Abstract

Parametric down-conversion is the most standard source of pairs of polarization-entangled photons, which is relevant to many problems of quantum information. However, the realization of the entanglement between three or more photons is considered so far as a difficult problem. In this report we present a novel scheme for producing three-photon entangled states. The scheme involves cascaded second-order χ⁽²⁾-nonlinearities inside the same twice resonant cavity pumped by a frequency ω and is accessible to an experiment. Two processes form the generation of subharmonic modes at ω/3- and 2ω/3-frequencies: the parametric splitting of pump photons ω→2ω/3+ω/3 and the two-photon down- conversion 2ω/3→ω/3+ω/3 with different nonlinear coupling constants.

© 2000 IEEE