Tunnelling Definition and 50 Threads

Which physics concepts and phenomena other than "CP violation" have to deal with the breaking (not validity) of "Invariance of Time Reversal", like for the Weak Force (e.g. for beta-decay)? The underlying mathematical and physical theory to this inquiry is based on advanced physics textbooks as...

While reading something recently that mentioned the Casimir Effect, it occurred to me that the plates used in an experiment to measure the force between them would be close enough to allow quantum tunnelling if the plates were transparent, which led me to wonder whether (and how much) the force...

A macroscopic object has the order of Avogadro’s number of particles. That’s over 10^23. So the probability of all of them tunneling, at the same time, is on the order of that original small probability, to the 10^23 power. And then on top of that, you have to factor in the chances of it...

We know that thanks to the tunnel effect, in the case of a finite potential step (V) and considering a stationary state, when a plane wave with energy E < V encounter the step the probabability that the wave-particle coming from -∞ (where potential is V=0) will be ≠ 0, in particular the wave...

A lot of popular level explanations introduce the idea of tunneling by saying that "in principle" a person in one room can "find themselves" in the next room, i.e. one can tunnel through a wall Of course, the presenter then hastens to clarify that this is so unlikely that we would have to wait...

I just finished watching the video "The Last Light Before Eternal Darkness – White Dwarfs & Black Dwarfs" At 5:17 he mentioned quantum tunneling will take up a timespan so long that calling it forever is ok. But nothing takes forever,so,how long will it actually take? ps:I later realized...

Hi everyone, I have been studying the physics of solar cells for a long time. The only thing that I can not completely understand is the physical operation of solar cell based on band diagram. Can anyone briefly explain the movements of carriers from one electrode to the another based on band...

When I hear that mass of a particle has managed to hop through a solid barrier ..it tells me that the mass was a variable and not physical at the time.

Assume you have a 2 particles sitting inside a double potential well. Each particle occupies one side of the well and given enough time the particles may both be found on the same side or swap sides (tunnelling). Assume that the well is inside a gravitational field. It is positioned in such a...

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.)...

Hi all, This is my first post on PF so forgive any rookie errors. I'm a 17 year old British student. I have just finished a month long placement at Newcastle University researching my chosen topic of quantum tunnelling. The placement itself was very disappointing and I had no interaction with...

Is it correct that that the wavefunction of a particle is well defined in the classically forbidden region? This would seem to suggest that there would be a chance of finding it there. But I think that is not allowed. Have any experiments actually discovered particles in the barrier or do they...

Here we have a STM tip placing a potential V across a monolayer with a single electron on it. | STM (scanning tunneling microscope) Tip | | |...

Sorry for my abysmal level of ignorance, but I'm not understanding why quantum tunneling from nothing is considered a possible starting point for a multiverse, when the permanence of our pocket universe within the multiverse is also considered to be threatened by a phase transition if its vacuum...

Homework Statement The waves amplitude appears to decrease as it tunnels through the barrier. If we think of the amplitude as energy like in a sound wave etc, where does this energy go? The Attempt at a Solution I think it has something to do with the fact that for a matter wave the...

Homework Statement A particle with the energy E < V_{0} (V_{0} > 0) moves in the potential V(x) = 0, x<0 ; V(x)= V_{0}, 0<x<d and V(x)= 0, x>d. Measure the probability that the particle will tunnel through the barrier by calculating the absolute value of the ratio squared...

Homework Statement The tip of a scanning tunnelling microscope is placed 1.0 nm away from a conducting surface and a potential of dV = 0.03 V is applied to the surface relative to the tip. When the tip is moved laterally to a new position on the surface the tunnelling current increases by...

I have an undergraduate minor in astrophysics from a long time ago and have been brushing up to teach my kids, so I'm not an expert or even a great student of these things, but something I thought I'd log in and ask here: If special relativity stands for the premise that there is no preferred...

Just a quick question, that I'm not completely clear about; Quantum tunnelling allows particles to overcome barriers that they classically shouldn't be able to overcome, my question is simply, do/can particles escape a black hole after passing the event horizon due to tunnelling? If not, why...

I'm reading a little bit about electron microscopes. It states, "the exponential tunnelling factor is proportional to the square root of the mass. So, the lower mass means lower exponential decay of the wavefunction". Would anyone be able to let me know what this exponential tunnelling...

I'm in the process of studying for my final and I just can't solve this problem: 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...

Can anyone link to a synthetic and understandable explanation of radioactivity through basic quantum mechanics? It does not need to be a comprehensive explanation at all, examples or partial explanations are fine. Online class notes are welcome but so are books suggestions. Thanks in advance

I have been trying to calculate the transmission coefficient for a quantum tunelling case, but I seem to get the coefficient value more than 1. How is that possible? The equation i used is based on the wikipedia page (I am unable to link because I am underpost). Also typically what are...

Hi, This is a really basic question that I was hoping to get a simple answer for. What types of particles tunnel the most effectively? Do high energy electrons tunnel more effectively than if they were at low energy?

What does the piezoelectric scanner do? Does it record the electric current tunnelled by the tip or is it just used to move the tip in response to electric currents?

