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. K

    Heaviside Step Potential - Tunneling

    I'm working on a basic potential step problem from Griffiths QM. Its problem 2.34 in the textbook. I am having trouble understanding the transmission coefficient in this problem. I realize that I can calculate the reflection coefficient and just do 1 minus the result but I am looking for...
  2. Rorshach

    How Far Must Caesium Atoms Be for a 1% Tunneling Probability?

    Here is one problem I have, I think it is simple, but then again I thought that every problem I had was like that only to discover that there was some trick in the middle, so please help. Caesium has exit work Wut = 1.9 eV. This means, therefore, that there are electrons in the cesium such...
  3. D

    Do All Stars Rely on Quantum Tunneling for Fusion?

    Hello fellow scientists, Do all stars rely on quantum tunneling for fusion or do high mass stars break the Coulomb barrier without tunneling? Thanks
  4. D

    How Do You Calculate Electron Tunneling Probability Through a Barrier?

    Homework Statement Electrons with energies of 0.201 eV are incident on a barrier 2.386 eV high and 0.383 nm wide. Find the probability for these electrons to penetrate the barrier. Homework Equations Note: h = h-bar k=Sqrt[2*m (V - E)]/h T = (1 + (V^2 (Sinh[k*L]^2))/(4*R (V -...
  5. L

    Tunneling to a lower energy vacuum state

    I read that the mass of the Higgs boson is such that we may be living in an unstable vacuum state, and if a region of the universe tunnels to a lower energy vacuum state, and eventually the whole universe would be in that lower energy state (ending life on earth). Do physicists have guesses...
  6. H

    Tunneling at potential step

    Homework Statement A beam of particles of energy E = 9 eV strikes on a step potential and 25% of the beam's particles is reflected back. What is the height of the step potential? (A) 4 eV (B) 8 eV (C) 3 eV (D) 1 eV (E) 5 eV Homework Equations √(R) = [√(E)-√(E-U)]/[√(E)-√(E_U)] The Attempt...
  7. C

    Difference Between Tunneling and Hopping: Explained

    In my research, I've always seen variable range and nearest neighbor hopping referred to as tunneling processes. However, I've also read papers that differentiate tunneling and hopping as two different transport mechanisms. Can someone clear this up for me? Given the context, what exactly is...
  8. L

    Tunneling photons travel faster than light?

    I recently found an interesting read on the mysteries of quantum mechanics, here : Don't know about you, but I am personally confused by this result. How can a photon travel faster than itself? If it can travel faster than itself, than what does that mean for the universal speed limit? My...
  9. S

    Tunneling in a non-subatomic particles

    Hi, We now electrons do tunnel and for example FE happens because of this. However, is it true to scale up this effect for non-subatomic particles? For example, is it OK to say, if you are behind a wall and hit yourself to the wall, there is a chance that you might Tunnel and see yourself on...
  10. L

    Quantum tunneling of a car through a wall

    Hi everyone Homework Statement I have to calculate the probablity that someone can tunnel a wall with a car. I have the mass of the car and the velocity and I know that the wall is 20 cm wide. But I have troubles estimating the potential of the wall. Homework Equations - The...
  11. B

    Quantum Tunneling: Fusion possibilities.

    If an election can tunnel through atomic structures, or move through atomic barriers even when they don't have enough energy, could it be possible to create fusion through tunneling, even without sufficient energy, sufficient relative to standard energy levels needed? I am thinking that it...
  12. E

    What is the physics behind quantum tunneling

    Hi, My friends! According to quantum mechanics books ,a particle has some probability hop through the potential even when the potential is large than kinetic energy. They all explain the phenomenon by solving Schrodinger equation. Indeed, the wavefunction doesn't equal 0 behind the potential...
  13. P

    Understanding Quantum Tunneling: Is the Schrodinger's Equation the Key?

    Hi, I am a physics student but still a layman in QM. I got a task to explain Quantum tunneling and I did my researchs for 3 days (I have read almost all threads here regarding to the topic). I found many different interpretations but I believe the Schrodinger's Equation is the correct answer...
  14. U

    [quantum tunneling] Debate with a friend, am I right?

