Time-frequency Schmidt (TFS) modes of ultrafast quantum states are naturally compatible with high bit-rate integrated quantum communication networks. Thus they offer an attractive alternative for the realization of high dimensional quantum optics. Here, we present a quantum pulse gate based on dispersion-engineered ultrafast frequency conversion in a nonlinear optical waveguide, which is a key element for harnessing the potential of TFS modes. We experimentally retrieve the modal spectral-temporal structure of our device and demonstrate a single-mode operation fidelity of 80\%, which is limited by experimental shortcomings. In addition, we retrieve a conversion efficiency of 87.7\% with a high signal-to-noise ratio of 8.8 when operating the quantum pulse gate at the single-photon level.
@article{arxiv.1403.4397,
title = {Demonstration of coherent time-frequency Schmidt mode selection using dispersion-engineered frequency conversion},
author = {Benjamin Brecht and Andreas Eckstein and Raimund Ricken and Viktor Quiring and Hubertus Suche and Linda Sansoni and Christine Silberhorn},
journal= {arXiv preprint arXiv:1403.4397},
year = {2014}
}