Quantum computers are very powerful computers that arrange micro physical systems called quantum bits to increase the complexity of algorithms. On the one hand, it can break trillions of encryption schemes, while on the other it can create trillions of schemes. In other works, quantum keys will be able to decrypt any modern encryption algorithms, thus giving an advantage to those countries and organizations developing such machines. Reciprocally, quantum computers will offer the most secured forms of communication.
Source: The Next Digit