A beginner’s guide to quantum computing | Shohini Ghose

A beginner’s guide to quantum computing | Shohini Ghose


Let’s play a game. Imagine that you are in Las Vegas, in a casino, and you decide to play a game
on one of the casino’s computers, just like you might play
solitaire or chess. The computer can make moves
in the game, just like a human player. This is a coin game. It starts with a coin showing heads, and the computer will play first. It can choose to flip the coin or not, but you don’t get to see the outcome. Next, it’s your turn. You can also choose
to flip the coin or not, and your move will not be revealed
to your opponent, the computer. Finally, the computer plays again,
and can flip the coin or not, and after these three rounds, the coin is revealed, and if it is heads, the computer wins, if it’s tails, you win. So it’s a pretty simple game, and if everybody plays honestly,
and the coin is fair, then you have a 50 percent chance
of winning this game. And to confirm that, I asked my students to play
this game on our computers, and after many, many tries, their winning rate ended up
being 50 percent, or close to 50 percent, as expected. Sounds like a boring game, right? But what if you could play this game
on a quantum computer? Now, Las Vegas casinos
do not have quantum computers, as far as I know, but IBM has built
a working quantum computer. Here it is. But what is a quantum computer? Well, quantum physics describes the behavior of atoms
and fundamental particles, like electrons and photons. So a quantum computer operates by controlling the behavior
of these particles, but in a way that is completely different
from our regular computers. So a quantum computer
is not just a more powerful version of our current computers, just like a light bulb
is not a more powerful candle. You cannot build a light bulb
by building better and better candles. A light bulb is a different technology, based on deeper scientific understanding. Similarly, a quantum computer
is a new kind of device, based on the science of quantum physics, and just like a light bulb
transformed society, quantum computers
have the potential to impact so many aspects of our lives, including our security needs,
our health care and even the internet. So companies all around the world
are working to build these devices, and to see what
the excitement is all about, let’s play our game on a quantum computer. So I can log into IBM’s
quantum computer from right here, which means I can play the game remotely, and so can you. To make this happen, you may remember
getting an email ahead of time, from TED, asking you whether you would choose
to flip the coin or not, if you played the game. Well, actually, we asked you to choose
between a circle or a square. You didn’t know it, but your choice
of circle meant “flip the coin,” and your choice of square
was “don’t flip.” We received 372 responses. Thank you. That means we can play 372 games
against the quantum computer using your choices. And it’s a pretty fast game to play, so I can show you the results right here. Unfortunately, you didn’t do very well. (Laughter) The quantum computer won
almost every game. It lost a few only because
of operational errors in the computer. (Laughter) So how did it achieve
this amazing winning streak? It seems like magic or cheating, but actually, it’s just
quantum physics in action. Here’s how it works. A regular computer simulates
heads or tails of a coin as a bit, a zero or a one, or a current flipping on and off
inside your computer chip. A quantum computer
is completely different. A quantum bit has a more fluid,
nonbinary identity. It can exist in a superposition,
or a combination of zero and one, with some probability of being zero
and some probability of being one. In other words,
its identity is on a spectrum. For example, it could have
a 70 percent chance of being zero and a 30 percent chance of being one or 80-20 or 60-40. The possibilities are endless. The key idea here is that we have to give up
on precise values of zero and one and allow for some uncertainty. So during the game, the quantum computer creates
this fluid combination of heads and tails, zero and one, so that no matter what the player does, flip or no flip, the superposition remains intact. It’s kind of like stirring
a mixture of two fluids. Whether or not you stir,
the fluids remain in a mixture, but in its final move, the quantum computer
can unmix the zero and one, perfectly recovering heads
so that you lose every time. (Laughter) If you think this is all a bit weird,
you are absolutely right. Regular coins do not exist
in combinations of heads and tails. We do not experience
this fluid quantum reality in our everyday lives. So if you are confused by quantum, don’t worry, you’re getting it. (Laughter) But even though we don’t experience
quantum strangeness, we can see its very real
effects in action. You’ve seen the data for yourself. The quantum computer won because it harnessed
superposition and uncertainty, and these quantum properties are powerful, not just to win coin games, but also to build
future quantum technologies. So let me give you three examples
of potential applications that could change our lives. First of all, quantum uncertainty
could be used to create private keys for encrypting messages
sent from one location to another so that hackers could not
secretly copy the key perfectly, because of quantum uncertainty. They would have to break
the laws of quantum physics to hack the key. So this kind of unbreakable encryption
is already being tested by banks and other institutions worldwide. Today, we use more than 17 billion
connected devices globally. Just imagine the impact quantum encryption
could have in the future. Secondly, quantum technologies could also
transform health care and medicine. For example, the design and analysis
of molecules for drug development is a challenging problem today, and that’s because
exactly describing and calculating all of the quantum properties
of all the atoms in the molecule is a computationally difficult task,
even for our supercomputers. But a quantum computer could do better, because it operates using
the same quantum properties as the molecule it’s trying to simulate. So future large-scale quantum
simulations for drug development could perhaps lead to treatments
for diseases like Alzheimer’s, which affects thousands of lives. And thirdly, my favorite
quantum application is teleportation of information
from one location to another without physically transmitting
the information. Sounds like sci-fi, but it is possible, because these fluid identities
of the quantum particles can get entangled across space and time in such a way that when you change
something about one particle, it can impact the other, and that creates
a channel for teleportation. It’s already been demonstrated
in research labs and could be part
of a future quantum internet. We don’t have such a network as yet, but my team is working
on these possibilities, by simulating a quantum network
on a quantum computer. So we have designed and implemented
some interesting new protocols such as teleportation
among different users in the network and efficient data transmission and even secure voting. So it’s a lot of fun for me,
being a quantum physicist. I highly recommend it. (Laughter) We get to be explorers
in a quantum wonderland. Who knows what applications
we will discover next. We must tread carefully and responsibly as we build our quantum future. And for me, personally, I don’t see quantum physics as a tool
just to build quantum computers. I see quantum computers as a way
for us to probe the mysteries of nature and reveal more about this hidden world
outside of our experiences. How amazing that we humans, with our relatively limited
access to the universe, can still see far beyond our horizons just using our imagination
and our ingenuity. And the universe rewards us by showing us how incredibly
interesting and surprising it is. The future is fundamentally uncertain, and to me, that is certainly exciting. Thank you. (Applause)

