How Are Quasiparticles Different From Particles?

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The device you’re watching this video on is best understood by thinking about positive and negative charges moving around a circuit of diodes and transistors. But the only elementary particle actually flowing in the circuit is the negatively charged electron. And yet those flowing positive charges are there, in the form of a particle you may never have heard of.

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Hosted by Matt O'Dowd
Written by Fernando Franco Félix & Matt O'Dowd
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[fuuryuuSKK]

3:30 small correction, Boron is B, not Bo, although there is fringe historic precedent in Newland's periodic table

[luanmartins]

I do research in superconductivity and I love when someone explains my research better than I can do. Really really good video!!!

[VorpalGun]

Hats off to the animator for the episode! This channel usually has great graphics to help explanations, but this time there was a lot, and it was outstanding.

[tiberiusgracchus]

Being a musician I really like the concept of there being a quantum of sound. The fact that it plays a significant role in condensed matter physics is just a plus!

[robadkerson]

These are some of the best videos on the internet. Other producers--feast your eyes: the content is relatable and they trust their audience with the science in all its glory.

[SkylarNallick]

One of the most mindblowing episodes that I have seen on this channel. Which is saying a lot considering how often y'all blow my mind.

[realityChemist]

Always love to see solid state physics on this channel! It warms my materials scientist's heart (via a quantum scale buzz of phonons).

It would be cool to see more on some of the quasiparticles you mentioned and but didn't have time to cover (or even ones you didn't mention, like plasmons).

[michaeld]

This is the best description of the workings of these diode junctions I have seen. I have read a few book descriptions which always seem to confuse as much as explain. It is a pity this stuff was not around when I was doing my science degree over 50 years ago when it was so difficult to get any information on anything. What a great age it is now for anyone interested in these topics.

[kylesty]

You know I’ve read books on semiconductors and never really made the intuitive leap you just gave me regarding n-type and p-type semiconductors until now. Thank you, what a lovely presentation.

[basilbrushbooshieboosh]

I was an electrical engineer long before becoming a physics teacher, and I've watched your channel for a number of years. But this show episode is one that got me really quite excited. And that's not excited because you've shown me something new, you do that often enough. Excited because it's something new that's hiding itself on the reverse side of a basic schema that's in plain sight.

Good work here my man, this episode was definitely reinvigorating.

[Obliticus]

Thank you for the clearest explanation of how a diode works. I knew the result of what they do, but never understood how they actually do it :)

[stevosteffano]

Always a fan, but I really enjoyed this one. It hit a sweet spot for me where I somewhat understand your description, but I was also amazed (and delighted) by the consequences. Also it brought Cooper Pairs from 'heard of, but no understanding' into the 'vaguely understand' category. Just glorious. Thank you.

[das_it_mane]

I just play all these videos on repeat and slowly get smarter. 3 years ago, I didn't know anything about physics. Today, I'm more competent than all my friends and can have a reasonably deep convo with my uncle who's a physicist. Thank you Matt and thank you to the entire PBS team!

[Dinoenthusiastguy]

Incredible explanation. This made more sense of quasi-particles than an entire semester of solid state physics. Would love to hear your explanation for effective mass!

[BurningRoman]

Awesome work with this video! Another cool thing: when Cooper pairs are formed, they release a phonon with an energy of roughly 2 times the superconducting energy gap. These phonons can actually smash into another Cooper pair and split it back into two quasiparticles. This is currently one of the major obstacles in superconducting quantum computing.

High energy phonons can also be generated from cosmic events like gamma rays. Some research teams are burying their quantum computers several klicks underground and shielding them with lead bricks to reduce Cooper pair splitting due to high energy particles. The craziest thing? It actually seems to be working; the underground qubits are coherent for far longer than those studied topside.

[vanderkarl]

This is mind-blowingly cool and illuminating. I'd love to hear about more sorts and applications of quasiparticles in Space Time!

[gueropalma]

I dropped out of highschool because there were no teachers like you. I love your videos and I have to watch them twice to understand them sometimes 😂 I am quite good at math for a drop out and I love physics as a hobby. I even read "The Elegant Universe" in prison. Keep it coming, sir.

[theosib]

In silicon semiconductors, holes move about half as fast as electrons. To compensate for this, the conduction channels in PFETs are typically made wider compared to NFETs in the same position. Now, this doesn't strictly have to be the case, but it makes rise times slow compared to fall times, and this complicates computing static timing analysis. It's easier if a logic gate of a given type can be modeled as having the same speed whether its output is rising or falling. You could just model the gate's speed based on the slower of the two edges, but then that means your faster transistors are burning more energy than necessary for a given switching speed, and power dissipation and energy consumption are first-class concerns in modern large scale semiconductors, so you either want to size up the slower transistors or size down the unnecessarily fast ones.

[stadawg]

1:49 That missing electron up top was killing me, glad the animator fixed it later on 😂 great video!

[alanguile]

I lost it at college when they said the holes were positive particles. I never realised how deep the rabbit hole goes! Luckily these concepts travel straight through my brain without interacting with my understanding neuron's so I'm not too affected by it all. I just use the billions of transistors in my phone for serious research into cats🤣