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)

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

  1. Almost every quantum physicist give more or less the same explanation in layman's term..I am still waiting for someone who could give a better example. as someone rightly said “If You Can’t Explain it to a Six Year Old(Give or Take), You Don’t Understand it Yourself” 🙂

  2. If a person cannot explain what he/she does to a non-expert, it means this person doesn't understand the subject very well. Even if he/she pretends to.

  3. That’s ridiculous. The computer is playing by a different set of rule than the player. So of course it will win. Let the player pick percentages of square and circle, and the outcome is very different.

  4. As a software engineer with a strong physics background, I have to say that this should have been titled: How to not tell anyone anything in 10 minutes.

  5. nobody :
    literally not scientist people :

    AI and Quantum Computer make a collaboration :

    We're gonna end this human kinds whole career

  6. Thank you, Shohini, you are a great teacher. In ten minutes I went from being interested but knowing nothing about Quantum Computers to understanding the concept. Keep them coming!

  7. 1. Computer "flips" but does not observe so there is superposition of H and T. Right got it.
    2. Persons turn but also does not observe so superposition is preserved. OK right.
    3. Computer observes and therefore there is collapse to H or T. Ummm I don't get that. How does the computer "guess correctly". Don't get mad ok

  8. Every body says that this technology will prevent hackers from doing this or that, or may be that technology. But anyone who says stuff like that I assume he's lying, because there is nothing completely unhackable or even perfect. No matter you did, no matter the technology is awesome and rocking, there will be someone who can ROCK IT DOWN!!!

    I can't to see how will future hackers will hack quantum computers, well I guess then hackers would be physicians !

  9. "Sounds like magic, doesn't it? But it isn't. It's quantum physics. Here's how it works"
    MAGIC

  10. Not sure she picked the right example: No matter how cool and futuristic the technology is, if the point is to randomly generate a boolean answer with 50/50 odds, isn't her coin-toss game example a dismal failure?

  11. In theory, the quantum computer would be the most powerful hacker tool ever. Right now, in order to brute force a password, a regular computer has to try all the possible combinations one by one. This could take ages! Instead, because of its uncertainty state, a quantum computer would be able to try all the combinations at once. With the speed of light, the right answer would be revealed immediately. Just let that sink. The implications in our everyday lives would be enormous on so many levels!

  12. The example with the physical coin versus the quantum coin is incorrect.The quantum computer makes all possible calculations at the same time, and then chooses the optimal result. Predicting the outcome of a physical coin is not part of its system. Further more, you don't really believe in honest casino's do you?

  13. I love the fact that we are creating something super intelligent on a quantum scale!! Wait! "intelligent on a quantum scale + AI on a quantum scale" UH OH!!!!!!

  14. I think hackers only need to apply reverse engineering, the same way they always do, not require to break quantum laws

  15. simple.. you use a quantum computer to hack. it will match all the uncertainty and superposition variables of the quantum encryption 😛

  16. simple.. you use a quantum computer to hack. it will match all the uncertainty and superposition variables of the quantum encryption 😛

  17. Came here after hearing George explain the transition to quantum computers will destroy our current encryption system and expose our entire online lives to every crook & politician globally. The TED speaker confirms by explaining quantum computers exploit every outcome in their favor. AI is harvesting our data and serving as the bridge between our current computers. “Shall we play a game?”

  18. I think u got her name wrong .. she looks indian and sounds indian so she is probably indain! … and her name shohini ghosh should be correct name for Bengali…. I have never seen ghose.. I know English people pronounce it like gosh… , & I am commenting this bcz ghosh is my own surname!

  19. IBM's quantum computer has all the answers but there is no way to know what question is being answered.

  20. Terrible explanation of how a quantum computer ultimately has to give a classical answer to a real problem. What complexity of problem can the IBM solve? No one has cracked QC yet

  21. yet once more – quantum computing NOT explained.
    Described. Examples for applications given.
    Nothing explained

  22. I'm willing to admit that quantum computing is so hard to understand, that I can't (and I'm an IT engineer). Either that or people who understand quantum computing suck at explaining it.

  23. next time just let some men explain it. They created it so why to push PoC women instead just to push her? It is not for her.

  24. Wonderful!. Quantum physics is a panacea for all our security and trust issues of today's computing/internet/digital world!!

  25. So, I'd like to trade places with the computer, and see how the results work out! That way, it only makes one decision, without knowing any details. I expect the odds will return to near normal.

  26. Damn yo, she's telling them that they don't know how these computers work, and they laughing and have no idea how fucked they are. They are simply building what they have build in many cultures before, but using different technology.

  27. a quantum computer will be god-like, so we have no idea of the applications. "We have to tread carefully", she says; no elaboration, so its lips service. Of course her work is exciting. We will see what kind of god she and her colleages will create.

  28. It’s not the first time tedEx presenter claims to reveal how quantum works but in a 10min speach nothing is explained except the fact quantum bits are superposition of 1 and 0. Sad it was accepted by TedEx

  29. Quantum computing may one day affect our lives. Perhaps it will influence our lives. I assure you, however, that it will not “impact” our lives. (Your use of that terrible word is wrong on two levels, by the way.)

  30. One of the most useless videos on YouTube to date. Either watch some cats instead (Schrödinger or otherwise) or go and study the actual quantum computing.

  31. No matter what you call the thing, it's impossible to have that high of a winning percentage without knowing the opponents answer before giving your own. So how does the quantum computer know the opponent's answers?

  32. seems like this chick watched a Kurzegat video and the Wikipedia for quantum computers just so that she could describe herself as a "quantum physicist."

  33. Very interesting & helpful explanation about Quantum Physics 🙏☮️
    Thank you & Congratulations for the Young Girl Quantum Physicists, me like your Parents are very proud of you,long and prosper life for you ☮️🙏

  34. Yeah, let's use computers as a crutch — Let the computer do everything. Let a computer do something as simple as turning a light on instead of you flipping the switch. Then people will just end up like those fat blobs in the movie, Wall-E.

  35. I am certainly a fan of science but this is just weird. If the human player flips the coin and if the result remains unknown how can the machine (quantum machine) undo the result in its favour. And why were there operational errors? If you think about the first example, message encryption, 3% failure rate due to "operational errors" would be quite disturbing.

  36. I have a task for a quantum computer. The monitor can display the entire universe, we can look at other civilizations, and I have the task, find all the images combined into one.

    In this film we see each other and maybe we are ashamed of our stupidity.

  37. With that technology hackers would also adapt new ways to secretly control other devices if you agree like means yes and comments means no👇👇👇👇👇👇👇

  38. 1. You choose a side
    2. Computer choose a side
    3. You flip a coin physically and get the result
    4. The computer wins almost 100% of the flips. I don't think so.

  39. Is the given example just a metaphor? I mean what would be the possible outcome if the conditions were reversed (Head = Human Wins, Tail = Computer Wins)? How the probability distribution of two eigenstates are calculated in this specific example?

  40. If human intelligence is 1's and 0's, the qbit is 1/0 combined is God intelligence; don't you think it will win every time??

  41. Hi , future people.
    I knew you will come back to this classic computer to check your innovation's past.
    Just don't forget that we have gems called memes, preserve them, they are very precious.

  42. Probability dont even work that way lol. When head and tail has only two side doesnt mean you will get 50 heads and 50 tails in a 100 flips. It only means you will get 50% chance to get head and 50% to get tail. Wrong!

  43. Mmmm
    It's looks like you have to study some years to understand why a perfectly programmed quantum computer can always win the coin game or teletrasporting datas.
    10 minutes suits better for learning pancake recipe.

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