“quantum computing” By shivangi

gupta

Overview

Introduction Qubit. How to write and read a Qubit. Superposition Double Slit experiment. Schrodinger’s Cat experiment. Quantum Entanglement Applications

Introduction

Quantum computing is the computing which uses the laws of quantum mechanics to process information.

Quantum mechanics deals with motion and interaction of subatomic particles. Eg, atom, electrons.

Quantum computer works on qubits, which stands for "Quantum Bits".

QUBIT Qubit is similar to a bit in classical

computers. They store -0 -1 -0 and 1 both. Qubits are made with Sub atomic

particles .

How electrons can be used to store data? Electron is a charged particle When a charged particle move they

create a magnetic field. So electron behaves like a magnet. It

has 2 states Spin up. Spin down.

Taking 2 electrons to make Qubit.

====

11011011

Firstly, we apply a strong magnetic field , electron comes in SPIN DOWN position.

Spin Up – 1 Spin Down -0 Now for writing “1” , we apply a microwave of specific frequency , and

let the electron come in SPIN UP. For 0, it is already in SPIN DOWN.

How To Write a Qubit.

How To Read a Qubit. If the electron stores “1” , then if we remove the

microwave then a photon of particular wavelength is emitted, and electron comes in low energy states.

And in case of “0” nothing is emited.

2 important behaviours of electron

Quantum Superposition.

Quantum Entanglement.

Superposition

The principle of Superposition states that “while we do not know what the state of any electron is, it is actually in all possible states simultaneously, as long as we don't look to check”.

Superposition of Single elctron’s states

Superposition of 2 electron’s states

Schrodinger’s Cat experiment To illustrate this theory, we can use the famous analogy of

Schrodinger's Cat. First, we have a living cat and place it in a thick lead box. We then throw in a vial of cyanide and seal the box. We do not

know if the cat is alive if the cyanide capsule has broken the cat has died. Since we do not know, the cat is both dead and alive According to quantum law –It is in a superposition of states. “It is only when we break open the box and see what condition

the cat is then only the superposition is lost, and the cat must be either alive or dead.”

Cat is closed in a closed box .

Double slit experiment

On the left, we have a gun that can fire bullets The bullets will be fired at a wall that has two slits. Behind the wall with two slits, is a wall that will measure the number of

bullets that got through the wall and where they landed. The graph behind this wall will display the probability distribution for where

the bullets hit. First, we’ll leave the bottom slit open. The distribution is normal. When we leave the top slit open, the distribution is once again normal. When both slits are left open, the distribution is simply the sum of the two

previous distributions. This tells us that the bullets go though one slit or the other.

Particles

Interference of water waves

Wave

Superposition of waves

Interference of electrons

Electron

Interference of electrons

Which slit does an electron

pass through ?

It passes through both the

slits at the same time.

Why electron shows this behaviour?

Electron acts like “particles as well as wave”.

The double slit experiment

Interference of electrons

But when we

observe then then it starts

behaving like a

particle.

What are the conclusions?

When we “observe” the electron, it “behaves” like particles.

Electron may exist in 2 positions at the same time.

Quantum Entanglement

When electron start interacting with each other , then they start behaving in a coupled manner.

Here coupling means electron cannot represent the information individually, but if we read them together in some particular manner then we will get the information.

2 qubit 22 =4 bit

4 qubit 24 =16 bit

300 qubit 2300 bit

2300 is the no of particles present in this Universe

Application 1

all paths one by one and find which is optimum.But Quantum Computer traverse all paths at same time and this is how our quantum computer does computation on TSP.Traverse gives output which is optimum.

Travelling Sales Man Problem.

Application 2How much time would a human take to find out the prime factors of this number.

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Human would take time that would equal to the life time of Galaxy. But Quantum Computer would take about 30 Seconds.

Application 3 RSA encryption will not be safe in Quantum World.

This is because , RSA algorithm is based on prime factors. It computes n=pq, where p and q are prime numbers.

Quantum Computers can solve them in Seconds.

Application 4 Developing a new drug is a complicated process. Chemists have to test tons of different molecular

combinations to find one that actually has properties that are effective against a disease.

This process can take years and cost millions of dollars. Chemists bring tons of these combinations to later-stage trials and many of them still end up failing.

A quantum computer would be able to map out trillions of molecular combinations and quickly identify the ones that would most likely work, significantly cutting down the cost and the time of drug development.

Application 5 Accelerating space exploration Astronomers have discovered nearly 2,000 confirmed planets

outside our solar system using the  Kepler space telescope. The Kepler search involves peering at these distant so-called

exoplanets and waiting for them to pass in front of their host star.

When that happens, the exoplanets cast a shadow that astronomers can then analyze and make predictions about whether their atmosphere is suitable for life or not.

A quantum computer could tackle more data in any given telescope view, spot more exoplanets, and help quickly identify which ones have the most potential to harbor life. It could even uncover exoplanets that Kepler missed during its first run through older images.

Thank You