Generation of maximally-polarization-entangled photons on a chip

Abstract

We propose a method of generating maximally-polarization-entangled states by type-II spontaneous parametric down-conversion in Bragg reflection waveguides. Analytic expressions for the group velocities of down-converted modes are used to engineer zero group-velocity mismatch at the operating point, making the spectra of photons within a down-converted pair indistinguishable and thus leading to a maximally-polarization-entangled state. The results can be used for the creation and manipulation of polarization-entangled qubits entirely on a chip.