Adjust CUDA and Eigen settings to reduce compilation warnings

- Enable Eigen GPU support when CUDA is used
- Set specific CUDA source files and compiler flags
- Add compiler flags to suppress certain warnings

CMakeLists.txt

@@ -68,6 +68,11 @@ if(NOT eigen_fetch_POPULATED)
     add_subdirectory(${eigen_fetch_SOURCE_DIR})
 endif(NOT eigen_fetch_POPULATED)
 
+if(SCALUQ_USE_CUDA)
+    set(EIGEN_USE_GPU ON CACHE BOOL "Enable Eigen GPU support" FORCE)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DEIGEN_USE_GPU")
+endif()
+
 # nanobind
 if(SKBUILD)
     find_package(Python 3.8

scaluq/CMakeLists.txt

@@ -1,5 +1,17 @@
 cmake_minimum_required(VERSION 3.21)
 
+if(SCALUQ_USE_CUDA)
+    set_source_files_properties(
+        update_ops_dense_matrix.cpp
+        update_ops_sparse_matrix.cpp
+        PROPERTIES LANGUAGE CUDA
+    )
+
+    set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} -arch=sm_60")
+
+    set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} --expt-relaxed-constexpr -Xcudafe --diag_suppress=esa_on_defaulted_function_ignored")
+endif()
+
 target_sources(scaluq PRIVATE
     circuit/circuit.cpp
     gate/update_ops_dense_matrix.cpp