German scientists at the Max Planck Institute of Quantum Optics (MPQ) have created the first “universal quantum network” that could be feasibly scaled up to become a quantum internet. So far their quantum network only spans two labs spaced 21 meters apart, but the scientists stress that longer distances and multiple nodes are possible.

The network’s construction is ingenious. Each node is represented by a single rubidium atom, trapped inside a reflective optical cavity. These atoms communicate with each other by emitting a single photon over an optical fiber. Each atom is a quantum bit — a qubit — and the polarization of the photon emitted carries the quantum state of the qubit. The receiving qubit absorbs the photon and takes on the quantum state of the transmitter. Voila: A network of qubits that can send, receive, and store quantum information.