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I Radioactive decay, macroscopic objects

  1. Aug 3, 2016 #1
    Radioactive decay is known to be a pure quantum effect, the particle from the nucleus is in a superposition until we measure it (according to collapse interpretations). In the Sch. cat experiment the radioactive particle gets entangled with a macroscopic object (Geiger counter) and so the macroscopic object is also in a superposition before the decoherence and collapse. Now my question is, by which mechanism something so small effects something so big like an ordinary object and how does a similar effect happen in the environment of atoms in ordinary objects? It seems like nearby macroscopic objects very often enter the superposition state "affected by radiation/not affected by radiation" because of the uncertainty of the nucleus position, just like a measuring device for radiation experiences similar behavior. Is this true and how is it possible?

    Thanks in advance.
  2. jcsd
  3. Aug 3, 2016 #2


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    The Cat experiment is not real. It is imaginary. It is just used for discussion purposes.

    It is possible to entangled a quantum particle with a small macroscopic system, true enough. But such system could not be called ordinary in any sense of the word. Such are highly controlled and isolated systems, and it takes a lot of effort to create it and verify it. See below.


    "Quantum mechanics predicts microscopic phenomena with undeniable success. Nevertheless, current theoretical and experimental efforts still do not yield conclusive evidence that there is, or not, a fundamental limitation on the possibility to observe quantum phenomena at the macroscopic scale. This question prompted several experimental efforts producing quantum superpositions of large quantum states in light or matter. Here we report on the observation of entanglement between a single photon and an atomic ensemble. The certified entanglement stems from a light-matter micro-macro entangled state that involves the superposition of two macroscopically distinguishable solid-state components composed of several tens of atomic excitations. Our approach leverages from quantum memory techniques and could be used in other systems to expand the size of quantum superpositions in matter."
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