Fix qpy support for Annotated Operations

qiskit/qpy/__init__.py

@@ -167,10 +167,41 @@
 Version 11
 ==========
 
-Version 11 is identical to Version 10 except that for names in the CUSTOM_INSTRUCTION blocks
+Version 11 is identical to Version 10 except for the following.
+First, the names in the CUSTOM_INSTRUCTION blocks
 have a suffix of the form ``"_{uuid_hex}"`` where ``uuid_hex`` is a uuid
 hexadecimal string such as returned by :attr:`.UUID.hex`. For example:
 ``"b3ecab5b4d6a4eb6bc2b2dbf18d83e1e"``.
+Second, it adds support for :class:`.AnnotatedOperation`
+objects. The base operation of an annotated operation is stored using the INSTRUCTION block,
+and an additional ``type`` value ``'a'``is added to indicate that the custom instruction is an
+annotated operation. The list of modifiers are stored as instruction parameters using INSTRUCTION_PARAM,
+with an additional value ``'m'`` is added to indicate that the parameter is of type
+:class:`~qiskit.circuit.annotated_operation.Modifier`. Each modifier is stored using the
+MODIFIER struct.
+
+.. _modifier_qpy:
+
+MODIFIER
+--------
+
+This represents :class:`~qiskit.circuit.annotated_operation.Modifier`
+
+.. code-block:: c
+
+    struct {
+        char type;
+        uint32_t num_ctrl_qubits;
+        uint32_t ctrl_state;
+        double power;
+    }
+
+This is sufficient to store different types of modifiers required for serializing objects
+of type :class:`.AnnotatedOperation`.
+The field ``type`` is either ``'i'``, ``'c'`` or ``'p'``, representing whether the modifier
+is respectively an inverse modifier, a control modifier or a power modifier. In the second
+case, the fields ``num_ctrl_qubits`` and ``ctrl_state`` specify the control logic of the base
+operation, and in the third case the field ``power`` represents the power of the base operation.
 
 .. _qpy_version_10:
 

qiskit/qpy/binary_io/circuits.py

@@ -30,6 +30,13 @@
 from qiskit.circuit.gate import Gate
 from qiskit.circuit.singleton import SingletonInstruction, SingletonGate
 from qiskit.circuit.controlledgate import ControlledGate
+from qiskit.circuit.annotated_operation import (
+    AnnotatedOperation,
+    Modifier,
+    InverseModifier,
+    ControlModifier,
+    PowerModifier,
+)
 from qiskit.circuit.instruction import Instruction
 from qiskit.circuit.quantumcircuit import QuantumCircuit
 from qiskit.circuit.quantumregister import QuantumRegister, Qubit
@@ -130,6 +137,8 @@ def _loads_instruction_parameter(
 ):
     if type_key == type_keys.Program.CIRCUIT:
         param = common.data_from_binary(data_bytes, read_circuit, version=version)
+    elif type_key == type_keys.Value.MODIFIER:
+        param = common.data_from_binary(data_bytes, _read_modifier)
     elif type_key == type_keys.Container.RANGE:
         data = formats.RANGE._make(struct.unpack(formats.RANGE_PACK, data_bytes))
         param = range(data.start, data.stop, data.step)
@@ -408,6 +417,14 @@ def _parse_custom_operation(
         inst_obj.definition = definition
         return inst_obj
 
+    if version >= 11 and type_key == type_keys.CircuitInstruction.ANNOTATED_OPERATION:
+        with io.BytesIO(base_gate_raw) as base_gate_obj:
+            base_gate = _read_instruction(
+                base_gate_obj, None, registers, custom_operations, version, vectors, use_symengine
+            )
+        inst_obj = AnnotatedOperation(base_op=base_gate, modifiers=params)
+        return inst_obj
+
     if type_key == type_keys.CircuitInstruction.PAULI_EVOL_GATE:
         return definition
 
@@ -453,6 +470,25 @@ def _read_pauli_evolution_gate(file_obj, version, vectors):
     return return_gate
 
