Scientists from the Institute of Photonic Sciences (ICFO) have performed quantum teleportation of information over long distances for the first time. The team successfully transmitted quantum information from the photon to the photon of the solid-state qubit over a distance of 1 km. The solid state qubit was stored in a multiplexed quantum memory and an active transmission scheme was also used, which maximized the teleportation rate.

The architecture used in the research is compatible with telecommunications channels, allowing for future integration and scaling of quantum communication over long distances.

The researchers used two experimental setups, Alice and Bob, connected by a 1km-long optical fiber wound on a coil to simulate the physical distance between the parties. In the first installation, Alice, the team used a special crystal to create two entangled photons: a first photon with a wavelength of 606 nm and a second photon, called a single photon, compatible with telecommunications infrastructure. Once created, the first photon was stored in a multiplexed solid-state quantum memory, and the telecommunications photon created by Alice traveled along a 1 km optical fiber to a second experimental setup named Bob.

In this second setup, the team created a third photon and encoded the quantum bit they wanted to beam. The second and third photons interfered with each other in the so-called Bell state measurement, transmitting the information encoded in the third photon to the first photon, which was stored in Alice’s quantum memory at a distance of 1 km. The team was able to transmit information between two photons that had never been in contact before, and indeed connected via a third photon that had been mixed with the first photon.