The branch of physics that deals with subatomic particles and the universe within a tiny atom are known as Quantum physics. The laws of physics within atoms don’t act the same way as everything else in the universe at large. Please read this article as we get quantum computing explained.

On the atomic scale, the rules shift. The classical laws of physics that we take for granted in our daily life no longer work necessarily.

If you’ve studied light, you might know a bit about quantum theory. It would help if you understood that sometimes a beam of light acts as though it were made up of particles. And sometimes as if it were waves of energy rippling through space.

This is one of the principles of quantum theory known as wave-particle duality. It is pretty inexplicable how it behaves both as a wave and particle because this is utterly unknown to our daily experience.

A car is not a bicycle and a bus at the same time. However, in quantum theory, that’s just the sort of weird thing that can happen. The most striking case of this is the baffling mystery known as Schrödinger’s cat.

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## What is quantum computing?

What do computers have to do with all this? Suppose we try to push Moore’s law to make transistors smaller until they reach the point that they follow the more bizarre laws of quantum mechanics, not the ordinary physics (like old-style transistors).

Computers built in this way can do things that our traditional computers can not do. If we can mathematically foresee what they would be able to do so, can we make them function in practice like that?

For many decades, those questions were on peoples’ minds. Physicists Charles H. Bennet and Rolf Landauer from IBM were amongst the first.

In the 1960s, Landauer opened the door to quantum computing when he suggested that data was a physical entity that could be processed under physics rules.

One significant effect of this is that computers waste significant electrical power manipulating the bits within them. This is partially why computers use so much energy and get hot, even though they don’t seem to do very much at all.

Bennett demonstrated in the 1970s, building on Landauer’s work, how a computer could circumvent this problem by operating reversibly, which means that without using massive amounts of energy, a quantum computer could perform massively complex computations.

In 1981, Argonne National Laboratory physicist Paul Benioff attempted to visualize a straightforward machine that would function in a similar way to an ordinary device, but according to quantum physics principles.

The following year, Richard Feynman sketched roughly how simple computations could be carried out by a computer using quantum principles.

## How do quantum computers work (quantum computing explained)

Instead of bits, quantum computers use qubits. This is also called superposition as opposed to being ‘on’ or ‘off.’ They can be both on and off at the same time or somewhere in between.

If you flip a coin, it can be either heads or tails. If you spin it, it has a chance of landing on heads and a chance of landing on tails.

It can be either, before you weigh it, by stopping the coin. Superposition is like a spinning coin, and it is one of the aspects that makes it so efficient for quantum computers.

If you ask a standard computer to figure out its way out of a maze, it will try out every single branch one by one. Until independently ruling them all out before it finds the right one.

A quantum computer can go down any maze route at once. It can keep its head in uncertainty.

It’s a bit like keeping your finger on the page of the adventure book you are reading. If your favorite character dies, you can immediately choose a different path instead of returning to the book’s start.

Using the actual location of a physical state, classical computers conduct logical operations. These are typically binary, which means that one of two positions is the basis of its operations.

A single state, such as on or off, up or down, 1 or 0, is called a bit. In quantum computing, operations instead use an entity’s quantum state to create what is known as a qubit.

These states are the undefined properties of an entity, such as the spin of an electron or the photon’s polarization, until they have been observed.

Unmeasured quantum states exist in a mixed ‘overlay’ instead of having a specific location, not unlike a coin flipping through the air until it lands in your hand.

## What can quantum computers do that ordinary computer can’t?

Quantum computers are not just about doing things more effectively or more rapidly. They’re going to let us do stuff we couldn’t even conceive of. Stuff that even the strongest supercomputer is just not able to do.

They can accelerate the growth of artificial intelligence rapidly. Google is now using them to develop self-driving vehicle applications. In modeling chemical reactions, they will also be vital.

Right now, only the most simple molecules can be analyzed by supercomputers. Yet quantum computers use the same quantum features as the molecules they are attempting to simulate. Even with the most challenging responses, they should have no trouble handling.

Vastly improved solar panels, new battery technologies for electric cars, better and cheaper drugs are few possibilities. Scientists hope quantum simulations could help them develop a cure for Alzheimer’s disease.

Although people sometimes believe that quantum computers have to be better than traditional computers necessarily, that’s by no specific means.

So far, the only thing we know for sure that a quantum computer might do better than a regular one is factorization. Also, finding two unknown prime numbers that give a third known number when multiplied together.

## What are the early works that showed some possibilities?

Mathematician Peter Shor was working at Bell Laboratories in 1994 when he demonstrated the algorithm. Followed by quantum computers to find many prime factors. This is the algorithm that made the problem-solving process way faster than conventional computers.