 
+def _read_modifier(file_obj):
+    modifier = formats.MODIFIER_DEF._make(
+        struct.unpack(
+            formats.MODIFIER_DEF_PACK,
+            file_obj.read(formats.MODIFIER_DEF_SIZE),
+        )
+    )
+    if modifier.type == b"i":
+        return InverseModifier()
+    elif modifier.type == b"c":
+        return ControlModifier(
+            num_ctrl_qubits=modifier.num_ctrl_qubits, ctrl_state=modifier.ctrl_state
+        )
+    elif modifier.type == b"p":
+        return PowerModifier(power=modifier.power)
+    else:
+        raise TypeError("Unsupported modifier.")
+
+
 def _read_custom_operations(file_obj, version, vectors):
     custom_operations = {}
     custom_definition_header = formats.CUSTOM_CIRCUIT_DEF_HEADER._make(
@@ -547,6 +583,9 @@ def _dumps_instruction_parameter(param, index_map, use_symengine):
     if isinstance(param, QuantumCircuit):
         type_key = type_keys.Program.CIRCUIT
         data_bytes = common.data_to_binary(param, write_circuit)
+    elif isinstance(param, Modifier):
+        type_key = type_keys.Value.MODIFIER
+        data_bytes = common.data_to_binary(param, _write_modifier)
     elif isinstance(param, range):
         type_key = type_keys.Container.RANGE
         data_bytes = struct.pack(formats.RANGE_PACK, param.start, param.stop, param.step)
@@ -587,7 +626,7 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map, use_
             not hasattr(library, gate_class_name)
             and not hasattr(circuit_mod, gate_class_name)
             and not hasattr(controlflow, gate_class_name)
-            and gate_class_name != "Clifford"
+            and gate_class_name not in ["Clifford", "AnnotatedOperation"]
         )
         or gate_class_name == "Gate"
         or gate_class_name == "Instruction"
@@ -606,8 +645,8 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map, use_
         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
+    elif gate_class_name in ["ControlledGate", "AnnotatedOperation"]:
+        # controlled or annotated 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())
@@ -646,8 +685,10 @@ def _write_instruction(file_obj, instruction, custom_operations, index_map, use_
         ]
     elif isinstance(instruction.operation, Clifford):
         instruction_params = [instruction.operation.tableau]
+    elif isinstance(instruction.operation, AnnotatedOperation):
+        instruction_params = instruction.operation.modifiers
     else:
-        instruction_params = instruction.operation.params
+        instruction_params = getattr(instruction.operation, "params", [])
 
     num_ctrl_qubits = getattr(instruction.operation, "num_ctrl_qubits", 0)
     ctrl_state = getattr(instruction.operation, "ctrl_state", 0)
@@ -729,6 +770,31 @@ def _write_elem(buffer, op):
     file_obj.write(synth_data)
 
 
+def _write_modifier(file_obj, modifier):
+    if isinstance(modifier, InverseModifier):
+        type_key = b"i"
+        num_ctrl_qubits = 0
+        ctrl_state = 0
+        power = 0.0
+    elif isinstance(modifier, ControlModifier):
+        type_key = b"c"
+        num_ctrl_qubits = modifier.num_ctrl_qubits
+        ctrl_state = modifier.ctrl_state
+        power = 0.0
+    elif isinstance(modifier, PowerModifier):
+        type_key = b"p"
+        num_ctrl_qubits = 0
+        ctrl_state = 0
+        power = modifier.power
+    else:
+        raise TypeError("Unsupported modifier.")
+
+    modifier_data = struct.pack(
+        formats.MODIFIER_DEF_PACK, type_key, num_ctrl_qubits, ctrl_state, power
+    )
+    file_obj.write(modifier_data)
+
+
 def _write_custom_operation(file_obj, name, operation, custom_operations, use_symengine, version):
     type_key = type_keys.CircuitInstruction.assign(operation)
     has_definition = False
@@ -759,6 +825,9 @@ def _write_custom_operation(file_obj, name, operation, custom_operations, use_sy
         num_ctrl_qubits = operation.num_ctrl_qubits
         ctrl_state = operation.ctrl_state
         base_gate = operation.base_gate
+    elif type_key == type_keys.CircuitInstruction.ANNOTATED_OPERATION:
+        has_definition = False
+        base_gate = operation.base_op
     elif operation.definition is not None:
         has_definition = True
         data = common.data_to_binary(operation.definition, write_circuit)

qiskit/qpy/formats.py

@@ -139,6 +139,11 @@
 PAULI_EVOLUTION_DEF_PACK = "!Q?1cQQ"
 PAULI_EVOLUTION_DEF_SIZE = struct.calcsize(PAULI_EVOLUTION_DEF_PACK)
 
+# Modifier
+MODIFIER_DEF = namedtuple("MODIFIER_DEF", ["type", "num_ctrl_qubits", "ctrl_state", "power"])
+MODIFIER_DEF_PACK = "!1cIId"
+MODIFIER_DEF_SIZE = struct.calcsize(MODIFIER_DEF_PACK)
+
 # CUSTOM_CIRCUIT_DEF_HEADER
 CUSTOM_CIRCUIT_DEF_HEADER = namedtuple("CUSTOM_CIRCUIT_DEF_HEADER", ["size"])
 CUSTOM_CIRCUIT_DEF_HEADER_PACK = "!Q"

qiskit/qpy/type_keys.py

@@ -30,6 +30,7 @@
     Clbit,
     ClassicalRegister,
 )
+from qiskit.circuit.annotated_operation import AnnotatedOperation, Modifier
 from qiskit.circuit.classical import expr, types
 from qiskit.circuit.library import PauliEvolutionGate
 from qiskit.circuit.parameter import Parameter
@@ -113,6 +114,7 @@ class Value(TypeKeyBase):
     STRING = b"s"
     NULL = b"z"
     EXPRESSION = b"x"
+    MODIFIER = b"m"
 
     @classmethod
     def assign(cls, obj):
@@ -140,6 +142,8 @@ def assign(cls, obj):
             return cls.CASE_DEFAULT
         if isinstance(obj, expr.Expr):
             return cls.EXPRESSION
+        if isinstance(obj, Modifier):
+            return cls.MODIFIER
 
         raise exceptions.QpyError(
             f"Object type '{type(obj)}' is not supported in {cls.__name__} namespace."
@@ -191,13 +195,16 @@ class CircuitInstruction(TypeKeyBase):
     GATE = b"g"
     PAULI_EVOL_GATE = b"p"
     CONTROLLED_GATE = b"c"
+    ANNOTATED_OPERATION = b"a"
 
     @classmethod
     def assign(cls, obj):
         if isinstance(obj, PauliEvolutionGate):
             return cls.PAULI_EVOL_GATE
         if isinstance(obj, ControlledGate):
             return cls.CONTROLLED_GATE
+        if isinstance(obj, AnnotatedOperation):
+            return cls.ANNOTATED_OPERATION
         if isinstance(obj, Gate):
             return cls.GATE
         if isinstance(obj, Instruction):

releasenotes/notes/fix-annotated-qpy-6503362c79f29838.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    QPY (using :func:`.qpy.dump` and :func:`.qpy.load`) will now correctly serialize
+    and deserialize quantum circuits with annotated operations
+    (:class:`~.AnnotatedOperation`).

test/python/circuit/test_circuit_load_from_qpy.py

@@ -30,6 +30,7 @@
 from qiskit.circuit.gate import Gate
 from qiskit.circuit.library import (
     XGate,
+    CXGate,
     RYGate,
     QFT,
     QAOAAnsatz,
@@ -46,6 +47,12 @@
     UnitaryGate,
     DiagonalGate,
 )
+from qiskit.circuit.annotated_operation import (
+    AnnotatedOperation,
+    InverseModifier,
+    ControlModifier,
+    PowerModifier,
+)
 from qiskit.circuit.instruction import Instruction
 from qiskit.circuit.parameter import Parameter
 from qiskit.circuit.parametervector import ParameterVector
@@ -1725,6 +1732,40 @@ def test_clifford(self):
             new_circuit = load(fptr)[0]
         self.assertEqual(circuit, new_circuit)
 
+    def test_annotated_operations(self):
+        """Test that circuits with annotated operations can be saved and retrieved correctly."""
+        op1 = AnnotatedOperation(
+            CXGate(), [InverseModifier(), ControlModifier(1), PowerModifier(1.4), InverseModifier()]
+        )
+        op2 = AnnotatedOperation(XGate(), InverseModifier())
+
+        circuit = QuantumCircuit(6, 1)
+        circuit.cx(0, 1)
+        circuit.append(op1, [0, 1, 2])
+        circuit.h(4)
+        circuit.append(op2, [1])
+
+        with io.BytesIO() as fptr:
+            dump(circuit, fptr)
+            fptr.seek(0)
+            new_circuit = load(fptr)[0]
+        self.assertEqual(circuit, new_circuit)
+
+    def test_annotated_operations_iterative(self):
+        """Test that circuits with iterative annotated operations can be saved and
+        retrieved correctly.
+        """
+        op = AnnotatedOperation(AnnotatedOperation(XGate(), InverseModifier()), ControlModifier(1))
+        circuit = QuantumCircuit(4)
+        circuit.h(0)
+        circuit.append(op, [0, 2])
+        circuit.cx(2, 3)
+        with io.BytesIO() as fptr:
+            dump(circuit, fptr)
+            fptr.seek(0)
+            new_circuit = load(fptr)[0]
+        self.assertEqual(circuit, new_circuit)
+
 
 class TestSymengineLoadFromQPY(QiskitTestCase):
     """Test use of symengine in qpy set of methods."""