I am sure you have heard of Moore’s law, probably in some sci-fi movie, which talks about the fact that every two years the computing power of our microchip processors doubles. This has, in fact, been true for the past decades without fail but that might not be the case in the years to come.
When computer scientists talk about computing power what they mean is the number of transistors per unit area of a microprocessor chip. Every year we make smaller and smaller transistors which increase the total capacity of the microprocessor chip. But how long can we keep doing that? At some point, we can’t make the chips any smaller. And that point of time is not too far in the future.
Transistors at the 7 nanometer scale were first produced by researchers in the first decade of the 21st century – 7 nm is the size of about 130 hydrogen atoms. The process scale may represent the end of Moore’s Law scaling for electronic devices. At scales smaller than this, the stuff that the chip is made of i.e. the semiconductor transistor stops behaving in the normal fashion. At these scales the quantum effects become very pronounced and it becomes very difficult to make the chip function in a way we would like it to function.
In a transistor, electrons flow from one junction to the other when some energy is provided. But when we make the transistor really small, it becomes easier for the electron to just jump to the other junction via Quantum tunneling.
In 2008, transistors one atom thick and ten atoms wide were made by researchers from UK. They used Graphene, which is a potential alternative to silicon, as the basis of future computing. Graphene is a material with various interesting properties which makes it one of the leading contenders as a replacement for silicon-based microprocessors. It has a very peculiar structure – flat sheets of carbon atoms are placed upon each other in a honeycomb structure. A team at the University of Manchester, UK, used it to make some of the smallest transistors at this time: devices only 1 nm across that contain just a few carbon rings.
In 2012, a single-atom transistor was fabricated using a phosphorus atom bound to a silicon surface. Although it sounds crazy but making transistors smaller than this would require either using smaller atoms or using arrangement of subatomic particles like electrons and protons as functional transistors.
Innovations in material sciences have made it possible for us to make processors much smaller than the width of a hair, but there is a fundamental limit to how much processors we can put in a given area. Interestingly enough, there is no such limit for the processing power of a chip. We just have to find out a way of processing which needs lesser number of transistors or their analogs. There are people who are working towards this goal on different ways of computing. Till now, the most successful of them has been Quantum computing.
Quantum computing takes a much more sophisticated route and solves this problem in a much more simpler way. Quantum computers don’t need an assembly of transistors which perform the logical operations by turning switches but instead it uses the concept of Quantum entanglement which makes it possible to use a very small number of Qubits to do large number of processes simultaneously.