Current State of Quantum Computing – Computerphile
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Current State of Quantum Computing – Computerphile


Well, brief mentions in other videos about the Q-word, *Laughs* you know, the magic computers that are going to break all encryption and beat everyone at their own game and be the next big thing and be on all our smartphones. Should we put some reality on this? Where are we at with quantum computing? I Work at a company called Righetti computing. We’re a company in Berkeley, California And we build quantum computers from the ground up. We do the silicon fabrication all the way up to how we program the machines I in particular Think a lot about how we program the machines how we interface with it at some point Somebody has to type something into a keyboard to make it do something and that’s mostly where I think about things quantum computers Really should be thought of as a way to Augment our existing compute infrastructure exists in computers solve problems, and that’s not going away there. They will continue to solve good problems So a quantum computer really should be thought of as a is a special-purpose machine that can solve certain problems a lot better Than existing computers can solve them. In fact, I think thinking of it like a GPU is is pretty fruitful that GPUs are, are, they are computers in a sense. But really they’re they’re better thought of as like a coprocessor to your main computer. They GPUs are extremely good at solving a variety of problems you could sort of Wrangle a GPU to solve any problem you want to but it’s you know regular computers are good at that so quantum computers I think of as like on the side Unfortunately current quantum computers are gigantic. They’re they you know, they’re like the old computers like the ENIAC they fill a room But nonetheless you you hook your computer up to this and it does separate problem-solving as a company We build these quantum computers and deploy them there. They’re Accessible right now on the cloud. There’s something that I on my laptop anywhere Actually, I don’t need any special interface can connect up to them and do computations with them And we’re at a point now where? the fundamental unit of resource of a quantum computer just as we take regular computers and think about them in terms of bits and gigabytes and so on on a quantum computer These are measured in qubits, which are very special because every time you add a qubit You’re you’re doubling the capacity of the computer in some way. So Last year, we released a machine that has around eight qubits. And now the current machine we have is about nineteen qubits so it’s not that we Approximately just doubled the qubit because each qubit itself is doubling so you have to think of that number of doublings each time from eight to nineteen problems that deal with lots of interactions or lots of Possibilities so to speak are where quantum computer sort of shine so one big area of application is in quantum computing is the simulation of molecules molecules are are made up of a bunch of atoms and each of these atoms is is Applying a force to the other atoms they’re pushing and pulling each other and they’re just lots of ways in which the atoms interact with one another and a quantum computer is extremely good at Keeping track of all that and dealing with that in a very efficient way that classical computers which are normal computers Don’t deal with quite as well Likewise other types of problems like optimization which in mathematics means kind of finding the best or worst possible solution to a problem Quantum computers are showing a lot of promise and with that said though There’s one point I want to make which is sort of in popular science people think that quantum computers just sort of try every possibility At the same time you get all these sort of kooky Interpretations of multiple universes and so on and quantum computers, don’t do that. They do not try every possibility at the same time But the second point is that applications of quantum computing is a very active field of research quantum computers currently are They’re called noisy quantum computers. They they sort of act like analog devices not digital devices And so there’s all this a little bits of error and little bits of noise that come into the system and so it’s an active field of research to see what Algorithms and what problems are very robust to this noise and it turns out that this molecular simulation is an example of a problem That’s very robust to noise Whereas what? You might heard of like Shor’s algorithm and factoring and breaking encryption are not robust annoys at all They’re very difficult to to do so that’s a very active field of research both at the company that I work at As well as more broadly the community the sort of room size computers are sort of where we’re at the way in which these computers have been constructed is Using sort of off-the-shelf components that have not been specially made for the construction of that machine in general So you find generally with these quantum computers you find big racks of analog electronics these electronics that that have existed for other applications and so It’s definitely not at a point where we’ve we’ve sort of custom fabricated the entirety of the machine I’m not just talking about the quantum chip itself But the thing that the quantum chip is housed in the electronics that go with the quantum chip, etc, etc We’re only just starting We just in general as a in the field of quantum computation are only just starting to make like customized electronics and the like for these systems The other aspect of this is that just like the ENIAC for example Which had vacuum tubes that burnt out and you had to go replace them Literal bugs getting in there and so on neither of those things happen with quantum computers But what does happen is that the system in general isn’t shown to be stable across, you know? Five or ten years and just hasn’t existed that long And so components are are often swapped out often changed It’s not robust to changes in the environment like if somebody walks by with a big magnet the whole thing kind of goes awry, so it’s a really sort of Finicky machine not unlike the early computers like the ENIAC and so on How far are we off quantum smartphones? Yeah, that is that is really really far away because we need to cool these chips down to like the same temperature or colder than The temperature of outer space so you need big refrigerators as they’re called Not going to happen for a good while The interesting thing though is When we have multiple qubits, and this is really where the power of quantum computation happens We can actually think of it sort of simply Diagrammatically that if qubits if I just represent them sort of as a circle here, maybe we have three the idea Is that these qubits can interact this guy can interact with this guy?

