If you want to talk about your sincere awe and wonder at the incredible physical universe, I'm here for that. If you want to have cold water throne of your dreams of space colonization, Kelly is at your service. Today we're going to flip that script a little bit. It's my turn to be a wet blanket about overhyped technology. But along the way you learn just how amazing and weird our universe really is. No hype necessary, that's right.
Today we are tackling physics buzzwords two of my favorites, actually, quantum, probably the most overused word in pop side journalism, and the Internet, the classic woid make anything sound more high tech Internet of Things was supposed to make your toaster seem like something from the future. Right, So today we'll explore the science and the hype and the actual amazing, beautiful physics behind a pair of buzzwords that have come together to make a splash in the news. The quantum Internet.
It's not the latest ant Man movie, it's today's topic. Welcome to Daniel and Kelly's Extraordinary quantum Universe.
Hello, I'm Kelly Wiener Smith. I study parasites and space and when we come up with quantum parasites, you all better be worried.
Hi, I'm Daniel, I'm a particle physicist, and the only kind of parasite I want is a quantum one. I don't want two point seventy two tapeworms. I want zero or one, preferably zero.
Oh, but you really don't know until you actually look. You know, until you put the scope down your digestive system, you don't actually know if there's one in there or not.
That's true Schrodinger's tapeworm.
Oh fantastic.
But now I have a real question for you. Can you have a non integer number of parasites? They pit in some weird way where you're like, hm, I'm not really sure if that's another one, But.
You gotta have hard to count things. So, the way tapeworms work is they've got a head. The head holds onto part of your body, and then they form segments called proglottieds, and each proglotted makes its own sets of eggs, And sometimes the proglotted dissolves away and the eggs pass
with your feces into the environment. Other times, the proglotted just pops off and passes with your feces, and sometimes it looks like pieces of rice walking around in your feces, and that's proglotted, and so you can have you know, like pieces of the tapeworm that sort of like separate but are still moving. But we usually count how many tapeworms an organism has based on the number of heads that you find. So that's pretty straightforward.
So parasites are quantized. There you go, amazing. We went from quantum physics to parasites to poop in record time on the podcast. That's what happens when you have a particle physicist and a parasitologist.
Yeah, but you're right, we got there pretty fast. Today. I'm having a good day. We're having a good.
Day, all right, and we are moving at the speed of information, trying to understand how the universe works and sending it to you down the Internet tubes.
So there's a lot of misinformation out there about parasites. So there's also a lot of misinformation out there about what the word quantum means. So, Daniel, today we're talking about quantum Internet.
Yeah, that's right, the latest word to have quantum slapped in front.
Of it, that's right. So today we're gonna find out if that makes any sense, and if it's nearly as exciting as it sounds like it is on social media.
And I'm not actually that upset about the misinformation about quantum mechanics because it gives me an opportunity to clarify how amazing the universe actually is. It's not really a wet blanket moment where you're like, this sounded amazing, but it's really actually boring and nothing. It's like this sounds amazing, but the reality is even more cool.
I mean, I don't know why you gotta sound so down on wet blanket people, but all right, fine, I know you like to keep things upbeat around here.
Oh I see you thought I was throwing a wet blanket on the wet blanket people.
Well, on me in particular. I felt seen, but not in no way.
I wasn't talking about you, but I think it says something. He responded that way.
Yeah, you might be right.
All right, So let's hear how our listeners responded. I went out there and asked them if they knew anything about the quantum Internet, if you would like to contribute your thoughts for future episodes, we would love to hear from you. Please write to us two questions at Danielankelly dot org and you can join the choir. In the meantime, think about it for a minute. What is the quantum Internet? What does it mean? Here's what our listeners had to say.
What is the quantum Internet? Now you're just making stuff up.
I have no idea, but I'm willing to learn.
I assume the quantum Internet is the Internet that joins together quantum computers. Well, it sounds like the interconnected web of sub atomic consciousness, or maybe where Antman hangs out.
The quantum Internet is great and all, but every time I check my emails they're both read and unread at the same time. I would guess that's internet that can travel the quantum realm to go faster than the speed of light.
I would assume that it is a network of computers that have all been based on quantum computing infrastructure and quantum computing nodes.
Maybe the quantum Internet is to do with the Internet being both truthful and untruthful at the same time. I suspect mostly untruthful. The quantum Internet will know what you're searching for before you type it in. If someone asks me what quantum Internet is.
I would say that that is the current structure of our Internet.
It's either your email sent or not sent. At the same time, It's probably a place where astiophysicists and people who use quantum data exchange information.
I've never heard of the quantum internet before, but perhaps use of quantum computers on the Internet. I'm assuming it could do all sorts of neat things that we can't even imagine now. It could just be an entire Internet filled with cats in boxes, and I'm okay with that. The quantum Internet is a marketing term that's really just us.
