Left-handed Electrons - Sixty Symbols
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- čas přidán 3. 11. 2015
- A new paper on the chirality of electrons in graphene.
Discussed by Professor Laurence Eaves, one of the co-authors.
Extra footage: • Electron Chirality (ex...
Spherical electrons: • Spherical Electron - S...
Paper: bit.ly/Chiralty_Paper (fee for full paper)
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Visit our website at www.sixtysymbols.com/
We're on Facebook at / sixtysymbols
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This project features scientists from The University of Nottingham
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Sixty Symbols videos by Brady Haran
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Great video, but I would take issue with the explanation of “borrowing energy” and using the Heisenberg uncertainty principle to explain quantum tunneling. Quantum tunneling is just due to the fact that although the wave function decays in a region where the function for potential energy is higher than the energy of the particle, the wave function does not decay all the way to zero. Therefore there is a non-zero probability of the particle makes it through the barrier. Also, I am concerned that the title of this video may make people think that left-handedness is an intrinsic property of the electron, as opposed to something that arises from the structure of the material it is in.
+Eugene Khutoryansky Yea through most of the video I though that this would be some property that every electron has. Too bad he explained it only in the end that this is something "arise[ing] from the structure of the material it is in". Great video as always tho
+Eugene Khutoryansky Maybe it was a bit confusing what he said, but chirality is an intrinsic property of particles. It's a very interesting property too, for example, a part of the weak interaction only works with left handed particles. This is why Neutrinos are left handed.
When he is talking about "electrons" in graphene, he is talking about electron quasiparticles. It's not just the chirality which is based on the structure of the lattice, so is the effective mass for example.
+Zimty I think what +Eugene Khutoryansky is referring to here about the title is that the title might lead the less informed viewer to think that left-handed electrons are fundamentally different particles from their right-handed versions, as opposed to the chirality just being an intrinsic property of the electrons, which was the intended interpretation.
+Zimty If neutrinos have mass, all bets are off.
Only particles moving at c cannot change chirality.
It's nice to see Professor Eaves again. He's always been one of my favorite presenters, and he hasn't really been around much in these lately. Really interesting stuff, and well-explained.
I love hearing Professor Eaves speak, partly because he is a great communicator but also because I love to hear a top member of academia speaking in the Rhondda valleys accent. The professor was born just around the corner from me. Expectations are fairly low in the valleys but Professor Eaves gives me great hope that even folk from the valleys can excel.
Sorry to be off topic but does anybody know of a trick to log back into an Instagram account..?
I somehow lost my password. I would love any tricks you can offer me!
@Jaiden Vicente instablaster =)
I want to be an electron in my next life and spook scientists out.
Or a bacterium without a Hayflick-limit :D
cassandra5322 - I want to be an anti-electron and hide out with all of the other antiparticles and confound cosmologists everywhere.
Watch out, you may literally have no size
I just love how "it was quite fast. It only took 3 months" is a thing..
Maybe it's just because I'm in school (Probably is), but fast normally means days-weeks for me.
+Ludvig Nygaard 3 months really is extremely fast when it comes to research. I once had a leak in a machine and it took me and my group a couple of weeks to fix it before we could finally launch a single experiment. So if you intend to go into research at some point keep in mind that it's usually a long process and that you can't expect acceptable results after just a couple of days or weeks :)
***** Yeah, I realized that it was long, but.. Damn.
Just shows the massive difference between education and the real world. (At least when it comes to research)
+Ludvig Nygaard Similar to how 'a million years' is absolutely minuscule in the scale of the universe
+Fischmiep Wasn't he talking about the review process taking three months? Which would be quite fast, too, in some areas. Journal papers can take way over a year before being accepted or rejected.
+Penny Lane Yeah, he was. Didn't notice any reference to how long the research took in the video.
Interesting. It looks like the transistor will be able to work in either direction, depending only on the way the voltage is applied.
You can already swap C and E in most bipolar transistors, however the gain will be reduced. There's certain assymetry in how they're made.