100 Comments

  • penguins forall

    Also note a GPU ALSO has specialized RAM and bus. It's topology is significantly different from most CPUs. (Cell Broadband Engine Architecture being an exception). Quantum computers will need similar support hardware and interfacing making them even harder to use as general purpose computers on their own.

  • NEY Industries

    So, what the hell do quantum computers ACTUALLY do?!

    Please explain to a guy who could build a regular computer out of 7400 logic chips.

    They're always presented as some mystery boxes that "should have so much potential", but there's always like zero actual technical data.

  • Online Lobster

    Doesn't D-Wave have a 512 Qbit chip called vesuvius? I read a primer on Shor's algorithm and that was from a quantum computing department of a *.edu that it would take only 500 qbits to simulate a serial computer with 10^150 processors. We could solve NP-Complete problems like the Traveling Salesman, and that would break the asymmetry of math that all encryption (except the one time pad) is based on. Back in the early 2000's I remember reading about Japanese scientists finding an inexpensive way to mass produce qbits using what they call Cooper boxes… I hear so many wildly disparate things from many reputable sources that I don't know if people are lying, oblivious, uninformed or misinforming.

    IEEE even admitted after ripping D-Wave for being fake quantum computers that after sending scientists down there, their chips are in fact quantum computers. So which is it?

  • Richard Kaz

    Good to see the rose coloured glasses taken away and the current myths blown away. All too offend we have know all politicians and futurist (pseudo scientist) getting up and sprouting nonsense as if fact about the very near their initiatives will see technological paradise for their economy eg our prime minister Malcolm Turnbull had been tagged as virtually inventing the internet, look it up no joke.

  • Lawrence D’Oliveiro

    Remember the old analog computers? Back in the early 20th Century, analog computers could solve certain problems faster than digital machines, but with less precision. They fell out of favour as digital computers became able to match them in speed while maintaining greater precision. Also they were never any good at number-theoretic problems (e.g. factorization, code-cracking).

    Quantum computers are basically a reboot of the old analog-computer idea. The kinds of problems they can solve are in the same class — physical simulations and optimization — where speed is more important than precision. And they are similarly useless at number-theoretic problems.

  • Facey Neck

    Wow! Really loved this video. Thanks.
    Let's just say I saw a 'Linus Tech Tips' video about quantum computing, and it left me feeling like I just ate at McDonald's.
    Thanks again for the high quality content. 🙂 …and thank you for your time, Robert.

  • Joe Arend

    Anyone know of any molecular simulations done using a quantum computer that have results published in any papers? Asking for a friend…

  • David Wilkie

    Other than this Universe, which a computer of any sort can emulate in analogy, a "real" QC is impossible, because the actual structure and processing of information in spacetime is constantly shifting shapes and information "leaks" in and out of temporary existence. All conglomerations of structures have lifetimes of "chemical" resonances, so a good Analog Computer is as good as it can be?

  • El-Andalussi

    Quantum Computing as the Loch Ness Monster, everybody is talking (advertasing?) about but no one has seen it… 😕

  • Holographic Multiverse

    It’s a Conscious Digital Universe, already a quantum computer. But reinventing the wheel is fun

  • Jason Martin

    They won't need to be so big and you won't need super cold temperatures if we just discover room temperature superconductors

  • MichaelKingsfordGray

    Well, they don't build quantum computers. No-one does yet. If he starts with an outright lie, then I shan't listen to the rest.

