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4
votes
1answer
204 views

Does tunneling transmission probability depend on the density of states or velocity?

In some quantum text books [1], the tunneling transmission formula depends only on the density of states of 2 regions (DOS) involved in tunneling. ($T(E) = C \times DOS_1(E) \times DOS_2(E)$, where C ...
0
votes
0answers
21 views

Question on tunneling of alpha particle [on hold]

In the tunneling of alpha particles. How can i find number of alpha particle that will tunnel through the barrier per second?
0
votes
1answer
67 views

Quantum mechanical tunneling [on hold]

Keeping extraneous ideas and postulates to a minimum, How can we explain the process of quantum-mechanical tunneling?
0
votes
0answers
19 views

Tunnel diode/quantum tunneling

How does a tunnel diode work?/How does a tunnel diode use quantum tunneling, and how does quantum tunneling make the diode faster?
-1
votes
1answer
42 views

Wave-Particle Duality and Quantum Tunneling Experiment [closed]

Take this experiment. Setup a Wave-Particle Duality experiment, that is the double-slit experiment with a variable observer. Now perform a quantum tunneling test after, to see if any information can ...
0
votes
0answers
59 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 ...
2
votes
1answer
165 views

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?
1
vote
0answers
80 views

Funny relation with Quantum Tunneling and Newtonian Simulation [closed]

I just finished my first QM class, and have also been working on a 2d game engine for a while now. I learned about Quantum Tunneling, and the equations involved in calculating the odds of that ...
0
votes
0answers
24 views

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 ...
2
votes
1answer
223 views

What can tunnel through a graphene sheet?

In popularizations, people tunnel through walls or doors. But what can really tunnel through a graphene sheet without tearing it? According to Wikipedia, a single layer of graphene absorbs 2.3 % ...
0
votes
0answers
48 views

What is the connection between negative kinetic energy and tunneling?

In my QM lecture today prof showed that a particle going through a potential step for which the energy of the particle is $0 < E < V_0$ There exists a non-zero transmission coefficient into ...
0
votes
2answers
46 views

Strong force and quantum tunnelling

I am well aware of how quantum tunnelling works and how it is responsible (among other things) for the alpha decay. Inside a nucleon, there are two quarks with the same charge, so they will repel ...
2
votes
1answer
109 views

Calculating probability of finding the particle using Dirac notation

An electron can be in one of two potential wells that are so close that it can ‘tunnel’ from one to the other. Its state vector can be written $|ψ\rangle = a|A\rangle + b|B\rangle$, where ...
2
votes
1answer
123 views

Why is quantum tunneling most significant between states of equal energy?

Why is it, that quantum tunneling is only significant between states of nearly equal energy (as claimed here: 'Since tunnelling is significant only between states of nearly equal energy, tunnelling is ...
3
votes
4answers
156 views

Virtual particles/quantum tunneling - conservation of energy?

I'm confused as to how the above phenomena can take place since arent they breaking the law of conservation of energy (even, if temporarily)?
1
vote
0answers
108 views

Why the current through a resonant tunnel diode drops when the bound state goes below the conduction band?

The IV curve of a resonant tunneling diode is N-shaped. The rise in current flow happens because the bound state (the energy state in the well) enters the thermal area of the conductor ($\mu_1 + ...
2
votes
2answers
74 views

Why a tunnel diode (TD) is called a diode?

Traditionally, a diode is a 2-terminal device that limits current to flow in one direction, i.e. a rectifier. But a "tunnel diode", according to wikipedia, is not rectifying: In the tunnel diode, ...
0
votes
1answer
48 views

What's the difference between tunnel diode (TD) and resonant tunneling diode (RTD)?

According to wikipedia, a tunnel diode is a PN junction whose energies are shifted with bias, while a resonant tunneling diode is a quantum well between a double barrier, whose energies change with ...
3
votes
0answers
56 views

Tunneling from Dirac material into Schrodinger material?

