Control of visibility in the interference of signal photons by delays imposed on the idler photons

Abstract

Further interference experiments have been carried out with the two signal beams emitted from two coherently pumped parametric down-converters when the two idler beams are aligned. Because of the quantum entanglement between signal and idler photons produced in the down-conversion, it is found that the visibility of the interference of signal photons can be controlled by insertion of differential time delays between the idler photons.