Thirteen, 53 and 433. That’s the size of quantum computers in terms of quantum bits, or qubits, which has significantly grown in the last years due to important public and private investments and initiatives. Obviously, it is not only a mere question of quantity: the quality of the prepared qubits is as important as their number for a quantum computer to beat our existing classical computers, that is, to attain what’s called the “quantum advantage”. Yet it is conceivable that soon quantum-computing devices delivering such an advantage will be available. How would this affect our daily lives?
Making predictions is never easy, but it is agreed that cryptography will be altered by the advent of quantum computers. It is an almost trivial statement that privacy is a key issue in our information society: every day, immense amounts of confidential data are exchanged through the Internet. The security of these transactions is crucial and mostly depends on a single concept: complexity or, more precisely, computational complexity. Confidential information remains secret because any eavesdropper wanting to read it needs to solve an extremely complex mathematical problem.