  • TurboCMinusMinus

    Despite my tech degree I'm proud to have never helped the human race advance its technology. I've not helped governments expand their surveillance and oppression of the citizens nor have I helped doom the species with better weapons. Most humans don't even deserve technology. Quantum computers will simply be used to erase any last shred of privacy you fools possess.

  • Samuel Prevost

    Great video as always ! @ 4:20 when he's talking about "problems that are robust to noise" I think optimization of gradient falls perfectly into this category. One of the main algorithm to solve this kind of problem is called "stochastic gradient descent" where stochastic essentially means "random" cause it takes semi-random steps so a little bit of noise wouldn't be disturbing to this lol

  • zomgthisisawesomelol

    19 qubits? Whats the connectivity, can you actually entangle all 19 of those qubits? Can you factor 509771 for example?

  • Jason Purkiss

    So we could give a astronaut a quantum mobile phone if they was working on the dark side of the moon 🙂 not to sure of the reception 🙂

  • MrSlowestD16

    So I was thinking along the same lines that were mentioned in the beginning, about all crypto useless, all combinations at the same time, etc., the "cooky" idea of quantum computing, as he put it. That's how I've always seen it referred to, that was my understanding, that's obviously others' understanding, etc.
    So if that's not correct, care to explain where that misconception comes from & better define the scope that they can actually handle? Is it fair to say that although quantum computers are nowhere near the level now, that someday they will [may?] be able to try all combinations of a system at once?

  • Confused Dave

    Has quantum computing existed long enough to get a feel for whether a Moore's-Law-like effect is in evidence? Just wondering whether that might put a lower boundary on when we might see smartphone-sized quantum chips… 😛

  • Roderick Molasar

    I worked with a Burroughs 3600 in the fall of 1972. Keypunch card readers, bowling-sheet coded printouts and giant whirling reels of magnetic tape. Phew.

  • Miketar2424

    I hate to point this out, but people in the quantum computer industry seem to look down at modern computers in calling them "classical" computers. Instead, I think they should more accurately refer to them as "working, affordable , useful computers", as opposed to the opposite: quantum computers.

  • The Power of Zen

    I want the know how we eventually resolve the decoherence problem and the cooling issue before these can be reduced from the size of a walk in wardrobe to the size of a small box. Quantum biology shows that quantum mechanics does not need to operate at near absolute zero temperatures.

  • Neil Roy

    I still agree with Einstein about quantum physics. I think these computers are operating by something other than "quantum" physics. I think they are simply attributing something to quantum that is not.

  • Stephen Nielsen

    How is biology based (Muscle cell grid — actin and myosin) parallel computing (biocomputers) advancing? And could biological computers offer any kind of competition to the quantum computing that you’re working on now or are they too dissimilar?

  • ludvercz

    I don't trust QC. What if you need to turn it off and on again, but it is already on and off at the same time?

  • a solid state hard drive

    Hasn't D-wave released a machine, D-Wave 2000Q, with 2000 qubits (with only 1000 qubits enabled)?
    What am I not understanding with this machine and their current machine being 19 qubits – surely they would know about a 2000Qubit computer so what am I missing?

  • 01111011111101etc

    A quantum computer is a fascinating thing… – Will it blend? Or, which wins, a quantum computer or the Hydraulic Press?

  • TripeDemo

    So a quantum computer is a special purpose computer eh? kinda like the first computers were I suppose. I wouldn't be surprised if we had quantum computers in our pockets in 20 years or so

  • Overkillius

    I'm pretty sure smartphones already use cloud computing services regularly, and quantum cloud computing will probably be all that there is in the foreseeable future.

  • Luca Dorigo

    19 Qubits, if "it" doubles with every qubit 2^19 is about 500.000. But what is "it"? Is it storage? Processing power?

  • 808 Gang

    Is it future connecting your blockchain based app to quantum servers to do the math and return you output? This requires high network speeds but we do have them…

  • Akshay Aradhya

    Plot Twist
    This video is there just to fool the general public and to make them believe that Quantum Computers are still at their infancy.

    They are probably breaking all sorts of encryption with quantum computers, they just don't want to reveal it.

    Remember the imitation game ?

