# Quantum Computing: The Next Generation Computing Giants

*Hello Steemians, Merry Christmass to you all. I hope the Celebrations are full on with your family, friends and dear ones. Today I bring my new post on Quantum Computing as I promised. It is a revolutionary technology which will transform the face of our world and in future we may be Steeming in a much smarter way with the amazing technologies based on Quantum Computing. Lets see what Quantum Computing is.*

Invention of **Transistor** in the **1947** gave birth to the revolution of **Semiconductor Electronics** which was imminent in the later decades. It grew manifold in the later decades ranging to various domains of life. As per **Gordon Moore**’s prediction the number of **transistors** per chip area grew double every eighteen month which added a multitude in the computing speed of the computers.

**A Semiconductor Based Integrated Circuit**[

**Source**]

However, by the next few years this growth will reach its saturation as the size of the **transistor** will shrink to the size of an atom. At this dimension, **Quantum Laws** like **Tunneling**, **Quantum Confinement** etc. are prevalent and they hamper the normal operation of the **transistors**. It then prevents further minimization of the **transistors** and puts a saturation point on the computing power. Some organizations like the **ITRS(International Technology Roadmap for Semiconductors)**suggests some alternative devices(e.g. **FiFET**) which adds a minuscule computing power for few decades. However, these devices will also reach their saturation point in few decades.

There are certain problems in **Computer Science**, solving which requires a large computing power. For instance, the multiplication of two large prime numbers is an easy process. But, retrieving the two prime numbers from the product is almost impossible with our **Classical Computers**. The **RSA Algorithm** in **Cryptography** is based on this idea. No efficient **Classical Algorithm** has been designed till date which can solve the problem in a short time.

All these problems have a reliable solution in the form of **Quantum Laws**. The computer which uses the laws of **Quantum Mechanics** such as **Entanglement** and **Superposition** are known as **Quantum Computer**. For some applications **Quantum Computers** are exponentially faster than classical **transistor** based computers. **Shor’s Algorithm**, for example, is used to factorize a very large number in polynomial time. Similarly, **Grover’s Algorithm** can solve the binary search in a database in a very short time which a classical computer takes much longer time. Moreover, using **Quantum Computers** it is possible to simulate a **Quantum System** which is not possible in **Classical Computers**.

## Quantum Bits or Qubits

The fundamental unit of **Classical Information** is **bit** which is denoted by the **ON** and **OFF** state of a **MOS Transistor**. When the **transistor** is in **OFF** state it denotes the logic state **0** and when in **ON** state it denotes the logic state **1**. However, a **transistor** processes only one **bit** of information at a time. For larger information processing we need more than one **transistors** interconnected to form a large **digital circuit**. But, each of the **transistors** will have output as either **ON** or **OFF** state.

On the other hand, the fundamental unit of **Quantum Information** is **Qubit**(short for **Quantum bit**). A **Qubit** can be either in the state-**0** or state-**1** and a **linear superposition** of the states-**0** and state-**1**. It means that they can be in both the states at the same time until we measure it. Because of this feature, in a **Two Level Quantum System** we can represent infinitely large amount of information unlike a classical bit.

## Single Qubit

A **Single Qubit** can be represented with any **two level quantum system** e.g. the **1s** and **2s** state of the **H-atom(Hydrogen atom)** with one electron. This system can represent one **Qubit** of information if we denote the state of the electron being in the **1s** energy state as the logic state **0** and the one being in the **2s** energy state as the logic state **1**.

**The 1s and 2s Energy States of a H-Atom**[

**Source: Self Created**]

The logic states in **quantum computation** is denoted by using the ""notation as the states and . They can be in a superposition of the two states also which is denoted by,

In the matrix form a **Qubit** is written as,

Hence, the states and can be written as, and .

Any measurement on the system disturbs the superposition and the system normalizes to one of the states i.e. or with probabilities and respectively which satisfies the normalization condition,

## Multiple Qubit

A **Multiple Qubit** system can be represented by two or more two level atoms. An **N-Qubit** system can be represented with **N** **H-atoms**.

