What is Tunneling: Definition and 267 Discussions

In computer networks, a tunneling protocol is a communications protocol that allows for the movement of data from one network to another. It involves allowing private network communications to be sent across a public network (such as the Internet) through a process called encapsulation.
Because tunneling involves repackaging the traffic data into a different form, perhaps with encryption as standard, it can hide the nature of the traffic that is run through a tunnel.
The tunneling protocol works by using the data portion of a packet (the payload) to carry the packets that actually provide the service. Tunneling uses a layered protocol model such as those of the OSI or TCP/IP protocol suite, but usually violates the layering when using the payload to carry a service not normally provided by the network. Typically, the delivery protocol operates at an equal or higher level in the layered model than the payload protocol.

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  1. C

    I Are we in a simulation and quantum tunneling?

    Preface: As I understand it, according to quantum mechanics, there is a very good probability that I am sitting right in my chair right now, typing this question out. However, there is a non-zero, ever so small probability, however infinitesimally small chance that I am somewhere else in the...
  2. S

    A Wavefunction matching two different H, not just V

    Can the basic techniques of wavefunction matching that one would use to calculate the transmission through a step barrier potential and the Dirac hamiltonian of graphene be used for a situation where instead the fermi velocity changes in a step like fashion. i.e. instead of a Hamiltonian like...
  3. Y

    A Raman Spectroscopy vs. Inelastic Electron Tunneling

    I am a first year graduate student in physics and am becoming familiarized with Raman spectroscopy to study structure of materials based off of their vibrational states. In some personal study outside of this, I came across the idea of inelastic electron tunneling spectroscopy (IETS) and was...
  4. durant35

    I Can Quantum Tunneling Cause Objects to Instantly Swap Places?

    Hello guys, I have few questions about the well-known quantum tunneling. I'll start off with the animation from wikipedia So question #1 why doesn't the barrier collapse the wave function, is that even possible? What's the difference between the barrier and the measurement screen in double...
  5. L

    A Image force in normal metal electrode tunneling

    Hi there, I have a question that I think has an answer but I cannot find it in the literature in any convincing way: I am using two models, WKB based and TMM based to calculate the transmission probability of electrons through a (initially rectangular) thin potential of the order of 1-2nm...
  6. H

    B Free Intro-Level Tunneling Simulator - Download Now!

    Free download aimed at intro level.Thoughts? https://phet.colorado.edu/en/simulation/quantum-tunneling I can't tell the difference between quantum tunnelling and classical tunneling eg microwaves??
  7. S

    Infinite Square Well, Potential Barrier and Tunneling

    Homework Statement Consider a one-dimensional, non-relativistic particle of mass ##m## which can move in the three regions defined by points ##A##, ##B##, ##C##, and ##D##. The potential from ##A## to ##B## is zero; the potential from ##B## to ##C## is ##\frac{10}{m}\bigg(\frac{h}{\Delta...
  8. Alan Ezra

    I The barrier length in quantum tunneling

    Hi, In transmission coefficient T= exp(-2sqrt(2m(U-E)/hbar^2)L), L, as I interpret it, is the distance of the potential barrier. I am wondering if I have N particles all with kinetic energy E, approaching the barrier, can I integrate the transmission coefficient over a distance from infinity to...
  9. A

    References for tunneling decay in magnetic fields

    I'm looking for introductory references to the topic of time of tunnelling decay when besides the potential barrier there is also a magnetic field present. I have found a couple of articles about the topic but they treat complicated cases in condensed matter, I'm more interested in the basic of...
  10. G

    Quantum tunneling instantaneous

    http://m.phys.org/news/2015-05-physicists-quantum-tunneling-mystery.html Does this mean that the tunnelling time was actually zero, and the electron 'skips' over the gap, or does it mean that the electron wave traveled at the speed of light followed by an instantaneous jump later on
  11. P

