Experimental quantum teleportation of a two-qubit composite system

Quantum teleportation(1), a way to transfer the state of a quantum system from one location to another, is central to quantum communication(2) and plays an important role in a number of quantum computation protocols(3-5). Previous experimental demonstrations have been implemented with single photonic(6-11) or ionic qubits(12,13). However, teleportation of single qubits is insufficient for a large-scale realization of quantum communication and computation(2-5). Here, we present the experimental realization of quantum teleportation of a two-qubit composite system. In the experiment, we develop and exploit a six-photon interferometer to teleport an arbitrary polarization state of two photons. The observed teleportation fidelities for different initial states are all well beyond the state estimation limit of 0.40 for a two-qubit system(14). Not only does our six-photon interferometer provide an important step towards teleportation of a complex system, it will also enable future experimental investigations on a number of fundamental quantum communication and computation protocols(3,15-18).