I can't say what the quantum Internet is, but I can calculate various probabilities of what it might be. The quantum Internet is the name for the observation that any fact you find on the Internet is equally likely to be true or untrue.
There were some really fantastic answers here where your emails are both read and unread at the same time. I love that. I wonder if you get out of trouble if you're like, well, I know it was read and it was unread, and so I answered it and didn't answer it, but like, you know, move on.
Yeah, as usual, people either knew the answer, were wildly off or hilarious. I love this mixture. I always look forward to listening to these. There's so much fun.
Yep, I love y'all.
Thanks everybody.
This I think gave a really nice overview of the various thoughts that people have about quantum internet, what it does, or whether or not they have any idea at all what it does. So let's just start from the beginning, like, what is quantum internet.
Yeah, quantum internet is actually a real thing. It's not total nonsense. It's the idea that you could take quantum computers, which we'll dig into in a minute, and you could connect them in a quantum mechanical way, not in the same way that we connect normal classical computers that ship bits back and forth, but you could connect them using a fancy technology called quantum teleportation, which helps you move
quantum information between one computer and another. And it makes sort of sense, like we used to develop computers, and then we networked all the computers together because that has obvious advantages, sharing information, working in parallel, et cetera. And now we're developing quantum computers, and so you might think, oh, it could be beneficial to connect quantum computers to each other because maybe they could take over the world and
enslave us. No, I mean calculate our taxes faster, whatever quantum computers are supposed to do. So the quantum Internet really is two different ideas. It's quantum computers connected together with quantum teleportation.
Oh that sounds very star treky. But so my understanding of quantum computers is that we sort over getting a handle on it. But this is not something that you use, like every day to solve normal problems. Yep, connecting quantum computers it feels like you're jumping ahead five or six steps, Like, shouldn't we get the computers to work first?
Well, I don't know. I think we should work on all the problems at the same time. Right, It's not like we should finish physics before we get started on biology, because it's the colvision of everything, right, right, I'm agreeing with you.
I mean, you need to be motivated, and how can you stay motivated if you're just doing physics. You need the good stuff too.
You're right, we can't use the quantum Internet without quantum computers. But we also don't want to wait until quantum computers are a full fledged thing before we start thinking about how to connect them. And you know, everybody out there is excited about different stuff. So there's a group out there that recently made a splash because of their advance in quantum connection quantum computers, and we're going to talk about that in a minute, and that's why it's in
the news. But I think it's a good idea to push on all fronts simultaneously.
All right, fair enough, there's enough people excited about the question. You can work on more than one front. Can you give us a quick explanation of what a quantum computer is?
Right? So, the quantum Internet is a quantum connected bunch of quantum computers. The core that is a quantum computer. What is a quantum computer? And so there is so much misunderstanding and misinformation about quantum computers, especially recently because of Microsoft results and Google's claims and clickbait writing articles. Quantum computers are not computers that do infinite number of computations in parallel. They are not computers that tap into
the multiverse. There are computers that use quantum mechanics to do calculations instead of using classical physics. Or just normal bits. Right, So in a classical computer, the one that I'm using right now to record this podcast episode, and the one that's inside your phone or whatever device you're listening on, there's a bunch of bits. There's zeros and ones, and all of computation involves calculating new bits and flipping bits. You know. For example, when you take a picture, it's
stored in terms of those bits. When you add two numbers, it expresses those numbers in binary form, where every digit is a bit, a zero or one, and it adds them in binary form. So the lifeblood of normal computers are these bits that are zero or one, and we use the rules of logic to build up a bunch of stuff that computers can do. But that's just one kind of computer, right. Technically, anything is a computer, like a baseball is a computer. It just calculates only one thing,
like what a baseball can do. The cool thing about digital computers, the ones we know and love, is that they're programmable. We figure it out a way to take advantage of this very basic operation and map into lots and lots of really interesting problems. Cool, but there's some things that classical computers are slow at you know, just because you can map them into lots of things doesn't mean that they're very good at things. You know, like counting to a super high number. It can take a while.
Anybody who is like run a piece of code over massive data that knows it can take a day or something, even on fast computers. And so quantum computers say, well, what if there's another way to do computation. Instead of starting from something like a zero or one, let's start from a state that's more ambiguous, like a cubebit. A cubit is something that doesn't have to be zero or one. It can have a probability to be zero and a probably to be one, and so there's like more fuzz there.
And the rules of quantum mechanics are different from the rules of digital logic, and so that maps to a different set of problems that quantum computers can do quickly or do slowly.
Maybe this was when we were talking to Scott Arenson the other day. He said something about how quantum computers are better when you want to solve quantumy problems or things like protein folding, Like if I have a question about parasites, I wouldn't make a computer out of parasites. Why is using cubits make it easier to solve those kinds of problems?
