Quantum teleportation between light and matter

Teleportation: mix and match Quantum teleportation — the disembodied transfer of a quantum state — has been previously demonstrated between objects of the same type, between light pulses or trapped ions (material particles) for instance. Now Sherson et al . demonstrate teleportation between objects of a different nature — a quantum state encoded in a light pulse was teleported onto an atomic ensemble containing 10 12 caesium atoms. Besides being of fundamental interest to physicists, this experiment is relevant as a small step towards the practical implementation of quantum networks. Quantum teleportation has been previously demonstrated between objects of the same nature, such as light pulses or material particles. But this paper demonstrates teleportation between objects of a different nature: a quantum state encoded in a light pulse is teleported onto an atomic ensemble containing 10 12 caesium atoms. Quantum teleportation 1 is an important ingredient in distributed quantum networks 2 , and can also serve as an elementary operation in quantum computers 3 . Teleportation was first demonstrated as a transfer of a quantum state of light onto another light beam 4 , 5 , 6 ; later developments used optical relays 7 and demonstrated entanglement swapping for continuous variables 8 . The teleportation of a quantum state between two single material particles (trapped ions) has now also been achieved 9 , 10 . Here we demonstrate teleportation between objects of a different nature—light and matter, which respectively represent ‘flying’ and ‘stationary’ media. A quantum state encoded in a light pulse is teleported onto a macroscopic object (an atomic ensemble containing 10 12 caesium atoms). Deterministic teleportation is achieved for sets of coherent states with mean photon number ( n ) up to a few hundred. The fidelities are 0.58 ± 0.02 for n = 20 and 0.60 ± 0.02 for n = 5—higher than any classical state transfer can possibly achieve 11 . Besides being of fundamental interest, teleportation using a macroscopic atomic ensemble is relevant for the practical implementation of a quantum repeater 2 . An important factor for the implementation of quantum networks is the teleportation distance between transmitter and receiver; this is 0.5 metres in the present experiment. As our experiment uses propagating light to achieve the entanglement of light and atoms required for teleportation, the present approach should be scalable to longer distances.