BCS Theory simplified
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- Опубликовано: 4 окт 2024
- Want to understand how superconductors but don’t have a quantum mechanics degree?
Here is a simplified explanation of the BCS theory to help you, sing a clear explanation with animations, I help you understand the theory from a high school perspective
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Finally, a simple clear explanation of Cooper pairs. Thank you
Explanation is simply great . thanks for that. As a university student I need to know it quantum mechanically. If possible can you do the same?
I´m studying at he University and I found it very helpfull! THANKS!!
Mine too
Thanks so much for your explaination, God will give you kindness
Amazing video for high school level. Really appreciate it!
Cristal clear. Thank you for explaining this.
I am a MSc student (physics), and this is really cool
Only one word for your explanation.... AWESOME.....
BEST Explanation I found on youtube ! Congratulation ! ....but elektrons are green 🙂
Why won't the second e drag another one with it to form a chain? It seems odd that only pairs are formed as every e should be causing its own distortions as well when it moves through, which would drag the e behind it, etc. Is it that the distortions caused by a trailing e are too weak to attract the e behind it? So essentially, the length between the two cooper paired electrons would be of critical importance to explaining why they only form in pairs?
finally, I understood BCS Theory!!
love from india... thank a lot sir
Wonderful visual demonstration!
Excellent!!!
a very simplified and good explanation of theory............................
great video! Cheers from Brazil!
awesome....loved it
Loved it alot.... thanks to you for giving a great explanation
Loved your explanation!!!!
when the temperature of the lattice is higher than 10 k (no superconductivity) does the electron still create a distortion in the cristalline structure of the lattice?
Yes , but it is destroyed by vibrations created due to temperature
topic of superconductivity super explained
I'm doing a project about uranium di-telluride, but I didn't know anything about super conductors. Thank you.
very helpful thank you
Nice explaination
amazingly explained.... THANKSSS very much
Nice teaching sir
Very helpful...thank you
Brilliant explanation!
I was extremely confused with the wave functions. Anyways, thanks for your video, which helps me to understand briefly about the concept.
Superb sir
Wasted one hour for reading this before watching this video....
Thanks a lot for making this video. It gave me an idea what happens in this kind of super conducter. But I don't really see how this simplified model can help me to understand this effect. For example: If the one electron creates a positive charge by distorting the nuclei around it why is there no distortion around the other electron which creates another positive charge so that they repulse each other again? Also why does the distortion attract an electron that has a distance 1000 times the lattice distance and not one of the other Billions electrons that are close. How can they make a kind of stable bond and not be distorted by all the other electrons. I know it's a simplified model and for a real explanations quantum mechanics has to be taken into account. But like this I don't understand the purpose of this simplified model as for me it does not really explain the effect
I didn't watch the video after this comment, but honestly thinking of the congregation of positive charge around a electron as the attraction isn't the best picture. It's more like a box spring mattress being deformed by one ball and another ball falling into that deformation. The box spring mattress being the crystal lattice here.
The quantum way of this happening is via "phonons": the quantization of lattice vibration. The photon mediates an attractive force between two electrons, and this can be understood with a Feynman diagram. There is a wave vector dependence of this force and it can be swamped out by thermal effects as sufficiently high temperatures. I should stop here because there is so much more to say...
Great explanation!
thanks for explaining it was really helpful
I don't really get the necessity to imagine a 2nd electron being dragged in the wake of the first. It might well happen, but why is it significant to sc beyond the stability of the lattice no longer impeding electron transport? Is it that it creates resonances in the lattice that eases the next pair along? If this IS the case, then saying they are bonded is a bit misleading, though labeling them as paired due to an uusual closeness is okay.
great video
Thanks a lot sir!!!
Thank you for explaining this :)
Why lattice is distrorted due to electron ??
I mean to say to electron should have to attracted towards atoms due to their heavy masses . But here atoms are getting attracted towards electrons. Why ??
Please correct me ,if I'm wrong
electrons have much less mass than protons but they both have the exact same amount of charge, just opposite.
Because the atoms that the electron is attracting are symmetrically located on all sides of the electron. So which direction should the electron be attached to? (Resultant Force=0). So it stays there, and the protons come towards the electron as they are being exerted by a force from one side
sir if possible do explain the quantum mechanics too as we need it in uni.... found it very very useful
thanku so much sir
for the better feedback
The best explanation of superconductivity
whaaaw great explenation , and what analogues one can make with SPACETIME vs the Cristallatice and the 'ALCUBERRE warpdrive theory' with the distortion in the latrice.
Giving a free ticket w/o resitance for the electrons...warp drive --->faster than light w/o resitance or acrtual moving.
there goes my nightsleeep...or dreams about how to cool down the vacuum of space lower ...lol
grtzz Johny Geerts
thx dude very nice explanation
excellent explanation
Thank you sir
You’re welcome
Hint: Think of the brownian motion can only transition at a minimum quantity change of energy (like photons ability to transition electron energy states) below a critical temp, an effective freeze of effect occurs...