Well, actually, I disagree with you, Kelly. I think you should build a parasite computer. And let me tell you why. You know, Let's say you wanted to know what happens on a certain quantum process, right, Well, one thing you could do is you could try to simulate that process on a classical computer. You could like represent it abstractly using zeros and ones, and then encode the rules of quantum physics into that digital logic and run it. It might be kind of slow, or you could just ask the
quantum object itself. You're going to do the experiment, right, say, oh, I'm just going to ask the universe. I'm gonna put
the quantum objects in that situation. I'm going to see what happens, and then behind the scenes, the universe is following those rules of quantum mechanics for you, and the universe of the computation is free and kind of infinitely fast, and so in comparison, if you wanted to know, Kelly, like what happens if you drop a tapeworm into a can of coke, Just drop the tapeworm into a can of coke. That's a parasite computer right there. We think about computing sort of narrowly, like what it can be
done in Excel. But computing is really just like getting the answer to a question, and sometimes building the system itself that you have a question about is the most natural way to get the answer.
Okay, so one, I don't expect that Coke is going to be running any ads on our website for our podcast for the foreseeable future.
You don't think tapeworms like coke? What you think they prefer something else? Are they pepsi fans?
I was going to make a joke about coke being no worse once a tapeworm has dropped in there, But I'm just kidding. I'm just kidding.
Wait, have you done that experiment? Do you know the answer to that calculation?
I would never do something like that to a parasite. Do I have dropped some ethanol and formaline?
So then, backing up to Scott's comment, is natural to calculate quantum things using a quantum computer because it's simpler to express them. It's likely to be fast. Now, in principle, anything you can calculate on a quantum computer, you can also calculate on a normal computer. Why because you can simulate a quantum computer on a normal computer. Right, just design one in your symbolic logic and let it run
and simulate the laws of quantum mechanics. It's going to be slower the same way, like calculating exactly what happens to a baseball could be slower than just throwing the baseball. Right, let the universe do the computation. So the thing they know about quantum computers is that it's a different way to represent problems we might want to solve, and they're fast or slow at different things than baseballs or tapeworms
or normal digital computers. So they're like a radically different way to do computation, and potentially they're very powerful at some problems. So, you know, there's some problems that we think classical computers are going to be very very bad at. For example, finding out if a number is prime. If I give you a number, how do you know if it's prime? Like if I ask you ninety seven, is it prime? Well, technically you have to check all the factors that might go into it. Well, undt a time.
I mean, there's some clever ways to do it to be a little bit more efficient, but it's slow, and as the number gets big, that stays slow. And amazingly, there's a guy who figured out an algorithm to do that on quantum computers much more rapidly than on digital computers.
So that's an example of a kind of problem which for weird reasons, because of the way quantum bits come together and the way we can map that problem to mathematical problems, there are some things that would happen fast on a quantum computer than on digital computers, but there's
a very small number of those problems. People think like, oh, quantum computers can solve anything, you know, they can break into anything, and they're often used as like the mcguffin on these action movies, Right, don't let the terrorists get the quantum computer, or they'll get your bank account. In reality, cryptography is better protected than is often described in those movies, and nobody has a quantum computer that's powerful enough really
to do anything more quickly than classical computers. So quantum computers are a real thing. They're awesome in the future, and we have bigger quantum computers with more bits, they can maybe solve really interesting problems that otherwise would be very slow on normal computers. But no, they're not proof that the multiverse exists. They can do infinite computation in parallel, and they're currently not really useful for anything.
A couple questions, all right, First, so you were talking about bits being zero in one, and you're like, so we're going to use something a little fuzzier that to me doesn't necessarily seem like an easy way to get a better answer. So our quantum computers. You said they're better for some questions. Are they worse for a lot of other questions?
Oh?
Yeah, okay, so they don't always beat classical computers. No, okay, all right? And then you said they're not necessarily computing in the multiverse. Do all of the quantum computer people believe you, because I feel like I've heard some who are like, maybe this does prove the existence of the multiverse. Are you not teaching the controversy here, Daniel.
That's a fair question. I don't know anybody who I take seriously in quantum mechanics who thinks that quantum computers prove that the multiverse exists. I mean, how would you even steal man that argument? I think the argument is that quantum computers require superposition of multiple states. You know, for example, like your baseball can only have one energy, but an electron maybe it has a probability to have two different energies. It could have this energy or the
other energy, or maybe it has two possible spins. It can simultaneously be in two states, or more accurately, you can say you can have the probability to be in two states at the same time. This is something weird that quantum objects can do. Quantum computation relies on this because the law of quantum physics predicts what will happen to each of those probabilities, and we map our problems onto those quantum physics and use the outcomes of those
probabilities to get the answer. So it relies on superpositions existing.
But we've known superpositions exist for a long long time, you know, like we have obvious examples of quantum superposition, all the Bells experiments about quantum entanglement that we'll talk about, the interferometer experiment, the double slid experiment, Like we have proof that superposition is a real thing before quantum computers, So like, I don't think because superposition is real, that means there's any strong argument that the multiverse is real.
