Translator: Lisa Thompson
Reviewer: Peter van de Ven Let me begin telling you a story. I was a fifth grader. One day, my sister
came to me, and she said, “You’re just reading storybooks;
it’s time to read some science.” Then she took me to a bookstore
and bought me this book about atoms, and that was the beginning of my fascination
with the world of quantum physics. This journey continued. Twenty-five years later, now I am
part of a team of a scientists at Google, and we are working
to build a new type of computers based on principles of quantum physics. What is quantum physics? In the 19th century, we had a good understanding
of how nature works for large objects. For example, we could explain
how the Earth moves around the Sun or how steam can move a locomotive. But in the early 20th century,
scientists started going deeper. They wanted to know that if you look
at the tiniest building blocks of nature, like atoms or molecules, does nature still behave
the same way as we humans sense it? So they designed
a number of clever experiments, and they played with light
interacting with matter, and they found that what they observed
in those experiments cannot be explained
with the physics of the 19th century. So they invented
new physical laws for nature, and these new laws are called
principles of quantum mechanics, which are different from how we experience
the world in our daily lives. Let me tell you about one way
that quantum physics tells us nature behaves differently
from how we sense it. For us, any object at any moment of time
has a certain position. Like, I’m standing
on this stage; I am here. None of you sees me
at a different location in this room, I guess. (Laughter) But quantum physics tells us
that for tiny objects, like an atom or, like,
a particle like an electron, you cannot specifically say
where are they located. If I want to exaggerate – like, if I were a particle,
like an electron, you couldn’t tell where I am standing. There was a chance that every one of you will find me
at a different location in this room. (Laughter) This property is called superposition. That means being in all possibilities
at the same time. We use this property of superposition
to make faster computers. The computers that we have now, like our laptops or like
my cell phone that I’m using, the core of them is nothing
but a bunch of electric switches. Each electric switch
can store one bit of data at a time; it can be either zero or one,
just one number. It’s pretty boring because these computers
are from the last century. Now we can make quantum switches. A quantum switch,
or what we call the quantum bit, doesn’t need to be either zero or one, but it can be in a superposition
of zero and one. It can store a combination of two numbers. So when we have a number
of these quantum bits, they do not store or show
just one binary number, but they can store a combination
of all possible binary numbers. And that’s one main reason that quantum computers
can compute certain things way, way much faster
than classical computers that we have. Let’s make a simple comparison. Suppose you have a quantum computer
with 400 quantum bits. Four hundred is a small number. Imagine, like, my cell phone
has more than a billion classical bits. We are talking about 400 for quantum. Now, if we want
to transfer the information or write down the information
that is stored in 400 quantum bits on a number of classical computers,
like a number of laptops, how many laptops [do] you imagine we need to make this transfer of data
from quantum to classical? Use your imagination
to make your wildest guess – like, a thousand, a million laptops,
a billion, a trillion? The answer is that
the number of laptops that we need is more than the number of atoms
in the whole visible universe. And that was only about storing
the same amount of information. So from this simple comparison,
you can see that it may take forever for a classical computer
to do the same computation that a quantum computer
with a few hundred quantum bits can do. Therefore, quantum computers will make
some impossible calculations possible. I will talk more about this
in a few minutes. Now, you may want to see
[what] a quantum computer looks like. In this picture, you see
a piece of a quantum computer built by our hardware team
in Santa Barbara. This is an electric circuit
of nine quantum bits, and each of those white crosses you see
is the head of one of those quantum bits. And actually, I have it here. In this box, there is a spot [that is]
one centimeter wide by one centimeter, and this is basically the circuit
that you see in this picture. You can come and find me
and have a look at it. But with your bare eyes, you can see each of those quantum bits
that you see in this picture. Now, you may say, “Wait a second. You were just telling us
that quantum physics is important when we are talking about
small objects and small sizes, but this is pretty large.” Well, I haven’t told you the whole story. Quantum physics is,
as it becomes important, relevant, not only at the small sizes
but at low temperatures. So, in principle,
we can take any object of any size and cool it down, and eventually, it will start behaving
like in quantum objects. Imagine somehow this room
becoming colder and colder. Suddenly, our bodies will start going
into superpositions all over this room. So, to make this electric circuit quantum,
we put them in this special fridge. This fridge cools down the circuit
to near absolute zero temperature. Inside this cylinder is one of the coldest places
you can find in the whole universe. OK. Cool. So, this is the – (Laughter) This seems to be an amazing
technology we are developing, and sounds [like] these quantum computers have some extraordinary
powerful computation, but the main question is that – how this computer
can improve our daily lives. Right? Because for us humans,
when we make a new tool, we want to do something useful with that. Now let me tell you how a quantum computer can have
a serious impact on our daily life. This picture shows a basic cycle
of food production in our ecosystem. In this chain, between
the nitrogen in the air and the food that this cow is consuming, there is an unsolved puzzle
that a quantum computer can solve. What’s that? Nitrogen in the air is absorbed
by some bacteria in the soil that with some chemical process
turns nitrogen into ammonia. The details of this process –
how nitrogen turns into ammonia – [are] unknown. And why it is important
to find the answer for that is because then we can learn from bacteria how to cheaply and efficiently
produce ammonia, that is vitally used
as fertilizer for agriculture. Now, where [do] quantum computers
come into play to solve this puzzle? It all goes into solving the properties – finding the properties of this molecule, that plays a central role
in conversion of nitrogen to ammonia. The challenge is that
the classical computers that we have now are not capable [of solving] the equation
that describe this molecule. Why? Because a molecule
is a quantum system, and we know that a classical system [is] not capable [of doing]
a detailed modeling of even a small quantum system, but that’s not a problem
for a quantum computer. It’s natural for a quantum computer to solve the details
of another quantum system, like a molecule. And this was one example
of how a quantum computer can seriously change the way
we design molecules and new materials. Therefore, from the material science perspective, quantum computers can have serious impact in helping us [solve] some of the major
problems that we have in the world, like fighting global warming,
making more efficient car batteries, or better drugs for our health industry. With that, I want to say, stay tuned for big news
from the world of quantum computers. Thank you. (Applause)