Thank you for this wonderful video it was really helpful, but can you please make a video on effective current and rms circuit.
Good work
Thanks
if some conducter spend electron and no create heat. can we say that conducter is a super conducter?
wouldn't the second electron in cooper pair make its own distortion while passing through the lattice?
+Abhijitsingh Sisodiya no. It's more about energy levels and quantum phenomena so this video being a simplification does not how all that happens.
Great explanation of the cooper pair! But isnt a specific type of lattice required to make a cooper pair, what is this lattice called?
crystal lattice
and wouldn't the first electron be attracted to the second distortion? Plus why aren't they attracted to their own distortion? Are they travelling to a positive pole or something?
yes they are travelling to the positive pole wich has a big positive charge (bigger than that of the distortion) because there is tension so there is a flow of electrons.
thanks sir
really useful
Explain joshepson junction
How do you have a medium with only positive charged atoms? The first electron which try to pass why not get catched right to the first atom which it is interact with? Just in a very ideal case would go exactly in the middle, but if it is not exatly in the middle, it would bend towards the closest positively charged atom and stay there and neutralizing it. In this case when the second electron comes, and the third and so on, would just neutralizing out one by one all of them, till the point when no left positive charged atom and in a neutral space they can pass without bending off from their road. When this case starts, than the first electron generates a little wind behind it (like ships, airplains) and the next electron can be catched into it. This is the only way as I could imagine.
Great!!!!
Best explanation
A simplified exposition of the topic, a description of hypothesis or theory is superficially a "topical analogy", so if the underlying basic principles have already been covered, this is good, but to go back to the principles for the first time after this type of education only multiplies the work of learning from first principles unnecessarily. (That is a personal opinion and Teachers each have their own style that works OK for their particular students)
great job explaining!!!!
Thanks!
@@PhysicsHigh Totally! Thanks for replying lol :)
@@PhysicsHigh You mention we need a grasp of quantum mechanics to get a better understanding of superconductivity and BCS. Would you recommend any videos that explain quantum mechanics with a focus on their applicability to these concepts?
Thanks!
Depends how deep you want to go. There are lots of videos out there and I’m not familiar with man of them but one you could look at for a little deeper is this one
ruclips.net/video/h6FYs_AUCsQ/видео.html
@@PhysicsHigh Awesome!! If there's anything deeper that you recommend I'm totally interested :)
Great
Interesting
can you please explain including the quantum mechanics as well
I wonder why second electron does not distort the lattice. Very good explanation though. Nice animation!
it is distort the lattice and attracted another electron.. so it become another cooper pair..
If second electrOn also distort then there should be repulsion between the two distortions which are having positive charged space. But why its not happening?
Smd
In university we're told that the paired electrons have opposite momentum. That kind of destroys my understanding of what I just saw. How does this fact fit in this video?
Great question
We are dealing here with a quantum event. The momentum and spin are opposite but as a result form a new state.
As a result my explanation/model is simplistic to say the least and designed to give a high school student some understanding of superconductivity. In somewhat classical terms. So the model has limitations since it does not take quantum mechanics into account.
Can u explain the concept the prespective of the quatum mechanics
Why it stops with a pair of electrons and not a chain of electrons?
IN essence (and I qualify what I say by saying I am not an expert on Quantum mechanics) is that the two electrons are in the same quantum level and only two of them can exist together (must obey Pauli Exclusion principle) so that limits the 'chain' to 2.
I guess cooper pairs doesnot obey pauli's exclusion principle & thats why they form bose condensate (infinite no. of electrons at same energy level) at low temperature (thats why BCS theory fails to explain high temperature superconductivity). I referred other sources online & came across an explaination "not any random two electrons could form cooper pair. Only those which exhibit opposite K vectors could pair with each other. Since they are paired, their resultant K vector is zero and stable. A third electron with a finite K vector could not join the link" But i am not clear with what a K vector is.
Nivas Ramachandiran my book says binding energy of Cooper pair is maximum when electrons forming pair have opposite momenta and spin. it says nothing like electrons with same spin can't pair. k vector is wave vector of electron.
Does it mean electrons with the same spin could form a cooper pair but less probable? Pls tell the title of your book
this is the answer i am searching for.tanq very much
NYC explanation
VERY GOOD VEDIO, NOW I COULD IMAGINE HOW ELECTRON GET PAIRED UP THROUGH PHONON INTERACTION
Transistor this is the topic that I want you to explain Please
Why we are considering lattice as positively charged??
Because that’s the case for metals. Positive lattice and a sea of electrons relatively free to move.
Ohk thankyou so much
thnku so much sir
for the better feedback
friend if this quantum lock be invention? (false).
The nitrogen freezed Aether nearest magnetic poles inside material...think in this (the material now is magnetic ) AETHER CAN BE PROVED (true).
