Remote preparation of single-plasmon states

Quantum entanglement is a stunning consequence of the superposition principle. This universal property of quantum systems has been intensively explored with photons, atoms, ions, and electrons. Collective excitations such as surface plasmons exhibit quantum behaviors. We report the remote preparation of a single plasmon state through the projective measurement of a photon entangled with the plasmon. We achieved photon-plasmon entanglement by converting one photon of an entangled photon pair into a surface plasmon. The plasmon is tested on a plasmonic platform in a Mach-Zehnder interferometer. A projective measurement on the polarization of the photon allows the remote preparation of the interference state of the plasmon. Entanglement between particles of various nature paves the way to the design of hybrid systems in quantum information networks.