Shor’s algorithm sparked curiosity in quantum computing because virtually every conventional computer uses public-key encryption technology based on the virtual impossibility of quickly finding primary factors.

If quantum computers could easily factor in huge numbers, today’s online security could be made redundant at a stroke.

But what goes around comes around, and some researchers assume that quantum technology can lead to far stronger encryption types.

(For the first time, Chinese researchers showed in 2017 how quantum encryption could facilitate a very safe video call from Beijing to Vienna.) Does that mean that quantum computers are better than traditional ones? Exactly not.

Apart from Shor’s and Grover’s algorithmic search method, hardly any other algorithms that quantum methods would better perform have been produced.

Given ample time and computing power, conventional computers can still solve any issue that quantum computers will solve.

Who knows how traditional computers might advance in the next 50 years! What if it possibly renders obsolete and even impractical the concept of quantum computers. I hope this got a little of quantum computing explained.

## Building a quantum computer

Getting to know and having quantum computing explained, it’s tempting to know what building a practical quantum computer involves.

It requires keeping an object long enough to perform different processes in a superposition state. Unfortunately, whenever a superposition encounters materials that are part of a calculated scheme, it loses its in-between state.

It becomes a boring old classical piece in what is known as decoherence. While still making them easy to read, Devices must be able to protect quantum states from decoherence.

Whether using more efficient quantum methods or seeking better ways to search for errors or approach the problem from different angles.

Microsoft released a complete quantum development kit, which includes a new programming language, Q#, designed explicitly for quantum applications, in December 2017.

D-wave revealed plans to begin rolling out quantum power to a cloud computing platform at the beginning of 2018.

A few weeks later, Google unveiled Bristlecone, a 72-qubit array-based quantum processor. This could, one day, form the foundation of a quantum computer that could solve real-world issues.

Google declared in October 2019 that it had achieved another milestone. The achievement of “quantum dominance” (the stage at which a quantum computer can defeat traditional computing machines at a standard computing task).

Most experts believe that we’re not likely to see the appearance of functional quantum computers within the next several decades.

## When are we getting a working quantum computer?

Quantum computers remain mostly theoretical three decades after they were first proposed. Even so, there has been some promising progress towards building a quantum computer.

In 2000, there were two impressive breakthroughs. First, Isaac Chuang (now a professor at MIT, but then at IBM’s Almaden Research Center) built a primitive quantum computer of five qubits using five fluorine atoms.

The same year, Los Alamos National Laboratory researchers found out how to use a drop of liquid to create a seven-qubit computer.

At the University of Innsbruck, researchers added one extra qubit five years layer. This created the first quantum machine that could manipulate eight qubits (a qubyte).

These were tentative first steps but necessary. Researchers have announced more ambitious experiments over the next few years, introducing growing numbers of qubits gradually.

In 2011, D-Wave Systems, a pioneering company from Canada, revealed in Nature magazine that it had developed a 128-qubit quantum computer. The announcement was highly controversial because there were doubts about whether their computer showed any quantum behavior.

In 2014, Google revealed that it was recruiting a team of scholars (including the physicist John Martinis from the University of California at Santa Barbara) to build its quantum computers based on D-Wave’s model.

## What will change with quantum computing?

By now, we believe you have got a bit of quantum computing explained. What changes shall it bring forth?

RSA encryption relies on the practical impossibility of finding the correct prime factors of a large integer. For example, a sizeable 500-digit-long form from a classical machine.

On a classical device, this could take thousands of years. Atleast hundreds of years if we brute force to find the answer.

The explanation of why this is solvable with a quantum computer is that in 1994, Peter Shor had already solved it.

Shor’s algorithm requires a sufficiently powerful quantum computer to run on to crack RSA encryption, but one does not exist yet.

The Google team revealed in March 2015 that they were a step closer to quantum computation. They were creating a new way for qubits to detect and defend against mistakes.

Scientists from the University of Innsbruck worked with Isaac Chuang of MIT in 2016. They unveiled an ion-trap five-qubit quantum computer. It could calculate 15 factors.

One day, a fully-fledged encryption buster could grow into a scaled-up version of this system.

There is no question that these are enormously significant developments. And the signs that quantum technology will finally bring a computing revolution are gradually becoming more promising.

It will soon be as efficient as using a hook and loop latch on your front door to protect your house. We’re going to have to develop an entirely new way of protecting all our existing knowledge.

One example of problem quantum computers might solve is how to make these devices optimally balanced between cost and usefulness.