  Telecom photonic quantum networks with matter quantum systems enable a rich
variety of applications, such as a long distance quantum cryptography and
one-way quantum computing. Preparation of a heralded single excitation (HSE) in
an atomic ensemble by detecting a telecom wavelength photon having a
correlation with the atomic excitation is an important step. Such a system has
been demonstrated with a quantum frequency conversion (QFC) to telecom
wavelength employing a Rb atomic cloud. However the limited wavelength
selection prevents the next step. Here we for the first time demonstrate HSE
with a solid-state-based QFC and a detector for a telecom wavelength that will
have a great advantage of the utility of mature telecom technologies. We
unambiguously show that the demonstrated HSE indicates a non-classical
statistics by the direct measurement of the autocorrelation function.

Quantum Physics