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

A Entanglement between nuclei via fission

  1. Aug 19, 2016 #1
    Hi everybody! Wasn't sure whether to post this here or in Quantum Mechanics, decided I would start here.

    I was wondering how the entanglement structure between the nucleons of two nuclei would evolve during a fission event. Correct me if I'm wrong but wouldn't the two sets of nucleons initially have zero mutual information (assuming the nuclei had been isolated)? Then say one of the nuclei fissions. If one of the ejected neutrons was captured by the second nuclei via radiative capture, wouldn't the wavefunctions of nucleons in the three resulting nuclei be correlated with one another?

    Thanks!
     
  2. jcsd
  3. Aug 19, 2016 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Decoherence happens so quickly that you will never get any relevant superposition involved in nuclear chain reactions.
     
  4. Aug 19, 2016 #3
    But in order for decoherence to occurs, wouldn't the nuclei need to interact with some external system? Which process would that be?
     
  5. Aug 20, 2016 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Decoherence needs an interaction with the environment, but you can't avoid that for long even if you fully ionize your atoms. There is simply no way to do anything coherently with the state where its quantum nature would matter.
     
  6. Aug 20, 2016 #5
    What type of interaction would that most likely be? A magnetic interaction with the nuclear spins and some external particle seems most likely to me.

    I can appreciate that there is no way to leverage such coherence, I was just wondering if it exists in theory.

    I can see how the incoming nucleon would decohere into all the other nucleons in that nuclei. But then it seems like there is a hard barrier to any further decoherence given the strength of the strong force. Is this correct? Or maybe the nuclei would slowly decohere into it's environment slowly via magnetic interactions?? Sorry for rambling I'm just trying to explain my confusion.
     
    Last edited: Aug 20, 2016
  7. Aug 20, 2016 #6

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    If you really want, you can always use MWI to keep the wave function forever. But it really doesn't matter for any measurements, for those it is perfectly fine to assume classical results of individual nuclear reactions.
     
  8. Aug 20, 2016 #7
    Yes I admit I am talking about what is happening when we are not measuring the system. But I thought it was kind of an interesting question to think about the dynamics of entanglement even when we are not looking. Do you think my intuition is correct that the strong force would prevent the nuclei from further decohering with the environment? Also I am curious as to what you mean by "keep the wave function forever"? Again, thanks for your help.
     
  9. Aug 21, 2016 #8
    Hi everybody! I asked this question a few days back over in High-Energy/Nuclear/Particle Physics, and I got some good answers, but I think this is probably a better place for it.

    So my question arose in the thinking about the dynamics of entanglement and decoherence in the context of nuclear reactions. Imagine a system in which a U235 nucleus undergoes spontaneous fission and one of the ejected neutrons is absorbed by a Cadmium nucleus (via radiative capture).

    Now, because the ejected neutron was entangled with the nucleons which became the two daughter nuclei from the fission reaction, my intuition tells me that the the nucleons of the absorbing Cadmium nucleus should become weakly correlated with the nucleons in the two daughter nuclei. Is this a correct way of viewing this situation?

    Here is my second question: Assuming that the Cadmium nucleus was entangled with the two daughter nuclei, would the strength of the strong force act as a sort of 'decoherence barrier', preventing the now entangled Cd nucleus from further leaking out its entanglement? I know that there are electric and magnetic interactions between the surrounding electrons and the nucleus so would these electric/magnetic interactions be a vehicle for further decoherence of the system or not? Perhaps the entanglement would leak out more slowly because the energies involved are smaller?

    I would love if someone who understands the dynamics of entanglement and decoherence could chime in and send me down the right path.

    Thanks!
     
  10. Aug 21, 2016 #9

    berkeman

    User Avatar

    Staff: Mentor

    Please do not multiple post here at the PF. That is against the rules, and clutters the forums. I will merge your two threads into this one here in this forum that you think is a better fit.

    In the future, if you want your thread moved, please just click the Report link in your post, and ask the Mentors to move your thread. Thank you.
     
  11. Aug 21, 2016 #10
    Ayy, that's my bad. Sorry, I will ask a mentor next time. Thank you for merging them!
     
  12. Aug 22, 2016 #11
    Ok, I have been doing a little research and have realized that a key term I was missing was 'Informational Isolation'. So I guess what I am really asking about is the informational isolation between the nucleus of an atom and the external electrons. The electric and magnetic forces are pretty weak compared to the strong force, so I'm guessing it could actually take a somewhat long (in human terms) time for further decoherence to occur. I have no idea how I would actually go about doing those calculations though.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted