Talk:Quantum tunnelling/Archive 3

Archive 1

Archive 2

Archive 3

previously unheadered

It's been a while since my quantum class, but as I understand it quantum tunneling occurs because the square of a wave function can turn out to have a non-zero value outside the bounds of your "barrier". It's strange that there's no mention of this at all in the article - after all, it's supposed to be about quantum tunneling.

Also, the "classical" explanation offered in the article makes no sense to me. It seems to simply say that an electron can't pass through a potential barrier that is higher than the kinetic energy of the electron, and that the probability of finding the electron beyond the barrier will increase as the potential barrier drops below the electron's kinetic energy. While that's true, I don't see how it's relevant; quantum tunneling occurs when a particle passes through a potential barrier without actually overcoming it with kinetic energy, so the classical "explanation" that is offered here doesn't seem to really explain anything.

-June 17, 2005

The point of the classical explanation is that it makes no sense. The idea is that a classical viewpoint of absolute kinetic and potential energies are inconsistent with barrier tunneling. Barrier tunneling is explained by the wavelike nature of the electron and the time-energy uncertainty. The rollercoaster cannot reach higher than it has the energy to, however the energy of the wavelike electron is subject to uncertainity which allows it to be in what appears to be forbidden region. Like the attenuation of electromagnetic waves penetrating into a metal, the probability of the electron being found in a classically forbidden region ( due to energy considerations ) drops to zero at a finite rate, this rate being determined by the uncertainity priniciple, the bigger the uncertainity in energy ( i.e the height of the barrier) the smaller the time uncertainity ( i.e the time period characteristic of the attenuation of the probablistic wave function.) If the barrier is thin enough, then the probability of tunneling becomes significant enough to occur and detect.

- June 26, 2005

After doing some graduate studies in Tunneling, I think I had a bit of a better grasp and explaination than the original author. I rewrote most of it to be _correct_ and straightforward. Feel free to clean it up, but be careful that you keep the quantum mechanics precise and factual. I found it very difficult to write about quantum mechanics in such a way that nonphysicists wouldn't be confused by the abstraction that physicists use between themselves. (CHF 21:46:20, 2005-08-03 (UTC))

-January 9, 2006

I managed to write the descriptive paragraph on tunneling in the intro. Based on my intro quantum chemistry class, I believe that is correct. If anyone would like to modify that, or to draw a descriptive picture, that would work well (that might require rearrangement or rewriting of the article). The old intro babbled on about a wave localizing into a particle which is correct in a certain sense. I felt like it could mislead thought concerned to the confusing nature of the wave-particle duality. We don't understand wave-particle duality, so I felt like it should be removed.

Sorry, you described a Particle in a box, which you cannot tunnel out of. It's true that the original was badly written, but a particle cannot go through infinite barriers! - mako 08:20, 12 February 2006 (UTC)

My old babbling into was an attempt to be very correct. You've watered down things so that they are now less correct. I don't know what you mean about "we don't understand wave-particle duality". Some of us in the field of Quantum Mechanics do understand wave-particle duality. You localize a wave by some environmental interaction and you see a particle. That's the easy part. But seeing as this is the intro and should be readable by laymen, I'm not sure my attention to detail was warrented. CHF 01:05, 4 March 2006 (UTC)

WKB

The section titled semiclassical calculation is essentially a copy of the article on the WKB approximation. I think we should remove it and replace it with perhaps a more illustrative example. A simple idea that comes to mind is a finite potential barrier, and then showing that the amplitude of the wavefunction is nonzero there. I will do this soon unless there are objections. Threepounds 18:12, 27 November 2005 (UTC)

Actually it's the reverse. I wrote this before I checked for a WKB article. The WKB article was unfinished so I copied from here to there. The only problem I have with a simpler example is that a square well potential is unphysical and yields unrealistic results. If you are going to do so, you should use a smooth potential. This derivation shows how tunneling disapears in the classical limit. I would want to see that as well. What you want to include would be a great addition. There used to be such a graph in this article, but it was not tunneling. The wavefuntion was traveling over the potential. (CHF 13:01, 1 December 2005 (UTC))

Simplification

I know this article is perfectly accurate in a physical sense and commendably written but the complexity of some of the prose makes it perhaps a little difficult for novice physicists and lay people to penetrate. Is there any possibility of watering down some of the more complex terms a bit? Or perhaps providing slightly simpler examples...? Coricus 11:19, 1 February 2006 (UTC)

Can you be more specific. Tell us where you get lost. We can reword things, or we can insert helpful links to other articles. In my mind, the ball rolling up a hill that is too high is the simplest example I could imagine.CHF 01:16, 4 March 2006 (UTC)

