Quantum computers promise to solve certain problems very efficiently where traditional (super)computers fail. This applies in particular to problems that previously required tedious and lengthy guessing of the results. This feature is both an opportunity and a challenge: on the one hand, search algorithms could become significantly more efficient. On the other hand, the current IT security mechanisms are based on the fact that it is currently extremely difficult and costly to solve certain mathematical problems. In this respect, new ways of securing data and communication must be found in the future. How long the development of functional quantum computers will take cannot be predicted with certainty at present – but significant progress can be expected in ten to twenty years.