Take adjoint into account in xDSL MergeRotationsPass/merge_rotations_pass

doc/releases/changelog-0.43.0.md

@@ -530,15 +530,15 @@
   of equivalencies to compile certain patterns to efficient Clifford+T equivalents.
   [(#7748)](https://github.com/PennyLaneAI/pennylane/pull/7748)
 
-* New intermediate representations (IRs) :func:`~transforms.parity_matrix` and 
-  :func:`~transforms.phase_polynomial` are available in PennyLane. These IRs are 
-  used in compilation passes to optimize CNOT and phase polynomial circuits, respectively. 
+* New intermediate representations (IRs) :func:`~transforms.parity_matrix` and
+  :func:`~transforms.phase_polynomial` are available in PennyLane. These IRs are
+  used in compilation passes to optimize CNOT and phase polynomial circuits, respectively.
   Also added :func:`~transforms.rowcol`, which uses the parity matrix as its IR for CNOT
   routing under constraint connectivity.
   [(#8171)](https://github.com/PennyLaneAI/pennylane/pull/8171)
 
 * A new transform :func:`~.transforms.rz_phase_gradient` lets you realize arbitrary angle :class:`~.RZ` rotations
-  with a phase gradient resource state and semi-in-place addition (:class:`~.SemiAdder`). This can be a crucial 
+  with a phase gradient resource state and semi-in-place addition (:class:`~.SemiAdder`). This can be a crucial
   subroutine in FTQC when sufficient auxiliary wires are available, as it saves on T gates compared to other
   discretization schemes.
   [(#8213)](https://github.com/PennyLaneAI/pennylane/pull/8213)
@@ -643,7 +643,7 @@
 
 * :func:`pennylane.snapshots` can now be used with `mcm_method="one-shot"` and `mcm_method="tree-traversal"`.
   [(#8140)](https://github.com/PennyLaneAI/pennylane/pull/8140)
-  
+
 * An error is no longer raised when non-integer wire labels are used in QNodes using `mcm_method="deferred"`.
   [(#7934)](https://github.com/PennyLaneAI/pennylane/pull/7934)
 
@@ -1183,8 +1183,8 @@
 * Removes excess copies in `QuantumScript.copy`, and some other performance improvements to `resolve_dynamic_wires`.
   [(#8406)](https://github.com/PennyLaneAI/pennylane/pull/8406)
 
-* GitHub actions and workflows (`interface-unit-tests.yml`, `tests-labs.yml`, `unit-test.yml`, `upload-nightly-release.yml` and `upload.yml`) have been updated to 
-  use `ubuntu-24.04` runners. 
+* GitHub actions and workflows (`interface-unit-tests.yml`, `tests-labs.yml`, `unit-test.yml`, `upload-nightly-release.yml` and `upload.yml`) have been updated to
+  use `ubuntu-24.04` runners.
   [(#8371)](https://github.com/PennyLaneAI/pennylane/pull/8371)
 
 * Issues with imports and circular dependencies in files were addressed in the ``ops/``and ``templates/`` directories.
@@ -1196,7 +1196,7 @@
 * Enforce various modules to follow modular architecture via `tach`.
   [(#7847)](https://github.com/PennyLaneAI/pennylane/pull/7847)
 
-* Add CI workflow to test documentation using `sybil`. 
+* Add CI workflow to test documentation using `sybil`.
   [(#8324)](https://github.com/PennyLaneAI/pennylane/pull/8324)
   [(#8328)](https://github.com/PennyLaneAI/pennylane/pull/8328)
   [(#8329)](https://github.com/PennyLaneAI/pennylane/pull/8329)
@@ -1464,6 +1464,10 @@
 
 <h3>Bug fixes 🐛</h3>
 
+* `qml.compiler.python_compiler.transforms.MergeRotationsPass` now takes the `adjoint` property of
+  merged operations correctly into account.
+  [(#8429)](https://github.com/PennyLaneAI/pennylane/pull/8429)
+
 * Stops promoting numpy data to autograd in `qml.qchem.molecular_hamiltonian`.
   [(#8410)](https://github.com/PennyLaneAI/pennylane/pull/8410)
 

pennylane/compiler/python_compiler/transforms/quantum/merge_rotations.py

@@ -37,7 +37,16 @@
     "ControlledPhaseShift",
     "IsingXX",
     "IsingYY",
+    "IsingXY",
     "IsingZZ",
+    "MultiRZ",
+    "SingleExcitation",
+    "DoubleExcitation",
+    "SingleExcitationMinus",
+    "SingleExcitationPlus",
+    "DoubleExcitationMinus",
+    "DoubleExcitationPlus",
+    "OrbitalRotation",
 ]
 
 
@@ -74,33 +83,42 @@ def match_and_rewrite(self, funcOp: func.FuncOp, rewriter: pattern_rewriter.Patt
 
             param = op.operands[0]
             while True:
-                next_user = None
                 for use in op.results[0].uses:
                     user = use.operation
                     if _can_merge(op, user):
                         next_user = user
                         break
-
-                if next_user is None:
+                else:
+                    # No next_user was set because no user could be merged. Go to next op
                     break
 
                 for q1, q2 in zip(op.in_qubits, op.out_qubits, strict=True):
                     rewriter.replace_all_uses_with(q2, q1)
                 for cq1, cq2 in zip(op.in_ctrl_qubits, op.out_ctrl_qubits, strict=True):
                     rewriter.replace_all_uses_with(cq2, cq1)
 