I agree that this article could use some simplification. However, simplifying the topic could take away from the overall coverage of the subject. My suggestion would be to add a link to a separate article that somebody writes for a lay-person. Articles like this have been written for the articles on Quantum Mechanics and General Relativity, and are titled "Introduction to ...". The introduction articles are simply written for a person outside the field of physics who just wants to learn a little bit about the topic without having to sift through the advanced mathematics and scientific jargon that comes with topics such as this one. I would personally volunteer to write such an article, but I myself am a lay-person when it comes to physics, and feel it would better be left to somebody who knows the subject matter and can explain it well.--66.71.55.56 (talk) 11:15, 10 December 2009 (UTC)

Helium 6

Has anyone thought of inclding a piece on helium 6? Which has to orbiting neutrons, apparetny this is to do with quantum tnneling wolfmankurd

—The preceding unsigned comment was added by 81.132.230.13 (talk) 23:03, 6 December 2006 (UTC).

Probability of tunneling

I've seen the probability for tunneling written in the following ways:

• $P\propto e^{-2L/\hbar {\sqrt {2m(U_{0}-E}}}$

  $P=e^{-2KL}\$ [1]

where

$K={\frac {\sqrt {2m(V-E))}}{\hbar }}$

• $\Psi =Ae^{-\alpha x}\$ [2]

where

$\alpha ={\frac {\sqrt {2m(U_{0}-E))}}{\hbar }}$

I think this would be good information to have, if we could find a general equation for such probabilities. Fresheneesz 22:07, 30 May 2006 (UTC)

We have a square potential article, but it could use some fleshing out. - mako 08:32, 31 May 2006 (UTC)

There is also Finite potential barrier (QM) with the calculation. I just proposed to merge the two articles. -- Bamse 07:10, 16 August 2006 (UTC)

What about faster than c tunneling, and the transmission of classical music faster than c?

I reallly want to delete the above comment. What does it have to do with anything, and why classical music specifically? wtf? Fresheneesz 00:06, 7 September 2006 (UTC)

I would say it doesn't mean classical music as a kind of music, but as music treated as classical movement of particles. With respect to the "faster than c tunneling" idea, the matter is tunneling is not some jump from one side of a barrier to the other side. Its importance is the possibility of traversing the barrier, which classical mechanics wouldn't allow. --euyyn 13:07, 30 May 2007 (UTC)

Wikinews needs help on this subject!

Wikinews os looking for help on the article over at the article 'Two German scientists claim to have broken the speed of light. We require people with a good knowledge of the scientific principles involved to read the preprint of this new research, and write it up it the article. Please go over, register if you like, and then meet up on the articles talk page, where we are co-ordinating such efforts. Thank you. Blood Red Sandman ^{(Talk) (Contribs)} 22:39, 17 August 2007 (UTC)

Simplified Explanation

I've added a simplified explanation to the best of my ability, but as I'm not an expert in the field I'm not sure I have it exactly right. A fact-check would be much appreciated. 72.236.7.174 (talk) 00:30, 25 November 2008 (UTC)

A simplified explanation is a good idea here, but this one does have errors:

1. The most serious error is the statement "This is quantum tunneling" after a description of a classical (macroscopic) tunnel. In fact the tunnel is only an analogy; the real quantum explanation is that at a finite barrier, the wave function of the particle does not go to zero immediately but rather decreases exponentially and therefore penetrates into and through the barrier. This is explained with diagrams in many physical chemistry or quantum mechanics texts.

2. The effect has nothing to do with entropy or the second law of thermodynamics which both apply to macroscopic systems.

3. Tunnelling "uphill" is possible too, provided that the final potential energy is less than the total energy. The kinetic energy (= E - E_pot) can only be negative inside the barrier.

Tunneling uphill is almost always possible in quantum mechanics. The better question is how likely will it occur and how short lived the higher energy state will be. Quantum mechanics will not violate thermodynamics in the appropriate limits. (CHF (talk) 15:45, 16 December 2008 (UTC))

I will not delete your explanation as it is better than none, but it should be improved.Dirac66 (talk) 00:25, 26 November 2008 (UTC)

P.S. On reading the whole talk page quickly, I see that there has been some useful previous discussion of a simplified explanation. See especially sections 4 and 9 above.Dirac66 (talk) 00:44, 26 November 2008 (UTC)

Translation

The article's page in Turkish wiki is: http://tr.wikipedia.org/wiki/T%C3%BCnel_etkisi Can you please link it? I don't know how to do it.

Meandering and overly mathematical

First of all, this article betrays a poor grasp of the physical origin of tunneling phenomena. Tunneling occurs because particles exhibit wavelike properties, and are described by wave functions which satisfy the Schroedinger equation. By conservation of probability current, the wave function and its first derivatives must be continuous at a potential barrier. This results in an exponentially decaying wave function (and probability density) in the classically forbidden region. By the Heisenberg uncertainty principle, any attempt to localize the particle within the tunneling penetration length leads to a commensurate uncertainty in the momentum (and hence energy) of the particle such that its energy in the forbidden region is no longer known with sufficient precision.