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100 Replies to “A beginner’s guide to quantum computing | Shohini Ghose”

  1. we need to stop using quantum computers on earth , we should start using them in actual space to get faster quantum computers using solar panels and dry batteries also the quantum computer will suck the super cold temperatures of space to work way faster and 100 % energy efficient and cost way cheaper to run this is a real quantum computer not slow old school way of using quantum computers , Long Live the FutureSpace Quantum Computers.

  2. Not 1 shred of proof from any who want you buy this load of BS.its all snake oil.the idea is that quantum does not have errors.so much for her

  3. Let's try to make my current cell phone work first before we start making quantum computersπŸ˜‚πŸ˜‚πŸ˜‚

  4. I can't believe this stupid video that only mystifies QC has more than one million views. This is not an explanation of QC. This is an example of how Google algorithms can promote stupidity

  5. Let's ask an audience of more than 200 people to randomly pick an integer between 0 and 1. Let's pretend that we are stupid enough to not be able to predict the average answer.

  6. I can write a program on my computer to flip the coin heads 100 percent of the time…does this means my windows is turned to quantum computer, kind of scary

  7. The more I look into it, the parallels between this and cold fusion are hysterical. "It works, except we can't do it cold…. And that's the big thing we have to solve. "

  8. Bought yourself an ouija board..it has updated info.about time traveling.. An explanaciΓ³n..wow!! So realistic…

  9. Does the computer recognise the characteristics of the coin, which you don't? So you can win if some of your competitors opt out? Is that physics? Sniff.

  10. As in the above application of coin game when playing through the quantum computer, we first take the choice of head, so after all the process done by the quantum computer means after the last flip as quantum computer unmix the 0 and 1 and perfectly the recovering the heads. this is how it works.
    but when initially we don't know the coin (as in this case "heads") so that both gamer and quantum computer had equal amount of chance like 50% . Is this true?????
    can you please tell me the answer??(Shohini Ghose)

  11. The explanation for dummies and investors.

    At first, if they would interpret the collected 3072 results in backward manner (square – flip the coin , circle – not flip) would this mean, that humans won in 97 % cases?
    At second, this game is not based on calculations, but on the generator of random numbers (usually its a function of current precise time in microseconds). So, what actually quantum computer does to win this game?
    Quantum computers are good in brute force algorithms, when you need to check the result of 2^N variants in one time.

    But the most funny is the quantum network.
    When we entangle two particles, and then decohere one of them (check is state), them at the same time other particle takes the same state.

    But the choice of state is fully random! We can generate a random number with the set of pairs, and this number can be the key for encryption.
    But we see here no information transfer!
    Instant information transfer violates the principle of causality in relativity theory )
    We will send the signal in our past.

    But they work on it!
    They don`t have results yet , but they work )

  12. If you flip a coin (and as it is flipping) it is neither heads nor tails, until you stop it and read it. No $sh!t! That is still called digital – 2 states – heads or tails. What it is while it's being flipped is irrelevant !! And, much of what I have seen so far about quantum computing – is irrelevant. Someone please show from the electronic component level, how quantum computing works; just like that good looking IBM quantum computer (lol). No one has been able to so far…otherwise it's just more quantum BS.

