Quantum Key DistributionIn October 2019 Google claimed to have achieved quantum supremacy. This means that quantum computers are now capable of solving tasks that are impossible for classical computers to solve in a feasible time. Since before this goal was achieved, the growth of QC originated another problem: most classical cryptographic systems rely on heavy computational tasks, which are considered impossible to be solved in a reasonable time by classical computers, but can now be solved by quantum computers. Those systems include key exchange protocols and encryption protocols that are fundamental for modern communications. Researchers then started to study a new cryptography branch called Post Quantum Cryptography (PQC), which includes the sets of algorithms and protocols that can be considered secure even when facing quantum computers.