Secondly, most of the math in this article is irrelevant to understanding the basic physics. Tunneling can be sufficiently understood by studying the finite potential barrier or finite potential well systems. This should require three or four equations at most. Also, like many quantum phenomena, tunneling has analogues in classical physics (evasnescent waves). Such a discussion of evasnescent waves would aid in the understanding of quantum tunneling. --Brian C 07:00, 8 February 2006 (UTC)

Everything you say in words is included in the mathematics. This is an encyclopedic article, so it needs a watered down explaination and possibly an in depth explaination. You are free to add an in depth explaination that is English and not mathematics. A square-well potential would be good to add. It would show tunneling behavior. However, the square-well potential is unphysical and has an incorrect classical limit. CHF 00:59, 4 March 2006 (UTC)

---

I want to point out that this article seems much inferior and much less adherent to the spirit of quantum mechanics than the article of the particle in the square well. Yet, the questions in this discussion section, while highly schizophrenic and disorganized, are very good natural deep questions. In other words I think the article needs better organization, and better language (sometimes they are inseparable) so that the questions may asked in the more natural language and not seem so incongruent. For example when someone asks the perfectly natural question: Is tunneling the fact that the particle is in the classically forbidden region of the wall. As it turns out tunneling is not one thing, but a number of related behaviors, of which being *in* the forbidden region is one of them. Another is crossing the forbidden region. Yet another is crossing the forbidden region with much more likelihood than you should classically. Also a non normalizable barrier-Hamiltonian eigenstate being non zero on both sides of the barrier (the most common association to the word tunneling) is not tunneling in the true sense of the word since tunneling roughly means: first you're on one side of the barrier, then at a later time your on the other side, and you never had enough energy to get across. —Preceding unsigned comment added by 131.94.20.246 (talk) 21:25, 16 January 2009 (UTC)

Where am i JerryGarcia47 (talk) 12:49, 29 January 2022 (UTC)

Quantum field theory

Is there a reason that this quantum tunnelling page doesn't mention quantum field theory and virtual particles as being responsible for how the mechanism works? 130.88.117.230 (talk) 07:44, 4 June 2008 (UTC)

Yes because QFT does NOT tells us "how quantum mechanics works". QFT is the merging of QM and special relativity and the quantification of fields. It does not tells us why particles have wave-particle duality. QFT is based also on the same foundations of QM, just extended. — Preceding unsigned comment added by 155.69.191.250 (talk) 04:15, 28 February 2018 (UTC)

Figure

In the figure on the left, a particle "tunnels" through a barrier. What is the form of the barrier in the example? To me, it looks like the particle is crossing the barrier, not tunneling through it. If the barrier is finite, the incoming wavepacket will have components above the barrier, and those are the ones that are transmitted. If the barrier is infinite, there should be no transmission (or tunneling). --24.34.222.177 (talk) 06:01, 29 December 2008 (UTC)