Respectfully, Professor, I must disagree. My golf balls experience tunneling quite often - that's why I can never find the little buggers, I'm sure. :-)
+Scott Baker you deserve more upvotes
+Scott Baker Some fish on the Southern side of New Zealand (opposite side of the planet from the UK) are doing some major golfing on your account.
+Scott Baker DAD JOKE OF THE YEAR
***** Dude, that's awesome.
This is truly amazing research and amazing explanations. I'll just pop on over to Nottingham to audit all your classes!
Excellent video. Thank you for sharing your work with us.
Very interesting video as always form you all. Keep them coming.
THANKS FOR SHARING THIS INTERVIEW!!! GREAT CHANNEL!!!
I just love him & his work. More please.
Whoa, it's awesome that you now publish a video about a scientific work before it's even out there!
incredibly easy to follow and understand! Thanks for this video!
I think he's the only one of the speakers/professors who doesn't distract me with his presence (my fault maybe). I could completely focus on the content of his message.
Wow, this one was one of the best on the topic. Really liked it.
I bloody love these videos
I must admit, given I understand quite a lot of the content provided by sixty symbols, this went straight over my head.
I really appreciate your video and you clear presentation style. I learned a lot, thank you, Professor Laurence Eaves. May chirality always be with you!
Best regards,
Al Beeman
Hilo, HI
Thank you, Thank you for making this video.
As always... Interesting stuff !
I love this subject matter - thanks for uploading
Excelent as always thank you.
This video just made the video of Andre Geim's 2011 graphene talk from the Institute of Physics a heck of a lot more understandable for me. :) Prof. Eaves gave a very good explanation.
I physically moaned in pleasure upon seeing the length and topic of this video
Mandragara this...... is a great comment
Awesome video! I just took intro to quantum and special relativity at my university and we learned a little about the time-independent Schrodinger's Eq. I must say I got chills when you said the electrons could tunnel between the graphene layers. Tell me how thin must the barrier be for the electrons to tunnel through from top g layer to the bottom g layer? And please tell me if its not unreasonable to think this kind of transistor has potential application to the future of computers maybe quantum computers?
Thanks!
Great Video. Thank you
As an umpire of local league cricket, I very much appreciate the shout out. Thank you, professor! 🏏🏏🏏🏏🏏🏏🏏🏏🏏🏏🏏🏏
One of the first books that made me interested in science was The Left Hand of the Electron by Isaac Asimov, one of his collections of science essays.
Nice explantion of chiralty at the end, about it being an effect of the medium structure. I was wondering how something could have spin up or down and left or right!
I would contend that classical particles do engage in a sort of tunneling.
If you pull back one bead on a Newton's cradle and release it, it stops against the "surface" of the resting beads and a bead on the other end "jumps" out of formation.
Are we sure that these moving electrons are actually "tunneling" through materials placed between graphene, or do you have an electron on one side that occasionally impacts the substrate with just the right energy and momentum to cause a cascade effect, implanting itself in the substrate and popping an electron off the other side with an energy equivalent to that which was put in originally?
Damn, I love this channel!
I think chirality can be compared to a thread on a screw. It can be left or right handed. For a particle the complex value of a wave function when plotted in 3D space along the direction of particle's movement line can also be left or right-handed.
interesting, but dense, hard to wrap my head around what he was trying to make clear.
+12Rman21 Probably because 50% of what he talked about actually had to do with chemistry than physics.
+The Sandre Guy I have just watched the first half, but until now he has talked almost exclusively about quantum mechanics and solid state physics, which isn't chemistry at all.
+Claus Jensby Madsen Does it matter tho, what name you give the subject? The things hes talking about are important in chemistry and physics. Even I as a geologist deal with stuff like this.
+teekanne15 I don't care much whether something is labeled or not, but I care if something is mislabeled.
Claus Jensby Madsen
Quantum mechanics is an integral part in both physics and chemistry. Actually *most* of what he talked about could be classified as physical chemistry. Also I think you're missing the whole part about chemical bonds and the molecular structure of graphene ;)
Wonderful. What a fascinating subject, and masterfully explained. This channel is one of the best I've seen. Kudos.
