Experimental demonstration of five-photon entanglement and open-destination teleportation

Quantum-mechanical entanglement of three(1,2) or four(3,4) particles has been achieved experimentally, and has been used to demonstrate the extreme contradiction between quantum mechanics and local realism(5,6). However, the realization of five-particle entanglement remains an experimental challenge. The ability to manipulate the entanglement of five or more particles is required(7,8) for universal quantum error correction. Another key process in distributed quantum information processing(9,10), similar to encoding and decoding, is a teleportation protocol(11,12) that we term 'open-destination' teleportation. An unknown quantum state of a single particle is teleported onto a superposition of N particles; at a later stage, this teleported state can be read out ( for further applications) at any of the N particles, by a projection measurement on the remaining particles. Here we report a proof-of-principle demonstration of five-photon entanglement and open-destination teleportation (for N = 3). In the experiment, we use two entangled photon pairs to generate a four-photon entangled state, which is then combined with a single-photon state. Our experimental methods can be used for investigations of measurement-based quantum computation(9,10) and multi-party quantum communication(13,14).