Between the Unseen of Reality and the Big Bang14:19, 18 September 2016 (UTC)205.197.242.160 (talk) Therefore the molecular level of existence co-exist with our own. Which brings us to the Big Bang, Why, because space isn't empty . . . These Lines of Force give rise to early thread theory=>energy wells, quantum tunneling, etc. . . . Such accredited to astrological studies & other related events; event horizon, black holes, etc. Why the Big Bang? Actually, I am not sure, why it has become so widely accepted? As of general theory, well I know less about the why? Let us start within & without, that is from the atomos & atomism to molecular & astrological. First of all, Closure : Einstein's Theory of Relativity doesn't extend closure where as Classical Physics has closure as a unconditional principle. As you can imagine this created quite an obstruction to acceptance of Relativity. Which resulted in a real rush to correlate (associate) these principles into single set of principles representative of both the Classic & Relativistic physics to maintain closure. Second the Interval : Reading an article (modern) particle theory, I made a comment in general about the atomos aspect of subdivision of elements down to it's basic particle forms. Another person put forth that at least, there will anymore about some infinite series of sub particles, the addendum infinitesimal. The statement made me ponder, what was said & what was meant by the saying? I was having difficulties with the mass-less aspect 7 & still being a particle. Later, I started thinking about it? Yes & No ! Note Previously statements : All matter is energy (electromagnetic) & as the e-m spectrum exist as a continuous range of frequency (wavelengths) which extends infinitely in both directions, an opened ended statement ? Big Bang ? Ahh, one open & one closed ? Relativity, extends or states that there are two separate reference systems (well at least two). Mass [matter] is composed of atoms that co-exist & form separate functions which form our existence Energy extends across the e-m spectrum just as inertial mass . . matter is neither created nor destroyed : it only changes form . . . Therefore : If mass has different forms then energy [must form] a corresponding resonant form . . . Chemistry: a reaction must yield a stable compound, a [Closure] resonant form to contain that energy: then energy is stored . . . Also note that they co-exist relatively,the open or closed nature of shells & orbitals extend from individual elemental configuration. If Elemental Forms exist as stable structure; therefore these structure must Co-Exist relative to each other . . that is the structure of hydrogen co-exist the structure of carbon, etc, etc. Relativistic speaking, the Periodic Table of Elements extends the co-existence of different levels, shell theory, orbital configurations, etc. all co-exist in each element. Then they exist relative to form as consistent structural units within the atom's nucleus; as the electron-proton paired describes by electron orbital configuration & the periodic nature formed by the table of elements. Native American Tradition In native art design is open ended, (spirit) can follow through the design, just as the dream catcher has design parameters based upon their belief system. (bad dreams pass but good become entangled by the web, sense awareness) Not only is Energy stored as mass but it is also transferred, in photography the halogen groups (grain) alter the emulsion's rate of reaction. Therefore we could extend an electronic effect to the Primordial Atom aspect, atoms exist as basic systems of particles, some of these particles are formations of sub-particles. These systems act as the step-down transformers in electrical distribution system, the system of elemental particles & sub-systems act to change the high frequency & therefore higher voltage energy of transmission lines (wave guide) to the lower frequencies (voltage) the service lines to our homes & factories. by Clay Turtle Okay, now Just spent an hours, to find the key board wasn't connected? Gee . . In my dazes, we were taught " all forms of energy were one & mass" . . . that "the change in form" is an important aspect . . Mass is neither created nor destroyed, it changes form. Ya, kind of stuck in the past . . . SPACE-TIME Einstein extended that of energy-mass equation; the speed of light in a vacuum as a Constant; a maximum velocity? . . cell phones, computer age integrated circuits, chips? Yes, No ? Atomos . . atomism: matter () exist as individual particles having the same characteristic; transmutation of lead into gold. NOTE: The lead & gold exist as elements where as corn & granite are compounds, well yes we can grind, both granite & corn, down into fine particles so essentially; yes. But compounds like the corn, no; its composition as flour would change its'characteristic nature, from the natural form continued existence of life to a granular form which mixed with water & baked into bread. 6 Note: an electron exists in realm of free space in terms of density, mass & has an associated negative charge and the proton, it's associated positively charged mass. 7 In chemistry the term particle is commonly used to or defined by mass. pg.3 Classical Physics based upon the man's conception of his existence in the (seen) physical Universe where Physics extends the predominant effect of inertial & gravitational forms of stored energy. Relativistic Physics based upon man's conception of existence of the individual (unseen) nature of the elemental form of existence. The nature of molecular form is the predominate effect of charge as the elemental of form. The molecular nature coexist within the order of co-existence, that is they exist as separate levels, more than one. Well, where do they exist? . . Good Question In fact I designed that aspect into 'Retro-Rocket' because those seen aspects, the physical prototype would be a conceptual reality. But the principles of the rockets involves the molecular particles of Chemistry, the unseen aspect. Another level & we would like a telemetry systems which include electronic structure or form arising within the unseen aspect. So where do they exist & we pull out our cell phone, point to it & say "They are in there." So are principles necessary for [Carbon-Base] Life to exist. *Note quantum tunneling: regarding level(s) existing resonant forms extend to other resonant forms with corresponding frequencies. Therefore All levels have resonant frequency & interlacing webs of force co-existing at all levels inclusive of any subsystem that exist. Relativity the existence of another reference system & exist relative to each. Is the Universe increasing or because energy extends Outward? Heard about a level of 'em' radiation so high, it would pass through the earth . . perhaps they come from nuclei within the molten core of the earth?

Medium Types

If I may be so bold, what the hell are medium type 1 and medium type 2? Was anybody planning to define these terms at any point, or is it just assumed that everybody magically knows what that means? 98.204.74.229 (talk) 01:51, 13 March 2009 (UTC)

Medium type 1 is where the wave-equation has traveling-wave solutions; medium type 2 is where the wave-equation has solutions that are rising or falling exponentials. This language is meant to apply to all wave-equations, and normally arises physically because different media (e.g., glass and vacuum, for a light wave) have different properties A new section attempts to explain in more detail how this arises, in the context of quantum mechanics and the Schrödinger equation. Sentence has also been added to lead section (RGForbes (talk) 02:33, 20 March 2009 (UTC))

I agree this "Medium Types" wording is cumbersome, unclear and unnecessary. The concept of different mediums is needed but it doesn't have to be so "jargony". I will try to reword when I get time. Feel free to beat me to it.

