Tunneling Definition and 247 Threads

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...

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...

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??

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...

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...

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...

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

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...

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...

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...

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...

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...

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?

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...

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...

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...

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...

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...

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...

Homework Statement [FONT=Times New Roman]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...

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...

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...

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.)...

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...

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)...

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!

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...

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

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...

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?

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?

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...

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...

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...

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...

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...

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.

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...

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?

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...

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...

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!

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]

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..??

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...

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...

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...

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...

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

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 -...