What Is A Quantum Computer?

What is a quantum computer and how does it work?

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Episode Transcript

Speaker 1 (00:07):
So you know how sometimes in physics there's a word,
and this word for people it's like magic. It means
like a big leap forward. It's like a huge transformation,
you mean, like dimensions, dimension is the worst, absolutely, and
stuff like that. And the one I'm thinking of in
particular is the word quantum. Quantum mechanics obviously a huge
transformation the way we think about the world that it

(00:29):
also seems to be a transformation and everything like you
can find like quantum massage, and you know, there's that
whole television show Quantum Leap, and like all this stuff
has nothing to do with quantum mechanics at all. It's
just the word quantum seems to represent some sort of
high tech, next generation high tech fanciness. You know, sometimes
it really does represent a transformative leap. Sometimes there really

(00:53):
is an opportunity to convert a normal version of something
into the quantum version and then take a huge step forward.
And so that's what we wanted to talk about today.
After my quantum massage hold on him and I'm Daniel

(01:24):
and this is our podcast. Daniel and Jorge explained the
universe in which we take the whole universe and chop
it up in the little pieces, turn each of them
into a quantum of understanding and download it into your
brain and in which you feel like you understand and
not understand at the same time. No, we're going for
a hundred understanding. We don't want to be one of

(01:46):
those podcasts where you feel like, oh, I heard a
lot of smart people talking about it, but I didn't
really get it right. Yeah. Yeah, because in this podcast
you only listen to one intelligent person, Joe and I
together making one intelligent person. We won't say which fraction
of each, but together we are one smart guy. We
are quantum entangled in our intelligence. That's right. That's right,

(02:08):
And this is just the latest in our projects together.
We also wrote a book called We Have No Idea,
A Guide the Unknown Universe, where we explore all the
big questions in the universe, what doesn't physics know yet
and what could it mean for humanity? And if you
search online on YouTube, you can also find a couple
of the videos that we've made together about the Higgs boson,
about dark matter, about gravitational waves. So check this out. Yeah,

(02:32):
so today we wanted to talk about quantum computers because
we feel like it's a word that's bandied around, and
we wanted to make sure everybody understood what it actually means.
Think about whether you know what a quantum computer is. So,
as usual, I went out and I asked ten random
people on the u c I campus if they knew

(02:52):
what a quantum computer was and how it works. And remember,
some of these people are computer science undergraduates, so they
really should know. Here's what they had to say. Nope, nope,
you never heard of a quantum computer? All right, cool,
I have no idea. Have you heard of the quantum computer?
This is the first time that I'm hearing it right now.
I'm not sure about how does it work, but I

(03:15):
know that it has four men bits or alphabet and
it is said to revolutionalize the computer science. I don't
know about a quantum computer, but you've heard of them. Um.
I've heard the term, but I don't know much else
about it other than that. Alright, So not a not
an impressive performance here by uc I Underground. That's right. Well, hey,

(03:37):
some of them understood it, right, at least most of
them have heard of it. The one guy like heard
about quantum computers. The moment I said the phrase, it
exploded in his brain. Like, what, I've never heard of
that until you mentioned it. I've never heard those two
words together. You've probably spend the next six hours googling
and reading about it. And maybe he's the next future

(03:58):
quantum computing genius. We have changed the course of human
history through this podcast or oh my god, it's possible.
But most people seem to have very little understanding of
what a quantum computer is. Um though, you know, somebody
out there had had some idea at least, so we
feel like this is a good topic for a podcast.
Let's clear out the weeds of everybody's understanding and make
sure everybody knows what we're talking about when we say

(04:20):
quantum computer. I mean everyone has heard of a computer,
but a quantum computer. That just sounds interesting, Right, What
do you what do you what did you think of
the first time you heard quantum computer? Do you think
like a tiny computer the size of an atom? What
did I think? I thought that it was? I think
I just had that good reaction. Also, it's like a
like a super new magic computer, right, Like I want