{isso explica porque o imã pode girar em seu eixo magnético...em supercondutividade isso não deveria ocorrer [variação do campo magnético geraria Ed corrent (fomos enganados?)] }.
Congratulaitions! like you!
can you explain me if there are two or more than two electron one below the other then howz the distortion takes place
Please explain about Levitation
+Rohith Bandi what do you mean?
Meissner effect?
Already have 2 videos on that
Sir will the Cooper pairs would form during a flow of current or just during the process after cooling 🧐
After cooling. It’s a quantum effect
@@PhysicsHigh Sir so these Cooper pairs give the diamagnetic properties to superconductor. If I am right they supports your statement too that maissner effect bends the magnetic fields and causes a flow of current inside superconductor (Faraday's law ) as it creates a changing magnetic field thus causing levitation.
Can u explain London's equations????
I'm no expert on the intricacies of superconductivity. I am currently working on a better explanation/description of the Meissner effect (one of my other videos)
In my research I found this article that may be helpful - portal.ifi.unicamp.br/images/files/graduacao/aulas-on-line/fen-emerg/lecture_notes_BCS.pdf
Kamerling Onnes looks like my grandfather
Where can we find the presentation as a pdf
nice..
Sir at 9:30 why second electron can not create a another phonon to
Repel first electrons phonon .
I have the same question.
When First electron emits phonon. It's energy level decreases. The second electron however is having slightly higher energy. Somewhat like a potential difference and thus there is an attraction between the two electrons.
sir Is your graph b/w resistance and temp. correct near T=0k for conductors
I noticed this a lot in your speech:
en.wikipedia.org/wiki/Double_copula
Not something I do deliberately. Now you’ll have me checking. Better then lots of ums and ahs
Why can't this happen in normal temperatures??
In simplistic terms, the atoms are vibrating too wildly and thus cause electrons to slow down, hence resistance.
This of course only applies to Type 1 superconductors.
ruclips.net/video/CEUo9VswoVI/видео.html That makes no sense to me , its basically how LHC works , and we know LHC is a power consumer , big one , so that means they spend power energy to do that , that doesn't help to reduce needed power . Makes no sense to me .
Bvb
Paper4 important question give mi
Electrons are paired, so that electrical resistivity vanishes. Why? because one electron in a pair pulls the other. The same idea appears at the two ends of the logic chain. Is this an explanation or circular logic?
The full explanation is quantum mechanical. An electron by itself is a fermion and a Cooper pair is a boson leading to rapidly different behaviour.
@@thecsslife "Fermion" and "pairing" are the same thing. This is circular logic. You haven't explained anything.
@@xuehengzheng7455 BCS superconductivity is explained by Cooper pairs. Electrons in themselves are Fermions and obey Fermi-Dirac statistics. However when two electrons couple to form Cooper pairs, they collectively behave as Bosons, which obey Bose-Einstein statistics. Bosons can occupy the same quantum state, which enables superconductivity to occur, which is impossible for Fermions. It seems you are confusing the meaning of "pairing" in this case. Electrons in orbitals exist as "pairs" but this is completely different to electrons in a Cooper pair.
@@xuehengzheng7455 You need to learn more as thinking "Fermion" and "pairing" is the same thing makes no sense
@@thecsslife A Cooper pair is made from two Fermions. Conceptually, they are on the same footing. Your further explanation is erroneous as well. The Cooper pairs are not in the same quantum state because they all have different energies. You do not seem to know much about BCS theory.
Nowhere is it explained why a Cooper pair will move from the one contact to the other without being accelerated. An absence of scattering by the atoms owing to supposed Cooper Pair formation does not explain why the applied voltage becomes zero. For example electrons travelling through a vacuum tube also do not scatter, but the voltage does not become zero owing to the absence of this scattering. There is no reason why Cooper pairs will, in contrast, move from one contact to the other after the voltage dropped to zero; as it foes for a superconductor. Until the BCS theory can explain this, this theory is nothing else but a BS theory!
You think BCS theory is BS when you have no idea how the maths and physics behind it works.
Which high school physics syllabus wants students to explain superconductors?! Ridiculous.
The old physics curriculum in NSW Australia. It’s aim was to introduce students to modern physics. It’s now no longer I’m the current curriculum.
@@PhysicsHigh Thanks for the quick reply. I teach A-level physics at the moment and it only goes into the briefest of details about semiconductors... it doesn't even talk about how to improve conductivity via doping or about diodes etc. On the other hand, BCS theory didn't even feature in my university physics syllabus!
How did you find students fared with it?
@@PhysicsHigh great video by the way. I reviewed it after watching Arvin Ash's new video on superconductors.
Not too bad but I only taught them a very simplified model as shown and that means no quantum physics. An oft asked question was “why isn’t there another electron following the cooper pair?” Of course difficult to really answer without going into QM.
I assume you have seen my semiconductor videos. Some of my earliest stuff.
Nice AD revenue mate...
You so oversimplified it that no, I didn't find it useful at all.
thank you so much sir !!