Classical optical analogue of quantum discord Jacob M. Leamer, Wenlei Zhang, Nicholas J. Savino, Ravi K. Saripalli, Sanjaya Lohani, Ryan T. Glasser and Denys I. Bondar Eur. Phys. J. Spec. Top., 232 20-22 (2023) 3345-3351 Published online: 18 September 2023 DOI: 10.1140/epjs/s11734-023-00988-1