The bi-photon correlation time, a measure for the conditional uncertainty in
the temporal arrival of two photons from a photon pair source, is a key
performance identifier for many quantum spectroscopy applications, with shorter
correlation times typically yielding better performance. Furthermore, it
provides fundamental insight into the effects of dispersion on the bi-photon
state. Here, we retrieve ultrashort bi-photon correlation times of around
100fs by measuring simultaneously spectral and temporal
interferograms at the output of an SU(1,1) interferometer based on an
integrated broadband parametric down-conversion source in a
Ti:LiNbO3​ waveguideComment: 8 pages, 5 figure