Remove qtape/tape property from QNode (#6825)

Completing the deprecation cycle.

No idea why those tests didn't complain in CI before when it was first
deprecated ... weird!

[sc-82149]

doc/development/deprecations.rst

@@ -9,12 +9,6 @@ deprecations are listed below.
 Pending deprecations
 --------------------
 
-* The ``tape`` and ``qtape`` properties of ``QNode`` have been deprecated. 
-  Instead, use the ``qml.workflow.construct_tape`` function.
-
-  - Deprecated in v0.40
-  - Will be removed in v0.41
-
 * The ``max_expansion`` argument in :func:`~pennylane.devices.preprocess.decompose` is deprecated. 
 
   - Deprecated in v0.40
@@ -68,6 +62,12 @@ for details on how to port your legacy code to the new system. The following fun
 Completed deprecation cycles
 ----------------------------
 
+* The ``tape`` and ``qtape`` properties of ``QNode`` have been removed. 
+  Instead, use the ``qml.workflow.construct_tape`` function.
+
+  - Deprecated in v0.40
+  - Removed in v0.41
+
 * The ``gradient_fn`` keyword argument to ``qml.execute`` has been removed. Instead, it has been replaced with ``diff_method``.
 
   - Deprecated in v0.40

doc/releases/changelog-dev.md

@@ -17,6 +17,10 @@
 
 <h3>Breaking changes 💔</h3>
 
+* The ``tape`` and ``qtape`` properties of ``QNode`` have been removed. 
+  Instead, use the ``qml.workflow.construct_tape`` function.
+  [(#6825)](https://github.com/PennyLaneAI/pennylane/pull/6825)
+
 * The ``gradient_fn`` keyword argument to ``qml.execute`` has been removed. Instead, it has been replaced with ``diff_method``.
   [(#6830)](https://github.com/PennyLaneAI/pennylane/pull/6830)
 
@@ -46,3 +50,4 @@ This release contains contributions from (in alphabetical order):
 Yushao Chen,
 Diksha Dhawan,
 Christina Lee,
+Andrija Paurevic

pennylane/workflow/qnode.py

@@ -29,7 +29,7 @@
 from pennylane.logging import debug_logger
 from pennylane.math import Interface, SupportedInterfaceUserInput, get_canonical_interface_name
 from pennylane.measurements import MidMeasureMP
-from pennylane.tape import QuantumScript, QuantumTape
+from pennylane.tape import QuantumScript
 from pennylane.transforms.core import TransformContainer, TransformDispatcher, TransformProgram
 
 from ._capture_qnode import capture_qnode
@@ -695,25 +695,6 @@ def get_gradient_fn(
             f"options are {tuple(get_args(SupportedDiffMethods))}."
         )
 
-    @property
-    def tape(self) -> QuantumTape:
-        """The quantum tape
-
-        .. warning::
-
-            This property is deprecated in v0.40 and will be removed in v0.41.
-            Instead, use the :func:`qml.workflow.construct_tape <.workflow.construct_tape>` function.
-        """
-
-        warnings.warn(
-            "The tape/qtape property is deprecated and will be removed in v0.41. "
-            "Instead, use the qml.workflow.construct_tape function.",
-            qml.PennyLaneDeprecationWarning,
-        )
-        return self._tape
-
-    qtape = tape  # for backwards compatibility
-
     @debug_logger
     def construct(self, args, kwargs) -> qml.tape.QuantumScript:
         """Call the quantum function with a tape context, ensuring the operations get queued."""

tests/devices/test_default_clifford.py

@@ -599,9 +599,9 @@ def circuit_fn():
         return qml.expval(qml.PauliZ(0))
 
     qnode_clfrd = qml.QNode(circuit_fn, dev_c)
-    qnode_clfrd()
+    tape = qml.workflow.construct_tape(qnode_clfrd)()
 
