Hi,
Qt 3D is undergoing a major rewrite and is not ready for release yet. See this post: http://lists.qt-project.org/pipermail/development/2013-February/009853.html
What are you planning to do? If it's just using custom OpenGL components with Qt Quick, you don't need Qt 3D. Just implement your own Scene Graph (example: http://qt-project.org/doc/qt-5/qtquick-scenegraph-openglunderqml-example.html )