  TheThe successful employment of high-dimensional quantum correlations and its
integration in telecommunication infrastructures is vital in cutting-edge
quantum technologies for increasing robustness and key generation rate.
Position-momentum Einstein-Podolsky-Rosen (EPR) entanglement of photon pairs
are a promising resource of such high-dimensional quantum correlations. Here,
we experimentally certify EPR correlations of photon pairs generated by
spontaneous parametric down-conversion (SPDC) in a nonlinear crystal with
type-0 phase-matching at telecommunication wavelength for the first time. To
experimentally observe EPR entanglement, we perform scanning measurements in
the near- and far-field planes of the signal and idler modes. We certify EPR
correlations with high statistical significance of up to 45 standard
deviations. Furthermore, we determine the entanglement of formation of our
source to be greater than one, indicating a dimensionality of greater than 2.
Operating at telecommunication wavelengths around 1550 nm, our source is
compatible with today's deployed telecommunication infrastructure, thus paving
the way for integrating sources of high-dimensional entanglement into
quantum-communication infrastructures.
