Do the SQUID experiments falsify Bohmian mechanics?

  • #61
f95toli said:
this is not really ambiguous. That the persistent current in the loop correspond to a certain flux follows from "classical" SQUID physics (flux quantization). you can find more about this in any standard textbook on superconductivity (say Tinkham's book).
The 3 junction SQUID used as a qubit is not in any way fundamentally different from a normal 2 junction SQUID. If you calculate the potential energy of the system you will find that the addition of an "extra" small junction gives rise to a double well potential, with the two wells corresponding to clockwise and counter-clockwise persistent currents flowing in the loop, respectively. If you then plug this potential energy into the Schrodinger equation you get what is more or less a complete description of the system (minus the effect of decoherence), anyone who has done say a first course in QM at university can do this.

I am going to be lazy and just refer to the following paper on the arXiv where you can find a brief summary and some references, just ignore the bit about the resonator. I am sure there are better references, but I can't think of one now.

http://arxiv.org/abs/0704.0727

Thank you for the reply but I would be grateful if you could clarify something.I'm fine with the correspondence between flux and current and with the superposition of two flux states. The ambiguity I referred to was that the sentence referred to earlier can be interpreted as the currents being in superposition as well as the flux states.
All I am trying to find out is whether there are any theoretical physicists who work in QM and who believe that there can be events such as an electron flowing in two opposite directions at the same time, or a bar which is vibrating at the same time when it is not vibrating,or a cat which is simultaneously dead and alive,and so on.I don't need details.Thank you.
 
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  • #62
Dadface said:
All I am trying to find out is whether there are any theoretical physicists who work in QM and who believe that there can be events such as an electron flowing in two opposite directions at the same time, or a bar which is vibrating at the same time when it is not vibrating,or a cat which is simultaneously dead and alive,and so on.I don't need details.
I believe I know a lot about different interpretations of QM, and yet I think I never seen a serious proposal for an interpretation that would claim exactly that.

Yet, there is an interpretation that claims something similar - the many world interpretation. But even in that interpretation, both possibilities exist at once only after the measurement (or more precisely, after the decoherence) - that is, when the observer can see explicitly that only one of the two alternative possibilities has been realized.
 
  • #63
Cthugha said:
Basically, I am working on the border between optics and semiconductor physics with a special interest in photon statistics and collective phenomena. As to the "inspiring" part I find it pretty neat that in standard qm you can treat (in rough terms) photon bunching, stimulated emission and stimulated scattering on the one hand and the exclusion principle and antibunching on the other hand on pretty much the same footing as there is just a sign changing between bosons and fermions leading to constructive or destructive interference of the probability amplitudes for events leading to species of the same type ending up in indistinguishable states. Also the "more is different" aspect of collective phenomena comes out quite clear.

Anyway I am aware that you can also treat these topics well in BM. Some of the approaches are just not my cup of tea. For example it is interesting and makes sense that degeneracy pressure can be attributed to a quantum force in BM, but it seems odd to consider the reverse process for bosons causing photon bunching. While it is consistent to treat them similarly ( and I am sure that are more sophisticated takes on the topic in BM which may be more elegant), a quantum force pushing massless photons together is just not intuitive for me.
Thanks! Basically, I agree with you: Any quantum phenomenon can be described by BM, but not all phenomena look equally intuitive with the Bohmian view.

Anyway, a recent book
http://www.panstanford.com/books/9789814316392.html
demonstrates that Bohmian mechanics may be useful in many branches of physics, even for practical people who are not interested in interpretations of QM.
 
  • #64
Demystifier said:
I believe I know a lot about different interpretations of QM, and yet I think I never seen a serious proposal for an interpretation that would claim exactly that.

Yet, there is an interpretation that claims something similar - the many world interpretation. But even in that interpretation, both possibilities exist at once only after the measurement (or more precisely, after the decoherence) - that is, when the observer can see explicitly that only one of the two alternative possibilities has been realized.

Thank you Demystitifier.It's interesting stuff.
 

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