(04:41):
a quantum Ferrari. We just said for my quantum mortgage
to be paid first. I love how the word quantum
is just like taken on this magical mystical power, you know,
and it's not bad. There's like no nuance to quantum
that's bad. It's not like dark or dangerous. It's just
like the new, fancy, glittery, shiny version of something. The

(05:03):
weird thing is is that it's not a new word, right, Like,
it's a word that's been around for a hundred years nearly, right, Well,
it's been around for a long time and it's been
applied to this kind of thing for about a hundred years. Yeah,
quantum mechanics is almost a hundred years old. To the idea,
the very basic ideas of quantum mechanics, you know, that
the universe is chopped into pieces and not continuous. That's

(05:24):
not a very new idea, right, Well, let's break it down.
What does it mean when you say the word quantum,
like quantum physics or quantum particles? You know, what does
it mean? Well, the word basically just means portion or
packet or unit, you know, it's like a quantity, like, yeah,
quant quantity, quantum is that where it comes from? Yeah,

(05:47):
it's connected. Why I think Jorge just had a realization
and live right there on the podcast. Um, Yes, it's
related to quantities, right. It says things that are are
quantized are things that are made out of little atomic pieces,
things that can't be broken into smaller pieces. Right, So
like our money is quantized. We don't have money less
than a penny, right, you can't spend less than a penny.

(06:09):
That's the basic unit. Everything is built out of that.
And it's relevant to physics because it turns out the
universe is quantized, like particles are made out of smaller particles.
You can't have like half a particle or three quarter
of a particle. And energy levels are quantized, you know,
the way electrons move around in nucleus. They can't just
have like any arbitrary amount of energy, just like a

(06:30):
ladder of energy levels. They can be on and they
can't be in between those steps. But it kind of
means more than just the idea of chopping things up
into a little bit. It's really more about what the
world is like when you get down to those little
little little bits. Quantum physics means the physics of those
little little little particles, which is very different than the

(06:51):
physics of like, you know, a basketball or a baseball
that's right. Quantum. That's what quantum means. It's a little
bit bits and quantum mechanics or quantum physics that deals
with how those things interact with each other. And it
turns out that those little tiny bits of the universe
interact in ways that are very unfamiliar to us. There's
very little intuitive understanding we can grasp the way those

(07:13):
things work because they follow very different rules than the
things than baseballs and basketballs follow. They follow more probabilistic rules,
and and your intuition that you developed through observing the
way baseballs and basketballs moved through the air doesn't work
when you're talking about electrons or other little quantum particles
because they follow different rules. Yeah, and those different rules

(07:34):
lead to a very different kind of logic. You see,
in normal logic, you can say something like a switch
is either on or off, but not both, right, But
in quantum logic it's different, which is why quantum computing
turns out to also be different. Yeah, they don't behave
like they do the big things behave, right, Like if
you had a baseball the size of a quantum particle,

(07:55):
you can just bounce it off of a wall, That's right.
And the most important feature of these little quantum bits,
and the one that's gonna be relevant for quantum mechanics,
is that we don't know everything about them. Like a baseball,
you know everything you need to know. You know it's
direction and you know it's velocity. From that, you can
predict its future. If you know where it is and
where it's going, you know where it's going to be. Right.

(08:16):
For a quantum particle, like an electron, you can't observe
it directly, and so there's some uncertainty about where it is,
which means that it can be like here or it
can be there. But the crucial thing about a quantum
particle is it's not actually in one place or the other,
and you just don't know it. It has a probability
to be in both places. Our lack of knowledge about

(08:37):
it reflects the fact that it's location is not actually determined.
It's like it could be over here and it could
be over there, which means it's a little bit of both.
And that's what I mean when I say the act
in ways that are different from the ways that are
normal things interact. You know, a baseball is either here
or it's there, right, But when you get down to
that size, it doesn't look like like an electron doesn't

(08:59):
look like a little tiny baseball. Nobody knows what an
electron looks like. Yeah, like when you try to zoom
in and you zoom in, it just becomes fuzzy, right,
like you see this little fuzziness right. Well, that's a
whole other funny question, like what would an electron look like?
Because an electron is has zero size, right, zero volume,
and so it doesn't really look like anything. But about

