Photonic quantum technology increasingly uses frequency encoding to enable higher quantum information density and noise resilience. Pulsed time-frequency modes (TFM) represent a unique class of spectrally encoded quantum states of light that enable a complete framework for quantum information processing. Here, we demonstrate a technique for direct generation of entangled TFM-encoded states in single-pass, tailored downconversion processes. We achieve unprecedented quality in state generation---high rates, heralding efficiency and state fidelity---as characterised via highly resolved time-of-flight fibre spectroscopy and two-photon interference. We employ this technique in a four-photon entanglement swapping scheme as a primitive for TFM-encoded quantum protocols.
@article{arxiv.1910.00598,
title = {Direct generation of tailored pulse-mode entanglement},
author = {Francesco Graffitti and Peter Barrow and Alexander Pickston and Agata M. Brańczyk and Alessandro Fedrizzi},
journal= {arXiv preprint arXiv:1910.00598},
year = {2020}
}