Quantum Locking Will Blow Your Mind—How Does it Work?

okay everyone today I'm going to be showing you the quantum locking experiment now this is one of the coolest experiments in my opinion that I've ever done on my channel so first I'm going to show the quantum locking in action and it's really amazing and then afterwards I'm going to be taking some time to explain how it works and it's gonna be a little bit long but I think I've made it understandable to a general audience even if you don't have a quantum mechanical background or even a physics background you'll probably be able to understand how this is working now this is a type 2 superconductor and what that means is that it can actually undergo quantum locking but in order for it to become a superconductor we have to cool it down so let's first cool it down and then I'll show you some really neat quantum locking experiments so in order to cool this down we need some liquid nitrogen now I'm just going to drop my superconducting puck in here so I'm gonna try a few things here first I'll try putting a small magnet on the superconductor and show you what happens and then I'll be putting the superconductor on some bigger magnets and then I'll finally I'll be putting it on a track where you can push it around and it's really amazing what happens okay watch me place the magnet on the superconductor watch this it always comes back to the same spa get it even closer notice how it's not touching but I can push the superconductor by touching the magnet it's like it's gripped on to it okay now let's try it with a few more magnets by putting the superconductor on top foam look how it just stays right where I put it so cool so now I'm going to place it on this track that just has rolls of neodymium magnets so that these are opposite poles so what it does is it creates a symmetric magnetic field in this direction but not in this direction now watch what we can do okay now watch this now as if that's not impressive enough let's flip the tract over and watch this so the superconductor is so strong it can actually carry other things on it let's try to carry an orange rotating bread so in order to understand how quantum locking works let's first understand how superconductivity works so if I were to graph here on the y-axis resistance so this is just electrical resistance versus temperature high temperatures the resistance would be high but then suddenly it would drop down to zero for the superconductor that I was using this is around point zero one ohms and the interesting thing is this is exactly zero ohms so once it drops down to this lower temperature the resistance of the material is exactly zero not really small but zero there's no electrical resistance now to make sure you know how crazy that sounds imagine I were to tell you that I begin stirring this liquid here and then I stop stirring it and you can see that eventually it just stops swirling around altogether but what if I were to tell you that there's a material that if I start swirling it it never stops ever there's absolutely no internal friction well that would sound preposterous but that's exactly what's happening in superconductors but instead of water flowing around in a circle electrons are flowing around in circles and it never stops in fact there's no internal resistance so with semiconductors you literally have perpetual motion of electrons once you start them moving as long as it stays below this transition temperature those electrons will flow indefinitely but how is this possible how could there be no internal resistance how could the electrons moving around in a material not cause the material to heat up very slightly well it has to do with quantum mechanics now normally an electron in a conductor can be thought of as a free particle moving so what that means is that the electron can move through the material and it can bump atoms in the material and bounce into them and get scattered now when an electron hits an atom in the lattice of some conductor what that causes it to do is lose some energy so when the electron hits this here it causes it to wiggle a little bit and that turns into heat and so the electron loses some energy and so by moving electrons through any conductor you eventually lose the energy to heat so the current will stop as long as you don't keep pushing the electrons so in a normal non superconductor material you throw electrons or try to move electrons through it they're gonna bounce around for a while but eventually they'll stop and the stopping comes because they're hitting atoms in there and they're moving around and everything starts jiggling and it turns into heat but for superconductors something interesting and weird happens once you cool it down to a very cold temperature electrons stop acting like individual particles and they actually pair up with other electrons and the electrons don't even have to be close to each other they can actually be hundreds of nanometers away and they act like they have some type of mysterious force connecting them and when the electrons are attracted to each other and pair up like this it's called a Cooper pair now a Cooper pair is interesting because normally electrons should repel each other not attract each other so let me explain why Cooper pairs so let me explain why electrons could attract each other in superconductors when an electron is moving through this lattice of ions the ions are positive the electrons are negative so the electron moves let's say the electrons moving in this direction so as the electron moves through it has a negative charge the ions in here have a positive charge and they're very large atoms so they don't move very much but they're actually attracted to the electron there so you can see that as the electron moved through it kind of attracted these positive ions near it and so it pulled these positive charges towards it so that an electron that's over here moving this way it actually doesn't feel repelled by this electron but it actually feels like it wants to go towards it because it kind of gathered these positive charges near it so this feels a little bit attracted to the electron now the attraction is very weak but what's interesting though is the though it's weak it acts over a long distance so that these two actually act like there are two pairs together so basically the only reason this is happening is because the electrons attract these positive charges that move towards it a little bit which attract another electron a little bit and that may sound like an insignificant thing that's happening but it's actually very significant what it causes to happen is that these two electrons stop acting like individual particles and act like one particle together now this new particle that forms it's at its lowest quantum state and in order to excite it to the next level it needs a certain