Kookaburra at 2:20 This should be the thumbnail :D
Is there a relationship of the lattice sheet's alignment and what left or right electron will tunnel? If so then two different data streams could be carried at near light speed. If you can contain the left and right electrons on either side then you have a very fast memory cell. There is also a new digital construct. A left holding cell and a right holding cell and an empty cell. Tri-state logic at near light speed.
Great Video. But I was just curious how do "they" know that the electrons coming out the "bottom" of the hBN aren't different electrons? I.E. were they free electrons dragged away from the garphene by negative voltage applied?
What a great communicator
It’s something the material is new to the scene. Measurement is an exciting thing.
A wall with height and thickness. A ball goves over, thus overcomes that potential (energy barrier). A ball (canon) goes through with requires more energy but this is like the electrovoltaic effect, dislogding bits of wall and replacing with ordnance.
I love this channel I love all of you guys thank you so much! But you said a electron can borrow energy to quantum tunnel the Barrier, and then it pays back that energy once it’s on the other side. My question is, where does that energy come from(the environment?) to pay back the energy loan if it’s spent the borrowed energy to pass through the barrier. So it would need to “earn”new energy to pay for the borrowed that the electron spent quantum tunneling the barrier, right?
This is why I really prefer the plasma/electric universe model where quantum tunneling can be described as a dipole interaction. Where the initial borrowed energy forces the particles to flip polarity or “spin flip” (“likes like likes”)and then it can be attracted or propelled through the material instead of repelled. Then the energy is spent and the electron settles down to its base polarity and spin state. I mean I’m paraphrasing but that seemed to be the rough idea. It makes sense to me and it does it without using mysterious quantum means.
Chirality. Cool word. Clear as mud. Is there a pattern to chirality within the lattice? In other words, do the spins work like adjacent gears? Looking forward to the additional footage.
physicists are like video game glitch finders in real life
Professor, can you give us a comparison of switching speed and operating voltages? Is this better than the best silicon transistors?
excellent
thanks for sharing
12:00 gloves
15:20 mirror image
the chirality of the nodes in the lattice gives rise to (causes) the chirality of the electrons, or exposes the chirality of the electrons?
If you had a letter A painted on your quantum cricket ball and tunnelling occurred would the cricket ball on the other side necessarily have the same label? In other words has an electron tunnelled or has one vanished and another appeared a certain distance away?
Graphene could work like a nerve or a neural network if you could add other elements into and on it's lactic to trigger and direct a piezoelectric effect.
I have a question that if you rotate the whole graphene sheet, wont the perspective change ? I mean left might become right and right might become left ? Does that mean that the left handedness and right handedness depends on the position and our perspective in which we are watching the electron to go ? @sixtysymbols
very clearly explained! Had a lot of fun! Congratulations for the video and for the publication!
You're right, we Americans by-and-large have never heard of those terms, although in baseball I think the analogy might be the curveball and the screwball, where the pitched ball undergoes the Magnus effect but curve- and screw- go in opposite horizontal directions (as seen by the batter, catcher, and home plate umpire) because the spin is exactly opposite.
this might be the best way to make an analogy about it
so your measurements does not effect if the electron in the left-hand/right-hand states? Meaning, allowing the phenomenon to occur that the electron is in both states ? In the left hand and not in the left hand. In the right hand and not in the right hand? or in the left hand and right hand.
The electron must 'sense' the contours of the lattice in terms of a charge-topography determined by uneven distribution of negative and positive charge according to the shape of the bonds relative to the shape of the protonic charge emanating from the nuclei. In a dipolar molecule like water, charge distribution is uneven due to unequal charge and inertia of the oxygen and hydrogen nuclei; but in graphene, the atoms are all carbon and the bond lattice seems to be symmetrical so you would expect charge distribution to be more even. However, because Lorentz' force causes charged particles to deflect perpendicularly to direction of a magnetic field line, there must be free charge present that interacts with magnetic field lines also present.
My question is in regards to the ability of the graphene to absorb energy from electrons and/or photons passing through it. Are the bonds so symmetrical and evenly distributed that their ability to absorb and diffuse energy inputs effectively prevents the bonds from ever being broken? I.e. is there any way to decompose graphene and/or somehow get the atoms to recombine with other atoms? Or is graphene like some kind of ultimate carbon ash whose bonds can never be broken until they are crushed together with the protons in an electron-degeneracy event, such as by falling into a neutron star?
