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What Are The Advantages of Quantum Computing?

By Oliver Bean - Engineering Student @ Wadham College, Oxford


Quantum computers are often hailed as the future of computing and the possible applications of quantum computers in physics simulations, cryptography and complex modelling could have wide reaching impacts. However, quantum computers have been in development for decades (the first physical realisation of a quantum computing component was in 1988) and yet still cannot outperform classical computers. In this article I will investigate the theory and engineering behind quantum computing and compare this with traditional computers.

The computers we use today are based upon a physical component being in one of two states - ‘on’ or ‘off’. The Harvard Mark 1 computer (used during the 1940’s) had mechanical switches which were electrically controlled. When an electrical signal was passed to the switch, a current would pass through a coil of wire. According to Ampere’s law, this generates a magnetic field which in turn attracts the metal switch and allowed the gate to be opened or closed. Due to the time delay for the physical component to move, this computer was only capable of performing 3 additions or subtractions per second. The computer was unreliable for a number of reasons - one time a moth was found to be the reason for a fault in the Harvard Mark 2 computer, and this is why programmers complain of computer ‘bugs’!

Computers have since advanced and have progressed from using vacuum tubes to modern day transistors in the internal switches. Transistors make use of electrodes and semiconductor materials to switch between ‘on’ and ‘off’ states much more rapidly than mechanical switches as they don’t contain any physically moving components. The engineering concepts behind transistors and vacuum tubes are equally ingenious and you can explore more about them in the links below.

Contrastingly, current quantum computing is based on an entirely different system. The fundamental building block of quantum computing is the quantum bit - or qubit. A qubit is a sub atomic particle, such as an electron or a photon, and hence is subject to quantum mechanics as opposed to classic physical theory. Quantum computing measures a property of this sub atomic particle to represent