Phancy Physicist (talk) 19:27, 8 July 2010 (UTC)

Marking for cleanup

The writing in the section beginning with "Three notes..." could do with some reworking. Would appreciate 128.8.177.9 (talk) 16:56, 1 May 2009 (UTC)

Spelling change. Please leave it.

Please don't change the spelling of "tunnelling" to "tunneling". both appear to be correct but the link to this article and the title are spelled "quantum tunnelling". I don't either way about spelling but the article should be self consistent. So I have changed it to match the title and link.

Phancy Physicist (talk) 17:58, 8 July 2010 (UTC)

12 years later 🦗🦗🦗 JerryGarcia47 (talk) 12:50, 29 January 2022 (UTC)

Orphaned text.

The following is some orphaned text from my rewrite of A semi-classical method for determining a formula for tunnelling probability

"

This classical limit would have failed in the unphysical, but much simpler to solve, situation of a square potential.

A related subject is above barrier reflection: in classical physics a particle will not reflect if its energy is above the potential barrier, but in the quantum case it is possible. In this case, the reflection coefficient is exponentially small in Planck constant. The semiclassical technique of calculation of the reflection coefficient is similar to the calculation of the tunnelling described above.

In a specific tunnelling problem, we might suspect that the transition amplitude is proportional to $e^{-\int dx{\sqrt {{\frac {2m}{\hbar ^{2}}}\left(V(x)-E\right)}}}$ and thus the tunnelling is exponentially dampened by large deviations from classically allowable motion.

"

I try to figure out what to do with it later.

Phancy Physicist (talk) 07:58, 15 July 2010 (UTC)

Copy of WKB subsection.

I feel pretty stupid but I rewrote the section Applying the WKB method to tunnelling probability without even checking the WKB article first! This section is a bad or maybe old copy of the this WKB subsection. There are some changes that I will transfer to the WKB article but I think that this redundancy is silly since the WKB method has no direct connection with quantum tunnelling except that it provides a way of calculating transmission and reflection coefficients. I am going to remove it soon unless there are objections.

Phancy Physicist (talk) 08:37, 15 July 2010 (UTC)

Spelling: tunnelling vs tunneling

This article is titled Quantum Tunnelling and uses the spelling tunnelling throughout, but that is not the correct spelling of the word. The correct spelling is tunneling (see references in Further Reading). Recommend changing the name of the page and all the spelling throughout. --Yoda of Borg (talk) 21:11, 12 August 2010 (UTC)

"Tunnelling" is proper English. This is the link to the Wikipedia Guidelines on American and British Spelling. As I said earlier on this talk page I don't really care which is used as long as the page and link are self-consistent, but there is no reason to change it now. Phancy Physicist (talk) 17:13, 15 August 2010 (UTC)

There is no doubt that "tunnelling" is just as acceptable in global English as "tunneling." In fact, "tunnelling" seems to be the preference on Wiktionary (although many spell checks prefer "tunneling"). It is also true that Wikipedia explicitly says that no spelling is preferred, except spelling should be consistent within an article . It can be seen that many American-authored articles use "tunneling." However, it is also found that neither the British, American, or physicists in general are consistent (most authors stick to one spelling, but groups are inconsistent). And, lastly, it should be pointed out that the Wikipedia article on Tunneling itself chooses a spelling, and, in turn uses that spelling to refer to this article, and it may be preferable to make the two consistent (or perhaps it is better to present both possibilities). For now, I think that there are greater issues to worry about with regard to this article, especially making sure that it captures the general, theoretical idea/concept well enough for a general audience.Brent Perreault (talk) 03:14, 18 August 2010 (UTC)

I second the above. There is more to worry about with this article than the spelling.:) Phancy Physicist (talk) 05:16, 22 August 2010 (UTC)

Personally, I'd like to see in the intro just a parenthetical note (also tunneling). The reason is that students using this page for assignment research, depending on what country they are in, could face a lower grade for misspelling if the teacher doesn't approve. Teachers have to be consistent in their classrooms, too.5Q5 (talk) 17:26, 2 October 2012 (UTC)

Here is an example of "(or tunneling)": http://www.sciencedaily.com/articles/q/quantum_tunnelling.htm. 5Q5 (talk) 15:28, 3 October 2012 (UTC)

I added to the intro "(also spelled quantum tunneling in American English)" based on these examples found in other articles, of which more can be found. 5Q5 (talk) 15:42, 5 October 2012 (UTC)

• Orthopedic surgery or orthopedics (also spelled orthopaedic surgery and orthopaedics in British English)
• Marshal (also spelled marshall, more commonly in British English than American English)

The main thing is consistency. I have amended all used of "tunneling" to match this article's title (except where used in cited reference titles). Also, I have re-added text in the lead to mention the alternative spelling. I don't understand why this was removed before. Bazonka (talk) 07:05, 27 July 2013 (UTC)

"Mechanical Energy"

I took the liberty of changing the reference to "mechanical energy" to read "kinetic energy" in the intro, since that makes sense in the particular context. Please reverse this change if you do not agree. The term "mechanical energy" according to wikipedia is the sum of kinetic plus potential energy anyway, so potential energy was already included in "mechanical energy" (total) that was compared with the potential energy barrier. Does that make sense?CecilWard (talk) 19:44, 12 January 2011 (UTC)

"Shining stars"?

