How Does Wave Packet of a Free Particle Yield?


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.

Share and Cite:

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.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Dirac, P.A.M. (2008) The Principle of Quantum Mechanics. Science Press, Beijing.
[2] Griffiths, D.J. (2005) Introduction to Quantum Mechanics. Prentice-Hall, Inc., Upper Saddle River.
[3] Shankar, R. (1994) Principles of Quantum Mechanics. Plenum Press, New York.
[4] Einstein, A., Podolsky, B. and Rosen, N. (1935) Physical Review, 47, 777-780.
[5] Wheeler, J.A. and Zurek, W.H. (1983) Quantum Theory and Measurement. Princeton University Press, Princeton.
[6] Bohr, N. (1935) Physical Review, 48, 696-702.
[7] Bertet, P., Osnaghi, S., Rauschenbeutel, A., Nogues, G., Auffeves, A., et al. (2001) Nature, 411, 166-170.
[8] Walls, D.F. and Milburn, G.J. (1994) Quantum Optics. Springer-Verlag, Berlin Heidelberg.
[9] Zurek, W.H. (2003) Reviews of Modern Physics, 75, 715-775.
[10] Feynman, R.P. (2004) The Feynman Lectures on Physics. Vol. 8, Pearson Education Asia Limited and Beijing World Publishing Corporation, Hong Kong, Beijing.
[11] Kocsis, S., Braverman, B., Ravets, S., Stevens, M.J., Mirin, R.P., Shalm, L.K. and Steinberg, A.M. (2011) Science, 332, 1170-1173.
[12] Akoury, D., Kreidi, K., Jahnke, T., Weber, T., Staudte, A., Schoffler, M., et al. (2007) Science, 318, 949-952.
[13] Liu, X.J., Miao, Q., Gel’mukhanov, F., Patanen, M., Travnikova, O., Nicolas, C., et al. (2014) Nature Photonics, 9, 120-125.
[14] Kushawaha, R.K., Patanen, M., Guillemin, R., Journel, L., Miron, C., Simon, M., et al. (2013) Proceedings of the National Academy of Sciences of the United States of America, 110, 15201-15206.
[15] Cherepkov, N.A., Semenov, S.K., Schoffler, M.S., Titze, J., Petridis, N., Jahnke, T., et al. (2010) Physical Review A, 82, Article ID: 023420.
[16] Schmidt, L.P.H., Lower, J., Jahnke, T., Schoffler, S., Schoffler, M.S., Menssen, A., et al. (2013) Physical Review Letters, 111, Article ID: 103201.
[17] Schmidt, L.P.H., Schossler, S., Afaneh, F., Schoffler, M., Stiebing, K.E., Schmidt-Bocking, H. and Dorner, R. (2008) Physical Review Letters, 101, Article ID: 173202.
[18] Landau, L.D. and Lifshitz, E.M. (1977) Quantum Mechanics. Pergamon Press Ltd., Oxford.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.