We propose fast all-optical control of surface polaritons by placing an electromagnetically induced transparency (EIT) medium at an interface between two materials. EIT provides longitudinal compression and a slow group velocity, while matching properties of the two materials at the interface provides strong transverse confinement. In particular, we show that an EIT medium near the interface between a dielectric and a negative-index metamaterial can establish tight longitudinal and transverse confinement plus extreme slowing of surface polaritons, in both transverse electric and transverse magnetic polarizations, while simultaneously avoiding losses.

We propose large low-loss cross-phase modulation between two coupled surface polaritons propagating through a double electromagnetically-induced transparency medium situated close to a negative-index metamaterial. In particular a mutual $\pi$ phase shift is attainable between the two pulses at the single photon level.Comment: 6 pages, 6 figure

Genuine multipartite entanglement of a quantum system can be partially destroyed by local decoherence. Is it possible to retrieve the entanglement to some extent by a single local operation? The answer to this question depends very much on the type of initial genuine entanglement. For initially pure W and cluster states and if the decoherence is given by generalized amplitude damping, the answer is shown to be positive. In this case, the entanglement retrieving is achieved just by redistributing the remained entanglement of the system.Comment: 4 pages, 5 figure