Quantum Computing Expert Explains One Concept in 5 Levels of Difficulty | WIRED

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hi my name is Talia Gershon and I'm a scientist at IBM Research today I've been challenged to explain a topic with five levels of increasing complexity it's a completely different kind of computing called quantum computing quantum computers approach solving problems in a fundamentally new way and we hope that by taking this new approach to computation we'll be able to start exploring some problems that we can never solve any other way hopefully by the end of today everyone can leave this discussion understanding quantum computing at some level what's this what do you think that is can't you share the Lear I think so too we jokingly call it the chandelier that's real gold you know this is a quantum computer it's a con it's a really special kind of computer what does it do it calculates things but in a totally different way to how your computer calculates things what do you think this is Hey yeah you know what your computer thinks that is this really specific combination of zeros and ones everything that your computer does showing you Pink Panther videos on YouTube calculating things searching the internet it does all of that with a really specific combination of zeros and ones which is crazy right that would be like saying your computer only understands these quarters for each quarter you need to tell it that you're gonna use heads tails and you assign it heads or tails so I can switch between heads and tails and I can switch the zeros and ones in my computer so that it represents what I wanted to represent like an A and with quantum computers we have new rules we get to use too we can actually spin one of our quarters so it doesn't have to choose just one or the other can computers help you with um your homework or really hard yeah it can especially if doing your homework involves calculating something or finding information but what if your homework was to discover something totally new a lot of those discovery questions are much harder to solve using the computers we have today so the reason we're building these kinds of computers is because we think that maybe one day they're going to do a lot of really important things like help understand nature better maybe help us create new medicines to help people what's your favorite kind of computer smartphone tablet regular laptop PC I've gotta go with my iPhone so what do you do with your iPhone social media use it for studying have you ever run out of space on your iPhone all the time always when I'm trying to see the photo so did you know that there are certain kinds of problems that computers sort of run out of space almost like you're trying to solve the problem and just like how do you run out of space on your iPhone when you're trying to take a picture if you're trying to solve the problem you just run on space and even if you have the world's the biggest supercomputer did you know that can still happen Wow so my team is working on building new kinds of computers all together ones that operate by totally different set of rules so do you know what that is no glue it's quantum computer a what you ever heard of a quantum computer I haven't have you ever heard of the word quantum No okay so quantum mechanics is a branch of science just like any other branch of science it's a branch of physics it's the study of things that are either really really small really really well isolated I mean really really cold and this particular branch of science is something we're using to totally reimagine how computing works so we're building totally new kinds of computers based on the laws of quantum mechanics that's what a computer is I'm gonna start by telling you about something called superposition so I'm gonna explain it using this giant penny is that like worth a hundred pennies know what it's worth but I can put a face up right and that's heads I can put a face down right so at any given time your point in time if I ask you is my penny heads or tails probably you could answer it right yeah okay but what if I spin the penny so let's do it okay so while it's spinning is it heads or tails hat while it's spinning oh I would know it's sort of it's sort of a combination of heads and tails right would you say so superposition is this idea that my penny is not just either heads or tails it's in this state which is a combination of heads and tails quantum property is something that we can have in real real physical objects in the world so that's superposition and the second thing that we'll talk about is called entanglement so now I'm gonna give you a penny when we use the word entangled in everyday language what do we mean that someone's intertwined or exactly that there's two things that are connected in some way and usually we can separate them again your hair is saying older whatever you can you can unentangled it right yeah but in the quantum world when we entangle things they're really now connected it's much much harder to separate them again so using the same analogy we spin our pennies and eventually eventually they don't stop and when they stop it's either heads or tails right so in my case I got tails and you got heads you see how they're totally disconnected from each other right our pennies in the real world now if our pennies were entangled and we both spun them together right when we stopped there if you measured your penny to be a head I would measure my penny to be a head and if you measured your penny to be a tails I measure my opinion to be a tails if we measured it at exactly the same time we would still find that they were both exactly correlated that's crazy the way that we are able to actually see these quantum properties is by making our quantum chips really really cold so that's what this is all about actually this is called a dilution refrigerator and it's a refrigerator it doesn't look like an Oreo frigerator right but it's something that we use actually there's usually a case around it to cool our quantum chips down cold enough that we can create super positions and we can entangle qubits and the information isn't loss of the environment like what could those chips be used to do so one of the things that we're trying to use quantum computers to do is simulating chemical bonding use a quantum system to model a quantum system yeah I mean I'm definitely gonna impress all my friends when I tell them about this they're gonna be like quantum what so what do you think that thing is is it some sort of conductor circuit that is a really good guess there's parts of that that are definitely about conducting this is the inside of a quantum computer oh wow yeah this whole infrastructure is all about creating levels that get progressively colder as you go from top to bottom down to the quantum chip which is how we actually control the state of the qubits oh wow so when