Biphoton engineering using modal spatial overlap on-chip

TL;DR

This paper introduces a novel approach to biphoton wavefunction engineering on-chip by exploiting modal field overlap via coupled waveguides, enabling advanced quantum state control for integrated photonics.

Contribution

It demonstrates the use of modal coupling as a new degree of freedom for biphoton engineering, expanding the design possibilities for on-chip quantum light sources.

Findings

Design examples for polarization entangled photon generation.

Design examples for heralded single photon sources.

Modal overlap as a controllable parameter for biphoton properties.

Abstract

Photon pairs generated by spontaneous parametric down-conversion are essential for optical quantum information processing, in which the quality of biphoton states is crucial for the performance. To engineer the biphoton wavefunction (BWF) on-chip, the pump envelope function and the phase matching function are commonly adjusted, while the modal field overlap has been considered as a constant in the frequency range of interest. In this work, by utilizing modal coupling in a system of coupled waveguides, we explore the modal field overlap as a new degree of freedom for biphoton engineering. We provide design examples for on-chip generations of polarization entangled photons and heralded single photons, respectively. This strategy can be applied to waveguides of different materials and structures, offering new possibilities for photonic quantum state engineering.