So I'm ninety nine point nine numb percent sure that quantum computing folks would say that this is just hype.
Have you let the Marvel folks.
Know there's a universe in which the Marvel folks have reached out to me for physics consulting, But it's not this universe.
Oh bummer, bummer, all right, that might have been the best universe to live in. But okay, so we've wrapped our heads around quantum compute. So let's take a break and when we get back, we're going to talk about quantum teleportation. All right, and we're back, Daniel in Star Trek is quantum teleportation how they move people from one place to another?
You're gonna ask me about the physics of something totally fictional.
I love that.
That reminds me of when I used to give presentations in elementary schools, and my favorite part about that was always opening the Florida questions.
Uh huh.
And I remember one day getting a question that totally stumped me, and the question was just very similar to your question. Actually, it was Hey everyone, just a note. While we were recording this episode, a minor earthquake hit southern California and my office shook a little bit. We decided to keep that audio in the record for the sake of transparency about life in California.
They just got quake, Aleric, Oh do you feel it?
Yeah, I'm like literally shaking.
Are you still shaking?
Nope? We're done. Wow, that was cool.
Do you need to check in with anyone?
No, just run in the mid day in California. Some kidner gardener asked me if lightsabers were real, would they be made of liquid nitrogen?
Wow?
Wow, I don't even know how to answer that.
Yeah, where do you start.
Here's a kyber crystal, Like you want to walk you through the physics of kyber crystals? Like, I don't know anyway, I don't know how they do it in Star Trek. But teleportation is a really interesting question philosophically, and you probably know that because every time we have a science fiction author on I ask them what they think teleportation means. Even does teleportation mean like your actual bits disappear and
appear somewhere else, like these atoms are now there? Or is it enough to tear you apart and rebuild you at of different atoms with the same arrangement. Right, Is it like a cut and paste? Is it like an email of what's going on? What is required for teleportation? Anyway, it's kind of a deep philosophical question. Where do you stand on that, Kelly.
Yeah, you're dead?
Yeah?
Yeah, No, you die and you get brought back somewhere else. You couldn't get me in one of those.
But that's only because I think you're assuming that they get torn apart and rebuilt. What if there was an actual teleportation device that took your actual atoms and appeared them somewhere else, would you get into that?
I would be the one millionth person in line for that.
Okay, that was a yes. I heard a yes. We have it on the air.
If you're in line in front of me, Daniel, then I will give it a shot.
I would like my ashes teleported into the center of the sun. How about that?
Oh? Interesting? All right, quantum teleportation. Let's step out of Star Trek and into the real world. How does quantum teleportation work?
Right? So, quantum teleportation is arguably not teleportation. I mean, it depends again exactly what do you mean by teleportation in that sense? But quantum teleportation is a way to transmit a quantum state. You know, there's a difficulty here, which is, like, let's say I have a particle in some quantum state, And by a quantum state, I mean like it has a probability to be this and a probability to be that. Right, take an electron, for example, and say it can just have two states up or down.
So let's say I have an electron and I've done some complicated thing to it so that it has a seventy percent chance of being up and the thirty percent chance of being down.
Can you actually do that? Like, you can tinker with the probability that it's up or down.
You can do lots of different stuff. Yeah, you can construct an experiment so that electrons have whatever probability you want of doing basically whatever. That's what experimentalists do. Yeah, exactly. Wow, force the universe to do something cool. And so let's
say that's like the outcome of your calculation or whatever. Now, maybe you want that information somewhere else, right, Maybe you want this quantum state to exist not here in California, but in some quantum computer in Virginia right where you're gonna use that as the basis of your next colcolition or I don't know whatever you folks do in Virginia with quantum states.
I know that we don't get earthquake alerts.
Wow, too soon to superpoint. I'm sorry, No, it's fine. And so if you want to copy a quantum state from here to there, it's a little tricky because if I interact with that electron, if I like measure it, or if I touch it, or if I put in
a box, I risk collapsing its state. Right, the universe allows things to stay in superposition till they interact with something that can't be in superposition, like a classical object like my eyeball or my detector or whatever, and then the universe picks okay, spin up or okay spin down. And that could be fine. But if what you want to do is preserve the quantum superposition, not to collapse it, and to copy that information somewhere else, then you do
something called quantum teleportation. So that's really what quantum teleportation is is it transmits a quantum state from one system to another without collapsing it, which is pretty cool. I don't know over it really qualifies as teleportation.
Are you actually moving the electron from one place to another.
