  We present, characterize, and apply a photonic quantum interface between the
near infrared and telecom spectral regions. A singly resonant optical
parametric oscillator (OPO) operated below threshold, in combination with
external filters, generates high-rate ($>2.5\cdot10^6~{\rm s}^{-1}$) narrowband
photon pairs ($\sim 7$ MHz bandwidth); the signal photons are tuned to
resonance with an atomic transition in Ca$^+$, while the idler photons are at
telecom wavelength. Quantum interface operation is demonstrated through
high-rate absorption of single photons by a single trapped ion ($\sim 670~{\rm
s}^{-1}$), heralded by coincident telecom photons.
