What is quantum computer and how does it work?

In a world where we are relying increasingly on computing, to share our information and store our most precious data, the idea of living without computers might baffle most people.

The massive amount of processing power generated by computer manufacturers has not yet been able to quench our thirst for speed and computing capacity. But if we continue to follow the trend that has been in place since computers were introduced, by 2040 we will not have the capability to power all of the machines around the globe, according to a recent report by the Semiconductor Industry Association.

Will we ever have the amount of computing power we need or want? If, as Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks.
Quantum computing is the area of study focused on developing computer technology based on the principles of quantum theory, which explains the nature and behavior of energy and matter on the quantum - atomic and subatomic level.
Quantum computing is still in the field of research and studies of theoretical computation systems that make direct use of the quantum - mechanism, such as superposition and entanglement, to perform operations on data. Development of a quantum computer, if practical, would mark a leap forward in computing capability far greater than that from the abacus to a modern day supercomputer, with performance gains in the billion-fold realm and beyond.
Quantum computers are different from binary digital electronic computers based on transistors. It follows the laws of quantum physics, which help to takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.
In classical computing, a bit is a single piece of information that can exist in two states – 1 or 0. Quantum computing uses quantum bits, or 'qubits' instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

Future of Quantum Computers

Last year, a team of Google and NASA scientists found a D-wave quantum computer was 100 million times faster than a conventional computer. But moving quantum computing to an industrial scale is difficult.

IBM recently announced its Q division is developing quantum computers that can be sold commercially within the coming years. Commercial quantum computer systems "with ~50 qubits" will be created "in the next few years," IBM claims. While researchers at Google, in Nature comment piece, say companies could start to make returns on elements of quantum computer technology within the next five years. 

But, quantum computers are still hard to manufacture because - scientists still have not found a simple way to control complex systems of qubits.