you say cold or you mean like physically colder yeah like physically colder so room temperature is 300 Kelvin as you get down all the way to the bottom of the fridge it's at 10 Mille Kelvin oh wow Amanda what he study so I'm studying computer science currently a sophomore and the track that I'm in is the intelligent systems tracks machine learning artificial intelligence you ever heard of quantum computing from my understanding with a quantum computer rather than using transistors is using spins you can have superposition of spins so different states more combinations means more memory so that's pretty good so you mentioned superposition but you can also use other quantum properties like entanglement have you heard of entanglement I have not ok so it's this idea that you have two objects and when you entangle them together they become connected oh and then they're sort of permanently connected to each other and they behave in ways that are sort of a system now so superposition is one quantum property that we use entanglement is another quantum property and a third is interference how much you know about interference not much okay so how do north canceling headphones work they read like wave like ambient wavelengths and then produce like the opposite one to cancel out they create interference so you can have constructive interference and you can have destructive interference if you have constructive interference you have amplitudes wave amplitudes that add to the signal gets larger and if you have destructive interference the amplitudes cancel by using a property like interference we can control quantum states and amplify the kinds of signals that are towards the right answer and then cancel the types of signals that are leading to the wrong answer so given that you know that we're trying to use superposition and tangle men and interference for computation how do you think we build these computers I have known so step one is you need to be able to have an object is achill device we call it a qubit or quantum bit that can actually handle those things can actually be put into superposition of states you know two qubit states that you can physically entangle with each other that's not really trivial right things in our classical world you can't really entangle things in our classical world so easily we need to use devices where they can they can support a quantum state and we can manipulate that quantum state atoms ions and in our case superconducting qubits we make qubits out of superconducting materials but as like a programmer how would quantum computing affect a different way of writing a program it's a perfect question I mean it's very early for quantum computing but we're building assembly languages we're building layers of abstraction that are gonna get you to a point as a programmer where you can interchangeably be programming something the way that you already do and then make calls to a quantum computer so that you can bring it in when it makes sense we're not envisioning quantum computers completely replacing classical computers any time soon we think that quantum computing is going to be used to accelerate the kinds of things that are really hard for classical machines so what exactly are some of those problems simulating nature is something that's really hard because if you take something like you know modeling atomic bonding an electronic orbital overlap instead of now writing out a giant summation over many terms you try and actually mimic the system you're trying to simulate directly on a quantum computer which we can do for chemistry and we're looking at ways of doing that for other types of things there's a lot of exciting research right now on machine learning trying to use quantum systems to accelerate machine learning problems so would it be like in five years or ten years but I would be able to have like one of these sitting in my laptop just in my dorm I don't think you're gonna have one in your dorm room anytime soon but you'll have access to one there's three free quantum computers that are all sitting in this lab here that anyone in the world can access through the cloud okay so quantum computing creates new possibilities and new ways to approach problems that classical computers have difficulty doing couldn't a said it better myself so I'm a first year masters student and I'm studying machine learning so it's in the computer science department but it mixes computer science with math and probability and statistics so have you come up upon sort of any limits to machine learning certainly depending on the complexity of your model then computational speed is one thing I have colleagues here that tell me you can take up to weeks to train certain neural networks right sure yeah and actually machine learning is one research direction where we're really hoping that we're going to find key parts of the machine learning computation that can be sped up using quantum computing yeah it's exciting so in a classical computer you know you have all sorts of logical gates that perform operations and they change an input to some sort of output but I guess it's not immediately obvious how you do that with quantum computers if you think about even just classical information like bits right at the end of the day when you store a bit in your hard drive there's a magnetic domain and you have a magnetic polarization right sure you can change the magnetization to be pointing up or pointing down right quantum systems were still manipulating a device and changing the quantum state of that of that device you can imagine if it's a spin that you could have spin up and spin down but you can also if you isolate it enough you can have a superposition of up and down sure so what we do when we try to solve problems with a quantum computer is we encode parts of the problem we're trying to solve into a complex quantum state and then we manipulate that state to drive it towards what will eventually represent the solution so how do we actually encode it to start with yeah that's a really good question this actually is a model of the inside of one of our quantum computers ok so you need a chip with qubits each qubit is a carrier of quantum information and the way we control the state of that qubit is using microwave pulses you send them all the way down these cables and we've calibrated these microwave pulses so that we know exactly this kind of pulse with this frequency and this duration will put two qubit into a superposition or will flip the state of the qubit from 0 to 1 or if we apply a microwave pulse between two qubits we can entangle them how do we make yes exactly also through microwave signals okay the key is to come up with algorithms where the result is deterministic interesting so what did those algorithms look like there's sort of two main classes of quantum algorithms there's algorithms which were developed for decades right things like Shor's