    Quantum Tunneling of a conduction electron in Copper

    Homework Statement A conduction electron moves through a block of Cu until it reaches the surface. At the surface the electron feels a strong force exerted by the nonuniform charge distribution in that region. This force tends to attract the electron back into the metal which is what causes the...
  12. sevenperforce

    Event horizon and quantum tunneling

    It's been a while since I took any QM so I'm fairly rusty...not even sure that I'm asking this in the right way. How does one set up the equations to determine the characteristics of quantum tunneling if you have a particle with a particular energy inside an event horizon? For example, suppose...
  13. J

    Pilot wave theory and quantum tunneling

    Just a question about pilot wave theory as an alternative to SQM. Researchers in ANU have recently shown that quantum tunnelling of a particle through a barrier is instantaneous. Does this finding verify the Copenhagen superposition interpretation of QM and at the same time invalidate the...
  14. M

    Percentage of Electrons Tunneling Through?

    Homework Statement A stream of electrons is of energy E is incident on a potential barrier of height U and thickness d. Even though U >> E, 5% of the electrons tunnel through the barrier. If the thickness of the barrier decrease to 0.86 d, what percentage of the electrons will tunnel...
  15. J

    Evanescent light waves, energy flow and tunneling

    In the full internal reflection case where we have a refracted evanescent wave, If another object is nearby, then we could have wave tunneling phenomenon(frustrated total internal reflection). 1) So, how can the evanescent wave which does not transfer any net energy produce another wave at the...
  16. goat-on-a-stick

    How can quantum tunneling create Big Bang after heat death?

    Wikipedia states that, after he heat death of the universe: "Random quantum fluctuations or quantum tunneling can produce another Big Bang in years." How would this work?
  17. I

    Quantum Tunneling from Bent Circular Wire

    Homework Statement The electron enters a straight pipe of circular cross section (radius r). The tube is bent at a radius R≫r by the angle α and then is aligned back again. Find the probability that the electron will jump out Homework Equations Tunneling probability in WKB approximation. The...
  18. L

    Finding the Optimal Distance for Electron Tunneling in Gold

    Homework Statement The work function (energy needed to remove an electron) of gold is 5.1 eV. Two pieces of gold (at the same potential) are separated by a distance L. For what value of L will the transmission probability for an electron to cross from one to the other be T≈ 10-3? Assume that G...
  19. S

    Massless fermions Klein tunneling

    QUOTE: "In 1929, physicist Oskar Klein[1] obtained a surprising result by applying the Dirac equation to the familiar problem of electron scattering from a potential barrier. In nonrelativistic quantum mechanics, electron tunneling into a barrier is observed, with exponential damping. However...
  20. MrPhoenix

    Tunneling with broadening of energy levels

    Dear all, I was wondering about the problem of calculating the probability that an electron will tunnel through a certain barrier (let's assume it is a constant value). Problem is that the initial and final energies of the electron are fixed and possesses a certain broadening (for example...
  21. J

    B How does quantum tunneling occur without an observer?

    I have question that involves quantum tunneling and wave function collapse that occurs when the state of an object is measured. I will try to explain what I mean. We don't know the exact location of an electron in an atom, because it doesn't have a location, it is in its wave form and we can't...
  22. A

    Calculating Quantum Tunneling Probability - 1.524 eV, 343 pm, 2.654 eV

    Homework Statement What is the approximate transmission probability (in %) of an electron with total energy 1.524 eV through a barrier of thickness 343 pm, and a potential height of 2.654 eV? (Does it matter what the potential energy is before and after the barrier? Not really, as long as it is...
  23. D

    Tunneling with an alpha particle

    Homework Statement In a simple model for a radioactive nucleus, an alpha particle (m = 6.64×10^−27kg) is trapped by a square barrier that has width 2.0*10^-15 meter and height 30.0 MeV. What is the tunneling probability if the energy of the alpha particle is 18.0MeV below the top of the...
  24. slatts

    Quantum tunneling from nothing

    General Relativity allows a potentially infinite number of spacetimes that are inaccessible to each other (except perhaps at the event--presumably lacking either duration or extent because of its instantaneity-- of their formation), as far as I can recollect from my sketchy reading of Sklar's...
  25. D

    Probability of quantum tunneling?