**N H-atoms With 1s and 2s Energy States[Source: Self Created]**

For example, a **Two Qubit** system can be represented with two **H-atoms**. The superposition state of a **Two Qubit** system is a **2 ^{2}=4** possible combination of all the states of the two atoms. It is denoted by,

Which satisfies the normalization condition,

## Quantum Computation: A Time Evolution Process

**Quantum Computation** is achieved in a **quantum system** which evolves with time. According to the postulates of **Quantum Mechanics**, **Time Evolution** of a **quantum system** is a **unitary transformation** and is described by the **Schrodinger’s Equation**,

If a system is initially in the state , then at a later time , the state of the system is,

is a unitary operator i.e. it satisfies the condition,

## Quantum Gate

A **Quantum Gate** is a unitary transformation which can be described as,

Where is a unitary operator i.e.

**Quantum Gates** are of two types: **Single Qubit Gates** and **Multiple Qubit Gates**.

### Single Qubit Gates:

A **Single Qubit Gate** operates on a **Single Qubit**. Some examples are as below:

#### Pauli-X Gate:

**Pauli-X Gate** is the quantum equivalent of the classical **NOT Gate** and is denoted by the symbol

**Pauli X-Gate** is represented by the unitary matrix,

It operates on the state to yield the state as,

And on the state to give the state as,

The **X-Gate** operation on the superposition state yields the state, which in matrix form is represented as,

#### Square Root of NOT Gate:

A **Square Root of NOT Gate** is represented by the unitary matrix,

It is called the **Square Root of NOT Gate** because,

#### Hadamard Gate

A **Hadamard Gate** is denoted by the symbol,

And is represented by the unitary matrix,

A **Hadamard Gate** creates superposition state of equal probability by operating on the states and as,

### Multiple Qubit Gates:

A **Multiple Qubit Gate** operates on a **Multiple Qubit** state. An example of **Multiple Qubit Gate** is:

#### CNOT Gate:

A **CNOT Gate** or **Controlled NOT Gate** is denoted by the symbol,

The top line is called the **control qubit** and the bottom line is called **target qubit**. The circuit works on a way that, if the **control qubit** is set to the state , then the **target qubit** gets flipped, otherwise remains unchanged i.e.

In matrix form **CNOT Gate** is represented as,

## Quantum Circuits:

A **Quantum Circuit** is a combination of one or more **Quantum Gates** to implement a certain computational problem. Since, a **Quantum Gate** is a unitary operation, a **Quantum Circuit** also must be a unitary transformation. Now, the unitary nature of the quantum circuits implies that they are **Reversible**. It means that applying the inverse of the **quantum circuit** at the output of the gate we can recover back the original input states. This feature also a factor which makes **Quantum Computers** superior to **Classical Computers**.

**The Reversible Nature of Quantum Circuits[Source: Self Created]**

### Universal Quantum Gates:

**NAND Gate** is known as the **Universal Gate** in classical computation because, any classical circuit can be implemented by using only **NAND Gates**. A similar concept of universality exists in quantum computation. There are some sets of **Quantum Gates** using them any **Quantum Circuit** can be designed. Such sets of **Quantum Gates** are known as **Universal Quantum Gates**. The family of the gate gates is a set of **Universal Quantum Gates**. There exist other families of **Universal Quantum Gates** also.

## Quantum Algorithms

Just like **Classical Algorithms** are implemented on **Classical Circuits** to perform classical computational problems, **Quantum Algorithms** are implemented on **Quantum Circuits** to perform quantum computational problems. **Quantum Algorithms** employ the concepts of **Quantum Parallelism** and **Quantum Interference**.

**Quantum Parallelism** is the property of performing more than one computation simultaneously. A classical processor processes only one computation at a time. To perform more than one calculation simultaneously classical computers need more than one processor interconnected, each processor performing one computation at a time. But, a **Quantum Processor** can perform more than one computation individually due to the superposition property of quantum states. This feature gives the **Quantum Computers**, a much larger raw computational power compared to a classical computer.

When two or more **Qubit** states are brought close to each other, they interfere with each other to form a superposition state much in a similar way two **coherent light waves** interfere.

