Generation of Tunable Three-Photon Entanglement in Cubic Nonlinear Coupled Waveguides

TL;DR

This paper presents a theoretical method to generate tunable three-photon spatial entanglement in cubic nonlinear coupled waveguides, enabling reconfigurable quantum states on a chip for advanced quantum applications.

Contribution

It introduces a novel approach to produce and control three-photon entangled states using third-order nonlinear processes in integrated waveguides.

Findings

Generation of path-encoded three-photon GHZ states.

Ability to produce heralded Bell, uniform, and GHZ-like states.

Demonstration of reconfigurable entanglement on a chip.

Abstract

We theoretically investigate the generation of three-photon states with spatial entanglement in cubic nonlinear coupled waveguides using third-order spontaneous parametric down-conversion and quantum walks. Our approach involves independently pumping two coupled waveguides to generate a path-encoded three-photon Greenberger Horne Zeilinger (GHZ) state, which then evolves with complex spatial dynamics governed by coupling coefficients and phase mismatch. By appropriate parameter tuning, we demonstrate the generation of robust heralded Bell states, uniform states, and GHZ-like states at the chip output. This work demonstrates an integrated source of three-photon spatial entanglement on a simple chip, offering additional reconfigurability for advanced multiphoton quantum applications.