You're not at all moving the electron. You're moving the arrangement, the quantum state. And so I have an electron here in California, you have an electron in Virginia. I want to get your electron in Virginia to have the same quantum state as my electron. I'm not like putting it on a ups truck and driving across the country. I could do that, that's no big deal. But if I just want to transmit the information the arrangement the quantum state,
that's what we call quantum teleportation. And some of the folks I know in the foundations of quant mechanics really hate that name. They're like, why they call it teleportation? Okay, I know why, because it sounds cool, but it's not really teleportation. It's misleading, and so it's important to understand
like what it actually means. But it kind of makes sense, right, Like if you have a network of quantum computer it's one basic thing you're going to want to do is take a quantum state from one and copy it over to another one so it can like continue the calculation or whatever. So whatever you call it, it's an important part of having networked quantum computers.
I feel like it's one of those darned if you do, darned if you don't situations. You know, like you call it teleportation and now it's awesome and I want to hear more. Or you could be like, oh, Jupiter's rings or ABC and D and I know I keep using it as an example, but like that is so boring. You've got to be kidding me. So trying to find the sweet spot for naming these things is tough.
What would you call Jupiter's rings, Kelly.
Well, I'm going to need some time to think about that. I don't know.
I'm sorry you've been complaining about the name for weeks.
You're right, oh, man, putting me on the spot.
I'm just calling your bluff, that's all.
Yeah, you are calling my bluff. Hmm. What's the name of the ring and Lord of the rings? Crashous that's what Gollum calls it.
That's what Gollum calls it. Yeah. The efficient name is something in Elvish, isn't it.
No?
Yeah, anyway, all right, focusing again, Okay, quantum teleportation we understand what that is now. And you said that we can connect an electron in California to an electron in Virginia. Mm hmmm, how does that process work?
Yeah, so to do that, we're gonna have to use something called quantum entanglement. So we're three layers deep. Now. Quantum Internet requires quantum computers connected by quantum teleport rotation,
which rests on the principle of quantum entanglement. All right, So now we're going to dig into what is quantum entanglement fundamentally, and then we'll come back and explain how you use quantum entanglement to do quantum teleportation to connect your quantum computers on the quantum Internet and play quantum doom with your quantum friends.
Oh nice, but that probably would be easier on a classical computer.
You can put doom on anything, though, right the day they pour doom to something, that's how you know it's a real computer.
Yep.
Amen.
All right, So what is quantum entanglement? And this is again something you hear a lot about in the Internet, and I know people are confused about because I get lots of emails from people saying like, why can't you use quantum entanglement to transmit information faster than light, and you can't. And we'll talk about why that is. But you should also understand the quantum teleportation is not faster than light. It's slower than light transmission of quantum information.
But before we get to that, let's understand what is quantum entanglement. Quantum entanglement has to do with the superpositions we talked about earlier, the probabilities for various outcomes. So let's say we have, instead of just one particle that can be spin up or spined down, say we have two electrons in California. Each one can be spin up or spin down. So how many possible states can they be in. Well, there's four. There's plus plus, plus minus,
minus plus and minus minus, right, so there's four possible states. Cool. And if you just like scrambled the electrons, they can be in any of those states with equal probability. Cool. But let's say we've done something clever. We're an experimentalist, and we've prepared these electrons in such a way that there's a constraint on them, like they have to have opposite spins. And this isn't so hard to do. If they come from some state that has a total spin zero.
The universe conserves angular momentum, and so when you create these two electrons, their spin has to add up to zero. It's not so hard. And so if you do that, it means that only two of the states are possible, the one that is plus minus or minus plus the plus plus state and the minus minus state no longer allowed. So we've crossed two of the states off the list, and boom, those two particles are now entangled. Why do we say they're entangled because their faiths are connected? Right?
If one is plus, the other one is minus. If one is minus, the other one's plus. And this is not some mystical thing where like you force one particle to be minus and it reaches out through the universe and makes the other one plus. It's just that you have a list of options, and that list is limited, and in every possible outcome they have the opposite spin.
I'm keeping track of, like how complicated all of these steps are. So you said it's pretty easy to get an electron that's entangled, so that one is plus and one is minus. What does pretty easy mean? Do you have to like go into the lac after spending billions of dollars, or is this something that can happen in a lab on a UC campus.
This happens all the time, like every time a photon turns into an electron and a positron. Those are entangled, like it's constantly happening all of the time, and it's not actually that hard to do in the lab. The thing that's tricky to do in the lab, and the thing that's important is separating those two and maintaining their entanglement. You create those particles, they're entangled, and it's a really cool state because it's not yet determined. Right, they could
be plus minus, so they could be minus plus. But then you could separate the particles. You can say, i'm gonna take particle B and i'm gonna drive it to Virginia. I'm gonna leave particle A in California. They're still entangled, right, And then if I measure particle A when it's in California and I get plus, then I know instantly what particle B in Virginia has to be. Because they're entangled.
