Prepared by Mohammad Ghorbani
University of Arak 2015
How quantum computer working?
Applications of quantuum computer
Waht is quantum computer?
What is quantum mechanic?
Whay quantum mechanic?
History of quantum computer
Yuri Manin (1937-he is still alive)
He is russian-german mathematicion . In 1980 he was first
to propose the idea of quantum computing.
He was american theoretical phisicist . in 1981 he presented
a Logical quantum computer model .
A classical computer performs operations using bits wich can be either
zero or one.
There are number of phisical objects that can be used as the qubit , a
single photon or a electron. But how this work ?
Well , all electrons have magnetic field , so they are basically like tiny
bar magnetic and this property is called spin.
In quantum world particles like electron are actually spinnning in all directions at
a same time and this is one of the wierd aspects of quantum mechanics this type
of phenomenon called superposition . We may measure by a measurement of
an electron and find it’s spinning in a direction but before we did the
measurement it was spinning in other ways at a same time. All at the same time !
Sounds crazy but true.
So what this mean ?
It means that electrons can spinning in many different directions at a same time
and they can doing many computations at a same time!
In contrast quantum computer uses quantum bits or qubits and they
can be both zero and one at the same time .interesting huh?
I guess that you are confused like me and others in first time so let’s consider the
example of all possible combinations of 2-bit data system .
We have 4 possible states.
A 2-bit classic computer can perform just one of these four possible functions
simultaneosly and in order to check all of them, the computer would have to repeat
each operation seperately.
A 2-bit quantum computer due to the phenomenon of superposition is able to
analyze all of possibilites at the same time in one operation!
So 2qubits contain information about four sates while 2bits only contain
information about one satate! Thus a machine with n qubits can
perform 2^n functions in a same time .
A 4-qubits computer could analyze 16 states in a single operation in
comparison a 4-bits classical computer can only analyze one state!
Are you still confused? Don’t be
This is quantum mechanics nature .“No, you’re not going to be able to understand it.
. . . You see, my physics students don’t
understand it either. That is because I don’t
understand it. Nobody does. ... The theory of
quantum electrodynamics describes Nature as
absurd from the point of view of common sense.
And it agrees fully with an experiment. So I hope
that you can accept Nature as She is -- absurd.”
Ok . Why we need quantum
computer?Becuase there are problems in our world that even fastest supercomputer can’t
solve them in
optimal time. Let me give you some example.
Problem : a salesman has to travel to many cities and
want to work out the shortest possible route? That sounds
like an easy problem!
For 14 cities a classical 1GHz it would take 100 seconds.
But happens for 22 cities? It would take 1.600 years! And
for 28 cities it’s longer than the lifetime of the universe.
Applications of quantum computer
Quantum computer give us a power that we can solve issues that deal with
enormous data. Indeed it can deal with enormous data and proccess it. Let
me give you some examples.
Discover distant planet
Detect cancer earlier
Develop more effective drugs
And so more....