Computers process information by breaking it down into the smallest possible chunks, called “bits.” A bit represents the distinction between two possibilities: True and False, Yes and No, or, as they are conventionally represented, 1 and 0.
The end point of Moore’s Law (which holds that computers get faster by a factor of two every year and a half or so) is a computer so powerful that it uses individual atoms to store bits of information: one atom, one bit. If we were able to work at subatomic scales and store bits on electrons or quarks, we might go further. But let’s stick with what we know we can do.
If current rates of miniaturization persist, your PC will store one bit on one atom sometime around 2050. But it’s natural to ask whether we can, in fact, achieve a bit-to-atom correspondence. Remarkably, prototype computers that store bits on individual atoms already exist in the laboratory. These computers are called quantum computers, because they store and process information at scales where the laws of quantum mechanics hold sway.