Quantum tunneling is a classically-forbidden quantum effect that allows an bound object with energy less than the boundary to penetrate it with a small probability. A notable example is $\alpha$-decay

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Mechanism for collapse of iron stars into black holes via quantum tunnelling

In the wikipedia page "Future of an expanding universe" it refers to the scenario of a future without proton decay. The page talks about how processes would lead to stellar-mass cold spheres of iron, ...
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Why we can't use quantum tunnelling still in nuclear fusion where sun uses this trick of nature easily?

Sun haven't enough temperature to break down coulomb barrier between two protons to be fussed.But yet nuclear fusion occurs through quantum tunnelling process.So,why we can't use quantum tunnelling in ...
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Scattering from a step potential barrier

Suppose a potential barrier of the form $$ V(x) = \begin{cases} V_0 & x>0 \\ 0 & x<0 \end{cases} $$ Then, for energy $E$ such that $E < V_0$, we have that the transmission and ...
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Tunnelling induced energy splitting

In 1D lattice, the energy splitting of the zero energy edge modes or Majorana fermion modes in the topological insulator seems to be due to the tunnelling between the modes at opposite ends. This ...
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What does it mean to have a transmission coefficient 1.03*10^-3

I solved a potential barrier problem. E=4.5ev V0=5eV barrier width a=950pm The transmission coefficient came out to be 1.03*10^-3 I was wondering what this means? isn't the transmission probability ...
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Applicability of wavefunction matching when Hamiltonian (not just potential) varies

A simple tunnelling calculation can be performed for a potential step by calculating the eigenfunctions for the Hamiltonian on either side of the step and matching the wavefunctions (and using ...
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How to calculate tunneling current between two metals separated by a dielectric?

If I have two metallic electrodes (e.g. Al, Cr) separated by a dielectric (ε, d; e.g. SiO2), how can I calculate the tunneling current as a function of applied voltage?
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What is the kinetic energy of a quantum particle in forbidden region?

I have read that if a particle is trapped in a finite potential well, it has a finite chance to tunnel out from it. Therefore, one can find a particle in a region where its potential energy is greater ...
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107 views

How can quantum tunnelling lead to spontaneous decay?

I have never understood what measuring process (if any) is supposed to be continuously polling the quantum state of an unstable bound system subjected to decay via quantum tunnelling. The reason I ...
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53 views

Quantum tunneling and the Gamow Factor

I've seen the equation for the probability of particles overcoming the Coulomb Barrier in the following form: $$P(E)=\exp\left[-\sqrt{E_G/E}\right]$$ Where I'm using the numerator $E_G$ as the ...
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In semiconductor devices, why is quantum tunneling “fast”?

I'm reading up on semiconductor devices that rely on quantum tunneling, such as the tunnel diode and the TFET. The big advantage of these devices is apparently that "quantum tunneling is extremely ...
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Klein tunneling in graphene including intervalley scattering

In calculations relating to Klein tunneling (in particular in graphene) I have seen the treatment of a "smooth" potential (on the scale of the Fermi wavelength) or the more typical treatment of a "...
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Calculation of Berry's phase due to monopole tunneling event of $O(3)$ NLSM on square lattice

I am currently reading the seminal paper by Duncan Haldane: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.61.1029 In this paper, he asserts that for a unit-vector field $\hat{\Omega}(x,y,t)...
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Showing the transmission coefficient is valid

In a semiconductor device, electrons accelerated through a potential difference of 7V attempts to tunnel through a barrier of width 0.5nm and height 10V. Assume the potential is zero outside the ...
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82 views

Single particle tunneling Hamiltonian

In reference to Problem 9, Chapter 2 in Modern Quantum Mechanics by JJ Sakurai, For a single particle tunneling in a 1D double well potential, with position eigenkets $\mid R\rangle$, $\mid L\rangle$....
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Explanation of crystal formation in a Fitzroy's storm glass with the change in weather conditions

I was recently reading about Admiral Robert FitzRoy's storm glass and how it was used to predict the weather conditions based on the formation of camphor crystals in a sealed glass tube containing ...
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136 views

1st Law of thermodynamics (conservation of energy) and quantum tunneling

Doesn't quantum tunneling contradict the 1st Law of thermodynamics? As far as I remember my school physics teacher told us that quantum tunneling is the reason why we can observe the alpha decay, as ...
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68 views

What exactly is Quantum Tunneling? [closed]

What is quantum tunneling How is it possible? I tried reading up on itbut i couldn't exactly grasp the concept.
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Tunneling in classical mechanics

According to a classical mechanics a particle that do not have enough energy will not be able to surmount a potential barrier. But what if we have a lot of particles(e.g. electrons)? They can ...
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55 views

Can photons undergo quantum tunneling? [duplicate]

Most leptons can do this so I'm curious to see if photons or any bosons at all can.
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Chiral tunneling in Weyl Equation

I am trying to understand perfect tunneling of particles obeying Weyl equation through a potential barrier at normal incidence. I know that this has something to do with chirality, but I am not ...
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71 views

Are coherent tunneling and incoherent hopping belong to quantum interference?

What the accurate definition of quantum interference in molecule or molecules? In some case, there is coherent tunneling in a molecule junction while sometime it is incoherent hopping, or even the ...
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Will using the WKB method for tunneling current give incorrect results for specifically low applied voltages?