algorithm which is for factoring Grover's algorithm for unstructured search and these algorithms were designed assuming that you had a perfect fault-tolerant quantum computer which is many decades away so we're currently in a phase where we're exploring what can we do with these near-term quantum computers and the answer is gonna be well we need different kinds of algorithms to really even explore that question yeah certainly having a search algorithm is very useful factoring those are definitely useful things that I would imagine could be done a lot faster on the quantum computer yeah they also unfortunately require fault tolerance right now the algorithms that we know of today to do those things on a quantum computer require you to have millions of error corrected qubits today we're at like 50 it's a it's actually amazing that we're at 50 there's things that we know or we have strong reason to believe are gonna be faster to do on a quantum computer and then there's things that we'll discover just by virtue of having one sure how could someone like me who's a grad student get involved in this or what kinds of challenges are you facing that someone like me could help out with I'm glad you're interested I think the place where lots of people can get involved right now is by going and trying it out and thinking about what they could do with it there's a lot of opportunity to find these near-term applications that are only going to be found by trying things out I'm a theoretical physicist I started out in condensed matter theory the theory that studies superconductors and magnets and you know I had to learn a new field of quantum optics and apply those ideas one of the nice things about being a theorist is you get to keep learning new things so Steve tell me about your research and the work you've been doing in quantum computing my main focus right now is quantum error correction and trying to understand this concept of fault tolerance which everybody thinks they know it when they see it but nobody in the quantum case can precisely define it it's something that we've already figured out for classical computing like something that amazes me is all the parallels between what we're going through now for quantum computing and what we went through for classical computing I was asking computer scientists recently where to read about fault tolerance in classical computing he said oh they don't teach that in computer science classes anymore because the hardware has become so reliable in a quantum system when you look at it or make measurements it it can change in a way that's beyond your control we have the following task build a nearly perfect computer out of a whole bunch of imperfect parts common myth how many qubits do you have that's the only thing that matters I just add more qubits what's the big deal pattern them on your chip the great power of a quantum computer is also its Achilles heel that it's very very sensitive to perturbations and noise and environmental effects you're just multiplying your problems if all you're doing is adding I think something that frustrates a lot of people about quantum computing is the concept of decoherence right you can only keep your information quantum for so long right and that limits how many operations you can do in a row before you lose your information that's the challenge I would say as much progress as we've made it's a frustration to still be facing it let's talk about some of the things we think need to happen between now and fully fault-tolerant quantum computers to get us of that reality I mean there's so many things that need to happen in my mind one of the things we need to do is build all these different layers of abstraction that make it easier for programmers to come in and just enter at the ground level yeah yeah exactly so I think there's gonna be a kind of coevolution of the hardware and the software up here and the sort of middleware and the whole stack another common myth in the next five years quantum computing will solve climate change cancer right in the next five years there'll be tremendous progress in the field but people really have to understand that we're either at the vacuum tube or transistors stage you were trying to invent the integrated circuit and scale it's still very very very early in the development of the field one last minute I think we should bus Steve quantum computers are on the verge of breaking into your bank account and breaking encryption and creative cryptography there does exist an algorithm Shor's algorithm which has been proven mathematically that if you had a large enough quantum computer you could find the prime factors of large numbers the basis of the RSA encryption that's the most common leaves thing on the Internet first we're far away from being able to have a quantum computer big enough to execute Shor's algorithm on that scale second there are plenty of other encryption schemes that don't use factoring and I don't think anybody has to be concerned at the moment and in the end quantum mechanics goes to the side of privacy enhancement if you have a quantum communication channel you can encode information and send it through there and it's provably secure based on the laws of physics you know now that everybody around the world can access a quantum computer through the cloud people are doing all kinds of cool things are building games we've seen the emergence of quantum games right what do you think people want to do with them I have no idea what people are going to end up using them for I mean if you had gone back thirty years and handed somebody an iPhone they would have called you a wizard things are gonna happen that we just can't foresee so I hope you enjoyed that foray into the field of quantum computing I know I've personally enjoyed getting to see quantum computing through other people's eyes coming at it from all these different levels this is such an exciting time in the history of quantum computing only in the last couple years have real quantum computers become available to everyone around the world this is the beginning of a many decade adventure where we'll discover so many things about quantum computing and what it will do we don't even know all the amazing things that's going to do and to me that's the most exciting part [Music]
Channel: WIRED
Views: 4,153,837
Rating: 4.8751702 out of 5
Keywords: 5 levels, quantum computing, quantum, quantum mechanics, computing, talia gershon, ibm, quantum research, computers, quantum computers, talia gershon ibm, binary, super position, quantum property, entanglement, entanglement theory, dilution refrigerator, quantum temperature, computer, quantum properties, physics, scientist, quantum computing expert, quantum states, quantum expert, computer science, quantum explanation, wired, wired.com
Id: OWJCfOvochA
Channel Id: undefined
Length: 19min 27sec (1167 seconds)
Published: Mon Jun 25 2018
Reddit Comments

