Observing which-way for fullerene molecules (buckyball)

[San K]

the buckyball has between 20-60 atoms.

This is a fairly large size. even if we "bounce" a photon or two off it, the molecule should not be effected.

Thus can we use some method to find out which slit the molecule went through, without disturbing the interference pattern?

or is it that, even if the photon were to not disturb the buckyball, we still would loose the interference pattern...because it's not about photon disturbing the molecule but about the fact that you simply cannot have which-way and interference pattern (at the same time) ...as a fundamental property of quantum mechanics?

 

[SpectraCat]

... you simply cannot have which-way and interference pattern (at the same time) ...as a fundamental property of quantum mechanics?

That is consistent with all of the experimental results. There are many different interpretations of *how* that phenomenon comes about.

Even more interesting, there are some "weak" detection schemes, where you do not get concrete information about which path was taken, but you can measure with say 70% certainty that it went through the left slit, rather than the right one. The amazing thing about this case is that the intereference pattern, while still visible, begins to decohere .. that is, the borders between the light and dark fringes get blurrier and blurrier as you increase the confidence of one of the paths. I think Dr. Chinese's website has links to and/or descriptions of the papers that demonstrate such "weak" detection.

 

[f95toli]

I suspect that what would find if tried this experiment, is that the visibility of the interference pattern will scale with the intensity of the light. The reason is that you would (in any setup I can think of) need to detect quite a few photons to actually be able to infer "which-path" information.
There are some quite fundamental relations in QM which relate the amount of information you can (potentially) get out of a system (per unit time) with the rate of dephasing (T2, which in turn is related to fringe visibility). Perfect information gives instant dephasing (not that this can happen).

Note that there are experiments quite similar to what you are proposing. Most notably experiments with ion-traps where the visibility of superpositions scales with the intensity of the probe laser as outlined above.

Edit: Spectracat was faster...

 

[San K]

That is consistent with all of the experimental results. There are many different interpretations of *how* that phenomenon comes about.

Even more interesting, there are some "weak" detection schemes, where you do not get concrete information about which path was taken, but you can measure with say 70% certainty that it went through the left slit, rather than the right one. The amazing thing about this case is that the intereference pattern, while still visible, begins to decohere .. that is, the borders between the light and dark fringes get blurrier and blurrier as you increase the confidence of one of the paths. I think Dr. Chinese's website has links to and/or descriptions of the papers that demonstrate such "weak" detection.

thanks SpectraCat, thanks f95toli... yes, I am aware of the above concept and agree, thanks to Dr Chinese.

however i was not aware that this has been tried on buckyballs as well.

however this also proves a very fundamental point:

Buckyballs (and not just our photons, electrons) are indeed experiencing quantum effects...

because...you cannot have both with 100% accuracy (probability would be a better word)

both = fringes and which-way = they are complimentary