Quantum computing explained in 10 minutes | Shohini Ghose

Quantum computing explained in 10 minutes | 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 Comments on “Quantum computing explained in 10 minutes | Shohini Ghose”

  1. Could you please explain why the Computer is given 2 chances to flip against one for us. Btw a private key is never transmitted over the Internet it is only the public key that is sent unencrypted over the Internet.

  2. The poetry of Quantum Computing … (at best). Ok, – she did get to the continuum of superposition of statevectors in the end. Schrodinger's cat – guys. I thought the hacking application was insightful. Curious to know how the decryption would match the key at the other end.

  3. This is what happens when a sales team takes over a product that they have no idea about and wants to sell it. Typical corporate situation.

  4. Lightbulbs and candles are simply not the same you guys. Think of it this way. A candle is made of wax, while a lightbulb is made of glass. A wax lightbulb would never work.

  5. Makes me wonder if you could tell a quantum computer every single lottery draw ever drawn in Camelot history, and then ask it to predict this Saturday's results 🤣🤣🤣🤣

  6. Correct me if I misunderstood it, and also forgive my dumbness, but isn't it cheating if the quantum computer's choice is an ambiguous intermediate value between heads and tails. I am sure I am missing something here, but in this particular case, if one of the parties playing is not choosing a specific outcome, head or tails, it is akin to cheating. I think this is a very bad example she picked or she did a lousy job of explaining. There is also the quantum outcome between those two cases, being I am too dumb to grasp the concept.

  7. What? How can I log into IBMs quantum computer? I dont HAVE a quantum computer at home. If a light bulb is differwnt from a candel…and a present day computer is differwnt than a quantum computer because they are different technology, then how can I log into IBMs computer. How do you marry the two?

  8. The reason that the computer always wins is because the outcomes where the computer loses have been eliminated.
    The last quantum computer gate flips if the coin was tails and doesn't flip if the coins was heads. It doesn't know which it is, it just puts it through a gate which WOULD do that and passes the still undetermined output for reading later.
    When the output is read, it will be heads, because no matter what the gate input was, the operation is performed to leave it as heads or flip if to heads from tails.
    Imagine the output was read as Tails and the computer lost. The output of the flip decision gate would have been Tails as well. However, there is no valid heads or tails input where the flipping gate output is Tails. So we know that the input and flipping action cannot be ones which result in Tails because they have 0% probability. Or quantum mechanics needs modification.
    The action of the last flip can only be determined in retrospect. The final result will be heads, so we can infer the gate operated if we were provided tails and did not operate if we got heads as an input state. We CAN know whether the gate operated by revealing our first two flips and noting the final coin state.
    The program shows that q-bits can go through conditional gates where their action is determined by some future probabilities and the manner in which they are measured.
    In another state of mind: the last gate is just handing you a coin with heads up and using the state of the initial coin to tell you whether or not the last flip was preformed. ie: it cheats. It takes the initial entropy of 50/50 chance of heads or tails with 100/0 chance of flip or not flip AND THEN converts it into 100/0 of heads vs tails and 50/50 of final flip vs not flipping. So total probability is preserved by moving it from the coin result to the gate action.

  9. still can be hacked why I CAN say if try to hack 100 times 60 out 100 failed 40 try succeded . if the hacker breaks law of quantum than it is not 100% there is possiblity 50% can be hacked or not

  10. can we check (the same game on Q-computer) what happens when the results are not pre-defined? Meaning it is not known ahead of time that Head will win or Tail?

  11. But the computer didn’t play the game as per the rules. It never chose head or tails. It was a flawed example and had no relevance to the talk. She did a pour job explaining quantum computing.

  12. this is challenging the Christian fundamental values of the Law of excluded middle, this is hitting at the root of Christianity which from time immemorial always tried to make everything logical into binaries (hence the explaination for big bang theory as it said everything begins from a POINT), either this or that, nothing shoudl be in the middle, thats why they excelled in binary operations of 0 and 1. They are not able to comprehend beyond the boundaries of their limitations!!
    But this new physics will blow that apart, as its taking into account the MIDDLE. The christian society will reject this, just watch.

  13. So, if you are getting happy that now hackers will not be able to break security …
    let me assure you that hackers are always ahead of time, they will surely be able to find out ways to do so.

  14. Lady, maybe you are a good physicist, however , I suggest you to go back to your probability 101 course and correct your view on this subject.Your quantum computer is cheating by both playing and refereeing the game of chance.

  15. Now I see. In Newtonian physics you have a 50% chance of winning a coin toss but in Quantum physics the House wins 97% of the time.

  16. Qbits involve massive arrays reflecting particles in various states. Or you can just measure from Pharaoh's fingers to his elbow and you get the same result.

  17. just to make clear it does not solve raising co2, global warming, clean water, clean air, free education, good road, better healthcare for the public problems!!

  18. Is she explaining quantum computer or cheating computer.. Or an app to protect computer from hackers….. Waste of time…. Why am I even commenting on this… May be to save someone's else time during existence….⌚

  19. Last I checked, quantum entanglement can't be used for instant communication. I won't explain why as I don't understand it well enough (link below), but I'm pretty sure what she's saying here is a lot of bs. This wasn't an explanation. It was a "Look at our awesome tech that can maybe do all this" presentation, which in my opinion is just disrespectful to the people actually working with quantum computing.

    Here's a link that explains why FTL communication doesn't work:
    http://curious.astro.cornell.edu/about-us/137-physics/general-physics/particles-and-quantum-physics/810-does-quantum-entanglement-imply-faster-than-light-communication-intermediate

  20. If the computer can choose whichever, in response to a binary choice on the human's end, does the ratio of percentage of each choice even matter? Or, am I fundamentally understanding how this operates, incorrectly? Is it the case that the possibility/ratio even determines the outcome? If so, when is the ratio even determined? Also, how does the computer know to choose which possibility? Also, this doesn't sound like the coin actually exists as something non-binary but only that it doesn't exist yet…which is why there are only two binary outcomes, no? Anyone who knows more about this than me want to respond and clear some of this up for me?

  21. Im still waiting on her to explain What a Quantum computer does! This is stupid, Just put quantum before a Word
    Quantum spagetti
    Quantum beef
    Quantum cybernetics and People would be: waow Thats smart! its science …
    … Now im like her, talking bullshitt

  22. to all critics here: you lousy cs:rs why don't you stand there and explain, this female has guts you'll never have.

  23. Not all known pronouns automatically become promising after being modified by "quantum"; but quantum computing seems really promising.

  24. She clearly explained how the computer cheated at the game…and how they clearly changed the rules of the game …third video I have watched EXPLAINING quantum computing….no explanation yet

  25. She not explain how quantum computing works at all. I very sure it's a secret that can't be revealed 🙂

  26. imalgamated Pi,you can do forgery of Pi-R-Square with T-R-EE -his story his tree history=fourgery=https://www.facebook.com/evolutionofwords/

  27. 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” 🙂

  28. 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.

  29. 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.

  30. 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.

  31. nobody :
    literally not scientist people :

    AI and Quantum Computer make a collaboration :

    We're gonna end this human kinds whole career

  32. 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!

  33. 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

Leave a Reply

Your email address will not be published. Required fields are marked *