One of the many things that technological evolution has taught us, is the ever-present need for systems that are more powerful than the existing ones. Today’s state-of-the art technology becomes obsolete tomorrow.

The same has happened with computers as well. Since their advent, computers have been associated with the term ‘bits’, referring to binary digits. These resemble tiny electronic switches that are either ‘ON’ or ‘OFF’. Based on millions of these bits, computers recognise data and perform various operations. This is classical computing.


Quantum computing is a fairly new technology that trounces classical computing. It makes use of quantum bits or ‘qubits’, rather than ‘bits’. These can represent ‘0’ and ‘1’ at the same time  and enable the computer to be faster by processing comparatively large amount of data simultaneously. Sounds confusing? Well. Read on!



Quantum computers use atoms, instead of transistors, to process data. This enables the qubits to obey the three laws of quantum mechanics.

  • Superposition – This refers to the ability of the qubit to represent multiple quantum states at the same time. Schrodinger’s cat could offer some help here!
  • Quantum tunnelling – This states that a particle can penetrate a barrier even if doesn’t possess the adequate energy, since there is a non-zero probability that the particle exists on the other side, by Heisenberg’s uncertainty principle.
  • Quantum entanglement – This is the phenomenon by which two qubits replicate each other, even if they are separated by large distances; they are said to be ‘entangled’.

Rather than just lying either in the ‘0’ and ‘1’ quantum states, qubits can also represent the superposition of these two discrete states. Such states have complex values, which are depicted by each distinct point within the sphere illustrated above. But this is feasible only at extremely low temperatures; around a few degrees above absolute zero. Since the number of possible values that a qubit can represent are more than two, they are capable of simultaneously processing a lot more data at a faster rate compared to classical computing.


These quantum computers are ideally suited for complex tasks such as molecular simulations and mathematical modelling. For example, advanced optimisation algorithms work on extensive data to select the methods that are best suited. Quantum computing is capable of assimilating such large amounts of data and hence could be used to carry out such optimisations.

Apart from the dramatic increase in system performance, quantum computing lets you upgrade the system without a major bump in the power requirement. In classical computing, performance upgrades made on a computer would demand additional power to operate it. On the contrary, a quantum computer can be made more powerful by just adding more qubits to the super-cooled medium; saturation of the medium doesn’t significantly affect the power required to maintain the system temperature.

One of the major players in the field of quantum computing is the Canadian firm D-Wave. They state that a quantum computer consumes about 15 kilowatts, where a quantum chip uses less than a microwatt. The rest is used for the immense cooling.

For now, building a quantum computer is hindered by the need for the super-cooled environment and ‘quantum de-coherence’; when deciphering a qubit, it transforms into a classical binary datum and leads to significant data loss.

Tech-giants like Google and Lockheed Martin are already experimenting with quantum computers. With a quantum computer developed by D-Wave, Google is spearheading the world’s quantum computing efforts in partnership with NASA.

This is The Verge’s take on quantum computing: