Optimal cloning of single-photon polarization by coherent feedback of beam splitter losses

Abstract

Light fields can be amplified by measuring the field amplitude reflected at a beam splitter of reflectivity R and adding a coherent amplitude proportional to the measurement result to the transmitted field. By applying the quantum optical realization of this amplification scheme to single-photon inputs, it is possible to clone the polarization states of photons. We show that optimal cloning of single-photon polarization is possible when the gain factor of the amplification is equal to 1/√1-R. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.