    As simply as possible, could someone try to explain how one would go about calculating the probability of a electron/(electric voltage) quantum tunneling through an insulator (preferably using an example please)? And how small would the insulator, and how large would the current/voltage have to...
  26. R

    Square Hill Barrier, weird question wording

    Homework Statement Consider a square hill barrier produced by a 10V potential. Incident upon this barrier is a steady stream of 5eV electrons. (a) If half the electrons are transmitted, how thick is the barrier? (Please derive the transmission probability rather than merely quoting it.)...
  27. A

    Quantum harmonic oscillator tunneling puzzle

    My problem is described in the animation that I posted on Youtube: For the sake of convenience I am copying here the text that follows the animation: I have made this animation in order to present my little puzzle with the quantum harmonic oscillator. Think about a classical oscillator, a...
  28. J

    Can Quantum Tunneling Explain the Energy Released by the Sun?

    Hi pf, I'm fairly new to QM so this may seem like a trivial question. As I understand it, an electron (or any small particle) does not have a definitive position in space until it is observed which causes the quantum wave like nature of the particle to disappear (collapse of the wave function)...
  29. F

    Exploring the Potential of Quantum Tunneling Composites for Load Cell Technology

    Is it possible to build a fast, accurate scale using QTC? If so, could someone explain the basics or point me toward a good resource? Thanks!
  30. Avatrin

    How can I animate quantum tunneling using Python and pseudocode?

    Hi Let's say I am supposed to animate the movement of some one-dimensional wavefunction as it hits a finite potential barrier like this: I was supposed to know how to do this over a year ago, but I am never certain how to write the algorithm. What confuses me the most is how to show the...
  31. M

    Any book suggestions for Fowler-Nordheim Tunneling?

    I need a nice pile of books that cover stark effect on semiconductors and metals and Fowler Nordheim tunneling for my thesis. Any suggestions?
  32. B

    Why does infinite potential well give rise to standing wave?

    For a particle in a box that is described with a wave function, why can there only be a standing wave when there is an infinite potential well? From my understanding, the infinite potential well makes it impossible for the particle to tunnel through the barrier and so the wave function cannot...
  33. T

    Fusion Due to Gravitation in Bosonic Atoms

    In a bosonic atom i.e. Hydrogen, why do we never observe quantum tunneling past the coulomb barrier leading to multiple atoms occupying the same area of space thus (due to Newton's law of universal gravitation) accelerating towards each other resulting in nuclear fusion?
  34. T

    Quantum Tunneling: Can Photons Escape Black Holes?

    Could a photon utilize quantum tunneling to escape the threshold of a black hole or the confines of the curvature of space-time? Could any particle for that matter?
  35. S

    Long distance quantum tunneling

    Is it possible to achieve teleportation of data or energy on long distances with help of quantum tunneling some day? Possibly it will require de Broglie wavelength manipulation? How de Broglie wavelength of an electron, for example, could be increased without cooling it to the one trillion's of...
  36. S

    Exploring Barrier Tunneling in Quantum Mechanics

    Barrier tunneling happens when, let say, an electron tunnels through a region when it has lower energy compared to the energy of the region (potential barrier). What differs Quantum from classical mechanics is that CM states the electron will never be able to penetrate the potential barrier...
  37. A

    Tunneling Transmission Probability: DOS or Velocity?

    In some quantum textbooks [1], the tunneling transmission formula depends only on the density of states of 2 regions (DOS) involved in tunneling. (T(E)=C×DOS1(E)×DOS2(E), where C is constant). However, in Landauer transmission formula (without tunneling) the transmission depends on both DOS and...
  38. D

    Crude Probability calculation for tunneling

    Say I have a potential barrier that is 4eV higher then an electrons energy and 5x10^-11 wide. Just by considering the change in amplitude of the wave function from the entry into the barrier vs the exit I am asked to make a rough approximation for the probability of tunnelling. I get the...
  39. S

    Tunneling from Rectangular barrier - Exponential Decay ?

