Fix custom pulse instruction conversion to Qobj. (#11829)

* Possible fix.

* Update releasenotes/notes/fix-custom-pulse-qobj-conversion-5d6041b36356cfd1.yaml

Co-authored-by: Will Shanks <wshaos@posteo.net>

* release notes fix

* Add test

---------

Co-authored-by: Will Shanks <wshaos@posteo.net>
(cherry picked from commit 060cb70)

qiskit/qobj/converters/pulse_instruction.py

@@ -62,10 +62,10 @@ def from_instance(
         Raises:
             QiskitError: When pulse instance is not recognizable type.
         """
-        try:
+        if isinstance(instance, library.SymbolicPulse):
             return cls(instance.pulse_type)
-        except ValueError as ex:
-            raise QiskitError(f"'{instance}' is not valid pulse type.") from ex
+
+        raise QiskitError(f"'{instance}' is not valid pulse type.")
 
     @classmethod
     def to_type(cls, name: str) -> library.SymbolicPulse:

releasenotes/notes/fix-custom-pulse-qobj-conversion-5d6041b36356cfd1.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed a bug in the conversion of custom pulse instructions to the legacy :mod:`qiskit.qobj` format. The bug was introduced in Qiskit 1.0.0
+    and caused conversion of instructions with custom pulse shapes to raise an error. After the fix, the conversion is
+    carried out correctly, and the custom pulse is converted to :class:`.pulse.Waveform` as it should.
+    Fixed `#11828 <https://github.com/Qiskit/qiskit/issues/11828>`__.

test/python/compiler/test_assembler.py

@@ -528,6 +528,24 @@ def test_pulse_gates_single_circ(self):
         self.assertEqual(len(lib), 2)
         self.assertTrue(all(len(item.samples) == 50 for item in lib))
 
+    def test_custom_pulse_gates_single_circ(self):
+        """Test that we can add calibrations to circuits of pulses which are not in
+        qiskit.qobj.converters.pulse_instruction.ParametricPulseShapes"""
+        circ = QuantumCircuit(2)
+        circ.h(0)
+
+        with pulse.build() as custom_h_schedule:
+            pulse.play(pulse.library.Triangle(50, 0.1, 0.2), pulse.DriveChannel(0))
+
+        circ.add_calibration("h", [0], custom_h_schedule)
+
+        qobj = assemble(circ, FakeOpenPulse2Q())
+        lib = qobj.config.pulse_library
+        self.assertEqual(len(lib), 1)
+        np.testing.assert_almost_equal(
+            lib[0].samples, pulse.library.Triangle(50, 0.1, 0.2).get_waveform().samples
+        )
+
     def test_pulse_gates_with_parameteric_pulses(self):
         """Test that pulse gates are assembled efficiently for backends that enable
         parametric pulses.