The thing that's hard is keeping them entangled, because to keep them entangled, you have to avoid them interacting with anything else. Like these electrons, they like to interact with stuff. You put them in a box, they'll interact with the box. You put them on a truck, they'll interact with a truck. So keeping these particles in that state while separating them means isolating them from everything else, because if they touch or interact with anything else, then they get entangled with
that thing, or they get entangled with you. And now you were part of that quantum entanglement state to do the things that we want to do in a minute to transmit information, and we need them entangled with each other and with nothing else. And that's where the sort of onto magic comes from. Right, these two particles are now really far apart. They can be a kilometer apart, a light year apart, and they both maintain the uncertainty of being in plus minus or minus plus. Then you
measure one of them, you get a minus boom. The other one is a plus. You know it, it's gone from uncertain to certain. That's the incredible thing about quantum entanglement, so that you can maintain the connection across distances, that's the non local part of quantum mechanics.
Can we dig in a little bit more about how you make them not interact with anything. Do you use like electric fields to hold them in the center of a box?
Electric fields are an interaction?
Oh man, yeah, exactly what do you do?
It's very hard. I mean, with the simplest way you can think about it as a thought experiment. It's like you're out in space. You have a photon. It turns into an electron and a positron, and they're going in opposite directions already naturally, right, Like if it had a lot of energy, then that energy is going to get transmitted to those particles. They're just going to fly apart, and so along the way they're not they interact with anything if it's really empty, and so they'll get further
and further apart and still stay entangled. So on Earth, of course, it's much more complicated, and people have all sorts of tricks for keeping these things separated and keeping them isolated. It's not easy. It depends a lot on the details of the quantum system exactly the particles. We can dig into that in a future episode. I think that's a cool idea, but it's not easy. Right. The particles like to interact with everything else. And to decohere, this quantum state is very very fragile.
All right, So that is really awesome. You mentioned that this can't be used for faster than light communication. Could you dig into that a little bit more.
Yeah, it sounds like you should be able to use it for faster than like communication because there is something non local and instantaneous happening. Particle a's in California, particle b's in Virginia. Both of them are maintaining their superposition. Both of them could still be plus or still be minus. The entanglement just says they have to be opposite. Both
of them could still be plus or minus. Right, I make a measurement in California, I get plus instantly know that you would get a minus if you measured yours in Virginia. So there is some sort of instantaneous across space and time thing happening there, which is very very cool, and it sounds like you should be able to use
that for faster than like communication. And a lot of people write it and say, well, what if Daniel measures his and Kelly is watching, and so she knows, and you have a series of these things and Daniel measures them at a certain time, and Kelly is watching the pattern or something. It feels like you should be able to maybe use that for faster than like communication. The problem is if I measure mine in California and I get plus, I know that you're going to get a minus,
but you don't know that. The Only thing you can do is look at your particle and measure it, and you don't know if it's collapsed or not. You can't tell that it's collapsed. I know that it's collapsed, but there's nothing about the particle itself that shows you that it's collapsed. You can measure it and get a minus. Cool, but you don't know if you got a minus because I already collapsed it, or because it was not collapsed and you collapsed. It's no like your particle has been collapsed.
Light that goes on. There's no way to manipulate these things. And I also can't change it. It's not like I can say, oh, I have a plus, I'm gonna flip it to a minus to make Kelly's go the opposite. And as soon as I've measured mine, I break the entanglement. Right it's over. It's interactive with something that was a
one time deal. So in science fiction novels where they have like entangled particles and they put one on a ship and they take them to Alpha's centauri and then they can use it as the basis of some answerable technology where they do FTL communication. Yeah, that's pure nonsense. It's fun. I'd love it, but it doesn't work.
Okay, so it can't be used for helpful communication. But does the bit flip at a rate that's faster than light? So you bring them to opposite sides of the universe, do they communicate faster than light?
Great question, Yes, but I wouldn't say bitflip. So the collapse is instantaneous, right, If I measure mine in California, then instantaneously yours collapses faster than light.
Okay. Wow.
Yeah, and that's weird and that's cool. And that's the thing about quantum mechanics that we call non local, right, there's something global that's happening there, and people who've heard of Bell's experiment. Bell's experiment proves to us that it's not like one particle was always plus and the other one was always minus. We just don't know it. It means that this uncertainty is real, that they really do maintain the possibility of both outcomes until you do measure it.
Bell's experiment proved that there's no like hidden information there that determines the outcome. It really is uncertain or at least and this is important, but it proved that there's no local hidden information. Quantum mechanics has to be non local in some way either. It really is probabilistic, and it maintains these probabilities and collapses instantaneously across space time when one of them is measured. So you should really think of it as like not two particles but one
big quantum state. You collapse it anywhere, the whole thing collapses or there are some other crazy theories about global quantum information, you know, like super determinism or whatever that we can get into another time. But you know, the way most people think about it is that it does collapse instantaneously across space and time, which is crazy. But you can't use it to transmit information because you can't control it. Right. You can ask it, you can query it,
you can collapse it. I can't even tell whether you've collapsed it or not. And you can't tell whether I've collapsed it or not.