(09:20):
the electrons fuzziness, we say the electron has a probability
to be in a few different places. That's the fuzziness.
But it's not determined before you ask. But when you
want to interact with the electron, like if you want
to measure where it is, then those probabilities collapse into
a specific outcome. We call that collapsing the wave function
because remember electrons are particles, but they're controlled by wave equations,

(09:45):
which determine the probability of being in various places, kind
of like if you're not looking at it, it's sort
of like a cloud almost, and then when you look
at it, then boom, it's a little point. That's right,
And this is the deep question of quantum mechanics that
that a lot of people do and understand. Most people
don't understand. I think maybe everybody doesn't understand. How does
that make any sense? Right? How does it make sense

(10:07):
that something can be in both places at once until
you ask look at it? How does it make sense
that you asking changes where it's going to be? Right?
It's it's it's a situation, and that's all. There's a
huge philosophical debate about that. You know, is it the
asking that makes a decide where it's it going to be?
Or does the universe split into two options where you know,
on one hand it's on the left and then the

(10:29):
other universe it's on the right. And different people argue
about this stuff for for decades and decades. So it's
certainly not something we can address in twenty minutes on
a podcast. But the thing you need to know to
understand quantum mechanics is that there's a probability for it
to be in one place or the other, and that
both probabilities exist simultaneously. So if I'm not if I'm
not looking at the electron, it looks like a little

(10:50):
fuzzy cloud and you're saying that cloud is it's it's
kind of like it's in all those places at the
same time with a certain probability. Yeah, I think the
most correct statement would say it has a probability to
be in all of those places. To say it actually
is in all those places, I mean you don't. It's
not actually anywhere. It just has a probability to be
those things. It's like the answer is not determined or known.

(11:11):
It's not like God has it written down on a
golden tablet somewhere. We just don't know. It's not actually anywhere.
It just has a probability to be this or that.
It's like it's like a die you haven't ruled yet.
It's not like it already is a four and you
just haven't looked yet. You haven't rolled the die, so
you don't There isn't an answer. The same way the
electron has a probability distribution to be in various situations,

(11:32):
but until you measure it, it's not in all of
those at the same time. It just has a probability
to be in those things. Man, So you're saying all
of us, all of our particles are if you get
down to that level, they're all unthrown die, yes, exactly,
until you interact with them and forces the universe to
throw the die. And that's one of the deep questions

(11:54):
about about econom mechanics, is like where's that die? Who's
doing those random number process you know? So when Einstein
famously said God doesn't play dice, it's kind of true.
It's like, really, things are all just unthrown dice. Yeah,
he didn't like that description of it at all. He
really believed that the dice was already thrown. We just
didn't know the answer, right, That's a big difference. That's

(12:17):
a big difference. And then eventually they proved that actually
the dice is not yet thrown until you ask the question.
And that's a whole other podcast. We can talk about
how they proved that. It's called the bell inequality, and
it's a whole other topic we can get into. But
I think for today's episode, people just need to understand
that a quantum particle can be different from a classical particle,

(12:37):
from like a thing you're you're understand because it can
be kind of a probability to be in two different
situations at the same time. Okay, So that's that's what
quantum means. And now let's get into quantum computers. But
first let's take a break, all right. So that's what

(13:05):
quantum means. It's like the how the world behaves when
you get down to those little tiny pits of the universe,
which is totally different and kind of fuzzy and probabilistic. Um.
So now let's combined it with the word everyone knows,
which is a computer. So what does it mean to
like have a quantum computer. Yeah, so the idea there is,
let's build a computer. Let's build out of pieces that

(13:25):
can do these weird things, because then maybe you can
solve problems that are otherwise hard. I mean, I think
it's also important to think about how a normal computer works,
and like what does it mean to say a computer
before we think about what is a quantum computer um?
And for those of you out there listening, you probably
know what a computer is. You have one in your
in your office or whatever. You're banging on it right
you download stuff and play Mario card or whatever. But

