Quantum Computing – Spooky Action at a Distance – Extra History – #4
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Quantum Computing – Spooky Action at a Distance – Extra History – #4


There was one thing, more than any other, that bothered Einstein about quantum physics, It was a phenomena he would dub: *clap clap* “Spooky Action at a Distance™”. *evil laughter* [Birth Of The People] by Demetori *coughs* Oo, sorry about that. *clap clap*
Alright. So, what is this “Spooky Action at a Distance™”
that so worried Einstein and why is it important to quantum computing? Well, it’s this strange phenomena where, in certain sets of particles, when you do something to one of them, the rest are instantly affected. It’s what we know today as, Quantum Entanglement. And it’ll be at the heart of how a quantum computer functions. The idea is this: when two particles are entangled, you have to see them as not two particles, but as one complete system. And anything you know about the complete system has to be true when you look at the component parts. So, let’s say you’ve got a pair of entangled particles and you know the spin of these particles adds up to zero. Now, let’s say you mess with one of those particles and increase its spin a bit. The other particle’s spin will instantly change to correct, to keep the whole system at a spin of zero. This happens no matter how far away those two particles are: they could be in the same room or… they could be across the galaxy. This is what Einstein meant by “Spooky Action at a Distance”. and this bothered Einstein, because a lot of his work was related to signal transmission. In an era, when we were finding dozens of new ways to communicate and when precise synchronized measurements of time were vital for everything, from running trains to managing modern navies, this patent clerk spent many a day pondering, abstract ways of transmitting signals. And to him, the fastest thing was light. Nothing could move faster than light. So the fastest you could ever transmit a signal from one body to another was the speed at which light moved. But consider our two particles a galaxy apart: we nudge one of them in our lab here on Earth and the other one instantly shifts. Instantly! It shifts faster than light could have possibly gotten to it. This breaks down causality. No physical chain of events could have caused the second particle to shift, because no signal could have been transmitted to it that fast. From the perspective of anything like classical physics, this is magic. In fact, it calls all of classical physics into question, as it did in Einstein’s mind. When we think of the world classically we think of chains of events; we think of action and reaction, cause and effect. But what if there’s no physical way to link something’s cause and the effect? What if there’s no chain of actions between the cause and effect? What if there’s no temporal difference between the cause and the effect? Can you even say something is caused by something that happened, at the same time as the thing you’re suggesting caused it? If you find these questions troubling, you’re not alone. Many physicists continue to be troubled by them today. But for the most part, we’ve come to accept that the phenomena of quantum entanglement is real. And instead of fighting it, we have begun to ask questions about how we might make use of this “Spooky Action™”, that’s so concerned Einstein. And there are many potential applications. China just sent up satellites that use pairs of entangled particles as encryption keys. And people are experimenting with the possibility of using this principle to send information instantaneously, rather than be constrained by the speed of light. But for our purposes, we’re interested in quantum computing and the idea of the “Qubit™” Now, “Qubits™” or “Quantum Bits™”, if you’d like to get fancy, are incredibly complicated and we’re not going to do them justice here at all. But the basic idea is simple, in classical computing, everything is represented by a 0 or a 1. Each bit of information is just that, either a yes or a no answer to a question. So, for example, in the classical computing world, if you’re trying to figure out if John Doe is staying at a hotel, you’d have to check his name against each entry in the register. The computer would check the first entry, saying: “Does this name match ‘John Doe’?
Y/N,” and if the answer is no, it would move on to the next name and do the operation again. But “Qubits™” function differently. And again, this is a super-loose, 101 definition but remember how, with the double-slit experiment, we showed that quantum states can be viewed as a wave of possibilities. And that these waves can combine and interfere with each other to create another wave. Well, that last wave, the combined wave, is called a quantum superposition, because basically it’s the sum of other waves. And “Quantum Bits™” can take advantage of this. They can basically function as the superposition of both a classical 0 and a 1. And that already makes them more efficient, in some ways, than a classical bit. But the real trick, comes from when we add entanglement. As we entangle more and more bits together, turning them into a combined system, we effectively, at least for algorithms that can take advantage of this style of computing, get an exponential increase in processing power. This potential exponential growth is why you’ll often hear people throw around numbers like “a hundred “Qubits™” as the goal for quantum computing. At the time, this was recorded, the largest number of successfully entangled “Qubits™” we’ve been able to perform operations with is 20. But, with each “Qubit™” we managed to add to that matrix of entangled “Qubits™”, we get an exponential jump in calculation. So if we could… ever reach something like a hundred, a somewhat arbitrary number, admittedly, the resulting machine would be enormously powerful. So, why haven’t we managed it yet? Why is achieving this so hard? Why are we counting the steps forward in terms of single bits? Because of a phenomena called, “Quantum Decoherence™” A phenomena we’ll get into next time. That is, of course, if the zeros and ones of current computing will still let us. Are we cool? Awesome. Knew I could “COUNT” on you.
See what I did there? Sorry, won’t hap”PUN” again.
Hehe-he [Subatomic Fugue] by Tiffany Roman [Subatomic Fugue] by Tiffany Roman
Written By, James Portnow. [Subatomic Fugue] by Tiffany Roman
Art Supervision By, Robert Rath. [Subatomic Fugue] by Tiffany Roman
Narrator & Showrunner, Matthew Krol. [Subatomic Fugue] by Tiffany Roman
Edited By, Joe Russel and Tracy Lawton. [Subatomic Fugue] by Tiffany Roman
Art By, Alisa Bishop. [Subatomic Fugue] by Tiffany Roman
Communications Director, Belinda Zoller. [Subatomic Fugue] by Tiffany Roman
Creative Director, James Portnow. [Subatomic Fugue] by Tiffany Roman [Subatomic Fugue] by Tiffany Roman
Contact {[email protected]} if you want [Subatomic Fugue] by Tiffany Roman
James to come speak at your school or organization. [Subatomic Fugue] by Tiffany Roman
Subtitle Written By, BreakableTime

