Fix qpy for controlled UnitaryGate

qiskit/qpy/binary_io/circuits.py

@@ -157,12 +157,13 @@ def _loads_instruction_parameter(
     elif type_key == type_keys.Value.REGISTER:
         param = _loads_register_param(data_bytes.decode(common.ENCODE), circuit, registers)
     else:
+        clbits = circuit.clbits if circuit is not None else ()
         param = value.loads_value(
             type_key,
             data_bytes,
             version,
             vectors,
-            clbits=circuit.clbits,
+            clbits=clbits,
             cregs=registers["c"],
             use_symengine=use_symengine,
         )
@@ -577,12 +578,21 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map, use_
         or gate_class_name == "Instruction"
         or isinstance(instruction.operation, library.BlueprintCircuit)
     ):
-        if instruction.operation.name not in custom_operations:
-            custom_operations[instruction.operation.name] = instruction.operation
-            custom_operations_list.append(instruction.operation.name)
         gate_class_name = instruction.operation.name
+        # ucr*_dg gates can have different numbers of parameters,
+        # the uuid is appended to avoid storing a single definition
+        # in circuits with multiple ucr*_dg gates.
+        if instruction.operation.name in ["ucrx_dg", "ucry_dg", "ucrz_dg"]:
+            gate_class_name += "_" + str(uuid.uuid4())
+
+        if gate_class_name not in custom_operations:
+            custom_operations[gate_class_name] = instruction.operation
+            custom_operations_list.append(gate_class_name)
 
     elif gate_class_name == "ControlledGate":
+        # controlled gates can have the same name but different parameter
+        # values, the uuid is appended to avoid storing a single definition
+        # in circuits with multiple controlled gates.
         gate_class_name = instruction.operation.name + "_" + str(uuid.uuid4())
         custom_operations[gate_class_name] = instruction.operation
         custom_operations_list.append(gate_class_name)

releasenotes/notes/fix-qpy-controlled-unitary-26355d6ffa4cd2fb.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed a bug in QPY serialization (:mod:`qiskit.qpy`) where controlled unitary gates in
+    a circuit could result would fail to deserialize.  Fixed `#10802
+    <https://github.com/Qiskit/qiskit-terra/issues/10802>`__.

test/python/circuit/test_circuit_load_from_qpy.py

@@ -175,6 +175,22 @@ def test_unitary_gate(self):
         self.assertEqual(qc, new_circ)
         self.assertDeprecatedBitProperties(qc, new_circ)
 
+    def test_controlled_unitary_gate(self):
+        """Test that numpy array parameters are correctly serialized
+        in controlled unitary gate."""
+        qc = QuantumCircuit(2)
+        unitary = np.array([[0, 1], [1, 0]])
+        gate = UnitaryGate(unitary)
+        qc.append(gate.control(1), [0, 1])
+
+        with io.BytesIO() as qpy_file:
+            dump(qc, qpy_file)
+            qpy_file.seek(0)
+            new_circ = load(qpy_file)[0]
+
+        self.assertEqual(qc.decompose(reps=5), new_circ.decompose(reps=5))
+        self.assertDeprecatedBitProperties(qc, new_circ)
+
     def test_opaque_gate(self):
         """Test that custom opaque gate is correctly serialized"""
         custom_gate = Gate("black_box", 1, [])