The future of the Internet begins in Braunschweig. In Jochen Kronjäger's laboratory 4.34 at the Physikalisch-Technische Bundesanstalt (PTB), yellow fiber optic cables converge from all directions. The “supreme authority in Germany for all questions of correct and reliable measurement” regularly sends time signals from its atomic clocks to German and European institutes via these lines. But a 78-kilometer-long light guide serves a very special purpose. With him, Kronjäger and his team are researching how communication on the Internet can be better protected from hackers and spies using quantum physics processes.
