Séminaire de l'INPHYNI: Florent Baboux

Waveguide arrays are engineered photonic media in which light propagates through evanescent coupling between neighboring guides (see figure). Their evolution is governed by a tight-binding Hamiltonian, making them powerful platforms for simulating condensed-matter phenomena and studying wave interference, localization, and topological transport in a highly controllable setting.

I will present our recent work on semiconductor nonlinear waveguide arrays, where photon pairs are generated directly inside the lattice through parametric down-conversion and subsequently evolve via quantum walks. This approach combines, on a single chip, the generation of quantum light with its continuous manipulation in a lattice, a configuration with no direct counterpart in bulk optics or conventional discrete photonic circuits. It enables the generation of high-dimensional entangled states and reveals how indistinguishability, interference, and correlations are shaped by lattice geometry [1,2]. I will then discuss how topology can be used to engineer robust photonic states, focusing on Su-Schrieffer-Heeger waveguide arrays, where edge modes offer a route to protect quantum light sources against disorder and fabrication imperfections [3].

Finally, I will outline future directions toward quantum simulation in these platforms. By exploiting the propagation direction as an effective time, waveguide arrays can simulate time-dependent Hamiltonians and quantum state transfer protocols such as topological pumping. In parallel, electro-optic modulation could be used to couple frequency modes and create synthetic dimensions, opening a route to the simulation of higher-dimensional phenomena, such as quantum Hall physics, within geometrically one-dimensional systems.

[1] A. Raymond, A. Zecchetto, J. Palomo, M. Morassi, A. Lemaître, F. Raineri, M. Amanti, S. Ducci, F. Baboux
Phys. Rev. Lett. 133, 233602 (2024)

[2] A. Raymond, P. Cathala, M. Morassi, A. Lemaître, F. Raineri, S. Ducci, F. Baboux
Optics Express 33, 45869 (2025)

[3] A. Zecchetto, J.-R. Coudevylle, M. Morassi, A. Lemaître, M. Amanti, S. Ducci, F. Baboux
arXiv:2510.23796 (2026)