    It involves quantum tunneling, both of us know very little about physics but I watched a video on youtube about a guy explaining quantum tunneling, from what I underdstand a particle can, with enough energy pass right through other solid surfaces? So I said that if you had a penny, and shot it...
  15. Q

    Quantum Tunneling VS Water (or any other) Waves

    Would a water wave leak just like an electron with a barrier?
  16. Demon117

    Quantum Mechanical Tunneling Probability

    I recently took an exam in which the professor asked the following question: Suppose an object of mass 2 grams were incident on a rectangular barrier of height 20 cm and width 2.0 cm. What is the probability that the object will quantum mechanically tunnel and appear on the other side? I...
  17. P

    Methods to stabilize scanning tunneling microscope(STM)

    When the STM becomes unstable(large variations in the current), what procedures should I take in order to fix it? I am new to the STM, but after a few month`s experience I notice that one of the main problems is stabilizing it. When the tunneling current becomes unstable, I`ve tried to...
  18. R

    Quantum tunneling and the universe

    Alexander Vilenkin has a model of cosmic origins which describes the universe coming into being as a quantum tunneling event. The problem that I see with this, is that this requires the universe to be closed. However, we know the universe is probably flat with a margin of error of less than 1%...
  19. M

    Probability of Quantum Tunneling

    Homework Statement I am given a metal-oxide-semiconductor device. I apply a positive voltage (30 V) on to the metal. Theoretically, the electrons should tunnel through the oxide. I want to calculate the oxide thickness for only 5% of electrons tunneling through the oxide. Homework Equations...
  20. M

    What Determines the Barrier Field in Fowler-Nordheim Tunneling?

    What is the barrier field in fowler-nordheim tunneling?i'm having a hard time understanding it please help.
  21. C

    Quantum Tunneling: Particle location

    A quantum particle can tunnel through a barrier and we can describe why this is so by the uncertainty principle. However, there is something I want to clarify about the reasoning behind this. I believe the argument goes like this: Imagine the quantum particle never entered the barrier and we...
  22. K

    Quantum tunneling and extra dimensions

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  23. S

    Superconductivity by quantum tunneling?

    We have some material with metal atoms inserted in substrate.Maybe by dopping. Electric current is able to move only be quantum tunneling jumping from atom to atom. Could we obtain superconductor in this way?
  24. H

    Inelastic Tunneling Current Equation help

    In this paper ("Molecular Vibration Spectra by Inelastic Electron Tunneling" by J. Lambe & R.C. Jaklevic Phy.Rev. Vol 165, Article 3), the author showed that when external voltage is applied across a metal-insulator-metal, the current passing through the insulator is shown to be: I(V) =...
  25. bayan

    Quantum tunneling and radioactive decay.

    Homework Statement The edge of a nucleus can be roughly modeled as a square potential barrier. An alpha particle in an unstable nucleus can be modeled as a particle with a specific energy, bouncing back and forth between these square potential barrier. Consider a nucleus of radius r and an...
  26. bayan

    Barrier Tunneling Probability (Proton)

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  27. L

    How long would it take for a can of beer to fall over due to quantum tunneling?

    It's on page 4 (this isn't homework, just something I stumbled upon, it's also in Griffith's 8.17):http://www.physics.udel.edu/~msafrono/425/Lecture%2018.pdf . Can someone help me understand this solution? What exactly is happening...are there particles at h/2 that are smashing against the...
  28. S

    Can quantum tunneling in solids generate useful energy when heated?

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  29. D

    Calculate thickness of barrier for tunneling effect

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  30. Z

    Question about quantum tunneling?

    You know how every particle has a non zero probability of being anywhere, but what about outside the particles Hubble sphere? In other words, does is there exist a nonzero probability that a particle can travel at superluminal speeds across the universe?
  31. D

    How to block tunneling current?

    Dear forum members How to block tunneling current? Apart from barrier dimensions like height and thickness are there any other options? Say barrier geometry or chemical property, maybe some magnetic impurity to induce Kondo effect and scatter the tunneled electrons. Thank you in advance Dilema
  32. T

    Does a single electron transistor really need the tunneling junctions?

    If you know how a single electron transistor works, can you please explain to me what the tunneling junctions are necessary for? I mean, if we would remove the two tunneling junctions and connect the drain, the source and the island into one long wire, wouldn't still it be possible to create a...
  33. I

    Alpha Decay from Uranium: Electrical or Strong Nuclear Force?

    Hi, In case of alpha decay from Uranium atoms, i thought the barrier is the strong nuclear force, but i had seen many textbooks saying that it is electrical barrier, and i did rethink the subject and i imagined it as a barrier that have electrical force from one side and strong nuclear force...
  34. S

    Analyzing STM Scans for Tunneling Current Changes

    Homework Statement Suppose that an STM scans a surface at a distance of a=1.000nm. Take the height of the potential barrier to be U°-E=2.00 eV. If the STM tip movies away from the surface by 2.00%, estimate the percentage change in the tunneling current. Homework Equations The...
  35. T

    Particle Tunneling/ Barrier Potential

    1. Show that as the height of the barrier approaches the electron's incident kinetic energy E an approximation to the transmission that includes just a (the barrier width) and the wave number of the incident electron k=((2mE)^1/2)/(h/2pi) can be obtained. The expression has no Vo term. (Hint...
  36. J

    The Flash quantum tunneling vibration problem.