100 Comments

  • Extra Credits

    "Spooky action at a distance" — a strange phenomena where, in certain sets of particles, when you do something to one of them, the rest are instantly effected. It’s what we today know as Quantum Entanglement, and it’ll be at the heart of how a quantum computer functions.

  • Sneder

    I've seen the hundreds of comments about quantum entanglement yes. But isn't that machine with 20 qbits kind of a hoax? They are processing something using quantum mechanics yes, but not in the way usually described when people talk about qbits. Correct me if I'm wrong please.

  • James Endicott

    100 qubits is not when quantum computers become useful, it's a benchmark for undeniable quantum supremacy. 100 qubits would be more powerful than every supercomputer on earth that could possibly exist with all of the earth's silicon combined. 50 qubits is probably enough to outpace all supercomputers existing today.

    However, error correction is a huge problem. That's why Google couldn't conquer the world with its 72 qubit computer.

  • Hanro50

    Personally I feel like a asterisks should've been added "We're explaining it as it was theorized at the time. This not how it actually works"

  • arsenelupin123

    No, people are not experimenting with ways to transmit information instantaneously. That's highly, highly misleading. The propagation of information is still limited by the speed of light in quantum theory.

  • drdca

    The previous videos in this series seem good, but this video is bad in that it promotes the myth that entanglement can be used to instantly transmit information, which goes against the no cloning theorem of QM.
    I'd recommend that everyone interested in learning accurate information about quantum computing read Scott Aaronson instead of this.

  • deadspaceman111

    The real spooky part is that occult societies saw the different color of light spectrum reflected off the planets as different religions as bodies of light..they have a way of viewing God forms of bodies of light from planets. If that is the case then observation and magnetism of gravity can have a role of how the waves organize and can explain occult science and quantum physics..portraying that Saturn in occult is the cube and each planet is assigned to a Platonic solid that would lay an underlying element or frequency

  • Aman Singal

    Guys, many have said this. I will too. If you have a system of two entangled particles, say for example a system of two spin-1/2 fermions that has a total spin 0, then measuring one of the fermions' spin z-component determines the spin-z of the second one. No information has transferred, or travelled.
    If one could, by changing the spin of one of them, change the spin of the other instantaneously, then causality is violated. However, if you try to influence just one of the two particles, depending on what you do, you would strongly or weakly decouple the two fermions. So if you try to flip the spin of the one fermion you encountered, it would not change the spin of the other one.

  • Thomas Kilmer

    And here's where you're wrong. I'm sorry, you've been doing great up to this point, but as a quantum communications researcher I have to tell you that at this point you have messed up. Really badly actually, fatally so.

    You cannot use quantum entanglement in the way you are describing. if you ensure a pair of particles share a net spin of zero and separate them and then add some spin to one of them, the other does not experience a corresponding reduction in spin. That is not true. That is not what Einstein was referring to as spooky action at a distance.

    You cannot use quantum entanglement to transfer information faster than the speed of light. You can establish mutual correlations in noise which in a classical system could only occur if you had faster-than-light communication, and perhaps beside beforehand to act in a unified fashion with a partner based on those correlations, but one may not actually cause physical effect or transmit information faster than the speed of light in such a manner.