Homework Statement COnsider electrons tunnelling through a 10eV barrier over a distance 0.001mm. Find E_{1}. (The energy of the first tunnelling resonance.) Homework Equations I have an equation for the tunnelling probability...

Zee's QFT in a Nutshell makes a short comment in the first chapter about the possibility of particles tunnelling outside their light cone - is there some probability that a particle could do this? I know the neutrino thing has been debunked as a faulty cable, but did not see this offered as an...

does not occur because the probabilities are of the magnitude of exp[ -1 / h ], give or take a few decimal places, correct? i.e. 1 / some number with > 10^30 zeros after it (trying to explain this simply to my daughter)

Homework Statement It's not really a given problem, it's more of a section of my lecturing I truly just don't understand. I'm given that the probability of transmission (T) is the ratio of the intensities of the transmitted wave and the incident wave. However, a bunch of math gives also that...

Hi, I wanted to explain quantum tunnelling to people with no scientific background - I've come up with the following analogy, but I'm only a physics undergrad and I'm not sure if it's a good enough analogy. I can do the maths behind tunnelling but it's just the concept I'm trying to get across...

Hi All, I have a question regarding the WKB method for computing tunnelling through barriers. I understand the method and the ability to arrive at a solution as given in the first part (summary) of the first page here: http://www.physics.udel.edu/~msafrono/425/Lecture%2018.pdf Is it...

In quantum tunnelling,as I understood,when a particle reaches the boundry of a potential barrier,it is possible,that the particle passes the barrier and it is performed like disappearing before the barrier and appearing after it.If the latter is the case,so there should be a motin which is...

Hey guys what are some technologies that use Quantum Tunneling? I've been looking on Google and i havnt had much luck! I just need a point in the right direction so links to websites and such would be greatly appreciated! BTW when searching google i found Quantum Tunnelling Composites which...

I understand quantum tunnelling while thought as the one happening in fusion.But could someone explain the process when we're talking about a particle passing through a physical barrier not just a potential barrier? thanks

On the sitcom 'The Big Bang Theory', one of the jokes goes: "A physicist walks into an ice cream parlor and orders an ice cream for himself and one for the empty seat next to him. He does this for weeks until the owner asks him what he's doing. The physicist says, "well, I'm a physicist, and...

This is what it says on Wikipedia : Quantum tunneling refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount because its total mechanical energy is lower than the potential energy of the barrier. But I would like to...

Hey guys.i have heard it has been experimentally proved that even atoms can tunnel through a metal surface.I tried searching all over the web but just could not get any references on that.So,is that true?if somebody know where i can read more about that experimental proof,please point it out...

Homework Statement What is transmission probability (T), when the incident particle energy (E) is equal to the energy of the barrier (U)? Homework Equations Equations to transmission and reflection probabilities. http://i950.photobucket.com/albums/ad348/gs5720/img099.png?t=1278212132...

Homework Statement At x=0, a proton with a kinetic energy of 10 eV is traveling in the x direction (potential energy = 0). At x = 1nm, it encounters a potential barrier of height 12 eV and width .2nm. The potential returns to 0 at x = 1.2nm. Give the amount of the particle on both sides...

Or not?

Nimtz and Stahlhofen claim that their recent tunnelling experiment proves that tunnelling time for light between double prisms is zero. In Herbert Winful's response to this (http://arxiv.org/ftp/arxiv/papers/0709/0709.2736.pdf) he explains that the evanescent wave formed in the gap only has real...

I'm just making sure... after a particle tunnels through a potential barrier, assuming that there are no forces acting on the particle, like friction, etc. which dissipates energy, the particle should have the same energy as it did before it tunneled through, right?

''The Scanning Tunnelling Microscope probes the density of states of a material''... What does this actually mean?

Homework Statement The probability of a person quantum mechanically tunnelling through a wall Homework Equations The Attempt at a Solution I'm not too sure how to approach this problem, I calculated the de Broglie wavelength of the person (mass = 60kg, velocity = 30 m/s; These values are...

I am dealing with the classic problem of a potential barrier of finite width, with a particle tunneling through, in the case of E < V. I am to calculate the transmission/reflection coefficients, and we first start off with the wavefunctions for the three regions. Before the barrier, we...

I'm continuing to read Jim Al-Khalili's book Quantum: A Guide for the Perplexed. I'm on page 190; today I just read a few paragraphs and page 176 about quantum tunnelling. My question is this: what does it take to say that an electron, for example, has successfully and definitely tunnelled...

Hi, I wanted to know how the pre-exponential and exponential terms of the standard Fowler Nordheim Tunnelling is calculated to a certain value. So can anyone give the calculations of these two terms? The FN Expression is given as J = A.F^2.exp(-B/F) Where J = Current Density, A =...

Does relativistic quantum mechanics make use of 4 dimensional Minkowskian geometry? Or does it just use special relativity formulated in 3 space dimensions and 1 time dimension? And if quantum mechanics can apply to Minkowskian spacetime, then can something tunnel through time?

In the quantum tunnelling process, where an electron tunnels though the potential barrier, we known this to be true by always seeing the electron we test for. We have always found what we were looking for and therefore have NEVER considered or thought about any other vallid or acceptable...

Could some please explain me how quantum tunneling works?