Waveguide-based swappable hyperentangled photon states in a multi-period, postselection-free device

Abstract

We explore the generation of four postselection-free, photonic hyperentangled states with the help of a multi-period waveguide device based on potassium titanyl phosphate. The output photons are emitted in the much-in-demand telecommunication wavelengths of 1550-nm and 1310-nm. The device geometry and design enables hyperentanglement in the spatial mode and polarization bases, through multi-period quasi-phase-matching involved in different spontaneous parametric downconversion processes. The spatially entangled part of these hyperentangled states are rendered swappable with the help of two embedded electro-optic phase modulators. A two-path design provides the flexibility of such a device in the choice of polarization-entangled states which is important in relevant experiments. Through the biphoton joint spectral amplitude, we decipher the parameters that make frequency correlation and further entanglement of the photon pairs feasible. Such maximally-hyperentangled biphoton states are useful in quantum information applications.