I´d love a video about atomic clocks (and optical clocks). It´s a very interesting topic :)
This is so well explained, as with all the videos from the professors at Nottingham!
Great video.
I feel like i would be unstoppable if this man was my professor.
Could you please explain the Scharnhorst effect? Thanks!
I dont get the difference between Chirality and spin, unless by that they mean that spin they mean it is arbitrary which you shoose as up or down. If i understand correctly, Chirality is absolute whilst spin is relative, in other words, whatever direction your instrument is set up in?
You explained everything perfectly, and the visual helped out a lot. I don't understand most of it, or all of it... I guess I'm just uncertain about the whole thing... Get it... because uncertainty principle... Ok I'm done.
Electrons have come a long way since I did 'A' levels. More please.
When there is a magnetic field applied, wouldn't the electrons experience Larmor precession, much like protons in an MRI machine? Is that a factor in chirality?
For a rule of thumb, a left hand is like a right hand rule, where you turn your hand around a 180. I know, it's hard to understand left handedness as a right hander.
There is a little mistake but i'm sure that the profesor made it intentionally trying to simplify, I remember a video where prof. Moriarty said "Spin is not spin, is an intrinsic property of the electron". It'd be better if you put an annotation in min 2:55.
very interesting
He said scotch tape method as if it was super technical but isn't that just peeling away graphine with scotch tape?
+DMitsuki Indeed it is. The method won a Nobel Prize in 2010, by the way.
+caino666 I think it was made as a joke, such a simple method to produce the result.
+DMitsuki How did he make it sound super technical? :S
Carbon can ordinarily bond with 4 atoms, and taking a look at that model, each carbon has 3 represented bonds. Are each of those unit cells like benzene rings, where there are alternating single and double bonds?
+rchandraonline They behave pretty much like benzene rings just that there are no hydrogens on the carbons since they are bonded to other carbons. However it's not like there are alternating double and single bonds but the extra electrons are delocalized (just like they are in benzene). I gave a more detailed explanation in an answer to +mendali 's question.
If you made a square grid lattice instead of a hexagonal one, would that eliminate the chirality behaviour?
I didn't really understand the difference between left- and right-handed electrons from the explanation given. Wouldn't any electron traveling across the hexagonal lattice travel through atoms identified as having horizontal bonds in both directions?
I find the sound of him dragging the cricket ball across the graphene really satisfying for some weird reason :)
I would like to propose that, if there is a unit of measurement unique to Landau states, that it should be named the "Martin."
How do the properties of graphene differ under extreme cooling conditions?
I've read so many times that the "spin" property of an electron doesn't describe a physical rotation (like a ball spinning on it's axis). Can someone elaborate on this? The prof. made it look like "spin" would be a physical rotation... was it just for simplification?
+Lars Richter Yes, that was a simplification. That's a pretty common way to describe it because it appeals to our physical intuition. In actuality, spin is an intrinsic property of the electron (and other particles) which does not correspond to the particle's motion.
+Ada Warren But then, what would a spinning electron even look like? It's perfectly symmetrical in all directions so rotating it is kind of a no-op, isn't it?
+Penny Lane Even for traditional rotation, symmetry doesn't mean the rotation isn't there.
John Petersen Non-elementary particles are never truly symmetric though, are they?
+Penny Lane I didn't think that was the question. If you really want me to ruin the fun, electrons don't "look like" anything, and neither does spin.
The Landau levels: well spaced, higher up you go more closely bunched up - kinda of like musical harmonic series?
I really love professor Laurence Eaves. Not that I did not like all the others :D
Doesn't the chirality come from the fact that the carbon valence electrons actually form a tetrahedron (instead of the mercedes brand shown in the video)?
8:30 quantum tunneling sounds super interesting
That's Sean isn't? I thought I heard heard him at 1:18.
I don't understand why the carbon atoms are only bonded to three other atoms. What about the additional valence electron? Is that why the graphene conducts electricity?