In the intro, it says that quantum tunnelling is related to the phenomenon of "shining stars." Now, I'm not an expert on the subject, but I'm assuming that this refers to how light from stars reach Earth and how it is measured. I'm not sure how this could relate to the concept of quantum tunnelling, as the phrase is very ambiguous. If this isn't vandalism, some clarification would be beneficial, since the the reference is from a textbook and thus not readable by everyone. Eridani (talk) 18:47, 5 May 2011 (UTC)

Here is the quote from the book: "It's interesting to note that a quantum effect is key in making sunshine. Temperatures inside stars like the Sun are not high enough to allow colliding protons to overcome the Coulomb repulsion. In a certain percentage of collisions, however, the nuclei pass through the barrier anyway, an example of quantum tunneling". Dauto (talk) 21:42, 5 May 2011 (UTC)

Where is the Japanese Physist who invented Tunnel Diode? There were 3 winner of 1973 Nobel Prize, why you obmit the third one? This is a biased article. Please remove it. — Preceding unsigned comment added by 67.124.39.78 (talk) 11:54, 5 January 2012 (UTC)

Major rewrite

I'm planning a major rewrite of this article. Most of the actual information in the article is correct, but poorly organized. I will start next week or two, I will try to take into account the most recent discussion, but please weigh in if you have strong opinions about how the article should look. — Preceding unsigned comment added by Infinitooples (talk • contribs) 22:51, 6 January 2012 (UTC)

I hope this is not considered unimportant or redundant given the above discussion, but if a total rewrite of the article is being done then SOME principled (non-coin-flippy) decision should be made about the preferable spelling of the key word "tunnelling/tunneling". There is no argument about the broad linguistic acceptability of both spellings. It appears, however, that the spelling of the word in the article's reference sources is (almost always?) the one-L variant. If indeed there is a dominant spelling in the professional literature, then clearly that's what should be used in this article as well! And if it turns out that a noteworthy number or category of professionals use the less-common spelling perhaps this fact could be mentioned parenthetically in the article's introduction. The less-common spelling can have a redirect page to the more-common one so no existing links are severed. Ontyx (talk) 05:31, 12 July 2012 (UTC)

A rewrite is definitely needed. Parts of the article are wordy, meandering, and unfocused. The point another poster makes about incomplete descriptions and explanations is also valid.

As for spelling... There's a rule in English that if vowels are separated by a single consonant, the first is long. "Tunneling" is therefore incorrect, unless you want to pronounce it "tu-nee-ling". There are other examples where the incorrect spelling is now accepted as correct (most notably "kidnaped"). WilliamSommerwerck (talk) 17:09, 22 May 2013 (UTC)

teleportation as a tunneling effect

In James Blish's Spock Must Die!, the possibility of using quantum tunneling to transport objects (rather than disassembling/reassembling them) is briefly discussed. Such a discussion might make an interesting addition to this article. WilliamSommerwerck (talk) 17:09, 22 May 2013 (UTC)

Question about history

From the article: "Friedrich Hund was the first to take notice of tunnelling in 1927 when he was calculating the ground state of the double-well potential.[4] Its first application was a mathematical explanation for alpha decay, which was done in 1928 by George Gamow and independently by Ronald Gurney and Edward Condon.[5][6][7][8] The two researchers ..." To whom does "The two researchers" refer?

Incorrect Description of 1973 Nobel

Hey, I'm not a Wiki editor but just wanted to note that the article in its present form mischaracterizes the various independent experiments on tunneling in semiconductors and superconductors that were jointly awarded the Nobel Prize in physics in 1973. It currently reads "The work of Leo Esaki, Ivar Giaever and Brian David Josephson predicted the tunnelling of superconducting Cooper pairs, for which they received the Nobel Prize in Physics in 1973."

This is incorrect. Esaki experimentally verified tunneling in semiconductors in 1958 (his work had nothing to do with superconductivity). In 1960 Giaever used tunneling to measure the superconducting band gaps predicted by BCS theory. In 1962 Josephson alone predicted the tunneling of Cooper Pairs. — Preceding unsigned comment added by 130.132.173.233 (talk) 17:27, 17 January 2014 (UTC)

Clearance

If all the energy in the universe creates a singularity where time holds still does it mean something is always left out in order to satisfy the consistency principle?

I had no idea talk was forbidden, are you with the government?

