Seminar On

QUANTUM COMPUTINGGUIDED BY:

MRS. J. V. MEGHA MS.VRUSHALI NADRE

PRESENTED BY-

PRAVIN R PUNDGE

SHRI GURU GOBIND SINGHJI INSTITUTE OF ENGINEERING AND

TECHNOLOGY NANDED-431606

CONTENTS

INTRODUCTION

THE STORY OF QUANTUM

GENERAL CONCEPT OF INFORMATION

THE QUBIT

COHERENT SUPERPOSITION

ADVANTAGE OF USING COHERENT SUPERPOSITION MEMORY

ROLE OFCOHERENT SUPERPOSITION IN COMPUTING OPERATIONS

DEMONSTRATING QUANTUM COMPUTING

ADVANTAGE OF QUANTUM COMPUTING

DESIRABLE FEATUERS OF IDEAL SYSTEM

CONCLUSION

INTRODUCTION

The history of computer technology .

The story of quantum computation started as early as 1982.

when the physicist Richard Feynman introduce this concept.

From gears to relays to valves to transistors to integrated circuits and so on.

The size of the logic gates become comparable to the size of atoms.

On the atomic scale matter obeys the rules of quantum mechanics

If computers are to become smaller in the future.

quantum technology must replace or supplement for this.

INTRODUCTION(CONT ) Support entirely new kind of computation.

Quantum technology can offer much more than cramming of more bits to silicon.

multiplying the clock-speed of microprocessors.

Qualitatively new algorithms based on quantum principles.

With fast operational speed.

THE STORY OF QUANTUM Quantum computation started as early as 1982.

By physicist Richard Feynman .

Peter Shor design first quantum algorithm.

can perform efficient factorisation.

GENERAL CONCEPT OF INFORMATION Quantum computers so different from their classical counterparts.

Different states is no or yes, false or true, or simply 0 or 1.

One bit of information can be also encoded using two different polarizations

of light

Or

two different electronic states of an atom.

THE QUBIT

the basic unit of information is a bit.

from the two distinct electronic states (the excited state and the ground state).

Coherent superposition of the two states both 1 and 0.

This concept is the backbone of the idea of quantum computing.

Follows intrinsic randomness.

COHERENT SUPERPOSITION

wavefunction of that state(1 ).

superposition is stable.

coherence between the two states .

coherent superposition equation:

c11 + c22

ADVANTAGE OF USING COHERENT-SUPERPOSITIONED MEMORY

If the register of store 3 bit.

It can be EIGHT combination

000, 001, 010, ... 111.

Qubit can store both the values of 0 & 1 simultaneously.

Memory size grows slowly.

Operation speed increases.

HOW IT WORKS

ROLE OF COHERENT SUPERPOSITION

IN COMPUTING OPERATIONS

We generate a massive parallel computation with one piece of quantum

hardware.

2L different input numbers encoded in coherent superpositions of L qubits.

Classical computer repeat the same computation 2L times or one has to use 2L

different processors working in parallel.

Enormous gain.

ALGORITHMS FOR QUANTUM

COMPUTERS

A specification of this set of instructions is called an algorithm.

Algorithms are fast (e.g. multiplication) other are very slow (e.g. factorisation)

in classical.

Searching, especially algorithmic searching (Grover's algorithm).

Factorizing large numbers very rapidly (Shor's algorithm).

DEMONSTRATING QUANTUM

COMPUTING

Due to technical obstacles, till date, a quantum computer has not yet been

realized.

Important technologies that are used to demonstrate quantum computing

• Nuclear Magnetic Resonance.

• Ion Trap.

• Quantum Dot.

• Optical Methods.

Nuclear Magnetic Resonance Invented in the 1940's and widely used in chemistry and medicine today.

Quantum computer is based on control of nuclear spin.

The spin manipulation is of magnetic pulses within a magnetic field produced

by the NMR chamber.

A qubit is created by the chemical bonds between neighboring atoms.

The major drawback of this method is scalability.

