  We present a source of polarization entangled photon pairs based on
spontaneous parametric downconversion engineered for frequency uncorrelated
telecom photon generation. Our source provides photon pairs that display,
simultaneously, the key properties for high-performance quantum information and
fundamental quantum science tasks. Specifically, the source provides for high
heralding efficiency, high quantum state purity and high entangled state
fidelity at the same time. Among different tests we apply to our source we
observe almost perfect non-classical interference between photons from
independent sources with a visibility of $(100\pm5)\%$.