  • Rory Clague

    I wonder if David Baker's group is working on this? Protein crystallography is rapidly becoming obsolete due to advances in cryo electron microscopy. Cryo EM may soon be a redundant as well, once we can brute force protein folding with a quantum computer.

  • Joshua Folly

    Yeah, well I "work" for Quantum Silicon in Alberta, and we'll have 500 qbits in a year. Room temp. Birches

  • 8iaventri

    I notice that I don’t use the letter Q in my life as much as I now realize that I have been needing to.

    Positively life changing

  • Joshua Penner

    I would have liked some discussion on D-Wave's quantum computer. Aren't they planning on making a 2000 qubit quantum computer? Seems to me that D-Wave is worthy to be discussed.

  • Lázaro Carvalhaes

    What does the data set you feed a quantum device with look like? I mean, is there a math treatment like a DAC between the two interfaces or can it deal with binary logic just as well as the electronic ones?

  • CreeDo Lala

    can someone expand on the robustness to noise issue he mentioned? I remember hearing in another video, maybe a computerphile video, that there are two types of quantum computer… one of them gives correct and consistent answers every time, while the other one is somehow not a "true" quantum computer because the process is somehow subject to error and inconsistency. So you don't always get correct answers. Would that be the noise they're referring to? and would that mean that the type of quantum computer he's referring to cannot be used for problems that need a single specific and accurate answer like cryptographic problems? are we ever going to reach that level of computing?

  • Don Kiwi

    The current state of quantum computing is a superposition. There's no way to know with certainty where it will be going.

  • Connect to Soul

    😇 Thank you for all your beneficial video, it certainly is greatly valued and I definitely value your hard work !👍

  • SupremePancakes

    well the title of this video is Current State of Quantum Computing not Introductory Course to Quantum Computing isn't it? He actually answered the question. I like this guy. He sounds like my (American) professors and makes a lot of references to industry.

  • lkajsdf l;kasjdf

    Why are they still so big they should be able to start making them smaller thanks to higher-order topological insulator and time crystals. These things fix the high temp super conductor problem and coherence problems respectively

  • ERD Epoch

    Its scary…. computers in the 70's were size of a room, they ran off binary. Look at where we are now with binary computers.. In 40 years time we will have quantium computers inside of what we call a laptop now.

  • jose mourinho

    So if quantum CPUs don't conceptually "multi-core" (to a power rather than linearly) with additional qubits, then how exactly do QPUs work? I know roughly how they work, quantum logic gates, superpositions of superpositions, entanglement, interference and so on. I'm also familiar with applications such as optimization (traveling salesman) and modeling of quantum, or natural systems (molecules, fundamental particles, etc). My background is physics/finance not computer science. From a physics POV I think of superposition and especially superposition of superpositions (e.g. young's double slit) as implying multiple processes simultaneously – so the electron or photon exhibits wave-particle duality and in some sense travels all possible paths before deciding upon a definite outcome upon observation, an outcome that is influenced by past and future events as well as the present (evidenced by the clearly defined interference patterns). This is analogous to qubits being 0 and 1 at the same time (a superposition) but that means the value could be anything between 0 and 1 until we measure it. Does adding qubits not allow the system to solve branching math problems by branching out probabilities (superpositions of superpositions) in a similar way to an electron in young's double slit? That is to say when you ask a QPU to perform an action the qubits in a sense know the answer and all possible answers to the question upon input, the perceived delay is just how long it takes the observer (measurement, output) to experience the output in their reality.

  • Vaggelis Basoukas

    If sciense fabricate a new material that could allow a new CPU with the same advadages BUT to work in normal computers temperature we will have Quantum computers.Although a very importand question is not asked so far.If we can create a so powerfull CPU, what could happen if we overclock it ?

  • Gainster

    Isn't a quantum computer the same as a regular computer but instead using the spins of say a photon to represent a bit unlike conventional computers which use a voltage?

  • KLJF

    see what he says at 3min , well people that is recording a very fast RANDOM process THAT IS NOT COMPUTING .
    THE QUANTUM BY DEFINITION ONLY DOES RANDOM ! DONT YOU CRETINS GET IT , THE QUANTUM BIT CANT DO THE ACTUAL COMPUTING ….. YOU TOTAL CRETINS .

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