  13. This is clearly a difficult concept to describe to simple-minded people, but the gist of this is they are building (crude at this time) devices that attempt to simulate actual life – based on molecular states which are of course always in motion. The human mindset is always tending toward black/white, on/off certainty because otherwise it quickly gets confused. Any surprise that Chinese are doing much more with this than other countries? Consider that 80% of US doctoral degrees are awarded to foreign students. Many of those return to China, where they will teach others, soon removing the need to cross oceans, and in so doing, begin to concentrate development at home.

  14. Wait just a minute! Flip the coin OR NOT? I don't think that leads to a 50/50 chance. In other words, the option to NOT flip does not equate to flipping every time. I believe that changes the probabilities.

    Ms. Ghose also more than once brings up the question of honesty. She's not the only one who has to be honest. So honesty is a variable to consider . . .

  15. Clear explanation! Now I can see the IBM's quantum computer is different from current ones. What does computer use for doing calculation ? LSI?

  16. Doesn't sound like any kind of stretch. Sounds like programming picked to be programming with random outcomes. Trying to imitate the human brain and then apply that "theory" 10 fold isn't quantum computing, it is a programmer cheating to assume an outcome. Quantum computers are going to act like the humans that programmed them and no quantum computer will act or solve the same way if programmed in different ways. Foolish Humans do not think about the small things.

  17. People from Other Nations:- That's why we say Indians imagine a lot 🀣🀣🀣
    U guys can even imagine that you already landed on Moon 🀣🀣🀣🀣😁
    To measure the Imaginative power of Indians we need to have a Quantum Computer πŸ€£πŸ€£πŸ€£πŸ€£πŸ‘‹πŸ˜

  18. Same vague explanation as everywhere else. I imagine that "Quantum Computing" is simply a buzz word for regular old variable state transistors just like "cloud computing" was an overblown marketing term for the age old services of off-site servers. But for the life of me I can not find any sort of detailed explanation.

  19. This is like one of those videos that say how to get rich, but they never really tell you how.
    In hear last 3 examples, bank came first, health was second lol what an imbecil

  20. I'm ever more skeptical of quantum computing. This lady really helped with that. The fake laughs in the audience were a bit strange also.

  21. when you talk about teleportation, I recall two things one in Buddhism, where it talk about sending message from one mind to another and in another instance of scripture found in a book called "Ramayana", where it talk a vimana (vehicle) that appear as you think and travel over your thought.

    after all these, I think we will ended up going back to our roots which we cant see due to the bright light of modern development

  22. quantum does not exist full stop . there will never be a quantum computer AS QUANTUM IS A MATERIALIST ANTI GOD AGENDA LIE .. OKAY FOOLS WAIT 20 YEARS AND STILL NO QUANYUM COMPUTER .

  23. Getting into quantum physics is, I believe, the closest natural beings can get to the supernatural realm. Its crazy. And considering where our world is today, while it is great technology, it is all the more dangerous.

  24. Good for the TED, but not tech at all. That kind of information should be technical. IBM videos is really better at that )

  25. Is there anyone in the comment section who understood how the coin game is won by the quantum computer?
    Is there anyone understood anything from this video?

  26. I still don't understand how the game work. With the explanation in this video, it seems that the player, which has the final move, is always win by simply flip the coin to Head all the time. She did successfully provide Quantum information in term of its spirit at the end, but not so well throughout the speech in aspect of technical.

  27. Possibilities are limitless.
    Medicine – Cured a lot of diseases, new era of good, healthy drugs controlled by gov. More happiness Longer life span.
    New materials -> development of new technologies – > new methods of production -> more new tech -> new jobs
    BBB or Bye Bye Byrocracy -> saved a lot of time, instant administrative regulation -> even more happiness. Everything you want is INSTA done.
    Security A word Hacker becomes historical term -> No free downloads.
    Math Solving some math problems -> New tech and all over again.

    Oh damn, it's 2019…

  28. You can do the coin thing with regular computers as well! Cause in the first place, the computer here is allowed to know whether I finally pick head or tail…. And then it needs a simple NOT gate to turn the result different than what I chose! Done and dusted

    Why even explaining quantum computer's functionality with this example! Shouldn't they have gone with something more sensible?!

  29. wow….to be zero or not to be zero….turns into being zero as well as not zero…quantum physics will alwas crack my head πŸ˜‰

  30. Madam, I am from India.. What a nice and almost easy explanation you have given , though Quantum Physics is not an easy topic…

  31. Very nice presentation about something that interested me nowadays as an engineer …. can you tell me please what was the algorithm used to resolve the coin game you presented or where I can find something written about it …. just to have an example how the quantum computer resolve it !! Thanks a lot .

  32. definitely a very beginners guide…A quantum computer can break the encryption because thats what they are also designed to do….if you make it we can break it..sorry

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