(13:49):
what it's doing on the inside is really is that
it's doing calculations. Right, a program on your computer or
something that does a calculation, Maybe that calculation is how
do I draw Mario card on the screen? Or you know,
how do I predict this the trajectory of this cannonball
that I want to fire at my opponent's castle or whatever.
In the end, it's doing a calculation. And the way
it does that calculation is that it represents the problem

(14:11):
that needs to be solved in terms of a bunch
of numbers, because all the computer really, in the end
is doing is manipulating numbers. I mean the memory and
your computer is a bunch of ones and zeros. That's
what we call bits, and those represent a number. And
a computer is useful when you can take a problem
you want to solve and represent it in a way
that the computer knows how to solve it right. Right, So,

(14:33):
for example, how do I hit my baseball in a
way that goes over the fence? What angle is the
best angle to do that? Right? Do? You want to
solve that problem? But you first have to break it
down into math and then have your computer basically act
as a calculator and crunch those math equations. And the
kind of math you use to break it down depends
on the kind of computer you have and the kind

(14:53):
of calculations that computer can do. So the kind of
computers we use, classical computers have ones in zeros, and
all they can do are a few basic logical operations
on those ones and zeros they can do and they
can do or they can do x or or nand
and you can build those up to do all sorts
of more complicated things like addition or subtraction or Mario

(15:15):
Kard and other video games. Right, And the way it
does that you're saying, is that it takes the problem,
you know, whereas Mario and Mario card or how much
is tu plus two and then breaks it down into bits,
which is are which are ones and zeros. So everything that,
like most of our language, all the math that we
know about, all that can be essentially eventually breaking down

(15:37):
into ones and zeros. That's right, and we'll see later.
The quantum computers don't use ones and zeros, and they
have a different kind of logic, so they can solve
different kinds of problems. And in the end, it's all
about efficiency. Which kind of computer is faster at which
kind of problem running Mario cards or breaking into the
n s A does it take one second or does

(15:59):
it take a build in years? Well, let's talk a
bit about why you want to break it down into
ones and zeros, right, Like, why is why is that important?
Because once you break it down to ones and zeros,
then even like a simple computer can then add and
subtract those, Right Like, if you can break the whole
world into ones and zeros and everything into simple operations
like plus or minus, then you can have a machine

(16:21):
basically do it. Yeah, you can do simple logic operations
on ones and zeros, and there's a theorem that shows
that you can combine those to do any logical operation.
So if you combine enough of those together, you can
have any operation on your inputs. That doesn't mean necessarily
the best way to do any problem. Like you might say, hey,
I want to know where this baseball is going to go.

(16:43):
So one way to do that is build a computer,
have inside the computer a perfect model of how the
baseball works, and do the calculation. Another way to do
that is just hit the baseball. Right from that perspective,
like a baseball is a computer that calculates one thing,
how far does this base ball go? Right. It's very powerful,
it's very fast, but it only does that one thing.

(17:05):
The advantage of a classical computer with ones and zeros
is that it can solve lots of different kinds of problems.
They can do your baseball problem, and they can do
Mario Kart right, Okay, So that's the basis of regular computers,
Like even the computer and the phone that people are
listening to this podcast on. It's taking our voices, breaking
them down to one and zeros, chopping those up, mixing

(17:26):
them up, and then basically recreating our voices and flappy bird. Right,
that's right exactly. And so what is a quantum computer. Well,
a quantum computer is a computer built out of different
little pieces. Right. Whereas the normal computer uses ones and zeros,
a quantum computer uses quantum mechanical objects that have different properties.
They can be zero, they can be one, or they

(17:48):
can be some combination of zero and one. The way
a quantum particle is like, maybe it's here, maybe it's there.
A quantum bit, what we call a cube bit, is
maybe zero, maybe one, has a probability be zero and
a probability to be one. And again it's not secretly
zero and secretly one. Like a dice you've already rolled
and you just haven't looked at. It's not determined. It's

(18:11):
some combination of zero and some combination of Wow. I see,
what if he had a computer that was fundamental little
processing unit is not just black and white, but maybe
like some something in between the shades of gray, shades
of great, Like what would happen if you add and
mix those up and try to make calculations with things
that can be not just ones and zeros. Yeah, And

