Over the past few decades, we have seen almost unimaginable progress in computation speed and power. A watch today is a more powerful computer than the first Macintosh that my parents bought me in 1984 (I was very lucky). The weakest and lightest laptop today is more powerful than the computers that I programmed on during my undergraduate studies in university. Do you remember the days of computers with 64 kilobytes of RAM? Now we count in gigabytes and, soon, terabytes.
Yes, I know that I’m old (but at least I’m not reminiscing about punch cards and vacuum tubes), but that’s not really the point. The point is to understand where all of these extremely fast advancements in computing power came from.
The answer is a combination of Moore’s law (stating that the number of transistors on a chip doubles every two years, although this has now slowed down), together with many architectural improvements and optimizations by chip manufacturers. Despite this, the basic way that our most powerful computers work today is the same as in the 1970s and 1980s. Thus, although improvements are fast and impressive, they are all in the same playing field.
Enter Quantum Computing
Quantum computing[1] is a completely different ball game. Quantum computers work in a radically different way and could solve problems that classical computers won’t be able to solve for hundreds of years, even if Moore’s law continues. Stated differently, quantum computers don’t follow the same rules of classical computing and are in a league of their own. This does not mean that quantum computers can solve all computationally hard problems. However, there are problems for which quantum computers are able to achieve extraordinary speedups.
Some of these problems are closely related to much of modern cryptography, and include the number
