Teleconferencing in the quantum world
Transferring information from one quantum system to another is now part of everyday life in many physical laboratories. Usually, this so-called teleportation occurs between two atoms that are extremely tightly coupled-a connection scientists call entanglement. There is only one transmitter and one receiver. A British-Japanese team has now succeeded in sending the signals to several recipients at the same time. Under the name of quantum teleclones, another building block is thus available for the targeted computers of the future.
Sam Braunstein from the University of York and Akira Furusawa from the University of Tokyo and their collaborators have succeeded in this step. Instead of atoms, a laser beam was the information-carrying unit in their experiments. They copied its amplitude and phase with an accuracy of 58 percent and transferred them to two receiver beams. The value may appear low at first glance, but more than 66 percent is theoretically not possible due to quantum mechanical limitations imposed by Heisenberg's uncertainty principle.
For quantum computers, which in the indefinite future will be able to perform countless uniform calculations at once, it is essential to be able to split information and pass it on to different places. Braunstein, Furasawa and their teams have basically solved this problem. Even if it will probably be a few centuries before Braunstein's joke is within reach and we can beam ourselves "to the office and to the beach at the same time" in the morning.