### Deutsch-Jozsa Algorithm: Superiority of Quantum Computers over Classical Computers

**Deutch-Jozsa Algorithm** named after its developers **David Deutsch** and **Richard Jozsa** in **1992** is a **Quantum Algorithm** which shows the superiority of **Quantum Computers** over **Classical Computers** in terms of computing power. The algorithm solves the following problem:

Suppose, **Alice** in **Amsterdam** selects a number from **0** to **2 ^{n}-1** and mails it in a letter to

**Bob**who is in

**Boston**. Upon receiving the number

**Bob**calculates a function and replies with a result

**0**or

**1**. Now, is confirmed to be either

**constant**or

**balanced**. being

**constant**means that its value is either

**0**or

**1**for all . being

**balanced**means that for half of the values of , is either

**0**and for the rest half of the values of , is 1. Now,

**Alice**’s job is to determine whether

**Bob**had chosen

**constant**or

**balanced**, by corresponding to

**Bob**as little as possible.

In a classical framework **Alice** needs to make at worst queries to **Bob** to know whether is **constant** or **balanced**. It is because, **Alice** may get **0**s before finally getting **1**, which proves that was **balanced**. But, using **Deutsch Jozsa Algorithm** a **Quantum Computer** can prove with single evaluation that whther is **constant** or **balanced**. Let us see how.

Instead of the classical calculation, the two decides to calculate using the unitary transformation . The whole circuit set up is shown in the figure below.

**The Quantum Circuit for Deutsch-Jozsa Algorithm**[

**Source**]

**Alice** has an **n** **Qubit** register to store her query and one **Single Qubit** register which she gives to **Bob** to store the answer in. **Alice** now prepares a state,

i.e. all the **Qubits** in the query register are in state and in the answer register the qubit is in state. She prepares superposition states by applying **Hadamard Gates** to the query registers as,

Now, **Bob** evaluates the function by using as: which gives,

**Alice**, now applies **Hadamard Transform** to the query registers. **Hadamard Transform** on the state can be written as,

**Hadamard Transform** on an **n-Qubit** state is written as,

The equation can be written in a precise manner as,

Now, the state after the **Hadamard Transform** can be written as,

**Alice** now observes the query register. We notice that the amplitude for is,

Now, if is **constant**, then the amplitude of is **1** or **-1** and for all other **Qubit** states the amplitude vanishes because, the amplitude of is normalized to **1**. If is **balanced**, then the amplitude for vanishes as the positive and negative contributions to the amplitude cancel out to zero.

Hence, if **Alice**’s measurement results in all **Qubits** to be **0**s, then **Alice** can say that is **constant** and if she gets at least one **Qubit** to be **1**, then is **balanced**. In this way **Alice** could decide with only one evaluation whether is **constant** or **balanced**.

Many other **Quantum Algorithms** have been developed which proves the superiority of **Quantum Computers** over **Classical Computers**. Among them, **Shor’s Algorithm** and **Grover’s Search Algorithm** are the most popular ones. **Shor’s Algorithm** can factorize a very large number exponentially faster than a **Classical Computer**. **Grover’s Algorithm** is used to search an unsorted database in much smaller time than a **Classical Algorithm**.

## Challenges of Quantum Computation

Building an efficient and reliable **Quantum Computer** is a challenging process. A **Quantum System** is very delicate to external environment. The **electromagnetic noises** in the environment causes disturbance and destroys the original state of the Qubits. For this reason, the system has to be isolated from the environment by keeping the system at extremely low temperature. It requires a lot of maintenance cost and the system becomes bulky. Researches are underway to to make **Quantum Computers** of the future much efficient and reliable.

**Readers can watch the Documentary on Quantum Computing Posted by the Youtube Channel "PD Knowledge" below:**

Though **Quantum Computer** is in its infancy we could easily foresee the revolutionary future it has, its impact on the world in the future. **Quantum Computers** will revolutionize the way how technology works. **Quantum Computers** will make early detection of **Cancer** possible, very efficiently by analyzing large number of factors causing the disease in a faster way. It will make weather forecast extremely efficient by analyzing a very large number of variables very quickly. **Quantum Computers** will be able to analyze vast numbers of data transmitted by the telescopes and help detect distant planets very easily. It will also help develop more effective drugs for superior drug based treatments. **Quantum Computing** is a major key to the success of **Artificial Intelligence**. From these facts it is well evident that the future of the world is much smarter compared to the present world. **Quantum Computers** will bring a revolution in much a similar way **Classical Computers** had brought in the last few decades. It is evident from the fact that most of the tech giants of the world like **Google**, **IBM** are in a rigorous race to develop **Quantum Computers**. **Google** is already developing driverless cars based on **Quantum Computing**. The race to develop these computing giants is bringing them close to a newer milestones every year to develop them for commercial purpose and well-being of human society. May be in a few decades we may start to see the impact of **Quantum Computers** in our life.

