 ++++
 .../notes/fix-InstructionDurations-b47a9770b424d7a0.yaml  | 5 +++++
 test/python/transpiler/test_instruction_durations.py      | 8 ++++++++
 3 files changed, 17 insertions(+)
 create mode 100644 releasenotes/notes/fix-InstructionDurations-b47a9770b424d7a0.yaml

diff --git a/qiskit/transpiler/instruction_durations.py b/qiskit/transpiler/instruction_durations.py
index 85d89bb16a18..56f8b5587c0c 100644
--- a/qiskit/transpiler/instruction_durations.py
+++ b/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"):
diff --git a/releasenotes/notes/fix-InstructionDurations-b47a9770b424d7a0.yaml b/releasenotes/notes/fix-InstructionDurations-b47a9770b424d7a0.yaml
new file mode 100644
index 000000000000..ce8b789462de
--- /dev/null
+++ b/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>`.
\ No newline at end of file
diff --git a/test/python/transpiler/test_instruction_durations.py b/test/python/transpiler/test_instruction_durations.py
index de68fbadf86a..c59d0ff2a6cc 100644
--- a/test/python/transpiler/test_instruction_durations.py
+++ b/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)