Okay, so it's not useful for faster than light communication, but it is useful for quantum teleportation. So after the break, let's jump back up a level to quantum teleportation and try to understand that. All right, we're back. So we now have a firm understanding of quantum entanglement. Maybe we have a firm understanding, and then we have two quantum computers and we want them to be able to communicate with quantum teleportation. Yes, tell us some more about how that works.
Right, So remember the problem we want to solve is I have my electron. It's in some state, maybe it's like seventy thirty plus or minus or whatever, and you have an electron in Virginia, and I want to put your electron in the same state as my electron, and I don't want to collapse it, and I also don't want to put in a truck and drive it across the country. How do I get that quantum information without
collapsing it and make your electron have it? Right? And so the way we do that is through quantum entanglement, because I can interact with my electron without collapsing it if I use with another quantum particle. So if I touch the electron, or if I poke it with something classical that can't be in a superposition, it will collapse the electron. But if I let that electron interact with some other quantum thing that can be in a superposition, it'll get entangled with that quantum thing. So I have
my electronics in the special state. I bring in another particle, and I have those two interacts somehow, and now they're entangled. You have the particle we want to copy and some other particle entangled with it. Now if I planned ahead and had entangled this other particle with a third particle that we then sent to Virginia, we'd be ready to
do quantum teleportation. So here's the setup. I have the original source particle I want to copy, and a pair of particles that are entangled with each other but separated, one in California and one in Virginia. I entangle my California particle with the source particle without breaking the entanglement because it's a quantum particle, and so the entanglement just spreads. It doesn't break like it would if it interacted with
a classical object or with the whole environment. So I have my California end of our entangled particle pair, and now I've entangled that with the source particle I want to copy, and I can see what happens to the California end of the entangled pair. They can use the information in that new special particle. I can read that off and send you some information. I can email it to you, or I can send it to be a carrier pigeon or whatever some slower then like process, because
everything is slower than night. I send you that information, and there's a recipe for using that information to copy the state of my particle onto your electron. I'm telling you what you have to do to your end of the California Virginia entangled pair to make it a quantum
copy of my original source particle. So, to summarize, we entangled two particles, separate them while keeping them entangled, entangle my California end of it with the source particle, read off some information about that, and send it to you, so you know how to manipulate your Virginia end to make it a copy of my source particle.
Okay, so you have something going on in your computer where you've got entangled cubits, Yes, and you send me an email with instructions for how to do that on my computer. Yes exactly, and now my computer has the same entanglement stuff going on as your computer.
Yes exactly. There's a lot of little bits that we've skipped over because the math is a little complicated. But the crucial thing to understand is that I've avoided collapsing my cubit by interacting with a quantum particle, which now stores the information from it. And I can extract that information from my quantum particle and send it to you,
so you can reverse the process. If we have kept our entangled pair nicely entangled, you can prepare some fond of part of in that state, have it interact with your electron, and then your electron will be in the same state as my original one was. And so this is what quantum teleportation is. It's a way to interact with the quantum objects, extract their information without collapsing it, encode it into something that we can transmit across the world or whatever, and then reverse the process.
But when your quantum particle entangles with an electron in your computer, and then you look at what the quantum particle is doing, so that you can tell my computer what to do. When you look at your quantum particle because it was entangled, doesn't it mess up the system?
It does actually mess up the system. And so when you copy the state, it destroys the original state. So the electron that I had in California is no longer going to be in that state that we both wanted. So I extract that information, I send it to you. You use that to create the quantum state over there in Virginia. But there's a no cloning theorem that says that you can't extract that information without also destroying it. But here we are extracting it in such a way
that we can recreate the state in Virginia. Yes, we've destroyed the state of the California electron. So I'm not like just emailing you a PDF where like I also still have it. I have to like shred that PDF somehow and send it to you so you can recreate it.
So the teleportation, and maybe this is where we discovered that teleportation actually wasn't a great term for this, But okay, so the teleportation is actually just that you've used entanglement to figure out what's happening with another electron. You're sending me that information and you are like teleporting it by email quote unquote, and that's where the teleportation is happening.
Yeah, it's very equivalent to saying, like, hey, Kelly, I built a really cool Lego house over here, and I'm going to send you the recipe to do so. I need to like tear apart my Lego house so I can keep track of exactly how you're going to build it. Then I'm email you the recipe and you guys are going to build the same Lego house over there. I had to destroy my Lego house to develop the recipe, and I just emailed it to you, or I send it to you via mail or whatever. But now you
have the recipe to create exactly the same thing. And this is tricky only because these are quantum particles and it's not to read them off and to create these states. But this essentially is quantum teleportation. And I'll kind of argue the teleportation it's not a terrible name for it.
I mean, if the Star Trek teleporter is scanning you and reading the quantum state of all your particles and then beaming that information to another machine that can reverse that process, then Yeah, that's kind of what we're talking about here.
