Quantum computing will not replace classical computing, but it will excel at tasks that are too complex for current computers, such as searching through huge databases or finding prime factors of large numbers. The latter is so hard that it forms the basis of encryption, which protects online activities.
Quantum states can also be used for more-secure communication schemes. One application of quantum computers is to calculate the behaviour of other quantum systems. For example, quantum computing could be used to fully understand the chemistry of molecules, which requires knowledge of the quantum mechanics of their electrons, or to find the optimal configuration of a folded protein, for which there are vast numbers of arrangements.
Classical computers can calculate the behaviour of quantum systems of about 50 qubits. When quantum computers with more than 50 usable qubits become available, they are set to establish ‘quantum supremacy’.
A new type of computing is needed, one that can take advantage of the very complexity that computers are trying to penetrate. Enter quantum computers, which were first mooted in the 1980s, when it was suggested that it might be possible to construct computers based on the laws of quantum physics instead of on classical physics.
Physicists, mathematicians, computer scientists and engineers at universities around the world are wrestling with the issue of how to construct and operate a quantum computer that is sufficiently large to beat classical computers at certain tasks. Commercial companies are getting involved, too. Just what a quantum computer will eventually look like, which quantum systems it will use, and which problems it will solve remain open questions. And these are fuelling exciting research.