Signal strength of the answer decreases exponentially with the number of

qubits.

Ion Trap Based on control of nuclear spin.

Ions are Isolated or trapped by electromagnetic field which is produced

electromagnetic chamber.

The trapped ions are cooled to the point where motion is essentially

eliminated.

Manipulated by laser pulses for superposition of lower and higher energy spin

states.

Great disadvantage is that it requires a cryogenic environment.

Quantum Dot Particle of matter so small that the addition or removal of an electron changes

its properties in some useful way.

In biochemistry, quantum dots are called redox groups.

A Quantum Dot quantum computer can involve manipulation of electrical

charge, spin, or energy state.

Quantum dot typically being a small "hill" of molecules on a silicon substrate.

Quantum dots have already been demonstrated and can be done using the

industry standard silicon substrate.

Optical Different polarizations of a light beam to represent two logical states.

Polarization of a light beam in the

vertical plane to represent a logical 1 .

horizontal plane to represent a logical 0.

Based on manipulating the polarization of individual photons.

The superposition of polarization or phase state is manipulated using polarizing

lenses, phase shifters, and beam splitters.

Major technical obstacle to a photon-based approach.

Several laboratories are working on a practical demonstration.

ADVANTAGES OF QUANTUM

COMPUTING

If we keep adding qubits to the register we increase its storage capacity

exponentially.

(three qubits can store 8 different numbers at once.)

Required less power.

Processig speed is fast .

The data security increase.

WHAT WILL QUANTUM COMPUTERS BE

GOOD AT? Cryptography: Perfectly secure communication.

Searching, especially algorithmic searching (Grover's algorithm).

Factorizing large numbers very rapidly (Shor's algorithm).

Simulating quantum-mechanical systems efficiently.

OBSTACLES AND RESEARCH

The building of two- and three- qubit quantum computers capable of simple

arithmetic and data sorting operation.

A few potentially large obstacles still remain.

These difficulties among with building a quantum computer

• Error correction

• Decoherence

• Hardware architecture

FUTURE OUTLOOKAt present, quantum computers and quantum information technology remains

in its pioneering stage.

Quantum computers up to their rightful position as the fastest computational.

machines in existence.

Decoherence and Error correction will overcomes.

Quantum computers will emerge as the superior computational devices at the

very least.

One day make today's modern computer obsolete.

DESIRABLE FEATURES OF AN IDEAL

SYSTEM

If ever a quantum computer is being practically realized, then an ideal one should have some desirable features. They are as listed below.

Be a Scalable Physical System.

Be Initializable to Simple state

Have Much Long Decoherence Times.

BE A SCALABLE PHYSICAL SYSTEMWhen the number of qubits keeps on increasing.

The clause ‘a scalable physical system’

Under ideal conditions, does not suffer from any kinds of loss of signal.

strength when the number of qubits increases.

Which would lead to the occurrence of a large obstacle in the construction of

an efficient quantum computer.

BE INITALIZATION TO SIMPLE STATE The term Initialization would have the same meaning it has as far as

classical computers.

If a particular address or a memory location is given.

Then we should be able to initialize it to a particular state, may it be a

single state or a superpositioned state by a single step.

at least, using a very few number of steps.

HAVE MUCH LONG DECOHERWNCE TIMES No quantum memory is till date completely free from the grip of decoherence.

So our aim should be as to reduce the troubles caused by it.

Another approach is to improve the algorithms used.

The time that a data is to be stored in a location would decrease.

CONCLUSION

Experimental and theoretical research in quantum computation is accelerating

world-wide.

New technologies for realizing quantum computers are being proposed

Quantum computation with various advantages over classical computation are

continually being discovered

The quantum theory of computation world view of anyone seeks a fundamental

understanding of the quantum theory and the processing of information.

REFERENCES

[1] IEEE PAPER:QUANTUM COMPUTING: AN INTRODUCTION by Tony Hey Publication in Year: 2000

[2]www.qubit.org

[3] www.tph.tuwien.ac.at

Thank you