## Quantum computer

Computers have become a very important part of our lives. Whatever the point of research, space exploration, and technological advancement, nothing is possible without a computer. In the past few centuries, we have reduced the size of the computer or even the power of computing has been greatly enhanced. If we use the example of today's smart phone's computing power, then it is much better than the military computer which was the equivalent of a room.

Despite all those things, our classical computer today is not perfect in many ways. If you talk about their general limitations, then it is their speeds. Because it takes a lot of time to solve complex mathematical equations. Among other problems, storage space issues and energy consumption plays a very important role. For this, we need a computer that is many times better than today's computer.

Companies like Google, IBM (International Business Machines Corporation), and Intel are using the rules of quantum physics to create computers that we can be called futures computers. These computers are named Quantum Computers.

This kind of computer has been built or even used in small calculations. Now, these companies are trying to make this computer at a bigger level. If these computers start to be built at a larger level,  then they will replace the computers used today. In this article, we will know -

1. How Quantum computer work?
2. Problems with making Quantum computers
3. What a Quantum computer can do?

## How Quantum computer work?

Quantum computer is a computer that uses qubits or quantum bits for computing. If you are not familiar with qubits, then let's get to know qubits first.

Usually the computers we use such as desktops, laptops, tablets, and smartphones we call them binary computers. Because all of the functionality in them depends on 0 and 1. For any calculations within a binary computer, the processor uses transistors to perform.

Any transistor may be in the on state or off state, that means either yes or not. Where 1 represents the on and 0 represents off state. In any program or algorithm, what will calculate at the next step is determined by one or zero.

The thing is that the computer that uses 1 and 0 for computing is called bits. Now if we talk about quantum computers, it uses qubits instead of bits which is also called as quantum bits. These qubits also have an additional function that is not contained in the bits. Usually, the bits exist only in two states either 1 or 0. Now if I talk about qubits, it could be one, zero, or two states at a time. Which increases the computation speeds in the computer.

Until they are not observed they staying in the all possible state at the same time which is also called spinning state. Instead of measuring the states of this spinning state with 1 and 0, they are measured with three states called up, down, and both.

The functionality of these qubits is based on the superposition phenomenon in quantum physics. These qubits can influence each other using quantum entanglement even though they are not physically connected.

 Two qubits phi-minus entangled state

If you do not know about superposition Phenomenon, let's know about it briefly. In quantum physics, we see that this world is not as ordinary as it appears. Because how quantum particles behave when they are observed is completely different when they are not observed. A very good example of this is the double-slit experiment.

It shows us that when quantum particles are observed, they behave like particles, but when they are not observed, then they behave like a wave. The reason behind this phenomenon is that the original quantum particles are neither particle or wave.

Usually, they are present in their all possible state as a probability and we call it the wave function. Which means that they are at the same time both in the particle and in the wave. But when we observe them, the wave function collapse, as a result, one of these conditions is selected and we get that at the end.

Quantum computer simulates these behaviors of quantum particles in nature using qubits. As a result, its capacity is increased several times. How this happens let's understand with a simple example -

When we rotate a coin, the coin may show us head or tail in its stable state. The binary computers we have today are similar to this where we might have 0 or 1. So it takes a lot of time for today's computers to solve such cases where there is an equal probability of getting many answers. Because it checks all the possibilities in a perfect way.

But if we talk about quantum computers then it works differently. As long as our coin is rotating we do not know whether it will fall head or tail. That means when the coin is rotating it is in two conditions at the same time. Qubits are also in this similar state until they are observed. That means they can test many possibilities at the same time. From here it can be understood that when a binary computer starts solving a problem, the quantum computer's problem will be already solved.

If you look at the comparison, Google's quantum computer is millions of times faster than your normal binary computer.

## Problems with making Quantum computers

The extraordinary power and speed of quantum computers are attracting many companies. But making them and working with them is not so easy. Because of the state of qubits changes during observation. And it produces very noise when using them. This means that when more qubits will be uses in it, the more error will be it is to show.

And the second challenge is that most quantum computers need to be kept at nearly zero temperature, which is even cooler than space. Even they need a lot of power to work well. That means a quantum computer is very costly to make it work. For this, It is not possible to use them extensively.

Only a handful of companies like Google, Intel and IBM are making quantum computers and trying to make them better. But it is certain that quantum computers will rule in the future. If we talk about Quantum supremacy, then Google has already announced a quantum chip called Bristlecone. In which, 72 qubits or quantum bits have been used, which has become the most widely used qubits chip in the field of quantum computing.

 Bristlecone processor for quantum computers
Earlier this record was the name of the quantum processor of IBM that the company created two years ago in which 50 qubits were used. Google says they are still testing this new chip and are confident that their chip will be acquired by Quantum Supremacy within the next year. That means the quantum computer created by this chip will outperform the current computational speed supercomputer.

## What a quantum computer can do?

Of course, quantum computers can do things that are impossible to do today's binary computers. Because quantum computers use qubits that can do a lot of work at the same time. They can solve many problems at the same time.

They do not have to look for solutions to a problem like the binary computer that will produce such a result if yes, and it will produce another result if not. A quantum computer will test two conditions at the same time and will give us the solution to that problem immediately.

Even quantum computers have the dangers of our security system for this skill. Because it wouldn't be a big deal to hack our current security system with such a computer. Keeping this danger in mind, researchers are looking to develop a technology that will be quantum hacking-proof.

In the future when we have a quantum-based cryptography system, then it will be much more secure. For which it would be impossible to hack. Researchers are much more interested in this quantum computer because it can be used to design complex chemical reactions. Which is very difficult to do with today's binary computer.

In July 2016, Google engineers first time simulate the hydrogen molecules for using this quantum device. If everything goes this way and they succeed in making quantum computing efficient, we will see many new molecules in the future. And we can use them starting from making medicines to other fields.

Whether it is space exploration, new exploration, or the development of artificial intelligence, quantum computers can provide a lot of support. If we are successful in using a quantum computer properly, it will increase our development speed many times.

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