I am simulating quantum tunneling through a rectangular potential barrier, as a function of applied voltage across the barrier as well as barrier thickness. I am following the theory from the book "...
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69 views

What's the bubble's wall made up of in false vacuum decay? [closed]

It is well known that for some kind of double well potentials, there are two minima with one is unstable called the false vacuum while the other stable one called the true vacuum. The tunneling is ...
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Two-Band k.p Model is not Hermitian for imaginary wavevectors

In E. O. Kane's original work on Zener Tunneling, he uses a two-band $k\cdot p$ model for the semiconductor bandstructure: $$H=\begin{pmatrix}E_g+\frac{\hbar^2k^2}{2m_0}&(\hbar/m)kp\\(\hbar/m)kp&...
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Tunnelling from a normal metal into a superconductor

a similar question has already been asked in the forum but unfortunately I cannot yet comment and still think that some things left unanswered. My question is in general concerning the tunnelling ...
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187 views

How can I understand the tunneling problem by Euclidean path integral where the quadratic fluctuation has a negative eigenvalue?

I came across the S. Coleman's seminal papers 'Fate of the false vacuum' (http://dx.doi.org/10.1103/PhysRevD.15.2929, http://dx.doi.org/10.1103/PhysRevD.16.1762) where he describes the tunneling ...
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Refraction: Energy flow, tunneling and Evanescent EM waves

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). I am ...
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Does quantum tunnelling drill holes in solid state drives?

The solid state drive (SSD) consists of numerous data storage elements. Each element (NAND flash memory element) reminds me of a microscopic battery. An electron is supposed to enter the element ...
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Why do wider double wells have a lower $\Delta E$ than thinner ones?

In this diagram, in which an $n=1 (E_{1})$ and $n=2 (E_{2})$ wave have been superimposed, the probability density of the new, combined wave changes with time. The period of its shifting density is ...
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63 views

Can the internal energy of a system change by itself?

Thermodynamically it is not possible. Internal energy of a system can not change until and unless an external work is done on the system or by the system. But I came across a very strange process of ...
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Can a particle tunnel from inside a black hole?

Event horizon isn’t special from GTR standpoint, and at least in AdS/CFT correspondence gravity can be “removed” from consideration entirely. So can a particle whose wave function is completely inside ...
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Dimensional Analysis of tunnelling current expression

I have been racking my head trying to get the units to work on an expression for 1D tunnel current through a potential barrier. This expression is straight from S. Sze's "Physics of Semiconductor ...
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What is the electron barrier tunneling mass, and why it is necessary? What is the ebarrier tunneling mass of AlGaAs?

I am doing solar cell simulations in synopsys software. I am getting a persistent error saying ebarrier tunneling mass has not been defined. Is anyone familiar with this error? What is this ...
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Why is there an energy gap in superconductors?

I'm a little out of my depth here... I'm trying to understand quasiparticle tunnelling in superconductor-insulator-superconductor junctions. Many books use the "semiconductor model" to explain this: ...
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Where does particle borrow energy from to tunnel?

Where does particle borrow energy from to tunnel? It is implied that particle can borrow energy and leaped over to the other side wherever that is, the shorter the gap the more energy it borrows my ...
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47 views

How are resistivity and tunneling related?

If we consider a sandwich with three nanometric layers: conductor-insulator-conductor and apply voltage (lower than breakdown voltage) from both sides tunneling will occur. Is tunneling dependent on ...
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Why does transmission probability decrease, increase, then decrease again?

We did a quantum tunneling lab online. We used a Java program to model the electron wave function and show what happens when there is a step potential (U is less than E). Our value for the ...
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Probability conservation in WKB tunneling

Suppose we have quantum mechanical plane waves of energy $E$ incident upon a one-dimensional potential barrier $V(x)$ with sloping sides. One can compare the WKB solutions in the three relevant ...
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The Tunnelling Man [closed]

What's the probability that I will tunnel through a solid wall? By "tunnel" I mean, the probability of finding me on the other side of the wall. Assumptions Wall thickness = $d$ Clearly state any ...
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Layman's explanation of the mysterious occurrence of quantum tunneling?

I see much talk about probability and functions, quantum states and ball-in-a-pit analogies. Bah. I would like an easy summary about the principles behind, demonstrations of, and application from ...
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How to derive the Gamow factor in the simplest way?

I want to know how to derive the Gamow factor (how to solve the integral and which approximation I have to do) without the centrifugal correction. $$V(r) = V_N(r)+V_c(r). $$ The Gamow factor is ...
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What was the largest object/particle tunneling observed?

What is a current record? Reference to that would be nice. and what can be expected in near future? what are the theoretical limits?
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344 views

If an electron tunnels and loses amplitude, but maintains energy; where does the rest of the amplitude go?

I'm assuming the 'amplitude' is kind of like the MeV it has on it, so could be seen as a product of the voltage applied to that electron in a field. But how can it 'lose' volts when passing the ...
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What really happen with resonance inductive coupling

I can't figure out the picture of resonance inductive coupling I can image how magnetic inductive coupling works, It scatter magnetic around one coil and if second coil being near it then induce ...
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Can you communicate future information through the event horizon?

According to Hawking on "Particle Creation by Black Holes", there exists a relationship between the entropy outside of an event horizon, flux within the event horizon, and the area of that same event ...
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174 views

Quantum mechanical tunneling

Keeping extraneous ideas and postulates to a minimum, How can we explain the process of quantum-mechanical tunneling?
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107 views

Effective Coulomb barrier for deuteron

What is the effective Coulomb barrier for a Deuterium-deuterium fusion reaction? I am seeing temperatures of about $40 \times 10^7 K$ online, but have no idea how they are getting this. If we have $...
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In principle, can energy “tunnel” directly out of a black hole? If not, why not?

Energy seems to quantum tunnel through normally impenetrable barriers, so I wonder why not the back side of an event horizon?
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What are the conditions of wave function continuity when solving for Dirac Spinors as done in “Klein paradox” paper by Novoselov?

In the paper "Chiral tunneling and Klein paradox" paper by Katsnelson, Novoselov, and Geim, they use the wave function for Dirac spinors. What are the conditions for continuity of the wave function ...