    Tunneling from Rectangular barrier - Exponential Decay ?? Consider the Rectangular Potential Barrier. If one solves bound state Problem in this case, wavefunctions of Exponentially Decaying and rising kind are found for the Region in the Barrier. ψ = A eαx + B e-αx Yet Most Books and...
  40. R

    Simple (?) solving of equations re Tunneling

    Revising for my exams, stuck on how to do this: http://imageshack.us/photo/my-images/594/mr15.jpg/ please could someone tell me how to get (A/F)? thanks for any help! it's not a homework question, just revision so a direct solution would be more than welcome.
  41. PsychonautQQ

    How Does Quantum Tunneling Affect Electron Reflection Probability?

    Homework Statement Calculate the reflection probability for a 5 eV electron encountering a step in which the potential drops by 2 eV The Attempt at a Solution To answer this question, wouldn't I need to know where E > U or U > E? Also wouldn't I need to know the width of the...
  42. D

    How does graphene demonstrate quantum tunneling?

    Hi as an undergrad Physics student learning quantum mechanics for the first time, I'm having a hard time wrapping my head around quantum tunneling, why does it happen, why can it happen? I was also reading that Graphene exhibits tunneling as well, could someone explain this?
  43. PsychonautQQ

    What Is the E/U Ratio for a Half Reflection Coefficient in Quantum Tunneling?

    Homework Statement A particle of energy E approaches a step barrier of height U. What should be the ratio E/U be so that the reflection coefficient is 1/2. Homework Equations Transmission + Reflection = 1 Transmission = e^(-2a*alpha) a = mw∏/h alpha^2 = (8m∏^2/h^2)(U-E) Reflection...
  44. Hyo X

    Is spin conserved in tunneling?

    Say an electron tunnels from one state, through a tunneling barrier, to another state. Is the spin of that electron preserved (the same before and after)? If an electron is traveling through a bulk phase conductive metal (a wire), is its spin stable in one state? What will happen to its spin...
  45. M

    Electron tunneling barrier in DFT

    Hello all, I'm getting confusing about what to consider as a barrier for electron tunneling in DFT. What I'm doing is looking at the xy plane averaged effective potential, i.e. the potential that electrons feel. This potential in PAW formalism is composed of three terms: VHartree+Vxc+Vbar...
  46. P

    How does quantum tunneling enable nuclear fusion in the Sun?

    I know that the Sun radiates vast amounts of energy partly due to nuclear fusion. I've also heard that nuclear fusion can occur in the Sun due to quantum tunneling. I'd like to know how the process of quantum tunneling in the Sun allows nuclear fusion to take place. Thanks!
  47. O

    Quntum tunneling in financial markets?

    Is it possible that nuclear physics and financial markets to fallow the same laws of Nature? This paper suggest it. https://www.researchgate.net/publication/251876307_Quantum_Tunneling_of_Stock_Price_in_Range_Bound_Market_Conditions[/url]
  48. 1

    Elastic Tunneling: Electron Pathways Explained

    Hello everyone, here we have two types of electron tunneling paths of electrons. as shown here, In an elastic tunneling the electron goes directly into metal2 with out falling to Fermi level of metal2..?? or Is it going to fallback by radiating its energy..??
  49. O

    What happens to the energy of an electron after it tunnels through a barrier?

    Hello everybody, I am a first year student and I have a question about tunneling. If we have an electron which is bound by an atom. And that electron has a high probability to tunnel through the barrier that keeps it confined. So it manages to 'escape' from the atom. Shouldn't its energy...
  50. O

    Understanding Alpha Decay: Beyond Quantum Tunneling

    Hello everybody, I am a first year physics student and I have a question about the probability for 'heavy' nucleus to decay. I was thinking the other day, how can we know the probability for that nucleus to decay. Let's suppose that we have an alpha decay. Is the probability of the nucleus...
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