- #1
Jack
- 108
- 0
What is quantum tunneling?
Last edited by a moderator:
The square of the Wave Function of a particleOriginally posted by Jack
What is quantum tunneling?
Mmm.. no.. sorry. This is not quantum tunneling!Originally posted by schwarzchildradius
Twist two wires together and hook up a voltage potential across them. The electron has to tunnel through the barrier of the air that exists between the twisted together wires.
I'm sorry, that's incorrect. The electrons have enough thermal energy to cross the energy barrier. There is no tunneling in normal semiconductors or poor conductors.Originally posted by Alexander
All semiconductors and most poor conducting metals conduct current due to tunneling (atom-to-atom jump of electron from time to time).
Originally posted by chroot
I'm sorry, that's incorrect. The electrons have enough thermal energy to cross the energy barrier. There is no tunneling in normal semiconductors or poor conductors.
Find the height of the energy barrier. Determine whether or not the interaction is classically possible. If it's not classically possible, but yet still occurs, it's quantum tunneling. :)Originally posted by marcus
Could you give me a rule that I can apply so as to be able to distinguish cases of true tunneling?
Fascinating !Originally posted by chroot
Quantum tunneling happens all the time -- it
is the reason the Sun is able to produce
energy. Without the tunneling mechanism,
much higher temperatures would be required
in the Sun's core -- but the Sun would not
be massive enough to generate those temperatures.
Perhaps you should do a little more research. I'd love to see some references.Originally posted by schwarzchildradius
Copper oxide can easily have an energy barrier of >10 eV. An electron with less than this will not cross the barrier classically.
Originally posted by chroot
Perhaps you should do a little more research. I'd love to see some references.
(Psst: there's no quantum tunneling going on here.)
- Warren
Originally posted by chroot
I'm sorry, that's incorrect. The electrons have enough thermal energy to cross the energy barrier. There is no tunneling in normal semiconductors or poor conductors.
- Warren
Since when did ALL the electrons have only 0.025 eV of energy? I thought we were talking about THERMAL energy, which is a DISTRIBUTION.Originally posted by Alexander
Incorrect. Explain, how 0.025 eV electron (room temperature) can jump even 0.1 eV gap between atoms without tunneling (and usually gaps in poor conductors are even higher, say 0.8 eV in Si).
Uh.. yeah, thanks -- I understand tunneling... however, it doesn't happen in the situations listed here. :)Originally posted by schwarzchildradius
The time independent schroedinger equation is
Originally posted by chroot
Uh.. yeah, thanks -- I understand tunneling... however, it doesn't happen in the situations listed here. :)
- Warren
You do? then you understand that U > E, tunneling happens. Feynman used the twisted wire situation as an example of tunneling.Uh.. yeah, thanks -- I understand tunneling... however, it doesn't happen in the situations listed here. :)
I hope you understand that thermal energies of electrons in a wire can be much higher than several tenths of an electron volt.Originally posted by schwarzchildradius
You do? then you understand that U > E, tunneling happens. Feynman used the twisted wire situation as an example of tunneling.
Originally posted by schwarzchildradius
Feynman used the twisted wire situation as an example of tunneling.
Originally posted by chroot
Mmm.. no.. sorry. This is not quantum tunneling!
Normal electrical circuits do not involve tunneling, but there are a variety of specialized devices that do -- for example, the aptly named 'tunnel diode.'
A zener diode is not the same thing as a tunnel diode.Originally posted by eNtRopY
P.S. Despite the name, the most prominent mechanism in a zener diode, or 'tunnel diode' as you like to call it, is actually avalanching not tunneling.
Originally posted by marcus
...Also I liked your example of the core of the sun. I happen to know the temp is 15 million kelvin which is 1300 eV. So protons are bumping each other with energy of several thousand eevee and you are telling me the barrier to their sticking to each other is much higher than that. What is the number that the proton-proton fusion chain has to tunnel thru---since you say that their thermal 1300 eV is not enough?
Would very much like some more concrete examples.
Originally posted by Jack
What is quantum tunneling?
Quantum tunneling is a phenomenon in quantum mechanics where a particle can pass through a potential barrier even though it does not have enough energy to do so according to classical physics. This is possible because at the quantum level, particles behave like waves and have a probability of existing in multiple places at once.
Quantum tunneling occurs when a particle's wave function extends beyond the potential barrier, allowing it to "tunnel" through and appear on the other side. This is possible because of the uncertainty principle, which states that the position and momentum of a particle cannot be known simultaneously with absolute certainty.
Quantum tunneling has many practical applications, such as in scanning tunneling microscopes which use the tunneling of electrons to create images of surfaces at the atomic level. It is also used in tunnel diodes, which have unique electrical properties due to quantum tunneling, and in quantum computing where it can be harnessed for information processing.
While quantum tunneling is a fundamental phenomenon in the quantum world, it is not typically observable in our everyday lives due to the extremely small scale at which it occurs. However, it is a crucial concept in understanding many natural processes and is essential in the design of modern technologies.
One of the main challenges in studying quantum tunneling is the difficulty in directly observing it due to its small scale. This requires sophisticated experimental setups and techniques. Additionally, there is still much to be understood about the mechanisms and implications of quantum tunneling, making it a fascinating and ongoing area of research in the field of quantum mechanics.