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ArcticMyst Security by Avery

Quantum tunnelling

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Hi,

in school, we talked about Quantum tunnelling. The teacher mentioned there is an experiment, pointing a high-powered laser (he said the laser used when he watched the experiment had about 250mW) on a piece of carton. Normally, the laser would not be able to shine through the piece of carton but in the dark you should be able to see photons that tunnled through it.
My teacher was not allowed to show this experiment since high powered lasers are allowed for personal use in Germany only, otherwise you have to own a certificate. He did not want me to do the experiment on my own, it would be "too dangerous" to use high powered lasers.

I am very interested in this experiment, does anybody know how to perform this experiment? Does anybody know similar experiments (especially experiments dealing with quantum physics)?

Thanks

Gabriel
 





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I am sorry for posting in the wrong topic, how can I move my thread to the Experiments & Modifications topic?
 
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^^Don't worry about the section. It should be alright over here.

At surface value, it does not sound much like quantum tunneling to me. What do you mean by carton?

Quantum tunneling would refer to the probability of finding a particle i.e. electron with an energy level higher than the average energy. The "tunneling" refers to that particle with an energy such that it could be probabilistically found on the other side of a barrier, or even inside the nucleus of another atom.

I don't know if your teacher was talking about "tunneling photons" or about burning through a chunk of plastic/cardboard. The photons of a laser each carry the same energy. There is no band of energy that the photons in the beam carry - only a single energy.

A laser's photons are one exactly one color, which means one wavelength, which means one frequency, which means one level of energy.

e = hv
 
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@Chromagnum: this is a very interesting video, thanks :)

@Meatball: Thank you for the explanation.
By carton I meant a very thick sheet of paper. My teacher was talking about tunneling photons when we dealt with quantum physics. He said you could see a sample at the other side of the paper.
Chromagnum mentioned this video experiment on youtube, dealing with microwaves. Microwaves have a specific wavelenght like lasers and it is possible to do an experiment on quantum tunnelling.
It is a pity I do not go to school any more so I can't ask my teacher about the experiment (and if I were he would not tell me).

Edit: I found an experiment for lasers to show the quantum tunneling. It works like the experiment using the microwaves. Unfortunately the experiment is described in German, but you can see the construction of the experiment in the last four pictures of the following website:
http://www.lokriem.de/html/tunneleffekt.html
I do not think it is the same experiment my teacher spoke of, but I think this experiment is interesting anyway :)
 
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@Meatball: Thank you for the explanation.
By carton I meant a very thick sheet of paper. My teacher was talking about tunneling photons when we dealt with quantum physics. He said you could see a sample at the other side of the paper.
Chromagnum mentioned this video experiment on youtube, dealing with microwaves. Microwaves have a specific wavelenght like lasers and it is possible to do an experiment on quantum tunnelling.
It is a pity I do not go to school any more so I can't ask my teacher about the experiment (and if I were he would not tell me).

Unless those microwaves are MASERS, then the photons do have a band of energy. If it were a MASER, there would be only one specific energy/photon.
 
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I have proved this myself , where the middle of my chicken bowl is hotter than the outside, in a microwave. It also uses radio frequency to heat up my food. :)

I like that the girl in the video was more than happy to help :)
 
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Uh... wat tha fzkcu? That guy is spewing bullshit like there's no tomorrow. That's not quantum tunneling, that's total internal reflection.

Did you watch the entire video? He was attempting the double prism experiment and showed that the detector signal increased when a second, spatially separated, prism was introduced? :beer:
 
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Did you watch the entire video? He was attempting the double prism experiment and showed that the detector signal increased when a second, spatially separated, prism was introduced? :beer:

And that's due to total internal reflection no longer taking place. It has NOTHING to do with quantum tunneling.
 
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And that's due to total internal reflection no longer taking place. It has NOTHING to do with quantum tunneling.

The info in the links from BShanahan14rulz seem to suggest that tunneling takes place between to prisms separated by a gap.

Here's another link about the same experiment and shown in the you tube clip above, but performed by Guenter Nimtz: Faster Than Light Transmission Of Signals In A Double Prism

So what prevents the total internal reflection from taking place if the prisms are separated? :beer:
 
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Go have a look at your microwave. You'll notice all microwave ovens have metal sheets with lots of little holes in them for the window. Why can't the microwaves get through those holes?

The wavelength of light is ~3cm he says, right? Light has difficulty interacting on scales smaller than its wavelength. That's why bluray can read a smaller dot than DVD, that's why we can't see atoms using light, that's why a bunch of paraffin pellets has the same effect as a block of paraffin, and that's why the light can "jump" the gap - it just doesn't "see" it.
 
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Thanks, but that still doesnt answer the question. If total internal reflection took place initially with one prism, why do you think the total internal reflection no longer takes place when a second prism is introduced (and separated by a gap, which this case can be up to 60 cm)? According to your argument, the light would "jump the gap" to the detector even in the absence of the second prism, which it obviously doesn't. Only after the second prism is placed next to the first one, does the count increase on the detector opposite. :beer:
 




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