Moore’s law states that the number of transistors in an integrated circuit doubles about every two years, and this has approximately been true up until now.Transistors are the fundamental building blocksof electronic devices; they amplify and switch electronic signals on and off. More transistors on a chip result in more processing power. However, due to quantum tunneling, there is a limit on how small transistors can get, and this will make it very difficult to make a cryptocurrency mining application-specific integrated circuit (ASIC) chips more powerful than they already are.
Quantum tunnelingarises from the wave-particle duality of electrons and is specifically associated with an electron’s wave characteristics. An electron’s wave doesn’t instantly stop at a barrier. It tapers off and if a barrier is small enough, the wave of the electron gets to the other side of the barrier, albeit significantly attenuated. If there are enough electrons impacting the barrier, then some effectively teleport through the barrier.
In the case of transistors less than 5 nm or so, quantum tunneling results in an “on” state all the time, which makes them unusable. Transistors need to be switched on and off with 100% accuracy for a computer to correctly function, so quantum tunneling would compromise a computer that has transistors which are too small.
Currently, the smallest transistors on cryptocurrency mining chips are 7 nm – Japanese firm GMO has developed a 33 TH/s Bitcoin mining rig with 7 nm transistors. Scientists generally thought that 7 nm would be the smallest size for a reliable transistor due to quantum tunneling. IBM actually developed 5 nm silicon chips in 2017 but had to utilize different technology from usual to accomplish this.Even a 1 nm transistor has been developed by Lawrence Berkeley National Laboratoryusing molybdenum disulfide and nanotubes, but they can’t mass produce the transistors to create a chip and even if they did, quantum tunneling would probably be a problem.
Perhaps quantum tunneling can be circumvented by using completely new technology to produce transistors, but when it comes to transistors on silicon chips it would seem that they can only get so small and current technology is already close to the limit. This will inhibit the acceleration and evolution of cryptocurrency mining hardware. Of course, mining manufacturers can always pack more chips into a device resulting in a higher hash rate, but nothing increases hash rate like mass producing chips that have smaller and smaller transistors since that exponentially increases processing power.