+                # Whether op is adjoint will determine adjoint of new_op, and how to combine angles
+                is_adjoint = getattr(op, "adjoint", False)
                 rewriter.erase_op(op)
+
                 next_param = next_user.operands[0]
-                addOp = arith.AddfOp(param, next_param)
-                rewriter.insert_op(addOp, InsertPoint.before(next_user))
-                param = addOp.result
+                next_is_adjoint = getattr(next_user, "adjoint", False)
+                if is_adjoint == next_is_adjoint:
+                    # If both op and next_user are adjoint, or neither is, we add angles
+                    combOp = arith.AddfOp(param, next_param)
+                else:
+                    # If one of op and next_user is adjoint, we subtract angles
+                    combOp = arith.SubfOp(param, next_param)
+                rewriter.insert_op(combOp, InsertPoint.before(next_user))
+                param = combOp.result
+
                 new_op = CustomOp(
                     in_qubits=next_user.in_qubits,
                     gate_name=next_user.gate_name,
                     params=(param,),
                     in_ctrl_qubits=next_user.in_ctrl_qubits,
                     in_ctrl_values=next_user.in_ctrl_values,
-                    adjoint=getattr(next_user, "adjoint", False),
+                    adjoint=is_adjoint,
                 )
                 rewriter.replace_op(next_user, new_op)
                 op = new_op

pennylane/ops/qubit/attributes.py

@@ -96,8 +96,16 @@ def __contains__(self, obj):
         "ControlledPhaseShift",
         "IsingXX",
         "IsingYY",
+        "IsingXY",
         "IsingZZ",
         "Rot",
+        "SingleExcitation",
+        "DoubleExcitation",
+        "SingleExcitationMinus",
+        "SingleExcitationPlus",
+        "DoubleExcitationMinus",
+        "DoubleExcitationPlus",
+        "OrbitalRotation",
     ]
 )
 """Attribute: Operations for which composing multiple copies of the operation results in an

tests/python_compiler/transforms/quantum/test_xdsl_merge_rotations.py

@@ -29,6 +29,8 @@
 class TestMergeRotationsPass:
     """Unit tests for MergeRotationsPass."""
 
+    pipeline = (MergeRotationsPass(),)
+
     def test_no_composable_ops(self, run_filecheck):
         """Test that nothing changes when there are no composable gates."""
         program = """
@@ -43,8 +45,7 @@ def test_no_composable_ops(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_composable_ops(self, run_filecheck):
         """Test that composable gates are merged."""
@@ -61,8 +62,7 @@ def test_composable_ops(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_many_composable_ops(self, run_filecheck):
         """Test that more than 2 composable ops are merged correctly."""
@@ -83,8 +83,7 @@ def test_many_composable_ops(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_non_consecutive_composable_ops(self, run_filecheck):
         """Test that non-consecutive composable gates are not merged."""
@@ -102,8 +101,7 @@ def test_non_consecutive_composable_ops(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_composable_ops_different_qubits(self, run_filecheck):
         """Test that composable gates on different qubits are not merged."""
@@ -121,8 +119,7 @@ def test_composable_ops_different_qubits(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_controlled_composable_ops(self, run_filecheck):
         """Test that controlled composable ops can be merged."""
@@ -144,8 +141,7 @@ def test_controlled_composable_ops(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_controlled_composable_ops_same_control_values(self, run_filecheck):
         """Test that controlled composable ops with the same control values
@@ -169,8 +165,7 @@ def test_controlled_composable_ops_same_control_values(self, run_filecheck):
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
 
     def test_controlled_composable_ops_different_control_values(self, run_filecheck):
         """Test that controlled composable ops with different control values
@@ -193,8 +188,36 @@ def test_controlled_composable_ops_different_control_values(self, run_filecheck)
             }
         """
 
-        pipeline = (MergeRotationsPass(),)
-        run_filecheck(program, pipeline)
+        run_filecheck(program, self.pipeline)
+
+    @pytest.mark.parametrize(
+        "first_adj, second_adj, sign",
+        [
+            (False, False, "+"),
+            (False, True, "-"),
+            (True, False, "-"),
+            (True, True, "+"),
+        ],
+    )
+    def test_adjoint_property(self, first_adj, second_adj, sign, run_filecheck):
+        """Test that composable ops with and without adjoint property are merged correctly."""
+        adj_string_0 = "adj" if first_adj else ""
+        adj_string_1 = "adj" if second_adj else ""
+        arith_op_str = "arith.addf" if sign == "+" else "arith.subf"
+        program = f"""
+            func.func @test_func(%arg0: f64, %arg1: f64) {{
+                // CHECK: [[q0:%.+]] = "test.op"() : () -> !quantum.bit
+                %0 = "test.op"() : () -> !quantum.bit
+                // CHECK: [[new_angle:%.+]] = {arith_op_str} %arg0, %arg1 : f64
+                // CHECK: [[q1:%.+]] = quantum.custom "RX"([[new_angle]]) [[q0]] {adj_string_0} : !quantum.bit
+                // CHECK-NOT: "quantum.custom"
+                %1 = quantum.custom "RX"(%arg0) %0 {adj_string_0}: !quantum.bit
+                %2 = quantum.custom "RX"(%arg1) %1 {adj_string_1}: !quantum.bit
+                return
+            }}
+        """
+
+        run_filecheck(program, self.pipeline)
 
 
 # pylint: disable=too-few-public-methods
@@ -204,7 +227,7 @@ class TestMergeRotationsIntegration:
 
     def test_qjit(self, run_filecheck_qjit):
         """Test that the MergeRotationsPass works correctly with qjit."""
-        dev = qml.device("lightning.qubit", wires=2)
+        dev = qml.device("lightning.qubit", wires=1)
 
         @qml.qjit(target="mlir", pass_plugins=[getXDSLPluginAbsolutePath()])
         @merge_rotations_pass