Add decompositions of RX, RY and RZ into one of the other two + Cliffords

doc/releases/changelog-dev.md

@@ -15,6 +15,10 @@
 
 <h3>Improvements 🛠</h3>
 
+* Added decompositions of the ``RX``, ``RY`` and ``RZ`` rotations into one of the other two, as well
+  as basis changing Clifford gates, to the graph-based decomposition system.
+  [(#8569)](https://github.com/PennyLaneAI/pennylane/pull/8569)
+
 * The new graph based decompositions system enabled via :func:`~.decomposition.enable_graph` now supports the following
   additional templates.
   [(#8520)](https://github.com/PennyLaneAI/pennylane/pull/8520)

pennylane/ops/qubit/non_parametric_ops.py

@@ -726,13 +726,9 @@ def compute_diagonalizing_gates(wires: WiresLike) -> list[qml.operation.Operator
         **Example**
 
         >>> print(qml.Y.compute_diagonalizing_gates(wires=[0]))
-        [Z(0), S(0), H(0)]
+        [Adjoint(S(0)), H(0)]
         """
-        return [
-            Z(wires=wires),
-            S(wires=wires),
-            Hadamard(wires=wires),
-        ]
+        return [qml.adjoint(S(wires=wires)), Hadamard(wires=wires)]
 
     @staticmethod
     def compute_decomposition(wires: WiresLike) -> list[qml.operation.Operator]:

pennylane/ops/qubit/parametric_ops_single_qubit.py

@@ -23,7 +23,13 @@
 import scipy as sp
 
 import pennylane as qml
-from pennylane.decomposition import add_decomps, register_resources, resource_rep
+from pennylane.decomposition import (
+    add_decomps,
+    adjoint_resource_rep,
+    change_op_basis_resource_rep,
+    register_resources,
+    resource_rep,
+)
 from pennylane.decomposition.symbolic_decomposition import (
     adjoint_rotation,
     flip_zero_control,
@@ -180,7 +186,25 @@ def _rx_to_rz_ry(phi, wires: WiresLike, **__):
     qml.RZ(-np.pi / 2, wires=wires)
 
 
-add_decomps(RX, _rx_to_rot, _rx_to_rz_ry)
+def _rx_to_ry_cliff_resources():
+    return {change_op_basis_resource_rep(qml.S, qml.RY): 1}
+
+
+@register_resources(_rx_to_ry_cliff_resources)
+def _rx_to_ry_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(qml.S(wires), qml.RY(phi, wires))
+
+
+def _rx_to_rz_cliff_resources():
+    return {change_op_basis_resource_rep(qml.Hadamard, qml.RZ, qml.Hadamard): 1}
+
+
+@register_resources(_rx_to_rz_cliff_resources)
+def _rx_to_rz_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(qml.Hadamard(wires), qml.RZ(phi, wires), qml.Hadamard(wires))
+
+
+add_decomps(RX, _rx_to_rot, _rx_to_rz_ry, _rx_to_ry_cliff, _rx_to_rz_cliff)
 add_decomps("Adjoint(RX)", adjoint_rotation)
 add_decomps("Pow(RX)", pow_rotation)
 
@@ -349,7 +373,41 @@ def _ry_to_rz_rx(phi, wires: WiresLike, **__):
     qml.RZ(np.pi / 2, wires=wires)
 
 
-add_decomps(RY, _ry_to_rot, _ry_to_rz_rx)
+def _ry_to_rx_cliff_resources():
+    return {change_op_basis_resource_rep(adjoint_resource_rep(qml.S), qml.RX, qml.S): 1}
+
+
+@register_resources(_ry_to_rx_cliff_resources)
+def _ry_to_rx_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(qml.adjoint(qml.S(wires)), qml.RX(phi, wires), qml.S(wires))
+
+
+def _ry_to_rz_cliff_resources():
+    return {
+        change_op_basis_resource_rep(
+            resource_rep(
+                qml.ops.op_math.Prod,
+                resources={adjoint_resource_rep(qml.S): 1, resource_rep(qml.Hadamard): 1},
+            ),
+            qml.RZ,
+            resource_rep(
+                qml.ops.op_math.Prod,
+                resources={resource_rep(qml.S): 1, resource_rep(qml.Hadamard): 1},
+            ),
+        ): 1
+    }
+
+
+@register_resources(_ry_to_rz_cliff_resources)
+def _ry_to_rz_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(
+        qml.Hadamard(wires) @ qml.adjoint(qml.S(wires)),
+        qml.RZ(phi, wires),
+        qml.S(wires) @ qml.Hadamard(wires),
+    )
+
+
+add_decomps(RY, _ry_to_rot, _ry_to_rz_rx, _ry_to_rx_cliff, _ry_to_rz_cliff)
 add_decomps("Adjoint(RY)", adjoint_rotation)
 add_decomps("Pow(RY)", pow_rotation)
 
@@ -556,7 +614,41 @@ def _rz_to_ry_rx(phi, wires: WiresLike, **__):
     qml.RY(-np.pi / 2, wires=wires)
 
 
-add_decomps(RZ, _rz_to_rot, _rz_to_ry_rx)
+def _rz_to_rx_cliff_resources():
+    return {change_op_basis_resource_rep(qml.Hadamard, qml.RX, qml.Hadamard): 1}
+
+
+@register_resources(_rz_to_rx_cliff_resources)
+def _rz_to_rx_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(qml.Hadamard(wires), qml.RX(phi, wires), qml.Hadamard(wires))
+
+
+def _rz_to_ry_cliff_resources():
+    return {
+        change_op_basis_resource_rep(
+            resource_rep(
+                qml.ops.op_math.Prod,
+                resources={resource_rep(qml.S): 1, resource_rep(qml.Hadamard): 1},
+            ),
+            qml.RY,
+            resource_rep(
+                qml.ops.op_math.Prod,
+                resources={adjoint_resource_rep(qml.S): 1, resource_rep(qml.Hadamard): 1},
+            ),
+        ): 1
+    }
+
+
+@register_resources(_rz_to_ry_cliff_resources)
+def _rz_to_ry_cliff(phi, wires: WiresLike, **__):
+    qml.change_op_basis(
+        qml.S(wires) @ qml.Hadamard(wires),
+        qml.RY(phi, wires),
+        qml.Hadamard(wires) @ qml.adjoint(qml.S(wires)),
+    )
+
+
+add_decomps(RZ, _rz_to_rot, _rz_to_ry_rx, _rz_to_rx_cliff, _rz_to_ry_cliff)
 add_decomps("Adjoint(RZ)", adjoint_rotation)
 add_decomps("Pow(RZ)", pow_rotation)
 

tests/ops/qubit/test_parametric_ops.py

@@ -151,7 +151,24 @@ def test_validity(self, op):
         )
 
 
+SKIP_ASSERT_VALID = {
+    qml.GlobalPhase: True,
+    qml.QubitUnitary: {"skip_differentiation": True},
+    qml.DiagonalQubitUnitary: {"skip_differentiation": True},
+    qml.ControlledQubitUnitary: {"skip_differentiation": True},
+}
+
+
 class TestOperations:
+
+    @pytest.mark.parametrize("op", ALL_OPERATIONS)
+    def test_assert_valid(self, op):
+        kwargs = SKIP_ASSERT_VALID.get(type(op), {})
+        if kwargs is True:
+            pytest.skip()
+
+        qml.ops.functions.assert_valid(op, **kwargs)
+
     @pytest.mark.parametrize("op", ALL_OPERATIONS + BROADCASTED_OPERATIONS)
     def test_parametrized_op_copy(self, op, tol):
         """Tests that copied parametrized ops function as expected"""