189.58.174.240 (talk) 05:34, 3 February 2014 (UTC)

ADDENDUM: http://www.businessinsider.com/atoms-reach-record-temperature-colder-than-absolute-zero-2013-1 apparently proves that Heisenberg can be cheated. Probably because "infinite" energy is not infinite, just a lot. Meaning, it doesn't take all the energy in the universe to cheat Heisenberg. Just a lot. Because traditional models in physics assume the real domain perhaps? Maybe.

189.58.174.240 (talk) 07:45, 3 February 2014 (UTC)

Introduction to the concept needs a clarity boost

There are a couple of things that make this section hard to understand.

It says "In quantum mechanics, these particles can, with a very small probability, tunnel to the other side, thus crossing the barrier. Here, the "ball" could, in a sense, borrow energy from its surroundings to tunnel through the wall or "roll over the hill", paying it back by making the reflected electrons more energetic than they otherwise would have been."

"These particles" has already been introduced as "particles that do not have enough energy to classically surmount a barrier", which is fine. The "ball" represents that inability, which is also fine, but where did the electrons come from and why and how are they reflected? 78.144.72.141 (talk) 18:50, 6 September 2014 (UTC)

External links modified

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"last two decades"

The article says "Tunnelling is a fundamental technique used to program the floating gates of flash memory, which is one of the most significant inventions that have shaped consumer electronics in the last two decades." This needs to be rewritten so it is accurate in the future. Bubba73 ^{You talkin' to me?} 20:10, 27 February 2018 (UTC)

External link problem

The link named: "Quantum Tunneling of Water in Beryl: A New State of the Water Molecule" Should be removed or replaced.

It currently leads to a web page hosting malware. — Preceding unsigned comment added by Brofitable (talk • contribs) 11:47, 26 June 2018 (UTC)

Edit this language in the second paragraph: "Quantum tunneling is projected to create physical limits to how small transistors can get, due to electrons being able to tunnel past them if they are too small.[4][5]"

Replace with: "Quantum tunneling suggests a lower limit to the physical size of transistors because electrons can tunnel past barriers (like transistors), if the barriers become too small." Kprainville (talk) 01:32, 19 August 2018 (UTC)

Replace this sentence in the second paragraph: Quantum tunneling is projected to create physical limits to how small transistors can get, due to electrons being able to tunnel past them if they are too small.[4][5]

With this: Quantum tunneling suggests a lower limit to the physical size of transistors because electrons can pass through barriers (like transistors), if the barriers become too small.

This is a second alternatice to a post provided within one hour of this post. Kprainville (talk) 01:45, 19 August 2018 (UTC)

Tunneling

It does not appear that whoever wrote this article really understands what quantum tunneling is. as in the wave form diagram it states that the particle tunnels through the barrier, which is not true. The particle does not pass through the barrier, as the barrier is impassible. The particle appears on the other side of the barrier. The author states that the particles move, whereas in reality they don't. The equations states that the particle's position is proportional the probability that he particle will be there. As the equation describes that the electron, say, is in a certain position at a certain time that does not mean that the electron orbits the nucleus, but rather that the probability of the electron's position is a wave and that the wave appears similar to a planet orbiting a star. However, the electron merely appears at a position that is most probable within the uncertainties for he particle actually being in that position. Then we describe the position of the electron as a cloud around the nucleus. This is common mistake like thinking electrons travel down a wire and power a light when the other end of the wire is attached to a generator. However, the electron does not travel down the wire, only the wave does in an AC circuit. We can then describe the position of an electron in the filament of an incandescent light bulb, but the electron described is not the electron that was in the generator, but rather one that was already in the filament. The wave heats up the light filament by the action of the rotation of the magnets in the generator that pull the electrons back and for the creating a wave, but the electrons do not travel down the wire at close to the speed of light, but rather only the wave travels down the wire. Similarly in quantum tunneling the electrons do not pass through the barrier as it is impassible, but rather the position of the electron due to the probability of finding it there, appears on the other side of the barrier and like in an AC circuit the electrons doe not travel down the wire and light the light, but rather the wave causes the position of the electrons to vibrate at the relative speed of the turning of the generator. There are no true motions of electrons, but rather the field is described by the equation to change according to the qualities of the Hamiltonian. These kinds of errors in thinking are similar that the sine wave that appears on an oscilloscope is a wave, when in fact it is a circle.

Zener Effect

There is a breakdown that occurs in highly doped PN diodes. In the wikipedia article of Zener diode they mention quantum tunneling is the reason the charge carriers are able to cross the depletion region barrier. I think this article should mention something about this phenomenon. — Preceding unsigned comment added by Aditya8795 (talk • contribs) 18:26, 23 August 2019 (UTC)

Possible error in Case 1 (and maybe Case 2) WKB Approximations

In case 1, I believe that in the final result, the denominator of the amplitude contains an additional h^2 term that should not be there. The denominator should be (I think):

4√(2m(E-V(x)))

e.g. without the 1/h^2. Note that the '4' above means the 4th root.

