1Quantum computing is frequently described as a coming technological revolution, yet surprisingly few people can explain precisely why.
2Unlike ordinary computer bits, which must be either zero or one, quantum bits can exist in both of those states simultaneously.
3This peculiar property, known as superposition, allows a quantum machine to explore many possible answers to a problem at once.
4For certain kinds of problems, such as simulating the behaviour of new medicines, the potential speed-up could be truly extraordinary.
5A task that might occupy today's fastest supercomputer for several centuries could conceivably take a mature quantum device mere hours.
6The implications of all this for global cyber security, however, are considerably more unsettling than most newspaper headlines suggest.
7Many of the encryption methods that currently protect our banks and our governments could eventually be broken by sufficiently powerful quantum machines.
8Researchers all around the world are therefore racing to develop post-quantum cryptography before that dangerous day finally arrives.
9Building a reliable quantum computer remains immensely difficult, since the fragile quantum states collapse at the slightest disturbance.
10The machines must be cooled to temperatures far colder than deep space just to keep their delicate quantum states stable.
11Commercial machines that genuinely outperform classical computers on practical everyday tasks may still be a decade or more away.
12Nevertheless, the nations and companies investing billions of dollars today are betting heavily that the long wait will prove worthwhile.