(18:32):
so what happens is you get a very different kind
of computer, one that's much better at things that classical
computers find difficult, but also is worse at some things
that classical computers find very easy. Like what, Yeah, just
the way, like a baseball is a good computer for
calculating what a baseball does, it's not very good at
organizing your recipes or doing Mario Kart, right. A quantum

(18:55):
computer is built differently, it's but it still runs in
the physical universe, you know all the things. These computers
are just ways to manipulate physical objects to represent calculations
that we want done. That's what a computer is, right,
And sometimes the classical computer is really good at that.
A quantum computer, because it's made out of different things,
is good at at different kind of calculations. It's like

(19:16):
do you want to build your house out of wood
or out of brick? Well, you know wood is good
for some things and brick is good for other things.
You get a pretty different kind of house. Um, so
they're pretty different, but you know they're related, but they
have different strengths, and those strengths and weaknesses come from
the essential differences in how those bits work. Okay, so
let's get into some of these differences from where they

(19:37):
come from. So, like, what's happening now instead of when
I'm mixing these cube bits that's what they're called, right,
the quantum bits, they're called cube bids. Yeah, Um, so
what's happened? What's happening when I mix them? Like if
I do a calculation with these fuzzy bits. Right, So
there's really two things you have to understand about how
quantum calculations work. First of all, is that you when
you have two cube bits, they're not independent. It't Okay,

(20:00):
you have two bits and a computer, then they can
have four different states zero zero, zero, one, one zero
or one one. Right, So two bits means two to
the end different states. But you really just need two
numbers to specify that, right, you need the first number
in the second number totally specifies the configuration. So it's
really just two bits means two pieces of information for

(20:21):
a classical computer. That's because those two bits are totally independent.
For a quantum computer, the cubits are not independent. They're entangled, okay,
so they're connected to each other. And so you can
have different states. You can have zero zero, you can
have one one. You can have some mixture of one
zero and zero one. You can have other mixtures of zero, zero,

(20:41):
zero one. There's four combinations there, and what you get
are you need four piece of information to specify which
state you're in. You have simultaneously some probability to being
zero zero, some probability to being zero one, some probability
being one zero, and some probability being one one. So
two cubits means four pieces of information needed to store

(21:04):
the configuration. So two to the end pieces of information
from two cubits, right, Whereas in a classical computer, if
there are end bits, there are two to the end
different states, but you only need end pieces of information
to specify the state. So if there are two bits, right,
then there are four different states that can be in,
but you only need two pieces of information to tell

(21:27):
you exactly which state it's in, and a quantum computer
with two cubits you need to specify the probability of
each of the two to the end different states it
can be in at the same time, which means you
need four pieces of information to totally kneel down the
state of a two cubit quantum computer, right, because you're
mixing two things that are that could be a wide

(21:49):
range of things, right, that's right, because you not just
have the things, you have the relationships between them. Right,
So as the number of things grows you have like
thirty cubits, then you not just have is the state
of this bit? You have the state what is the
relative state of these two things? How closely connected are they?
So if you have, for example, thirty cubits, you need
to to the thirty numbers to specify the state of

(22:12):
that quantum system. And that that's very powerful because you
know how many particles are there in the universe. There's
like two to the three hundred particles in the universe.
So a quantum computer that had three hundred cubits in it, right,
it has as much information as like all the numbers
of the particles in the entire universe. Boomation. Wait, that

(22:38):
just means that a simple operation in the quantum computer
can represent a much bigger, sort of richer result. Is
that kind of what it means? Like, there's two different
there's two pieces to a computer. There's the information in it,
on the operations you can do right right now, we're
just talking about the information in it. But yes, a
smaller quantum computer can represent much more information with a

(23:01):
smaller number of bits. I see. So like three hundred
regular bids from a regular computer can maybe store the
yes or no voting information from three hundred people, right, yeah,
whereas three hundred quantum bids can store the information from
basically the entire universe. Now, let's be careful not to
oversell it. It takes two to the three hundred numbers

