We present an experiment demonstrating entanglement-enhanced classicalcommunication capacity of a quantum channel with correlated noise. The channelis modelled by a fiber optic link exhibiting random birefringence thatfluctuates on a time scale much longer than the temporal separation betweenconsecutive uses of the channel. In this setting, introducing entanglementbetween two photons travelling down the fiber allows one to encode reliably upto one bit of information into their joint polarization degree of freedom. Whenno quantum correlations between two separate uses of the channel are allowed,this capacity is reduced by a factor of more than three. We demonstrated thiseffect using a fiber-coupled source of entagled photon pairs based onspontaneous parametric down-conversion, and a linear-optics Bell statemeasurement.
展开▼
