Supervisor: Thomas Pohl

With the increasing use of digital communications, cryptography is becoming more important. In the time of letters, an attacker would need to open a letter, which is time-consuming and would require physical access. Today, a few lines of code would be enough to copy thousands of unencrypted messages. Most cryptography protocols today rely on some calculations, like factoring, that are hard for computers to do. But the hardness of these calculations has not been proven, and there might be more efficient algorithms to solve them.
Quantum cryptography does not rely on these calculations but on the laws of nature to be secure. Specifically, protocols like BB84 use Heisenberg's uncertainty principle and the observer effect to make it impossible to listen in on the exchange of a key without alerting the communicating parties. Today, quantum cryptography is one of the first areas of quantum information in which there are already commercially available products on the market