We report on the implementation of quantum frequency conversion (QFC) between infrared (IR) and ultraviolet (UV) wavelengths by using single-stage upconversion in a periodically poled KTP waveguide. Due to the monolithic waveguide design, we manage to transfer a telecommunication band input photon to the wavelength of the ionic dipole transition of Yb+ at 369.5 nm. The external (internal) conversion efficiency is around 5\% (10\%). The high energy pump used in this converter introduces a spontaneous parametric downconversion (SPDC) process, which is a cause for noise in the UV mode. Using this SPDC process, we show that the converter preserves non-classical correlations in the upconversion process, rendering this miniaturized interface a source for quantum states of light in the UV.
@article{arxiv.1610.03239,
title = {Quantum frequency conversion between infrared and ultraviolet},
author = {Helge Rütz and Kai-Hong Luo and Hubertus Suche Christine Silberhorn},
journal= {arXiv preprint arXiv:1610.03239},
year = {2017}
}