**References:**

**Book: Quantum Computation and Quantum Information by Michael A. Nielsen and Isaac L. Chuang****Book: Quantum Chemistry by Ira N. Levine****Youtube: Quantum Computing for Determined by Michael Nielsen****Youtube Channel "intrigano": Quantum Mechanics and Quantum Computation by Umesh Vazirani****Time: 9 Ways Quantum Computing Will Change Everything****Quantiki: Quantum Gates****Research at Google: Quantum A.I.****Youtube Channel "Quantum Computing": Deutsch-Jozsa Algorithm****Wikipedia**

### I hope you enjoyed learning about **Quantum Computing**. If you love dreaming and learning science then please follow me, **@physics-o-mania**

#### Don't Forget to Read My Previous Articles :

**Did the Science Channel Just Proved Ramayana to be Real!! Rama Setu or Adam's Bridge Not a Natural Creation, but Man-made****Nikola Tesla: The Man of Electricity****Quantum Cryptography and China's Quantum Satellite : A New Era of Hack-Proof Communication****Einstein : The Person Who Made People Love Physics****Mohenjo-Daro : A 4000 Years Old but Modern City****Mining The Lunar Surface : A New Race in Space ?****The ITER Project: Future of Endless Clean Energy?****ISRO : The New Glamor in Space Race****The Quest for the Grand Unification : The Theory of Everything****The Hunt for the Dark Matter : The Unseen Neighbor****The Strange Face of Reality : The Quantum Realm**

If you are interested in various domains of **Science** and **Mathematics** then join the **@steemstem** project, team to support high quality **STEM(Science,Technology, Engineering and Mathematics)** related contents. Join them in **steemit.chat** to interact with the science authors from all over the world.

leeuw (55)4 years ago (edited)nuclear fusion was also supposed to be a revolution in energy, same with the quantum computer fud. lots of hype to get fancy 'scientists' (showing complex formulea) funds from the taxpayers. we need higher taxes please. these quantum computers can only work at near absolute zero similar to nuclear fusion needing high temperatures like those inside the sun. oh what's up with global warming scientists? what's next scientists? oh i forgot AI which will drive automatic cars yet they cant even get trains to stay on the tracks

physics-o-mania (59)4 years agoOh...probably one should stop trying something that holds tremendous potential just because it is causing money. Right? Great thought dude.

Everything takes time. Its not like you'l enter the lab in the morning and come out in the evening with a design of a Quantum Computer or Nuclear fusion reactor.

leeuw (55)4 years agoTrue what you say, agree, but some science pumps are bogus bamboozeling money grabs like global warming, uh climate change uh global cooling uh quantum computing uh artificial stupidity

physics-o-mania (59)4 years agoAh...its better to try it while the world is facing an imminent danger in the future rather than sitting a mere spectator. And the electronic devices that you are using were not developed so easily. It took almost 7 decades to bring the computers to this form today. And quantum computing holds a lot of potential. It will take the world specially the medical sector to a much higher level

inksanity (51)4 years agogreat discussion guys...I'm all for AI after all humans are doing a pretty good job of screwing up the planet. And I'm less & less sure about the scientists - each day as per @leeuw However, I do know the sun and the solar cyles - they are extremely predictable. the past is the key to the future ie. the Maunder, Glassberg & Dalton minimum plus the Eddy minimum that is now upon us. My question is how will computers & AI benefit us or themselves when the lights go out ??? just a thought...

leeuw (55)4 years ago (edited)today's scientists claim huge

taxpayerfunded handouts by echoing gov goals do the math welcome to the future of science and don't you dare to counter argue this gov mandated 'science' for example by using contradicting measurement data, you will be called flat earther or worserahul.stan (63)4 years agoUm, let me guess, the earth is flat?

leeuw (55)4 years ago (edited)yes (not) and the icecaps had molten away years ago - oh not yet? they will melt SOOOOON!

krischik (61)4 years agobitcoinflood (74)4 years agoLoved this write up and totally can't wait for the next evolution in computers. We seem to be rather stuck here at 4.5 GHz and just keep throwing cores on instead of really progressing in speed.

