Experimental demonstration of four-party quantum secret sharing.

Secret sharing is a multiparty cryptographic task in which some secret information is split into several pieces which are distributed among the participants such that only an authorized set of participants can reconstruct the original secret. Similar to quantum key distribution, in quantum secret sharing, the secrecy of the shared information relies not on computational assumptions, but on laws of quantum physics. Here, we present an experimental demonstration of four-party quantum secret sharing via the resource of four-photon entanglement.

Compact source of polarization-entangled photon pairs.

We present a compact source of polarization-entangled photon pairs at a wavelength of 805 nm using a violet single-mode laser diode as the pump source of type-II spontaneous parametric down-conversion. The source exhibits entanglement and pair-rate comparable to conventional systems utilizing large frame ion lasers thus significantly increases the practicality of novel quantum information or quantum metrology applications.

Experiments on long wavelength (1550 nm) "plug and play" quantum cryptography systems.

An interferometric quantum cryptographic system at 1550nm wavelength using gated InGaAs Avalanche Photo Diodes as single-photon receivers is demonstrated for a transmission distance up to 40 km.