Exploring photon-number-encoded high-dimensional entanglement from a sequentially excited quantum three-level system. D. A. Vajner, N. D. Kewitz, M. v. Helversen, S. C. Wein, Y. Karli, F. Kappe, V. Remesh, S. F. C. d. Silva, A. Rastelli, G. Weihs, C. Anton-Solanas and T. Heindel in Optica Q. 3:99 (2025).