So everything we've just talked about sounds pretty complicated. Can you give me some situations where you would want to go through that process? Like, why would you create something in one computer destroy it just so you can create it on another computer. Couldn't you just create it and the second computer from scratch without making it on the other one first?
Yeah? Maybe, but perhaps it's the outcome of a very complicated, very expensive quantum computation, you know. And like, let's say I have a quantum supercomputer and you ask me to do some calculation about your tapeworm simulation.
I don't know, you have my attention.
I do it for you, and I want to send you the result, right, I want to use the quantum Internet to send you this quantum answer to your quantum could computer from my quantum computer. And yeah, you could recreate it, but it might be really really slow, and so might well just copy the answer in the same way that your computer can calculate your taxes much much faster than you can. And you might think, well, why
do I need that? I can just do it myself. Yeah, but you might as well skip ahead and get the answer so in that way, the quantum information here represents the results of a quantum computation, which could be extraordinarily valuable, right, and so you might want to save that. And people thought about ways to build super powerful quantum computers by tying together quantum bits across the quantum cloud, right the way you like, we make very powerful computers by spreading
information and computation across them. You ask Amazon to do a complicated calculation, it doesn't just run in a one computer. It runs on ten fifty one hundred, so that you get the answer faster. In the same way, maybe you take a big quantum problem, you break it into pieces. Each quantum computer does a piece of it, and then they want to send the answer back to some central node which puts it together to get the final answer. That requires a quantum internet of quantum computers that can
send quant states back and forth to each other. And so that's why this is a stepping stone to some future awesome globally linked quantum computer.
And so where are we now? Has somebody recently done this quantum teleportation thing?
Yeah, so people have been working on this for a while. And the bit that we talked about the quantum entanglement and sending information usually requires really specialized hardware. Keeping our two particles entangled is hard because we have to keep them isolated from any classical object. And what happened recently is a lab at Northwestern in northern Chicago managed to
do quantum teleportation over normal fiber optics. Right, So usually like keeping that information pristine and clean is very very hard, Right, you have specialized hardware to transmit this information because it has to be just right. But they were able to use fiber optic cables that were thirty kilometers long that already also had normal Internet traffic, so like people randomly emailing and texting pictures of their cats and whatever, and they were able to send this information to do quantum
teleportation across this noisy, totally and fiber optic cable. And so that was the excitement recently about the quantum Internet, is that we went from like you need specialized, dedicated hardware to do it for a single electron, to like, oh no, we can do it over long distances using standard equipment that already exists.
But you're not sending entangled electrons through fiber optics. You're just sending instructions through fiber optics that then set up the next computer on the other side.
Is that right, Yes, that's exactly right.
Okay, still totally awesome. I just wanted to make sure I was understanding all right, awesome.
Yeah, And so this is the first demonstration of quantum teleportation of entangled photons through busy optical fibers that are also carrying conventional telecommunications traffic. So, you know, it brings us a step closer. It's not like we have the quantum Internet. It's not like you can log on right now to the quantum Internet and do your quantum taxes
or anything like that. But you know, this is an important step forward in making this realistic because if we want to build a bunch of quantum computers and connect them, it'd be nice if we could use standard equipment to do so and not have to build a whole separate quantum Internet. So it's cool, it's like, very experimentally awesome.
Taxes are so complicated it wouldn't surprise me if next year we need to be doing our taxes on quantum computers. But I hope we're not getting there.
Yeah, well, you should think about whether you want to pay your taxes or not pay them or both.
Whoa, I know which one I'd rather do. But on the other hand, I really like my government services, so I feel complicated and.
I like not being in jail.
Yeah, me too, Me too. There's a lot of things that would be hard to do from jail, like this podcast.
Actually that might be possible. We'll find out maybe.
Yeah.
So the quantum Internet is a real thing, right. Quantum computers are real and they're awesome, not always in the way people say they are. They're not the multiverse, but they are a new way to do computation. And quantum teleportation is a real thing. It's not faster than light, it's not Star Trek, but it is a way to transmit quantum states across vast distances, which is very cool.
Bring them together and you get the quantum Internet. Quantum computers connected through quantum teleportation to do massive quantum problem solving. I think it's pretty cool.
The future is now, and so.
I hope I didn't throw too much of a wet blanket on the quantum Internet. There is really a lot of awesome physics happening there. And if one day we do have very powerful quantum computers. They may be able to solve problems that do stomp us today. So I look forward to the first time an episode of this podcast is released on the quantum Internet.
Well, you are now a member of the Wet Blanket Club. But it's going to be a while before your president. But I enjoyed spending this time with you.
Are you dictator for lives that hot works?
Yeah? Yeah, that's right, and Zach's first husband of the Dictator.
I'll start as as secretary, work my way up.
Oh right, good luck?
All right, thanks everybody for listening. I hope we didn't entangle your minds at least not too much.
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