Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 28: Poster – Quantum Optics

Q 28.32: Poster

Tuesday, March 3, 2026, 17:00–19:00, Philo 2. OG

Interaction-induced topological phase transition via spatially selective nonlinearity in photonic honeycomb lattices — •Bashar Karaja, Michael Fleischhauer, and Christina Jörg — RPTU Kaiserslautern, Kaiserslautern, Germany

We study interaction-induced topological phase transitions (IDTPs) in a photonic Haldane[1] lattice with spatially modulated Kerr nonlinearity. By applying nonlinear terms of opposite signs on A and B sublattices, we create an intensity-dependent effective mass term that can lead to local topology changes dynamically with the strength of the optical field. IDTPs appear only when the optical field exceeds specific thresholds: an inverse participation ratio (IPR) >= 0.004, indicating sufficient spatial localization of the field, and a population measure p5, defined as the summed intensity on the five brightest sites. Stronger nonlinearity opens a larger induced band gap, increasing the lifetime, the spatial confinement, and the edge-state propagation length of the topological phase. Because the nonlinearity togehther with spatially non-uniform laser intensity breaks lattice periodicity, we characterize local topology using the spectral localizer, which remains valid in strongly inhomogeneous systems. To enhance experimental viability, we propose a pump-probe scheme in which a strong pump beam generates the nonlinear potential and a weak probe excites edge states. Higher pump power yields smoother, more stable effective potentials and longer-lived induced topological phases.

[1]Haldane, F.D. (1988). Model for a quantum Hall effect without Landau levels. Phys. Rev. Lett., 61(18), 2015-2018.

Keywords: Toplogy; Photonics; Condenced matter physics; Nonlinear optics; Mean Field Kerr nonlinearity