When a Dirac material, like graphene or TI, has a connection with a normal metal which Schrodinger equation govern on their carriers, how could we manipulate the tunneling of electron from Dirac side ...
4
votes
2answers
113 views

Can Half Lives (hypothetically) be Measured by Wave-functions?

I understand that half-lives are measured over several days/months/years of observing a certain amount of an element and seeing how long it takes to decay a certain amount, but I'm curious as to ...
0
votes
2answers
111 views

Does quantum mechanics contradict macroscopic determinism?

I am wondering whether it is true to ask whether determinism is still completely viable at macroscopic scales given that the constituent particles behave according to QM when the dimensions get small ...
2
votes
2answers
191 views

What's the difference between hopping and tunneling?

My professor made a distinction between electron hopping (the closest wikipedia had an article on) and tunneling, saying that one (he didn't say which, but I assume hopping) was temperature dependent ...
10
votes
5answers
1k views

Is there a classical analog to quantum mechanical tunneling?

In comments to a Phys.SE question, it has been written: 'Tunneling' is perfectly real, even in classical physics. [...] For sufficiently large temperatures this can put the system above a hump in ...
2
votes
1answer
1k views

How is quantum tunneling possible?

How is quantum tunneling possible? According to quantum mechanics, each particle is represented by a probability density function. This function must be continuous, and therefore when we look at a ...
6
votes
3answers
425 views

Is quantum tunneling related to imaginary time?

I was studying for my exam and looking at the chapter which talks about Potential-energy graphs. Let's take this as an example: My book states that: "If the object is in $B$ and has a total energy ...
1
vote
1answer
227 views

Finding particles in the classically forbidden regions [duplicate]

Have particles ever been found in the classically forbidden regions of potentials? For example, in a square well: has an experiment been able to find an electron outside the rectangular well (i.e. in ...
4
votes
2answers
343 views

How much time does it takes an electron to tunnel through a barrier?

I know that in quantum mechanics there is no "time operator", so such a question is ill-posed. Anyway if the tunneling is instantaneous, this would imply an information transmission faster than $c$. ...
1
vote
0answers
93 views

Quantum tunneling in a time dependent potential

I wonder if I could use the technique for finding the tunneling rate given by $$ \Gamma=2 \Im[ F]$$ where $F$ is the free energy in case of time dependent potentials? Relevant to the previous ...
2
votes
2answers
120 views

Extra energy in quantum tunneling

In quantum tunneling, the probability of finding an electron inside the potential barrier is non zero (http://i.stack.imgur.com/v8Kr1.gif). So we can actually find an electron which had an energy E in ...
2
votes
3answers
276 views

What happens with a tunneling particle when its momentum is imaginary in QM?

In classical mechanics the motion of a particle is bounded if it is trapped in a potential well. In quantum mechanics this is no longer the case and there is a non zero probability of the particle to ...
0
votes
0answers
68 views

on understanding tunnel effect

i was reading a specific book on quantum mechanics, partiicularly on the tunnel effect section. I am trying to understand how the probability of an eletron passing a barrier of energy V0 is ...
3
votes
3answers
145 views

Why do tunneling photons outrace their non tunneling counterparts in vacuum?

If we describe a photons with a wave packet, moving towards a potential barrier and E smaller than V, there is a finite chance that it will tunnel to the other side. In this process it is likely that ...
2
votes
1answer
367 views

What is the derivation of the formula for the probability of transmission through a barrier?

This site has a formula for the transmission probability over a barrier (in transistors): $$ T \propto \exp [-2(2m^*/\hbar ^2)^{1/2}(q\phi)^{1/2} d ]. $$ Where $T$ is the transmission probability ...
1
vote
0answers
94 views

Is energy lost in an elastic tunneling process?

Suppose we had two metal plates separated by an Angstrom. Now, apply a voltage $V$ between the two metal plates. There will be a tunneling current $I$ between the metal plates. Since $P=IV$, does ...
2
votes
1answer
163 views

Phase Shift of Tunneling Wave

What is the phase shift of a wave that tunnels through a barrier, meaning the difference in phase between the incoming (in front of the barrier) and the outgoing (behind the barrier) waves? For ...
1
vote
2answers
566 views

From where does a particle get the energy to tunnel?

