Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

From the Schrödinger equation to the wavepacket reduction axiom

  1. Nov 30, 2004 #1
    In the very first pages of "Quantum Mechanics" by Landau & Lifchitz, the measurement process is described as an interaction between a quantum system and a "classical" system.

    I like this interpretation since any further evolution of the quantum system is anyway entangled with the "classical" system.
    I think it is quite plausible that this evolution as described by the SE, would agree to the evolution as postulated from the famous wavepacket "reduction axiom". (maybe by assuming further that "classical" means a very dense energy spectrum)

    Have some of you seen some proofs or some models that details/discuss this point of view?

    Thanks, Michel
    Last edited: Dec 1, 2004
  2. jcsd
  3. Nov 30, 2004 #2
    I don't have the book but I have read a paper which does not agree with that exact interpretation because the whole universe is a quantum system and all interactions are quantum interactions.
    However your remark about energy level density seems to be a reasonable way to view some interactions. For me measurement often involves some kind of amplification. Thus in a Geiger counter, photomultiplier tube or dot transistor, a single particle triggers the release of a large number of particles. While quantum rules still apply, the number of particles and energy are so large that we can ignore quantum and use classical rules which fortunately are much simpler.
  4. Dec 6, 2004 #3

    See decoherence program (google or arxiv). see for example quant-ph\0312059.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook