Update QuantumScriptSerializer.serialize_observables to better handle new operator arithmetic

.github/CHANGELOG.md

@@ -49,6 +49,9 @@
 * Add `isort` to `requirements-dev.txt` and run before `black` upon `make format` to sort Python imports.
   [(#623)](https://github.com/PennyLaneAI/pennylane-lightning/pull/623)
 
+* Improve support for new operator arithmetic with `QuantumScriptSerializer.serialize_observables`.
+  [(#670)](https://github.com/PennyLaneAI/pennylane-lightning/pull/670)
+
 ### Documentation
 
 ### Bug fixes

.github/workflows/tests_gpu_cuda.yml

@@ -119,9 +119,7 @@ jobs:
 
       - name: Install required packages
         run: |
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install ninja "cmake!=3.29.0" custatevec-cu${{ matrix.cuda_version }}
+          python -m pip install ninja cmake custatevec-cu${{ matrix.cuda_version }}
           sudo apt-get -y -q install liblapack-dev
 
       - name: Build and run unit tests
@@ -243,9 +241,7 @@ jobs:
         run: |
           cd main
           python -m pip install -r requirements-dev.txt
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install "cmake!=3.29.0" custatevec-cu${{ matrix.cuda_version }} openfermionpyscf
+          python -m pip install cmake custatevec-cu${{ matrix.cuda_version }} openfermionpyscf
 
       - name: Checkout PennyLane for release build
         if: inputs.pennylane-version == 'release'

.github/workflows/tests_linux_x86_mpi_gpu.yml

@@ -94,9 +94,7 @@ jobs:
       - name: Install required packages
         run: |
           python -m pip install -r requirements-dev.txt
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install "cmake!=3.29.0" custatevec-cu12
+          python -m pip install cmake custatevec-cu12
           sudo apt-get -y -q install liblapack-dev
 
       - name: Validate GPU version and installed compiler and modules

.github/workflows/wheel_macos_x86_64.yml

@@ -68,9 +68,7 @@ jobs:
         run: |
           mkdir -p ${{ github.workspace}}/Kokkos_install/${{ matrix.exec_model }}
           cd kokkos
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install "cmake!=3.29.0" ninja
+          python -m pip install cmake ninja
 
           cmake -BBuild . -DCMAKE_INSTALL_PREFIX=${{ github.workspace}}/Kokkos_install/${{ matrix.exec_model }} \
                           -DKokkos_ENABLE_COMPLEX_ALIGN=OFF \

.github/workflows/wheel_noarch.yml

@@ -44,9 +44,7 @@ jobs:
 
       - name: Install CMake and ninja
         run: |
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install --upgrade "cmake!=3.29.0" ninja
+          python -m pip install --upgrade cmake ninja
 
       - name: Build wheels
         if: ${{ matrix.pl_backend == 'lightning_qubit'}}

.github/workflows/wheel_win_x86_64.yml

@@ -64,9 +64,7 @@ jobs:
       - name: Install dependencies
         if: steps.kokkos-cache.outputs.cache-hit != 'true'
         run: |
-          # Omitting the installation of cmake v3.29.0 due to
-          # https://github.com/scikit-build/cmake-python-distributions/pull/474
-          python -m pip install "cmake!=3.29.0" build
+          python -m pip install cmake build
 
       - name: Build Kokkos core library
         if: steps.kokkos-cache.outputs.cache-hit != 'true'

pennylane_lightning/core/_serialize.py

@@ -21,7 +21,6 @@
     BasisState,
     DeviceError,
     Hadamard,
-    Hamiltonian,
     Identity,
     PauliX,
     PauliY,
@@ -34,10 +33,12 @@
 )
 from pennylane.math import unwrap
 from pennylane.operation import Tensor
-from pennylane.ops import Prod, SProd, Sum
+from pennylane.ops import Hamiltonian, LinearCombination, Prod, SProd, Sum
 from pennylane.tape import QuantumTape
 