When a particle is made to confine more and more to a particular position it breaks the energy barrier to get out because of the uncertainty principle. But, from where does the particle get the energy ...
5
votes
2answers
202 views

Quantum barrier for photons [closed]

In quantum mechanics, a particle may tunnel through a barrier it would not be able to surmount in a classical sense. My question is this: What are all the factors that may prevent a photon from ...
0
votes
2answers
724 views

Quantum mechanics potential barrier problem [duplicate]

While reviewing some quantum mechanics, I cam across a very interesting situation. For a potential barrier, if a particle has an energy $E$ less than the potential barrier $V_0$, it is possible to ...
3
votes
0answers
64 views

The relation between the action of tunneling and the energy

In the semi-classical physics, the probability of the penetration through a barrier is given by $$ p \sim \exp \left( - A_{0} (E) \right), $$ where $A_0$ is the imaginary part of the action and $E$ ...
1
vote
1answer
465 views

Tunnelling through a Dirac potential barrier

I am reading a QM book by Griffiths, which says it is possible for wave particle to tunnel through a barrier formulated by a Dirac function. This function is known to peak at infinity and also ...
5
votes
1answer
366 views

Quantum tunneling effect in a potential of the kind $V(x)=A\frac{x^2}{1+x^4}$

Given a potential: $$V(x)=A\frac{x^2}{1+x^4}$$ with $A\gt 1$ and a quantum particle inside the well around the point $x=0$. I'm stuck on the calculation of the transmission and reflection coefficients ...
6
votes
1answer
223 views

Does tritium hydride exhibit measurable spontaneous fusion via proton tunneling?

In a fascinating 30 June 2013 article in Nature Chemistry, researchers from the University of Leeds found that when molecules of hydroxyl (OH, a fairly stable radical) and methanol (CH$_3$OH) are cold ...
5
votes
3answers
3k views

Tunneling v. Hopping

Can someone explain the difference between hopping and tunneling? The context I'm considering is conduction in semiconductors, specifically between impurity states within the bandgap. It's always ...
2
votes
0answers
149 views

Definition of a 'tunneling lifetime'

I'm given a one-dimensional potential with two wells, one local minimum at some higher energy and one deep global minimum next to it, separated by a barrier of own shape and height (phase qubit). I ...
2
votes
1answer
1k views

How to solve Schrodinger Equation - Tunnelling

I have to solve analitically the Schrodinger equation in one-dimension with a barrier of potential (tunnel effect): $$ih \frac{d}{dt} U(x,t) = \left[ \left(-\hbar^2 \frac{d^2}{dx^2} \right) + q V(x) ...
7
votes
1answer
268 views

Understanding multiple instanton contributions to vacuum tunneling in a double potential well

I'm trying to understand the method of calculating the transition probability of one vacuum state to another in a double well potential, using instantons. The reference I am following is Sidney ...
0
votes
2answers
440 views

Quantum tunneling and a football permeating a wall

I was wondering if I can say to a layman that "upon throwing the ball on a wall an enormously large number of times, there is a small probability that the ball will go through the wall", while ...
11
votes
1answer
284 views

Hawking Radiation as Tunneling

Firstly, I'm aware that Hawking radiation can be derived in the "normal" way using the Bogoliubov transformation. However, I was intrigued by the heuristic explanation in terms of tunneling. The ...
-1
votes
2answers
642 views

Quantum tunneling is faster than light travel?

Quantum tunneling is faster than light travel ? My reasoning is that the particle cannot be detected inside the tunnel so if it travels from A to B it must be instantly going from A to B , hence ...
0
votes
1answer
679 views

Could Dark Matter be a manifestation of tachyons tunnelling between black holes? [closed]

Among the many Dark Matter candidates, I wondered if there are any along the lines of the title. The inner horizon of a black hole, with its mass inflation, and/or the high spacetime curvature, seems ...