Author(s)

Tianhai Zeng^*

School of Physics, Beijing Institute of Technology, Beijing, China.

Preparing a particle in a superposition or a wave packet of eigenstates of a physical quantity is to let it interact with a large object. The composite system composed of the particle and the large object evolves into an entangled state. When the state of the large object is considered to be approximately unchanged, the entangled state can be approximately considered as a product state, and then the particle is prepared in an approximate superposed state. We consider the Schrodinger equation for a composite system with interactions between subsystems as a fundamental postulate and a single particle’s Schrodinger equation must be approximately obtained from it. We argue that superposition of states exists only in composite systems. Interaction exchanging some quantities between subsystems makes conservation laws strictly hold, and no wave packet of a free particle yields. With this point, we can also understand the double-slit experiment and the tunnel phenomenon.

Superposition of Eigenstates, Interaction, Entangled State, Conservation Law, Double-Slit Experiment, Tunnel Phenomenon

Zeng, T. (2015) How Does Wave Packet of a Free Particle Yield?. Journal of Modern Physics, 6, 863-868. doi: 10.4236/jmp.2015.67090.