Are We Ready for Quantum Computing
[Music]
in 1988
when i’d studied computer science
electronics engineering
applied physics i’d done some research
on information theory
and i’d spent three years working on
designing electronics electronic systems
to prevent
lighting systems
industrial lighting systems from blowing
up
in the trade this is known as a a
non-passive
failure and at the time i was in the uk
working in research
working on these electronic systems and
i can remember at the time
hearing about the very first quantum
bits qubits
1988 now among the engineering and
scientific community
this was a client a little bit of a
sensation
but everywhere else it didn’t really uh
didn’t really
raise any eyebrows people didn’t really
notice it
but back then i thought oh this is this
could be interesting
something interesting could come out of
this
a year later i moved to germany
having fixed the problem with the
exploding light bulbs
and i became a midwife to the world wide
web
and back then this clunky
buggy document hypertext system
the very first of its kind scalable
hypertext system
we were working on this and i remember
thinking
and my colleagues as well this is
probably going to change
a lot this is probably going to be a
fundamentally new kind of technology
we didn’t realize it would be things
like cat videos and
fake news and cyber wars
and world of warcraft but
we did think it something momentous
would have would happen
i think if at the time if you’d asked
anybody generally about
the impact of the web people will just
have said
it’s a neat way to write documents
that’s all
but what the world wide web did for us
was give us a new way
to present information and a new way
to interact with each other
this interaction and information
presentation
was fundamental paradigm shift something
fundamentally new
it allowed a new level of
interaction between people
and at the time the
implications of that as i said were not
clear it’s
perhaps a coincidence that at the same
time of course
we had this beginnings of
quantum computing the first qubits
but if you want to
understand a little bit about quantum
computing we need a metaphor
we need some kind of stabilizer wheels
of kids when they learn to ride a
bicycle
they have stabilizer wheels we need
stabilizer wheels
and our stabilizer wheels today
are going to be coins and balls
so if you throw a coin
a thousand times then give or take
a standard deviation you’ll get 500
heads
and 500 tails incidentally the standard
deviation
the actual number of coins you see when
you toss a thousand coins
uh bears a very very deep mathematical
relationship
to the distribution of prime numbers
it’s not relevant here but it’s an
interesting fact
if you have two coins then
when you throw them both then
some of the time you’ll get in heads
plus heads head
plus tail tail plus heads tails plus
tails
and each of those variants will also
they will occur 250 times
plus or minus a standard deviation and
with three coins
eight different variations each one
occurring
125 times
for quantum computing we need a
different module
model this is where the ball comes in
now if we take this ball here and we
define a some arbitrary point on its
surface
say here
if we spin the ball and then stop it
then that point on the surface
is just as likely to point in one
direction as in any other direction
and we can describe that with two angles
an angle we call the azimuth
which is this way and an angle we call
the elevation
this way strictly speaking we also need
to know the size of the ball
but physicists are very clever about
cheating so normally in physics we
define the radius of the ball to be one
that makes the mathematics
very easy and some of the calculations
very simple
this is our simple model of a qubit
quantum bit
like a ball a qubit has a specific state
a specific
direction when we look at it
the interesting thing happens
when we put the ball on the cubit
behind a screen or inside a bag
just imagine that you can’t look inside
this bag it’s transparent for a reason
so you can see what’s happening so just
imagine that
we’ve got a spinning ball in here
something’s happening to it
with a quantum bit with a qubit
that ball can be in many possible
states have many possible positions at
the same time
we call this superposition also we can
link two
balls together so that the position the
direction of one of them completely
determines
the position and direction of the other
one and vice versa
you can even put three of them in there
or as many as you want
we call that entanglement
and entanglement and superposition are
the fundamental principles
of quantum mechanics the question then
becomes how can we use that
we need to convert these qubits
into bits the simplest example is if you
imagine a qubit
and you imagine that it’s you’ve done
something to it and it’s now
pointing at the equator
if we repeat that experiment like the
coin a thousand times
then 500 times we will measure it as
pointing upwards and 500 times
downwards so it’s just like a coin
the interesting part happens of course
when we’ve prepared the qubit in the
right way
when we’ve entangled the qubits in the
right way
then that’s no longer the case
then each qubit will favor a one or a
zero more
than just with a coin we found a way to
get
inside or behind the pure probability of
the coin
by using quantum mechanics the
trick with quantum computing is to
construct these interactions between the
balls between the qubits
in such a way that the right answers the
answer you’re looking for
occurs more often and the answers you’re
not looking for
occur less often we call this
constructive and destructive
interference and this is the principle
behind every quantum program in order
to understand how that actually works we
need to look a little bit at the
history how quantum computers actually
came into being in 1973
a man called charles bennett this is an
extract from his
scientific paper um
don’t worry you’re not supposed to
understand it he showed
that any computer program
can be reconstructed so it’s reversible
and that’s important because that means
that you can execute the computer
program
get it to produce a result and then run
it backwards
so that you’re in the initial state you
were when you started
this is important because it allows us
to now construct programs with quantum
mechanical systems
in other words we can run a quantum
program to produce a result
without actually changing anything this
is a major step
a few years later in 1988
when i was when i was fighting my
exploding light bulbs
the very first qubits were invented
and a few years later a physicist
called richard feyman came up with a
proof
that you could actually use these kinds
of programs to solve
problems a particular problem which was
infeasible to solve on a classical
computer
it was so complex and so difficult the
classical computer would never be able
to solve it
but a quantum computer was trivial
that changed again in 1994
when peter shaw developed an algorithm
for factoring numbers
factoring numbers is a difficult problem
we know that 5 times 3 is 15.
5 and 3 are the factors of 15. if we
want to factor a thousand bit number
and even with the biggest supercomputer
we have today this would take millions
or billions of years peter shaw’s
algorithm sped that up
and if we had a perfect quantum computer
it would mean we could factor such
numbers in weeks or days or maybe even
hours or minutes that was the
really the birth and the impetus that
quantum computing
needed
quantum computers are very beautiful
this is the inside of one
i i like to think that the reason they
are beautiful is because form follows
function
and quantum computing the function of
quantum computing is as fundamental as
it gets
we’re now at the stage where we have
quantum computers we’re able to use them
we’re able to program them we’re
searching for
better industrializable more robust more
stable
technologies we’re learning how to write
algorithms for them
we’re working on different types of
quantum computing different types of
qubit
different types of chips for doing this
so we’re now out of the stage of what we
call quantum the quantum physical era
we’re now in the stage of the era of
quantum readiness
and i see this when i look at the number
of students attending
university courses on quantum computing
or the number of attendees on
online summer schools and classes the
numbers
are astounding we are now at the stage
where
we’re getting ready to go into the phase
of quantum advantage and quantum
advantage means
the point where quantum computers
overtake classical computers
become so performant that they are
solving problems
way beyond what we will ever be able to
do
on current computers
we have quantum computers the technology
is starting to mature
and the question is are we ready for
quantum computers
i think we are i’d like to encourage you
to
everybody out there everybody here
you have access to completely free
quantum computers
you can try it out it’s very simple
give it a go i think we’re ready for
quantum computers computers
i’d like to invite you to join me on the
journey
to try this out and learn this
technology anybody want some qubits
thank you