+mendali The extra elctron is delocalized. You can imagine it by the atoms having a p-orbital that's perpendicular to the plane. When two p-orbitals are overlapping they can form a bond since they share the electron pair (that's how double and triple bonds are forming). If you bring in another p-orbital it's overlapping with the other two as well so the electrons can move there as well and you can't really tell where exactly they are anymore. Now you can bring in more and more atoms with p-orbitals and more and more electrons get delocalized. Since you can't tell where exactly they are anymore you speak of graphene having an electron "cloud". My explanation might not be exactly correct but i hope i could get the image across :)
+mendali some great explanations here but put simply: yes (i think, i'm only an A level student so i don't know what has been simplified for us or not)
+Reggie land If you're doing a-level chemistry, it's like the pi-ring in benzene.
i wasnt sure but i assumed it was something like that. thanks :)
+Reggie land The oversimplified but straight to the point answer: the 'leftover' pair is a double bond. So when you look at that model he holds up, you are in fact seeing four bonds for each carbon. Most model kits it's redundant to explicitly show double and triple bonds when building a large molecules, so they don't show them as they're considered to be understood.
Btw, the more complicated answers prior to mine referring to delocalization, when you have a network of alternating double and single bonds (plus a few other criteria), every bond in the network becomes what you could call (very loosely speaking) a 1.5 bond; effectively the network is like one large bond with no separate pieces.
Oh dear. Now I have to go to the brain doctor and get my brain stapled back together.
Another fine video that leaves me with a burning desire to go through this one a few more times.
matter and antimatter annihilate when they meet. a proton is a matter a positron is an antimatter,. what happens if they meet? if they annihilate what happens to the 2 positive charges?
I like this guy. His office is a total mess, just like my house. Glad to know success doesn't have to be organized.
Use a magnet reppelent sequence
It sounds like lef- or right-handedness is an intrinsic property of the electron.
But if I understood it right (I probably didn't), the property arises by moving through a structure. Would that mean that this property could have 3 possible values, if the electron would be moving in a 3-dimensional structure?
+Faxter313 No, due to the way it arises it has two possible values, unless you also count 'zero' as a value in which case you can have three values in both 2D and 3D materials.
I get how the electrons are different on the lattice, but I can see 6 different types, or 3 if you rule out the symetric cases. Where 2 comes from (right & left) ?
+m4c13k86 If you look at the 6 types they're really just 2 types rotated at different angles (0, 60, -60). It's the 60 degree angles that gives it that chirality, since the 3 that are right or left-handed clearly have preferential directions.
What's the difference between graphene and graphite? (I'm guessing the bonding)?
so this chirality property manifests only in hexagonal crystal structure? so for example in square crystal structure there would not be any chirality of electrons?
+lordicemaniac No, what matters is limiting the way electrons can travel so this chirality manifests. Even in most hexagonal crystals electrons have no chirality.
So chirality is a property of the electron but in the case of a graphene lattice it manifests itself in the form of left-handedness and right-handedness?
Kinda off-topic, but the talk of these graphene/boron nitride transistors got me thinking: how far off are these kinds of transistors from being used in electronic circuitry? Are they even useful for electronics?
+Ben Rowe My best guess is quite far off, if it can even be done. I think the largest problem is that the tunneling is probabilistic, and even if you don't apply a voltage (which would effectively cut off current flow in transistors used commercially today) there is still a decent chance that electrons will pass through. The transistors that we have working for us today are a lot bigger (meaning significantly lower chance of tunneling) and in the 'on' state, they let through tons of electrons, and in the case of tunneling in the 'off' position the quantity of electrons let through by the lowered tunneling chance are *very* much negligible.
+Voidfury Yes, but on the other hand you would have many, many more graphene transistors. They would be ideal for robust-first computer architecture.
Ooh, you raise a very good point, but I wonder just how much use we would get out of making each transistor less dependable and just adding more of them. I guess only time will tell.
If you have to do a lot of error correcting because of tunnelling it's not going to be a efficient or reliable system. Nope, i'm guessing we're going to be stuck with 7nm or maybe 5nm transistors for a long time, maybe forever.