-    conf_c, tape_c = dev_c.setup_execution_config(), qnode_clfrd.tape
+    conf_c, tape_c = dev_c.setup_execution_config(), tape
 
     with pytest.raises(
         NotImplementedError,

tests/ops/functions/test_map_wires.py

@@ -198,8 +198,8 @@ def qfunc():
         assert isinstance(m_ops[1], Prod)
         qml.assert_equal(m_ops[0], mapped_op)
         qml.assert_equal(m_ops[1], mapped_op_2)
-        assert m_qnode.tape.observables[0].wires == Wires(wire_map[0])
-        assert m_qnode.tape.observables[1].wires == Wires(wire_map[1])
+        assert m_tape.observables[0].wires == Wires(wire_map[0])
+        assert m_tape.observables[1].wires == Wires(wire_map[1])
 
     @pytest.mark.jax
     def test_jitting_simplified_qfunc(self):

tests/test_qnode.py

@@ -31,21 +31,6 @@
 from pennylane.typing import PostprocessingFn
 
 
-def test_tape_property_is_deprecated():
-    """Test that the tape property is deprecated."""
-    dev = qml.device("default.qubit")
-
-    @qml.qnode(dev)
-    def circuit(x):
-        qml.RX(x, wires=0)
-        return qml.PauliY(0)
-
-    with pytest.warns(
-        qml.PennyLaneDeprecationWarning, match="The tape/qtape property is deprecated"
-    ):
-        _ = circuit.tape
-
-
 def dummyfunc():
     """dummy func."""
     return None
@@ -482,47 +467,6 @@ def circuit():
 class TestTapeConstruction:
     """Tests for the tape construction"""
 
-    def test_basic_tape_construction(self, tol):
-        """Test that a quantum tape is properly constructed"""
-        dev = qml.device("default.qubit", wires=2)
-
-        def func(x, y):
-            qml.RX(x, wires=0)
-            qml.RY(y, wires=1)
-            qml.CNOT(wires=[0, 1])
-            return qml.expval(qml.PauliZ(0))
-
-        qn = QNode(func, dev)
-
-        x = pnp.array(0.12, requires_grad=True)
-        y = pnp.array(0.54, requires_grad=True)
-
-        res = qn(x, y)
-        with pytest.warns(
-            qml.PennyLaneDeprecationWarning, match="tape/qtape property is deprecated"
-        ):
-            tape = qn.tape
-
-        assert isinstance(tape, QuantumScript)
-        assert len(tape.operations) == 3
-        assert len(tape.observables) == 1
-        assert tape.num_params == 2
-        assert tape.shots.total_shots is None
-
-        expected = qml.execute([tape], dev, None)
-        assert np.allclose(res, expected, atol=tol, rtol=0)
-
-        # when called, a new quantum tape is constructed
-        old_tape = tape
-        res2 = qn(x, y)
-        with pytest.warns(
-            qml.PennyLaneDeprecationWarning, match="tape/qtape property is deprecated"
-        ):
-            new_tape = qn.tape
-
-        assert np.allclose(res, res2, atol=tol, rtol=0)
-        assert new_tape is not old_tape
-
     def test_returning_non_measurements(self):
         """Test that an exception is raised if a non-measurement
         is returned from the QNode."""

tests/test_qnode_legacy.py

@@ -32,21 +32,6 @@
 from pennylane.typing import PostprocessingFn
 
 
-def test_legacy_qtape_property_is_deprecated():
-    """Test that the legacy qtape property is deprecated."""
-    dev = qml.device("default.qubit")
-
-    @qml.qnode(dev)
-    def circuit(x):
-        qml.RX(x, wires=0)
-        return qml.PauliY(0)
-
-    with pytest.warns(
-        qml.PennyLaneDeprecationWarning, match="The tape/qtape property is deprecated"
-    ):
-        _ = circuit.qtape
-
-
 def dummyfunc():
     """dummy func."""
     return None