Today's computers are very good at fulfilling our needs. We are enjoying the benefits of today's classical computers. It is entertaining us, connecting us and even help us in each and every moment of life in one way or another. Classical computers are helping us to process huge amount of data in this data driven world and make the world is a better place. From medicine to finance, engineering and so many other areas, computers and computer knowledge is an essential for a human being to survive. The power of the computers are increasing day by day and it will continue to increase as we develop further. 

However, there are limitations to the classical computers. There are problems that cannot be addressed with classical computers. In other words, there are problems that cannot be addressed using a classical computer. There are many complex system in science which are so complex and massive that we cannot do it with even the powerful supercomputers using classical computing technology. This leads the scientists to seek new methods and approaches to tackle with this limitation of classical computers.

We need systems with computational power with the size and the complexity of the system itself. The best example we can choose is the simulation of atoms and molecules. Everyone knows that simulating an atom or a molecule is very complex due to the complex quantum mechanical calculation involved. The behavior of an electron inside an atom or molecule is very complex to compute, which is very essential in understanding the inner mechanism of that molecule.

The simulation of chemistry and simulation of even small scale macro molecules which are essential for life on earth is very complex for a classical computer. Nature is quantum mechanical and classical computer is very limited in simulating quantum mechanical aspects. So it is essential to use the object which obeys the same natural laws to simulate or understand the nature. A quantum computer can easily simulate these complex systems so that we can understand it. The implications this leads to is immense, opportunities in new drugs, new materials, understanding catalytic interaction in chemical reactions complex molecular interactions which are impossible to calculate using today's computing technology.