Physics Laboratory IV includes experiments of the atom and molecule spectroscopy, pulse nuclear magnetic resonance (pNMR) and magnetic resonance imaging (MRI), interference and communication of optical fiber, optical tweezer, scanning tunneling microcopy (STM), atomic force microscopy (AFM), etc. The teaching schedule includes the process of open experiment elective via internet (8 labs of 10 weeks) and the research project of 5 weeks. This course is a combination of teaching and research, aiming to let students know the research process and learn the research thoughts, methods and spirit to stimulate the physics interests. It specially improves the application and practical ability of physics theory.