Remove unneeded copy from LK ctor

pennylane_lightning/core/src/simulators/lightning_kokkos/StateVectorKokkos.hpp

@@ -115,60 +115,6 @@ class StateVectorKokkos final
         init_generators_indices_();
     };
 
-    /**
-     * @brief Init zeros for the state-vector on device.
-     */
-    void initZeros() { Kokkos::deep_copy(getView(), ComplexT{0.0, 0.0}); }
-
-    /**
-     * @brief Set value for a single element of the state-vector on device.
-     *
-     * @param index Index of the target element.
-     */
-    void setBasisState(const size_t index) {
-        KokkosVector sv_view =
-            getView(); // circumvent error capturing this with KOKKOS_LAMBDA
-        Kokkos::parallel_for(
-            sv_view.size(), KOKKOS_LAMBDA(const size_t i) {
-                sv_view(i) =
-                    (i == index) ? ComplexT{1.0, 0.0} : ComplexT{0.0, 0.0};
-            });
-    }
-
-    /**
-     * @brief Set values for a batch of elements of the state-vector.
-     *
-     * @param values Values to be set for the target elements.
-     * @param indices Indices of the target elements.
-     */
-    void setStateVector(const std::vector<std::size_t> &indices,
-                        const std::vector<ComplexT> &values) {
-        initZeros();
-        KokkosSizeTVector d_indices("d_indices", indices.size());
-        KokkosVector d_values("d_values", values.size());
-        Kokkos::deep_copy(d_indices, UnmanagedConstSizeTHostView(
-                                         indices.data(), indices.size()));
-        Kokkos::deep_copy(d_values, UnmanagedConstComplexHostView(
-                                        values.data(), values.size()));
-        KokkosVector sv_view =
-            getView(); // circumvent error capturing this with KOKKOS_LAMBDA
-        Kokkos::parallel_for(
-            indices.size(), KOKKOS_LAMBDA(const std::size_t i) {
-                sv_view(d_indices[i]) = d_values[i];
-            });
-    }
-
-    /**
-     * @brief Reset the data back to the \f$\ket{0}\f$ state.
-     *
-     * @param num_qubits Number of qubits
-     */
-    void resetStateVector() {
-        if (this->getLength() > 0) {
-            setBasisState(0U);
-        }
-    }
-
     /**
      * @brief Create a new state vector from data on the host.
      *
@@ -200,7 +146,6 @@ class StateVectorKokkos final
         : StateVectorKokkos(log2(length), kokkos_args) {
         PL_ABORT_IF_NOT(isPerfectPowerOf2(length),
                         "The size of provided data must be a power of 2.");
-        std::vector<ComplexT> hostdata_copy(hostdata_, hostdata_ + length);
         HostToDevice(hostdata_copy.data(), length);
     }
 
@@ -244,6 +189,60 @@ class StateVectorKokkos final
         }
     }
 
+    /**
+     * @brief Init zeros for the state-vector on device.
+     */
+    void initZeros() { Kokkos::deep_copy(getView(), ComplexT{0.0, 0.0}); }
+
+    /**
+     * @brief Set value for a single element of the state-vector on device.
+     *
+     * @param index Index of the target element.
+     */
+    void setBasisState(const size_t index) {
+        KokkosVector sv_view =
+            getView(); // circumvent error capturing this with KOKKOS_LAMBDA
+        Kokkos::parallel_for(
+            sv_view.size(), KOKKOS_LAMBDA(const size_t i) {
+                sv_view(i) =
+                    (i == index) ? ComplexT{1.0, 0.0} : ComplexT{0.0, 0.0};
+            });
+    }
+
+    /**
+     * @brief Set values for a batch of elements of the state-vector.
+     *
+     * @param values Values to be set for the target elements.
+     * @param indices Indices of the target elements.
+     */
+    void setStateVector(const std::vector<std::size_t> &indices,
+                        const std::vector<ComplexT> &values) {
+        initZeros();
+        KokkosSizeTVector d_indices("d_indices", indices.size());
+        KokkosVector d_values("d_values", values.size());
+        Kokkos::deep_copy(d_indices, UnmanagedConstSizeTHostView(
+                                         indices.data(), indices.size()));
+        Kokkos::deep_copy(d_values, UnmanagedConstComplexHostView(
+                                        values.data(), values.size()));
+        KokkosVector sv_view =
+            getView(); // circumvent error capturing this with KOKKOS_LAMBDA
+        Kokkos::parallel_for(
+            indices.size(), KOKKOS_LAMBDA(const std::size_t i) {
+                sv_view(d_indices[i]) = d_values[i];
+            });
+    }
+
+    /**
+     * @brief Reset the data back to the \f$\ket{0}\f$ state.
+     *
+     * @param num_qubits Number of qubits
+     */
+    void resetStateVector() {
+        if (this->getLength() > 0) {
+            setBasisState(0U);
+        }
+    }
+
     /**
      * @brief Apply a single gate to the state vector.
      *