(23:25):
to specify the state of three d cubits, that's right,
But that doesn't mean that a three hundred cubic computer
can usefully store two to the three hundred pieces of information, because,
as we will talk about later, cubits have a very
rich internal state, but the information is not as accessible
as it is with classical bits. Okay, like with the

(23:47):
electron that has lots of different probabilities. You only measure
it in one of them. So if all the particles
in the universe got together to vote on something, you'd
still need a pretty big computer. Who wants to exist
crazy he thinks Jorge should have another banana. Yes or no,
that's just the state of the system. Right. Then there's

(24:09):
the operation, and there's a there's another sort of magical
thing that happens. Oh, I shouldn't say magic, because none
of it's magical. It seems like magic because it's so weird,
but it's it's actually physics, right, um, And that's what
happens when you do in operation. You know, in a
normal computer, your operations like math. I'm gonna add one
and one and see what it happens when I get
to what happens when you do a quantum calculation. Remember

(24:32):
that the states can be in the superposition of different states, right,
It's like in state zero and sixty percent in state one.
Like it can be white in seventy percent black. That's
like one cuban right, right. And it's not that it
has the shade of gray which is white and black.
It's has a probability to be white. And a probability

(24:53):
to be black. If you look at it, you can
only see white or black. You'll never see gray. Oh
I see. But seventy of the time you'll see it
black and you'll see it as white exactly. Oh I see.
So it's not gray, it's just as a probability of
being black or white. That's right. When you do an operation,
you don't it doesn't collapse to black or white and
then do the operation. It does the operations on the

(25:15):
probabilities themselves. Okay, so it have you have the thirty
percent of zero and thirty percent of one, or thirty
percent of white and black or whatever, and you do
the operation. It does the operation on the zero and
it does the operation on the one at the same time.
So it keeps both probabilities and it evolves them forward

(25:35):
in time using quantum mechanics. So it's like doing two
operations at once. Is it kind of like as we
were saying earlier, a quantum bid is kind of like
an unthrown dice, right, So if you it's like, what
happens if I multiply this die that I haven't thrown
times this died that I also haven't thrown what's the
result exactly, And it needs to consider, well, you know

(25:56):
it might be too and so what would happen if
it were too okay? And what would happen if it
was four? And what would happen if it were six?
And it propagates all those forward simultaneously because the quantum
state reflects all those probabilities, and the quantum operation moves
all those operations, all those probabilities forward in time and
effect doing all of those in parallel. So you have
a massive amount of information density, plus you have massive

(26:20):
parallelism to do these conversations. It keeps all of those
possibilities inside of this new combination of information, like it's
like it has all the possibilities thwart into this little
imaginary multiplication. That's right. And then the new state is
some different arrangement of those possibilities, right, but it reflects
all the probabilities in the previous state. Now here's an

(26:42):
important place that a lot of people misunderstanding quantum computers.
A lot of people say, oh, quantum computers are super
powerful because they're basically infinitely parallel. You can do like
a million calculations in parallel because of quantum mechanics. Meaning
it keeps all these probabilities sort of in its head. Yeah,
and it sort of seems like magic, like you know,
I can try um, I can break passwords, because I

(27:04):
can try millions of things all at the same time. Well,
that's not exactly true. I mean there's some truth to it,
because there is parallelism in the quantum world because you're
keeping all these probabilities intact and you're operating on them,
and you're moving them all fullward simultaneously. The problem is
when you get the answer. Okay, you want to say, okay,
I have my quantum state, I did my calculation. Now

(27:26):
I want the answer, right, how do you measure that?
When when you measure it, you're gonna get your black
or your white. You're gonna get your zero or one.
You don't get all the information. You don't get all
the probabilities. You just get one answer. You roll the dice,
you get your four or you get your six, and
you look at it. You just get a number. You
just get a number. Yeah, And so a lot of
that information is lost, right, huge amounts of that information

(27:47):
is lost when you want to get the output from
the quantum computer. And so that's why it's not really
fair to say that it's like this huge massive parallelism.
There is some parallelism there, and you can't exploit it
to do certain kinds of calculations, but in the end,
most of the information is thrown away when you get
the answer. I see, it's a much harder problem than
you think. Kind of yeah, exactly, And so we've built