Oh, man that grad student had the perfect grad student look. Shell shocked but still aware of his surroundings.

👍︎︎ 90 👤︎︎ u/anti_pope 📅︎︎ Jun 26 2018 🗫︎ replies

Aw, I got all excited about this because I'd seen the jazz piano one, and liked it, but the final explanation to the jazz legend went right over my head. I know a bit about quantum computing so I thought they'd made a similar video but about a field I'm more familiar with.

However, in the fifth one she didn't even try to explain anything to him, just asked him questions and had a general chat about a few really well-known applications of quantum computing. Surely they could have picked something more obscure and specialized than 'what is a quantum computer' for that segment so that she'd have something more specific to explain to him that he doesn't already know?

👍︎︎ 49 👤︎︎ u/quitetentatively 📅︎︎ Jun 26 2018 🗫︎ replies

That computer looks like a Star Trek TNG prop.

👍︎︎ 20 👤︎︎ u/BluApples 📅︎︎ Jun 26 2018 🗫︎ replies

It's mentioned that we have access via the cloud. Where do we go to do that?

👍︎︎ 34 👤︎︎ u/chimichangaman07 📅︎︎ Jun 25 2018 🗫︎ replies

Wow she is a good teacher. I am also super confused on how old she is.

👍︎︎ 42 👤︎︎ u/tangoshukudai 📅︎︎ Jun 26 2018 🗫︎ replies

I still have no idea what she's talking about

👍︎︎ 12 👤︎︎ u/rationaljackass 📅︎︎ Jun 26 2018 🗫︎ replies

These videos are always neat.

But that teen not knowing how to spin a penny, despite it being done first a few seconds before, bugged the shit out of me lol

👍︎︎ 121 👤︎︎ u/zeusmeister 📅︎︎ Jun 25 2018 🗫︎ replies

Did she just suggest that that kid is watching 'pink panther' videos on YouTube?

👍︎︎ 26 👤︎︎ u/RedofPaw 📅︎︎ Jun 26 2018 🗫︎ replies

Awesome video.

Totally unrelated question: Does anybody know what kind of chairs they are sitting in? Brand?

👍︎︎ 8 👤︎︎ u/ClockParadoX 📅︎︎ Jun 26 2018 🗫︎ replies
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