amount of energy you can't just give it any amount of energy it has to get to the next quantum level this is another quantum effect because it means that you can't give something any amount of energy that you want it has to come in discrete packets so in order for it to be scattered meaning in order for it to bump into anything the thing that it's bumping into has to give it some minimum amount of energy so there's some amount of energy that's a minimum that it has to receive it can't receive anything less than that so it has to be greater than some value that I'll just call X so at higher temperatures this Cooper pair or these electrons can move through and bump into the lattice and get scattered and lose energy but what's interesting is if you cool it down colder and colder eventually this value here of each individual atom becomes so low that it's less than the minimum energy needed to scatter this Cooper pair meaning that that meaning that basically anything it bumps into doesn't have enough energy to do anything to it so it doesn't affect it at all it's not like it affects it a little bit it can't affect it at all and so this Cooper pair can now move through the lattice unaffected in any way the only way that it can affect it is if something bumps into it with enough energy to bump it up to its next quantum state now that can happen even at cold temperatures if you flow enough current through it and get them moving fast enough at a high enough voltage then it can in the stuff at a high enough speed so that the thing it bumped into gives it enough energy to scatter it so even superconductors if you flow enough current through them at high enough voltage you can scatter it and cause heat to form and you lose some of the flow of electrons so basically it's not a superconductor anymore so now that we know how a superconductor works let me explain how quantum locking works so how we can get the superconductor to start flowing current in it is just move it towards a magnet when you move it towards a magnet it exposes it to a changing magnetic field and when you have a changing magnetic field that induces a voltage and that voltage pushes electrons around an eddy currents in the material that's the reason why when you move like a block of aluminum towards a large magnet then that aluminum will slow down so it's like it's moving through water or something because it's causing small eddy currents to form in there and that movement of electrons in there causes a magnetic field that opposes the its own magnetic field that it's going through and so it pushes against it and slows it down so what that means is that when I move a superconductor towards a magnet it's going to repel it but that's not all we saw there we noticed that it didn't actually repel it we were able to turn it upside down and it was attracted to the magnet so it didn't want to only repel it it actually just wanted to stay right where it was and that doesn't happen with normal diamagnetism so because of its superconducting properties it makes it so that there cannot be a magnetic flux that goes through the material so the magnetic field lines cannot go through it so in a normal conductor let's say we had a sphere of aluminum or copper or something and this is our superconductor if you could measure the magnetic field lines around it when you put it next to a magnet this is what it would look like for a metal the magnetic field lines just go right through it but what's interesting for a superconductor that's not what happens because the superconductor is forming these eddy currents in there when you move it towards the magnet it's opposing the magnetic fields in there and so it doesn't let any magnetic fields form in there and this is a form of perfect diamagnetism but it also is called the Meissner effect so they go right around it the magnetic field lines can't penetrate it so there's no magnetic flux in the superconductor now this is a result of super conductivity but this still isn't quantum locking we're almost there so this is a type 1 semiconductor but what I have here is a type 2 semiconductor now type two semiconductors don't quite look like this type two semiconductors actually have impurities in them and these impurities allow some magnetic fields to penetrate it and the parts that it penetrates it creates this magnetic vortex it forces kind of a funnel down of the magnetic field lines so for a normal type 1 superconductor it can still move through a magnetic field just fine because the magnetic field lines just flow around it but for a type 2 semiconductor it can't move through these magnetic fields because it gets locked into place the magnetic field is funneled down through the center and it locks it so in order to move through it it has to push through those impurities and so the only way it can move through a magnetic field is if the magnetic field is symmetrical because then it just gets replaced with a new part of the magnetic field and so it doesn't matter where it is in that field that can just move through it but any magnetic field that's not symmetrical it can't move through it so basically it's like it has these strings going through it holding it in place they're kind of like these magnetic strings that don't let it move so in my experiment I can move it like this on the track because it was a symmetrical magnetic field and so it didn't matter where it was in the magnetic field it didn't affect the lattice inside there was no internal force on it but when I moved it up and down that wasn't symmetrical that was changing the magnetic flux through it and so it pinned it in place so basically I had to put some force on it to drag it through the magnetic field lines and once I stuck it there then a stayed in that place and once I stuck it higher than a stayed in that place and so quantum pinning is actually due to parts of the superconductor that aren't super conductive and it makes a part of it that gets pinned in place due to the magnetic flux that's able to penetrate it in a few spots it's actually more than a few spots it's actually a few billion spots so how this differs from a normal repelling force of a magnet is it's actually not repulsive or attractive it's both of them it just wants to stay in place no matter what and so you can put it in anywhere you want and it'll stay there well thanks for watching another episode of the action lab I hope you enjoyed it if you did remember to subscribe and hit the bell so you can be notified when my latest videos out and thanks for watching and I'll see you next time

Channel: The Action Lab

Views: 3,897,291

Rating: 4.9184041 out of 5

Keywords: quantum physics, quantum locking, flux pinning, superconductors, the action lab, type 2 superconductors, superconductors explained

Id: 8GY4m022tgo

Length: 17min 23sec (1043 seconds)

Published: Thu Jan 09 2020