(28:08):
this new thing. It's a bunch of um, you know,
states that can be black or white, and they're all
entangled or whatever. And then you can ask, can I
use this to do anything? Can I represents some calculation
I have in a way that this physical thing I built,
this entangled combination of quantum states, can effectively solve my problem,
right the way classical computer can by representing in terms

(28:31):
of math and zeros and ones or baseball, can solve
that one single problem. Right, Can a quantum computer solve
useful problems? Um? That's the next question. I see. Well,
let's um, let's get into that. But let's take a
quick break. Okay, So let's say that I build a

(29:00):
quantum computer, and you're saying it's not gonna be great
for playing Mario Kart unless you're playing quantum Mario card
quantum Marit card is awesome, Yeah, because you're both like
a dead and alive at the same time. Right, But
it wouldn't be useful for like, you know, playing flabby
Bird on your phone or surfing Facebook. So what what
would it be good of? What are people excited about

(29:20):
making quantum computers? Yeah, well, it took a while for
people to figure this out. You know, people thought about
the idea of quantum computers a few decades ago, like, okay, um,
the you know, the world is built in a quantum way,
maybe our computer should be quantum. And then it took
a few decades for people to come up with ideas
for how to actually use them. Like, let me take
a problem I have mapping into something that can be

(29:41):
represented with a quantum state, so that when I do
this experiment on it, do these operations on it, the
output of that experiment is basically answered to my question.
Remember that's sort of what we're thinking of as it
as a computer, right, because you can't just pretend to
be making a quantum computer. You actually have to build
it out of quantum things, things that are quantum, like

(30:02):
you know what I mean, Like I can I can't
just like add all these probabilities in my on my
regular computer, Like the computer itself has to be made
out of quantum things, right, Well, you know everything in
the universe is made out of quantum things, right, so
in that sense, you are a quantum computer. Or hey,
that's right, Yeah, I am stacular um. And so one
of the first things that people figured out was that

(30:24):
there's an algorithm you can write down for factorizing big
integers that says, take an integer and break it into
its factors. You know, like fifteen is five times three.
That's obvious, but what if you had a really big number.
It's hard to necessarily know how to break down you know,
one to four, seven, eight, ten into all of its factors.

(30:44):
It's a hard, hard thing. It takes a while to do.
You mean, like thirty can be five times six, where
it can be three times ten, right, yeah, Well you
want to break it down to all of its fundamental factors,
and so thirty is two times three times five. Right,
there's one unique set of factors for every integer um
and that's not easy to do, right for big numbers,

(31:05):
it could take a while because you basically just have
to check them. And this some slightly more clever algorithms
using normal computers. But normal computers it takes a long
time for them to do this because they have to
cycle through all the different possible You mean, like if
I told you, like million, three hundred four thousand, seven
dred and ninety nine, tell me all the numbers that
can multiply into that number exactly, that would be a

(31:25):
hard problem. May be a hard problem for me, and
uh a slow problem for a classical computer. But there
was a guy who figured out how to write an
algorithm to use these quantum states how to represent that
problem on a quantum computer, right, so that you can
manipulate that computer and out out get the answer. And
the way he did it, the algorithm that he came
up with is much much faster on a quantum computer

(31:48):
than on a normal computer, because in a sense, it's
using the parallelism. It's like, let me represent all this number,
how to build this number in lots of different ways
and then push all those forwards simultaneously, right, And so
he came up with an algorithm to do this. And
this is a big deal because the fact that this
is really hard for normal computers is the basis of

(32:08):
a lot of modern cryptography, meaning like how passwords are encoded,
that they use this idea of factoring large numbers. That's right.
If you can instantly factorize a large number, then you
can break a lot of modern cryptography. You can get
into the Department of Defense and the I R. S
and all that stuff, because all of those things, their cryptography,

(32:31):
their their protection, their their cyber protection, assumes that it
would take a long time to factorize a large number.
Cryptography is based on the idea that let's find problems
that are hard to solve but easy to check, right, Like,
if you give me a big number and you asked
me to find the factors, it might be take me
a long time to find them, but once I had them,
I could verify very quickly that they were correct. It

