Nonlocal cancellation of dispersion in Franson interferometry

Abstract

Dispersion and its cancellation in entanglement-based nonlocal quantum measurements are of fundamental and practical interests. We report a demonstration of cancellation of femtosecond-level dispersion by inverting the sign of the differential dispersion between the long and short paths in only one arm of a fiber-based Franson interferometer. We restore the otherwise limited quantum visibility to an unprecedented 99.6%, and put time-energy entanglement at the same level of quality as polarization entanglement for use in quantum information processing applications.