physics-o-mania (59)4 years agoSuch an aggressive study to develop something I think never happened. All the big companies are investing on Quantum Computing research

krischik (61)4 years agoWe stopped progressing at speed at around 4GHz because that is the limit for air cooling. Intel had plans all the way up to

single core8GHz CPUs and then at 4GHz hit the thermal wall and had to scrap there single core plans. Onlyafterhitting that thermal wall Intel started to go multi core.drumoperator (65)4 years agoI know it probably seems like a forced comment but a friend of mine was actually going on about quantum computing yesterday and this post fell completely in my lap...followed you here from an upvote on an overhead mic position drum article! Awesome. Steem is amazing.

physics-o-mania (59)4 years ago (edited)Thank you friend and Sorry for the late response. Following you.

nitesh9 (61)4 years agoAwesome post as always. You discussed almost everything of quantum computers. Even the Quantum Logic gates and the formula of Qubits.

Never read such a in-depth post on Quantum Computers. Just one word for this:

Impeccable.Keep sharing your knowledge and keep developing.

Merry Christmas. :)physics-o-mania (59)4 years agoThank you bro...keep steeming

gokhan83kurt (57)4 years agoWow!! What a post!! Thank you for those very precious information. As i am a physicist and a semiconductor process engineer, i now start to follow you.

physics-o-mania (59)4 years ago (edited)Thank you. Followed you too. Keep in touch and support me. So would I.

gomaji (25)4 years agoI agree.. great write up! I hope to see more of your articles.

physics-o-mania (59)4 years agoSure. With your support I'l be bringing more such contents

bitgeek (62)4 years agoCongratulations @physics-o-mania, this post is the most rewarded post (based on pending payouts) in the last 12 hours written by a User account holder (accounts that hold between 0.1 and 1.0 Mega Vests). The total number of posts by User account holders during this period was 3181 and the total pending payments to posts in this category was $5664.67. To see the full list of highest paid posts across all accounts categories, click here.

If you do not wish to receive these messages in future, please reply stop to this comment.

hemanthoj (61)4 years agoWhat an article, gave me lot of inputs at the right time. Do you know that microsoft has come up with a new programming language called 'Q#' - Quantum programming language. This is the hot news for people working on microsoft technologies and your article will surely give lot of information for people starting on the new technology. Keep writing. loved it.

physics-o-mania (59)4 years agoThank you bro. You are from India?

hemanthoj (61)4 years agoyes i am :)

physics-o-mania (59)4 years agoJoin me in the discord. The same username

hemanthoj (61)4 years agoSure i will

bewise (45)4 years agoWell that is a lot of formuli :D Great work though.

Anyway, I study molecular biology and I had an idea. As you wrote, quantum computer can help us to design better drugs. Actually I think it may help us to create ultimate super cool molecules, enzymes that can do literally everything.

The other day I thought how strange it is, that we discover a new protein and we arent simply able to tell its function. Although we know every amino-acid in the sequence, we arent able to tell its 3D shape (and then derive a fucntion from this shape). Our computers are just not enough for this task. So we just have to test them and look at the nature. Every enzyme that we use today to edit genomes are just enzymes that we discovered in nature. And they are far from perfect, they make errors. But we dont know what should we change in order to be more precise.

So maybe in the future we might be able to design molecules, their shapes that will do exactly what we want. Editing genomes with 0 mistakes for example. That would be extremely cool.

On the otherhand, it should not be problem to create something extremely deadly also...

Looking forward what will this revolution bring us.

physics-o-mania (59)4 years agoYeah, with Quantum Computing you'l get a genius machine with you to do the job for you. But, we may not see it happening at that level in our life.

Thank you for commenting.

digitalheretik (25)4 years agoQuantum Computing is some heavy subject matter, I'll say.

physics-o-mania (59)4 years agoYeah.. indeed heavy a lot

vnyrox (9)4 years agoGreat Article...! here i try to write article about ### Latest Gadgets

Let me know if you like it.

physics-o-mania (59)4 years agoYour link is not loading. I'm having network issues. Will check for sure. Thank you. Keep steeming

bijoy123 (5)4 years agoMerry Christmas! I love the Philippines!

rharphelle (58)4 years agotechnology always thrives to make life easier. i wonder how life would be without such technology

physics-o-mania (59)4 years agoyeah. Its impossible to live without them now