    I was reading "The physics of superheroes", and it mentioned The Flash being able to increase his kinetic energy to tunnel though walls. I tried to find out how fast he would have to go, assuming he is vibrating (as shown in the actual comic) so will have several tries at trying to tunnel though...
  37. J

    Quantum Interference in tunneling electron transport?

    Can anyone break down "quantum interference" in the tunneling transport through aromatic organic molecules? The Math is a little fuzzy, but with a few seminal reference or a conceptual description i might be able to wrap my mind lips around this knowledge pop! haha. any help would be appreciated.
  38. M

    Transmission probability (tunneling) question

    A beam of 11 eV electrons is directed towards a barrier of potential Vo = 3.8 eV. Compute the width of the barrier for which the reflection is maximized (Note: this is NOT asking for when reflection is 100%). Transmission probability for E > Vo: T = [ 1 + (Vo²*sin²(βa))/(4E*(E - Vo)) ]^(-1)...
  39. F

    Phase shift of tunneling particle

    Hi All, I'm sure this question has a trivial answer but for the life of me I've no idea :\ I am calculating (numerically because I am lazy and it scales/ports better to other cases) the phase shift of a particle in the non-rel Schrodinger equation tunneling through a potential step. This...
  40. K

    Aplha particle tunneling through coloumb barrier

    Homework Statement Let us approximate the Coulomb barrier of a heavy nucleus by a square potential with a height of V0 = 14.8 MeV and a width of L = 13.7 fm. What is the probability that an α particle with an energy of 5.70 MeV will tunnel through this barrier? Homework Equations...
  41. N

    Understanding the Physics of Resonant Tunneling Diodes

    Hello :) , Does anyone know some good paper or book from were it's possible to learn physics behind of work of resonant tunneling diode(RTD)? In last semester I had course in ˝microelectronics and nanoelectronics˝ and we studied basic principle on which RTD works, and it was very interesting...
  42. L

    Tunneling effect or barrier penetrability

    The wavefunction associated with a free particle must be continuous at the barrier and will show an exponential decay inside the barrier. Why it shows an exponential decay inside the barrier? After coming out of the barrier, there is reduced probability for the particle. When there is no loss of...
  43. J

    How Does Fowler-Nordheim Tunneling Apply to Scanning Tunneling Microscopes?

    Homework Statement For a project I am doing I have to use the concept of Fowler-Nordhiem tunneling to model a Scanning Tunneling Microscope. Basically we have to relate the current generated from the tip to the field to the tunneling probability. Then relate that current to the applied...
  44. N

    Negative Resistance in Resonant Tunneling

    Hi, I am a student who's learning about quantum mechanics. I was reading about the RTD (Resonant tunneling diode) and I got the general idea. However, I was looking at a I vs V graph and came up with a question. Since Resistance = V/I, the inverse slope of the I vs V graph has to be the...
  45. J

    Barrier and Tunneling Problem

    Homework Statement A 1.1 eV electron has a 10-4 probability of tunneling through a 2.4 eV potential barrier. What is the probability of a 1.1 eV proton tunneling through the same barrier Homework Equations eq 1) T= [1 + V02 sinh2(kL)/4E(V0-E)]-1 or if (kL)>>1 we use eq 2) T=...
  46. J

    Tunneling equation have all the pieces, just can't figure out the calculation

    Tunneling equation...have all the pieces, just can't figure out the calculation! Hi, I have an example from my book on Tunneling. All the parts of the equation are given, including the answer...put I keep comming up with the inccorect answer. Maybe someone can clarify how to calculate...
  47. Z

    Quantum Mech (Barriers and Tunneling)

    1. Two nanowires are separated by 1.3 nm as measured by STM. Inside the wires the potential energy is zero, but between the wires the potential energy is greater than the electron's energy by only 0.9 eV. Estimate the probability that the electron passes from one wire to the other. 2...
  48. Z

    Barriers & Tunneling: Find No Reflection & Max. Reflection Thresholds

    1. Let 11.0-eV electrons approach a potential barrier of height 3.8 eV. 2. (a) For what barrier thickness is there no reflection? (b) For what barrier thickness is the reflection a maximum? 3. For part (a) I tried using kL=npi where k=sqrt(2m(E-V))/hbar, because this is where the Probability...
  49. L

    When we want to show quantum behavior (like tunneling or double slit)

    When we want to show quantum behavior (like tunneling or double slit) of a large object like a buckyball molecule, what do we need to watch out for in an experiment? Is it the following? a, that all constituents of the object (the single atoms of the buckyball) are described by one coherent...
  50. C

    How Long Would it Take to Drop an Object Through a Tunnel on the Moon?

    I have always been curious about what would happen to the gravity at the center of the earth. After some googling I found some neat stuff. So IF it was possible to endure the heat and pressure to get there (impossible) it would feel weightless. So that answered my question but then I read it...
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