Scientists send quantum information to more than one recipient

Scientists say they have succeeded for the first time in sending quantum information to different recipients at the same time. This should help, among other things, to set up more secure techniques for quantum encryption.

The experiment was performed with entangled photons. Entanglement is a phenomenon of quantum mechanical particles that are ‘coupled’ with each other and thus assume each other’s properties. This means, among other things, that when the properties of one particle change, for example by measuring it, the properties of the second particle also change. Sending information based on this principle is also called quantum teleportation and has already been demonstrated with photon pairs.

Scientists at the University of Waterloo, Canada, say they have succeeded in teleporting quantum states to more than one location for the first time. They used not two, but three photons to carry out their experiments. After entanglement, the particles were sent separately over hundreds of meters to separate locations.

The calculations showed that it is possible to transmit the quantum states of the three entangled photons without locality. That is, the data transfer is direct and not ‘limited’ by the speed of light; so there are no hidden variables that can explain the interaction between the coupled photons to ensure data transfer. This principle of non-locality is something that is impossible in classical physics, but is necessary for explaining quantum mechanical observations. Incidentally, a non-local transfer of quantum mechanical states does not mean that communication faster than light is possible.

Teleporting quantum states across more than one location can be used to make quantum communication and encryption more efficient for quantum computers. According to the scientists, their technology can be used for quantum key distribution, a quantum mechanical form of encryption. Also, the use of different receivers makes communication in network form possible. Before this can be applied, a system must be set up that can function as a quantum communication network.