Preparing non-local superpositions of quasi-classical light states

Alexei Ourjoumtsev (1) , Franck Ferreyrol (1) , Rosa Tualle-Brouri (1) , Philippe Grangier (1)

1 Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique

Schrödinger cat states of the light [1], de- ned as quantum superpositions of quasi-classical (coherent) states, have recently emerged as an interesting alternative to single-photon qubits for quantum information processing (QIP) [26]. Their richer structure provides signicant advantages for quantum teleportation, universal quantum computation, high-precision measurements or fundamental physics tests [713]. Local superpositions of free-propagating coherent states have been realized experimentally, but their applications were so far limited by their extreme sensitivity to losses, and by the lack of quantum gates for coherent qubit rotations. We demonstrate a simple approach to generate strongly entangled non-local superpositions of coherent states, using a very lossy quantum channel. Such superpositions can be used to implement a coherent qubit rotation gate, and to teleport those qubits over long distances. The generation scheme can be extended to create entangled coherent superpositions with arbitrarily large amplitudes.

Domains: Optics [physics.optics]

Alexei Ourjoumtsev, Franck Ferreyrol, Rosa Tualle-Brouri, Philippe Grangier. Preparing non-local superpositions of quasi-classical light states. Nature Physics, 2009, 5, pp.189-192. ⟨10.1038/nphys1199⟩. ⟨hal-00551638⟩