Maybe a stupid question, but the molecular image of the graphene, and the plastic model shown by the prof don't match. Why is that? There are no hexagons in the molecular image...
qustion: for any massive dirac fermion the particle has both handednesses to it, right?
is this effect negligible in any way? I'm pretty sure your energies aren't much larger than the electron mass, and I'm pretty sure you didn't find a way to decouple it from the Higgs field, so what's going on?
+MooImABunny It's a subtle effect caused by the properties of the material. It's somewhat akin to how 'electron holes' can behave like particles even though they're an absence, not a presence. This is part of the reason why the lattices have to be so carefully aligned.
+Gareth Dean oh. gotta get into the details I guess. aren't the holes exactly like the electrons, thus having the same effective mass? and just to be clear, the lattice enables us to neglect the mass, right?
MooImABunny
Well in graphene effective mass can get iffy depending on how you define it. (You can make it anything from 0 to infinity which doesn't help. See for example dud dud dub philiphofmann.net/book_material/notes/graphene_mass2.pdf ) But yes, we can neglect the mass.
The effect works as follows. As you know an electron's spin points at a velocity-dependent angle from its momentum axis (higher velocities shrinking the angle) Normally you cannot assign an inherent chirality to a massive particle since a left-handed particle moving faster than you will 'flip' to a right-handed one if you increase your speed enough.
But this works only as long as you can do anything you want relative to the electron, move in any direction at any speed. In graphene the electrons movements are restricted, especially in relation to other electrons in the lattice. Because of this a sort of 'induced chirality' arises as long as you obey the 'rules'. As such the electron is only chiral in this particular situation form a certain perspective. Even then it is easily disrupted, the tiniest amount of defects or impurities cause things to break down.
I've been studying qft through books. It's really nice to talk to people who know this material, because half the things you said I didn't know but suddenly make sense to me :D
the relativistic spin was really troublesome for me, because all the books assume I know it already and I'm having a hard time finding info about it.
wanna share some knowledge with me? XD
I think the animation was a little bit off towards the end. The directions the hands were travelling in were quite different from the picture Laurence was explaining.
Free copy of the paper: arxiv.org/pdf/1509.06208v2.pdf
thanks a lot!
So an Electrons in an atom can’t be on the same exited level that’s occupied by another electron? And what’s the maximum number of electrons an atom can have?
We should have a video on superconductivity Brady. Plz
Can you build a quantum q-bit for a quantum computer from your research?
So to keep its formal charge low, doesn't carbon normally want to form 4 bonds, not 3?
How do they know it is quantum tunneling and not just the fact that there are spaces between the boron and nitrogen atoms that would permit the electrons to go through?
is an electron a naked singularity?
If this guy was a Super Villain in Gotham, rather than MrFreeze he'd be MrEnergy
Quantum tunnelling is a collision detection glitch. It's the exact same bug I used to get happening when I was learning programming because I was updating an object's position before I checked for collisions, so if the object was moving quickly enough it could pass straight through another object without a collision being detected. The problem was that I wasn't testing for collisions at a high enough frequency, which raises a big question: Could time have a finite resolution? I have toyed with the idea of there being a minimum distance that time can act over but I'd be interested to know of any real science researching this area.
+CowLunch wiki/google: planck time.
+CowLunch There are a couple of ways to mitigate collision tunneling in games. This is a bit off topic for the video though. You can limit objects' max speed to (tile size in pixels * frame rate) so that nothing can ever travel too fast, or you can do a line-line collision test instead of a point-area test, to determine if and where the object hits a wall. One line segment goes from position of the object in the previous frame, to the desired position this frame. Alternately, there is also the parallelogram method, where you have a leading edge (line segment) of an object whose frame delta produces a parallelogram, with two sides being the edge of the object, and two sides being the vector of motion that frame. That quad can be tested against any kind of collision data, whether it's tiles, line strip/segments, other polygons, or even single points. Or, you know, you could just use a commercial engine that has all this stuff figured out for you, and probably does it faster anyway. :p (This is assuming 2-D, but for 3-D you would just make points into lines, lines into planar quads, and quads into cuboids)