    What Einstein referred to as spooky action at a distance where these mutual correlations in noise, which after the Bell's inequality experiment he could not understand as being a product of anything other than faster-than-light action, albeit strictly limited action which could not actually carry any information content or carry any wave propagation. His spooky action at a distance did not actually do any action, not like what you're talking about.

  • That Girl With The Coffee

    This is no longer Extra History, please return to the History, or start up Extra Physics, but not this. Please.

  • mage davee

    So your explanation of spooky action a distances was flawed. Nudging one particle won't affect the other particle at all, this would be a serious problem. What happens when you nudge the first particle is you break the entanglement, something you hit upon in the last part of the video, decoherence. What you can do is measure the spin of one particle and instantly know the spin of the other particle, thus collapsing the wave function instantly. This is what bothered Einstein.

  • John Matthew Narofsky

    Everyone's complaining about the inaccuracy in this video's description of quantum entanglement, but it's worth noting that that's not the only problem. Quantum computers are not exponentially faster than classical ones.

    Comic intro to the topic: https://www.smbc-comics.com/comic/the-talk-3
    Wikipedia: https://en.wikipedia.org/wiki/BQP

  • Wackadoodles

    please tell me you guys did a whole series about quantum computing so that you could make a joke about spooky action at a distance during halloween time

  • Vicki Knoer

    Hey Extra Credits folks,
    I really appreciate all the female scientists you've got in your videos. It's really nice seeing smart women conquering physics, just like I and my of my colleagues will be doing.

  • Niek

    i'm not so much bothered by the science as by the terrible sense of humor lately. Seriously. I love this channel but every attempt at a joke of the new narrator just hurts.

  • Carrie Huneke

    The flashlight only appears or disappears wen the light turned off or on also the flashlight floats wen he clapped his hands the second time now that's spooky

  • Shen Kershner

    Man… I love your videos in general. But this one pains me. Let me jump on the pile of people pointing out that you totally got entanglement wrong here. That is one of the things that drives me crazy about media trying to popularize quantum physics. You can dumb it down without actually getting it wrong, but that's not what happened here.

  • P. Boscardin

    I would like to disagree with Dr. Einstein.
    According to my studies and calculus, Sonic the Hedgehog is, in fact, the fastest thing in the universe.
    Much obliged

  • Michael O'Connor

    What if I take an pair entangled partials, take one and leave it here on earth, then take the other one and accelerate it to near the speed of light to another location. Now lets send information, back in time?

  • Jamie Marshall

    Trying to alter entangled particles causes them to immediately collapse. It's like saying its a phone that works only if you don't talk into it. Thus nobody uses this aspect for any practical application. It is simply science fiction at this point.

  • Jamie Marshall

    I'm also pretty sure that entanglement is not a factor in the performance quantum computing as much as having more than two discrete states is. For example, binary is like having an alphabet with only two letters. Quantum computing could theoretically have infinite letters.

  • RedwoodTheElf

    As for cause and effect, there are plenty of people that believe that something 500 years later can be the cause of something that came before. Like when Al Gore proposed that the increase in CO2 500 years after the end of the ice age was the cause of the end of the ice age. So simultaneity wouldn't be all that weird by comparison.

  • Pradyumna Kanthamraju

    It would be great if you guys made vids on the history of complex numbers….anyway…you're videos are quite interesting…thanks for uploading them

  • Emmanuel explique Bitcoin

    Funny how quantum intrication is discovered roughly at the same time when Jung makes the concept of synchronicity a thing.

  • dragonfiremalus

    Quantum entanglement doesn't allow for "nudging" one particle and having the other affected. If you actually DO anything to the particles it will break entanglement. Quantum entanglement is more a statement about the strangeness of shared probability than any transmission of information.

  • The East Man

    Great stuff and very dynamic and fun presentation. One detail though: "phenomena" is the plural of "phenomenon" so you can't have "a phenomena", it's like saying "an oxen" or "a mice". Worth correcting I think.

  • Sriram Ramesh

    I have a question that I don't really know how to google: is there a speed at which electromagnetic fields change? Thinking of Einstein's worries about how 2 entangled particles could affect each other instantaneously, what if the particles both emitted a field in a way similar to electromagnetic fields, could the fields change instantaneously in response any distance away?

  • Tyler Almquist

    Quantum entanglement can’t be used to send messages. When you measure the particle, all that does is change the other if they are measured in the exact same direction. You can’t choose what spin comes out. Watch Veritaserum’s video

  • GOLDENSPIKE3000

    John Doe has lived a full. The dude has literally done everything. He's like 99% the cause of all programming solutions.

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