Quantum

computerPrepared by Mohammad Ghorbani

University of Arak 2015

Overview

Introduction

History

How quantum computer working?

Classical computer

Quantum computer

Applications of quantuum computer

Questions

Introduction

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.

Richard Feynmann(1918-1988)

He was american theoretical phisicist . in 1981 he presented

a Logical quantum computer model .

Classical computer

A classical computer performs operations using bits wich can be either

zero or one.

Quantum computer

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.

Quantum computer

Quantum computer

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!

Quantum computer

In contrast quantum computer uses quantum bits or qubits and they

can be both zero and one at the same time .interesting huh?

Quantum computer

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!

comparsion

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

afraid!

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.”

Richard Feynman

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

Predicting weather

And so more....

D-wave quantum computer

D-wave quantum computer

D-wave quantum computer

D-wave quantum computer

Questions

Thank You