How quantum computers are different! | Alireza Shabani | TEDxUCLA
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40 thoughts on “How quantum computers are different! | Alireza Shabani | TEDxUCLA

  • July 9, 2016 at 2:56 am

    Great talk!! Learned a lot

  • July 25, 2016 at 8:03 am

    Really , much impressive ! thank you sir Alireza Shabani !

  • July 28, 2016 at 2:26 am

    So tired of all this Gonz, Just want to go home!

  • July 28, 2016 at 1:03 pm

    quantum effects at room temperature (I have no idea if this article tells the truth) >

  • July 29, 2016 at 2:49 pm

    great talk!…

  • August 4, 2016 at 9:29 pm

    not being able to locate the position is the uncertainty principal

  • August 6, 2016 at 1:32 am


  • August 12, 2016 at 11:07 am

    Haha so easy to pick out that Iranian accent

  • August 25, 2016 at 12:48 am

    Ya know… I'm sick of hearing about how Quantum Computers work! Ya'll think it's so absolutely impossible to understand when we all actually get it and it's mind numbingly obvious! Loose the math! The observer is part of the equation! Whoop ty doo! We get it! Dendrites in our brains are quantum in nature and we should consider it some amazing thing that observation changes the results? The Bible says we have been given dominion. Go look up dominion in the context of ancient Hebrew thought if you have the guts! Want to shun that avenue of research? Chicken!

  • August 31, 2016 at 6:51 pm

    Odd the first positive thing I have heard about quantum computers after watching 40 bids over the last yr things like they are pulling info from other dimensions or by next year they will be able to Anything better than any human on the planet they are only feeding us bits of what these computers w heartbeats can do lol yah just Bits

  • September 3, 2016 at 12:02 am

    I dislike how sometimes quantum scientists look down on classical computing. Classical computing has been pioneered by so many brilliant people, it should be regarded with more respect.

  • October 2, 2016 at 7:45 am

    Love that accent.
    Also his forehead seems to be barely able to contain his brain.

  • October 8, 2016 at 7:51 pm

    quantum computers will only be able to do certain tasks. It cannot be a replacement for classical computer .

  • October 10, 2016 at 3:41 am

    Play at 1.25x playback speed. 😉

  • October 28, 2016 at 8:22 am

    QC is not happening anytime soon. it's a long way off.

