The simplicity of a question, such as wondering whether or not correlations characterize a certain system, collides with the experimental difficulty of accessing such information. Here we present a low-demanding experimental approach that refers to the use of a metrology scheme to obtain a conservative estimate of the strength of frequency correlations. Our test bed is the widespread case of a photon pair produced per downconversion. The theoretical architecture used to put the correlation degree on a quantitative ground is also described.
Sbroscia, M., Gianani, I., Roccia, E., Cimini, V., Mancino, L., Aloe, P., et al. (2018). Assessing frequency correlation through a distinguishability measurement. OPTICS LETTERS, 43(16), 4045-4048 [10.1364/OL.43.004045].