-pauli_name_map = {
+NAMED_OBS = (Identity, PauliX, PauliY, PauliZ, Hadamard)
+OP_MATH_OBS = (Prod, SProd, Sum, LinearCombination)
+PAULI_NAME_MAP = {
     "I": "Identity",
     "X": "PauliX",
     "Y": "PauliY",
@@ -243,11 +244,11 @@ def map_wire(wire: int):
 
         if len(observable) == 1:
             wire, pauli = list(observable.items())[0]
-            return self.named_obs(pauli_name_map[pauli], [map_wire(wire)])
+            return self.named_obs(PAULI_NAME_MAP[pauli], [map_wire(wire)])
 
         return self.tensor_obs(
             [
-                self.named_obs(pauli_name_map[pauli], [map_wire(wire)])
+                self.named_obs(PAULI_NAME_MAP[pauli], [map_wire(wire)])
                 for wire, pauli in observable.items()
             ]
         )
@@ -258,9 +259,8 @@ def _pauli_sentence(self, observable, wires_map: dict = None):
         terms = [self._pauli_word(pw, wires_map) for pw in pwords]
         coeffs = np.array(coeffs).astype(self.rtype)
 
-        # TODO: Add this
-        # if len(terms) == 1 and coeffs[0] == 1.0:
-        #     return terms[0]
+        if len(terms) == 1 and coeffs[0] == 1.0:
+            return terms[0]
 
         if self.split_obs:
             return [self.hamiltonian_obs([c], [t]) for (c, t) in zip(coeffs, terms)]
@@ -269,22 +269,20 @@ def _pauli_sentence(self, observable, wires_map: dict = None):
     # pylint: disable=protected-access, too-many-return-statements
     def _ob(self, observable, wires_map: dict = None):
         """Serialize a :class:`pennylane.operation.Observable` into an Observable."""
-        if isinstance(observable, (Prod, Sum, SProd)) and observable.pauli_rep is not None:
+        if isinstance(observable, NAMED_OBS):
+            return self._named_obs(observable, wires_map)
+        if isinstance(observable, Hamiltonian):
+            return self._hamiltonian(observable, wires_map)
+        if observable.pauli_rep is not None:
             return self._pauli_sentence(observable.pauli_rep, wires_map)
-        if isinstance(observable, Tensor) or (
-            isinstance(observable, Prod) and not observable.has_overlapping_wires
-        ):
+        if isinstance(observable, (Tensor, Prod)):
+            if isinstance(observable, Prod) and observable.has_overlapping_wires:
+                return self._hermitian_ob(observable, wires_map)
             return self._tensor_ob(observable, wires_map)
-        if observable.name in ("Hamiltonian", "LinearCombination"):
+        if isinstance(observable, OP_MATH_OBS):
             return self._hamiltonian(observable, wires_map)
-        if observable.name == "SparseHamiltonian":
+        if isinstance(observable, SparseHamiltonian):
             return self._sparse_hamiltonian(observable, wires_map)
-        if isinstance(observable, (PauliX, PauliY, PauliZ, Identity, Hadamard)):
-            return self._named_obs(observable, wires_map)
-        if observable.pauli_rep is not None:
-            return self._pauli_sentence(observable.pauli_rep, wires_map)
-        # if isinstance(observable, (Prod, Sum)):
-        #     return self._hamiltonian(observable, wires_map)
         return self._hermitian_ob(observable, wires_map)
 
     def serialize_observables(self, tape: QuantumTape, wires_map: dict = None) -> List:

pennylane_lightning/core/_version.py

@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.36.0-dev23"
+__version__ = "0.36.0-dev24"

requirements-dev.txt

@@ -14,6 +14,6 @@ clang-tidy~=16.0
 clang-format~=16.0
 isort==5.13.2
 click==8.0.4
-cmake==3.28.4
+cmake
 custatevec-cu12
 pylint

tests/test_adjoint_jacobian.py

@@ -1008,14 +1008,8 @@ def f(params1, params2):
             qml.RY(tf.cos(params2), wires=[0])
             return qml.expval(qml.PauliZ(0))
 
-        if dev._new_API:
-            # tf expects float32 with new device API
-            tf_r_dtype = tf.float32
-            h = 2e-3
-            tol = 1e-3
-        else:
-            tf_r_dtype = tf.float32 if dev.dtype == np.complex64 else tf.float64
-            tol, h = get_tolerance_and_stepsize(dev, step_size=True)
+        tf_r_dtype = tf.float32 if dev.dtype == np.complex64 else tf.float64
+        tol, h = get_tolerance_and_stepsize(dev, step_size=True)
 
         params1 = tf.Variable(0.3, dtype=tf_r_dtype)
         params2 = tf.Variable(0.4, dtype=tf_r_dtype)