(32:53):
just had to together, do I get the right answer,
Like it's hard to get two times three times five
from thirty, but it's easy to verify that two times
street terms five is equal to yeah, exactly. And so
if you can find a faster way to do these things,
then you break this assumption that's in most modern cryptography.
Not all, but most modern cryptography is based on the
idea that these things are hard to find but easy

(33:15):
to check. So quantum computers in theory can do this
much much faster because of the way they're constructed. So again,
they're better at some problems, like specialized problems, not necessarily
better at everything though, right, not that I would ever
have any need to break into the I R S
or anything like that. Not it's clear in case there's
any auditors listening here. But so how far away are

(33:42):
we from getting there? Like, what's the current state of
the art in terms of making quantum computers. We have
quantum computers. People have built cubits, individual ones, and they
built sets of cubits together. Um, you know, they're up
to probably by the time this podcast comes out, of
the numbers will be irrelevant, but you know, they're ten
cubic computers out there, fifteen cubic computers. There are even

(34:05):
ones you can access online. IBM has one that's connected
to the web, meaning you can talk to that. This
quantum com computerly have you can ask it questions. Yeah,
but it's hard because you have to get these cubits
built and then you have to get them to be stable,
and sometimes these things fall apart. I mean, the basic
principle of a quantum computer works if it's in isolation,

(34:26):
but no computer is really in isolation. Interacts with the
environment and so it gets messed up. And so these
things are really finicky. There's not they're not easy to build,
and so we're still getting good at building the bits.
Like if you look at it will collapse into black
or white, so you have to really protect it from
anyone looking at your quantum computer until you actually want
the answer exactly. Yeah, So technically these things are really tricky,

(34:48):
but you know, technical problems get solved, and when there's
a lot of money, it's stakes a lot of people
work on them. And so I think quantum computers are
going to come pretty rapidly and get larger and larger
and more complicated. And so you know, we're at the
point where we have ten fifteen cubic computers. They don't
last for very long, so you can't do long complicated calculations,
and they're huge, right, Like they take up the space
of our room the way classical computers used to. You know,

(35:11):
you have a little picture a classical computer from nineteen
sixty It could like do less than your iPhone and
it filled up a whole room. Right, Well, you might
want to have a quantum computer in your phone, but
like maybe right in fifty years, Yeah, perhaps if you
needed to do that kind of stuff. Um, you know,
if I if I pooh pooh the applications of quantum computers,
then I risk going down in history. Is like one

(35:31):
of those guys who said computers have a very specialized use.
You might sell five or six worldwide. Nobody can ever
predict how these things are going to change the side
and how people will think to use them. Nobody wants
to be that guy. No one wants to be that guy, right,
But yeah, I think the future holds a big promise
for quantum computers, and I think they'll crack open new
kinds of problems that were hard before um. So far,

(35:53):
there's sort of limited set of problems and quantum computers
can solve. It's like it's as a new toy and
we're trying to figure out exactly how to use it
to definitely, you fun kind of thing. This is are
having fun putting together. But it's not like it's can
speed up every problem. Some people think, oh, quantum computers
make everything faster. That's not the case. So it's not
gonna be like a quantum lead. It will be more
like a quantum skill. Are you saying it would be

(36:15):
more like a quantum massage whatever that means? Oh my gosh. Well,
I hope you guys enjoyed this deep dive into quantum computers. Yeah.
And if you have questions about what we said and
you didn't understand it, please send us feedback to feedback
at Daniel and Jorge dot com. And if you have
another question you think we we would take a part

(36:36):
nicely you'd like to hear us talk about, send that
to us as well. Or if you just want Daniel
to give you a massage, just write at quantum Massage
at Daniel Jorge dot com. That's right, I'll give you
one bit of a massage, one quantum bit. All right.
Thanks everyone for listening and tune in next time. See
you next time. If you still have a question after

(37:04):
listening to all these explanations, please drop us a line.
We'd love to hear from you. You can find us
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