  • November 8, 2016 at 3:02 pm

    Ok geniuses .. Give me one good example of what quantum computing has solved. The guys ad D wave are claiming they are accessing parallel universes while here they are trying to solve equations for biology … Which is it … I expect neither ….. More absurd funding down the rabbit hole with zero benefit to the average human ….

  • December 20, 2016 at 7:19 am

    Why does his forehead look so wierd?

  • January 7, 2017 at 11:57 am

    great thinking.
    we hope it'll be replace the world in new ways

  • February 9, 2017 at 12:04 am

    There is a good chance we read that same book as kids. 😀

  • February 16, 2017 at 1:00 am

    Quantum computers and CERN??? sounds about rite there really reaching lol

  • February 21, 2017 at 6:45 am

    quantum computers could be used to control matter and reality. you guys just wait. you will be able experience the most realistic VR game ever!

  • February 23, 2017 at 7:44 pm

    Quantum computer can solve almost all problems. Just ask a quantum computer "how to make human fly" it will tell u exactly the ingredients. Thats how people in atlantis do. They solved everything. That was also the main reason for their extinction.

  • February 28, 2017 at 3:12 am

    0:29 Hey, Vsauce!

  • March 13, 2017 at 5:11 am

    Just imagine how much more efficient our terminators will be.

  • April 14, 2017 at 8:58 pm

    Half a byte is a Nyble, 1/4 of a nyble is a bit. Infinite amounts of a single bit is quantum computing

  • April 15, 2017 at 2:36 am


  • July 14, 2017 at 8:00 pm

    They are undeniable

  • August 24, 2017 at 3:12 am

    scary stuff right here! scientists are pushing too many boundaries and they're going to wish they never saw the day quantum computers take over the world

  • September 14, 2017 at 3:39 pm

    Quantum computer seems quite interesting, I want to hear more details.

  • October 6, 2017 at 6:50 pm

    The haber bosch process gave us a pretty nice way of ammonia fixation from nitrogen. I don't know if understanding how bacteria do it would make our processes any better. I was hoping to actually learn more about how these computers work. Most speakers just toss around words like superposition and then just leave it there. It would be more meaningful to go beyond high school chemistry words in regards to explaining how a program running on a Quantum computer would actually work.

  • November 6, 2017 at 7:33 pm

    A very very basic talk.

  • January 13, 2018 at 6:39 pm

    except you are not considering organic chemistry because the ph of soil determines the output of crop and the fact that quantum computers can not predict environmental output and relative positioning in space time as well as predilection of sun spots which all of quantum is observed by the viewer,,,,I see your analysis although simplistic to the audience lack initiative substance on relative theory

  • February 2, 2018 at 9:29 pm

    We need Q computers because we have big questions about Univers Stimulation

  • February 14, 2018 at 6:59 am

    Was there an audience? Canned applause at the end. Alireza also didn't say anything of any consequence. An unusually large set of circuits and images of a bunch of tanks. This technology could help us understand complex processes? How? You have to produce a model to calculate complexity. Was this a hoax?

  • March 15, 2018 at 2:55 am

    Atoms and eves?

  • March 21, 2018 at 9:37 pm

    When will "Quantum Computers" become computers for us to use like Mac, Dell, HP, or Sony computers? 😎

  • June 19, 2018 at 2:23 pm

    computers will be used to enslave your children's childrens children

  • October 30, 2018 at 9:41 pm

    speaking of quantum computers makes feel like talking about Avengers:Age of altron and being serious about it ..

  • January 14, 2019 at 9:41 pm

    I am no genius, but even I can tell that the use of light as a switching source is fundamentally useless for any kind of reliability.
    Here's why ,,, lights frequencies are more gradual than potential switching spin position of electron field.
    It is very simple of what source to utilize for gating the switch on or off, without the potential of error.
    CLUE:> Remember that heat is always exchanging immediately it can be so subtle Eg:( the inside of insides symmetrically heating up or cooling down constantly) or more stable as holistically a star or galaxy, you begin to see my point?
    Light is just a small bandwidth of the potentially infinite act of heat exchanging and is a result thereof always lagging a tiny bit behind the actual more than enough to mess with spin.

    Think about how much potential energy we and our machines use that gets converted to heat,,,,,, this is regarded as waste but it is the direct return to balance from the potential imbalance implied by us and machines, heat is not a byproduct, heat in this catalyst is entirely useable.

  • October 24, 2019 at 2:36 am

    quantum computing is a scam


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