Add native controlled operation support for Lightning Kokkos (#950)

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- [X] All new features must include a unit test.
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      [`tests`](../tests) directory!

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------------------------------------------------------------------------------------------------------------

**Context:**
Native arbitrary controlled operations have already been implemented in
Lightning Qubit and Lightning GPU. This PR adds support for controlled
operations to Lightning Kokkos as well. This PR is the base branch of
combination of multiple PRs
([1](#952),
[2](#953),
[3](#954),
[4](#955),
[5](#956),
[6](#958),
[7](#965))

**Description of the Change:**
Controlled named-gates, matrix, generators, and adjoint differentiation
capability is added to Lightning Kokkos C++ layer.

**Benefits:**
Better performance for controlled operations in Lightning Kokkos (CPU +
GPU). Adjoint differentiation now supported in Lightning Kokkos.

**Possible Drawbacks:**

**Related GitHub Issues:**

[sc-78995]

---------

Co-authored-by: ringo-but-quantum <[email protected]>
Co-authored-by: Ali Asadi <[email protected]>

Author: 3 people

.github/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ### New features since last release
 
+* Add native N-controlled gate/matrix operations and adjoint support to `lightning.kokkos`.
+  [(#950)](https://github.com/PennyLaneAI/pennylane-lightning/pull/950)
+
 * Add native N-controlled generators and adjoint support to `lightning.gpu`'s single-GPU backend.
   [(#970)](https://github.com/PennyLaneAI/pennylane-lightning/pull/970)
 

pennylane_lightning/core/_version.py

@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.40.0-dev25"
+__version__ = "0.40.0-dev26"

pennylane_lightning/core/src/algorithms/tests/Test_AdjointJacobian.cpp

@@ -25,7 +25,6 @@ using namespace Pennylane::Util;
 
 #ifdef _ENABLE_PLQUBIT
 constexpr bool BACKEND_FOUND = true;
-constexpr bool SUPPORTS_CTRL = true;
 
 #include "AdjointJacobianLQubit.hpp"
 #include "ObservablesLQubit.hpp"
@@ -41,7 +40,6 @@ using namespace Pennylane::LightningQubit::Observables;
 
 #elif _ENABLE_PLKOKKOS == 1
 constexpr bool BACKEND_FOUND = true;
-constexpr bool SUPPORTS_CTRL = false;
 
 #include "AdjointJacobianKokkos.hpp"
 #include "ObservablesKokkos.hpp"
@@ -57,7 +55,6 @@ using namespace Pennylane::LightningKokkos::Observables;
 
 #elif _ENABLE_PLGPU == 1
 constexpr bool BACKEND_FOUND = true;
-constexpr bool SUPPORTS_CTRL = true;
 #include "AdjointJacobianGPU.hpp"
 #include "ObservablesGPU.hpp"
 #include "TestHelpersStateVectors.hpp"
@@ -72,7 +69,6 @@ using namespace Pennylane::LightningGPU::Observables;
 
 #else
 constexpr bool BACKEND_FOUND = false;
-constexpr bool SUPPORTS_CTRL = false;
 using TestStateVectorBackends = Pennylane::Util::TypeList<void>;
 
 template <class StateVector> struct StateVectorToName {};
@@ -140,41 +136,38 @@ template <typename TypeList> void testAdjointJacobian() {
 
         DYNAMIC_SECTION("Op=PhaseShift, Obs=Y - "
                         << StateVectorToName<StateVectorT>::name) {
-            if (SUPPORTS_CTRL) {
-                const std::vector<std::size_t> tp{0};
-                const std::size_t num_qubits = GENERATE(2, 3, 4);
-
-                const std::size_t num_params = 3;
-                const std::size_t num_obs = 1;
-                const auto obs = std::make_shared<NamedObs<StateVectorT>>(
-                    "PauliY", std::vector<std::size_t>{num_qubits - 1});
-                std::vector<PrecisionT> jacobian(num_obs * tp.size(), 0);
+            const std::vector<std::size_t> tp{0};
+            const std::size_t num_qubits = GENERATE(2, 3, 4);
+
+            const std::size_t num_params = 3;
+            const std::size_t num_obs = 1;
+            const auto obs = std::make_shared<NamedObs<StateVectorT>>(
+                "PauliY", std::vector<std::size_t>{num_qubits - 1});
+            std::vector<PrecisionT> jacobian(num_obs * tp.size(), 0);
+
+            for (const auto &p : param) {
+                std::vector<std::vector<std::size_t>> controls{
+                    std::vector<std::size_t>(num_qubits - 1)};
+                std::iota(controls[0].begin(), controls[0].end(), 0);
+                std::vector<std::vector<bool>> control_values{
+                    std::vector<bool>(num_qubits - 1, true)};
+                auto ops = OpsData<StateVectorT>(
+                    {"PhaseShift"}, {{p}}, {{num_qubits - 1}}, {false}, {{}},
+                    controls, control_values);
 
-                for (const auto &p : param) {
-                    std::vector<std::vector<std::size_t>> controls{
-                        std::vector<std::size_t>(num_qubits - 1)};
-                    std::iota(controls[0].begin(), controls[0].end(), 0);
-                    std::vector<std::vector<bool>> control_values{
-                        std::vector<bool>(num_qubits - 1, true)};
-                    auto ops = OpsData<StateVectorT>(
-                        {"PhaseShift"}, {{p}}, {{num_qubits - 1}}, {false},
-                        {{}}, controls, control_values);
-
-                    std::vector<ComplexT> cdata(1U << num_qubits);
-                    cdata[cdata.size() - 2] =
-                        Pennylane::Util::INVSQRT2<PrecisionT>();
-                    cdata[cdata.size() - 1] =
-                        Pennylane::Util::INVSQRT2<PrecisionT>();
-
-                    StateVectorT psi(cdata.data(), cdata.size());
-                    JacobianData<StateVectorT> tape{
-                        num_params, psi.getLength(), psi.getData(), {obs}, ops,
-                        tp};
-                    adj.adjointJacobian(std::span{jacobian}, tape, psi, true);
-
-                    CAPTURE(jacobian);
-                    CHECK(cos(p) == Approx(jacobian[0]));
-                }
+                std::vector<ComplexT> cdata(1U << num_qubits);
+                cdata[cdata.size() - 2] =
+                    Pennylane::Util::INVSQRT2<PrecisionT>();
+                cdata[cdata.size() - 1] =
+                    Pennylane::Util::INVSQRT2<PrecisionT>();
+
+                StateVectorT psi(cdata.data(), cdata.size());
+                JacobianData<StateVectorT> tape{
+                    num_params, psi.getLength(), psi.getData(), {obs}, ops, tp};
+                adj.adjointJacobian(std::span{jacobian}, tape, psi, true);
+
+                CAPTURE(jacobian);
+                CHECK(cos(p) == Approx(jacobian[0]));
             }
         }
 
@@ -671,4 +664,4 @@ TEST_CASE("Algorithms::adjointJacobian", "[Algorithms]") {
     if constexpr (BACKEND_FOUND) {
         testAdjointJacobian<TestStateVectorBackends>();
     }
-}
+}