Let us first focus on understanding what Quantum Computing refers to and why it is required. Let us have a brief look at working of a **Classical Computer** and **Quantum Computer**.

**The Working**

A classical computer is made up of very simple components doing simple operations, like representing data, means of processing data and the control mechanism. A classical computer chip contains basic modules inside which you can find logic gates. Logic gates have transistors inside them.

A *transistor* is the simplest form of a data processor which acts like an electronic switch, a transistor can block or allow the flow of data. This data is made up of bits which can be set to either ‘**1**‘ or ‘**0**‘. A combination of bits can represent a complex data. With help of combinations of transistors, logic gates are made.

Logic gates are of several different types which give result according to their functionality, by a combination of logic gates one can perform arithmetic operations.

by now you might be thinking that what it has to do with Quantum computing. Well, here is the answer to your thought. A typical transistor today is of size “**14 nm(**nanometer**)**” which is very small and if compared to the red blood cell a transistor is 500 times smaller than an RBC.

If the transistors are further shrunk to the size of few atoms then Quantum physics will cause trouble for the data flow within the transistor, remember that transistor is just a switch which can either block or allow the flow of electron.

But, when a transistor is shrunk to a size of few atoms it can no longer stop the electron flow as the electrons will be able to transfer themselves to another side of the switch even when it is off. This happens because of the **Quantum Tunneling** effect.

(*Quantum tunneling refers to the quantum mechanical phenomenon where a particle tunnels through a barrier which in normal conditions cannot be surpassed.*)

So, scientists teamed up and started searching for a solution to this limitation. Eventually, they found that the property(quantum tunneling) which limited the computational power of the classical computer can be actually be used for super fast computing. In results of this finding, they introduced Quantum computing and made Quantum computers.

**So, What was the magic in Quantum Computers?**

Let’s have a look at the difference between how the data is processed in classical computers and quantum computers. In a normal computer, a bit can either be ‘1’ or ‘0’ at an instance, whereas, a **qubit**(Quantum bit) can be ‘1’ and ‘0’ at once. This property is known as superposition. In order to check the value of a qubit, you need to pass it through a filter which will result in one of any state(1 or 0).

In simple words, if you have 2 bits (classical computer) then you will have 4 possible values (00,01,10,11) in which they can be one at an instance (eg 10). In case of qubits if you have 2 qubits which will also have 4 possible values (10,01,10,11) it can be all in one instance (i.e 11,10,01,00) because of the superposition.

Quantum physics also have a property called **quantum entanglement** which can help to deduce the state of the other qubit as the quantum state of each qubit depends upon the other qubit irrespective of how far it resides.

By the above properties of Quantum computing, we can understand that the quantum algorithms will require square root of the time taken by the classical computer to perform an operation.

Having such great properties which boosts up the computational speed and takes it to another new level, these are widely used in the field of IT security for mainly factorizing RSA keys and minimizing the time taken to search for a particular file in the database.

So far we have learned about how and why Quantum computers are used. Now, let’s have a look at pros and cons of Quantum Computing.