A stylish new way of surfing the Internet is coming to Vienna this fall. Researchers plan to flip the switch on the next step toward a quantum version of the Internet. They will build a network allowing users to send each other messages as virtually unbreakable ciphers, with privacy protected by the laws of quantum physics.
The Vienna net is admittedly just a prototype for research purposes. It is also not yet a true quantum version of the Internet. Although it can transmit ordinary data with quantum security, it can’t transfer quantum information, which encodes the states of objects that obey quantum rules. Such a breakthrough might be years off, but it’s getting closer.
Truth be told, it’s not completely clear what a fully quantum Internet would be good for. In fact, at first it even sounds like a really bad idea. Quantum information is notoriously wobbly. An object tends to live in a superposition of states — for example, an electron can spin in two directions at once, or an atom can be simultaneously in two different places — until interaction with the rest of the world forces the object to pick one state. Quantum reality is a limbo of coexisting possibilities.
And because any measurement done of a quantum system changes the system’s state irreversibly, quantum information is different every time it’s read. That makes it impossible, for example, to copy, broadcast or back up quantum data.