I think the same is probably true for case 2, but I haven't double-checked. — Preceding unsigned comment added by 79.73.43.136 (talk) 22:58, 30 April 2020 (UTC)

Claimed image of quantum tunneling.

I removed this image from wave packet; it was out of place.

Position space probability density of an initially Gaussian state trapped in an infinite potential well experiencing periodic quantum tunneling in a centered potential wall.

Not sure it belongs here either, it seems to have no documentation on what it shows. Johnjbarton (talk) 03:39, 28 May 2023 (UTC)

I think it doesn't belong here either: the kink in the wavefunction does suggests that the lowest-energy components are tunneling through the center barrier, but it lacks adequate description or explanation, too complex to illustrate any one point clearly, and the barrier is too tiny to illustrate tunneling clearly. Thanks for removing it from wave packet. –MadeOfAtoms (talk) 20:57, 29 May 2023 (UTC)

Oppenheimer

It seems strange that the wikipedia page for Oppenheimer lists as one of his major achievements the first prediction of quantum tunneling, and this article does not even mention Oppenheimer’s name. 31.10.131.222 (talk) 22:05, 17 August 2023 (UTC)

Good catch! Now find a reference, maybe in a history or a review of quantum tunneling that outlines Oppenheimer's role and add it the this article. Johnjbarton (talk) 23:35, 17 August 2023 (UTC)

Problems with the history

The history section claims that "Quantum tunneling was developed from the study of radioactivity", citing Razavy's book. Although Razavy does begin his historical survey from the experimental discovery of radioactivity and uses it as a background to introduce Gamow's theory of alpha decay, he never makes the above claim, but instead acknowledges that electron emission came first. A good historical survey on the early period can be found in Merzbacher's article.

The self-published article by Thomas Cuff which attempts to correct some of the history does not strike to me as a reliable source. The information about Robert Francis Earhart's contributions should be verified from another source.

The part about electron tunneling in solids is also problematic. The statement about Esaki's, Giaever's and Josephson's contributions is false, as Esaki's breakthrough had nothing to do with superconductivity. The water tunneling experiment is also only supported by a primary source, which cannot establish its historical notability. Jähmefyysikko (talk) 21:17, 24 August 2023 (UTC)

Concept: uncertainty or wave tail penetration?

The concept section ends with a puzzling discussion of the uncertainty principle and tunneling. I can't make out what it is trying to say.

It was my understanding that the qualitative model of tunneling was continuity of the wavefunction. The wave can't end abruptly at the barrier and thus it tails off with finite amplitude into and through the barrier. That is certainly the implication of TunnelEffektKling1.png later in the article.

I'm sure there is away to say this with the uncertainty principle, but I don't see why that would be advantageous. Johnjbarton (talk) 14:34, 27 August 2023 (UTC)

Agreed, it's very confusing. I intend to rewrite this section, and am currently looking for sources. Wolf's Principles of Electron Tunneling Spectroscopy does introduce tunneling by explicitly referring to the continuity of the probability amplitude (and Born rule) but its not really an introductory text. The approach of J.R. Taylor's Modern physics might be useful. Jähmefyysikko (talk) 18:48, 27 August 2023 (UTC)

The tunneling problem

I'm trying to understand the section "The tunneling problem". It does not seem to be a "problem" but rather an explanation.

It features an animation, which is presumably related to some solution to a tunneling problem. But nothing is said about either.

Both the analytic and WKB one dimensional solutions for tunneling are static, time-independent models. Therefore I assume that the wave packet animation shown here is a linear combination of solutions for different energies combined with a unitary evolution phase factor carefully selected to give a localized envelop. Isn't this original research? If not, what is the reference? Johnjbarton (talk) 00:08, 7 September 2023 (UTC)

The wave packet thing is altogether puzzling. It correctly shows partial transmission of the probability amplitude but, with the time dependent envelop, the partial transmission starts at zero, grows, then decays. What can that mean? What do we expect for the transmission cross section? Zero I suppose. So no tunneling right?

Are we to imagine that the wave packet represents a "particle" advancing from the left? So what then do we make of the transmitted wave? A tiny particle? The mass has split at the barrier? Is that tunneling?

Ok maybe I am beginning to understand why the section is named "the tunneling problem" ;-) Johnjbarton (talk) 00:36, 7 September 2023 (UTC)

And! There are two "quantum" effects in quantum tunneling: 1) transmission at energies below the barrier height and 2) probabilistic quantum transmission. The second is just as important: a full quanta crosses at an unpredictable time. This physical behavior is completely contradicted by the deterministic partial transmission shown by the wave packet animation. Johnjbarton (talk) 02:37, 7 September 2023 (UTC)