High-dimensional time-frequency encodings have the potential to significantly advance quantum information science; however, practical applications require precise knowledge of the encoded quantum states, which becomes increasingly challenging for larger Hilbert spaces. Self-guided tomography (SGT) has emerged as a practical and scalable technique for this purpose in the spatial domain. Here, we apply SGT to estimate time-frequency states using a multi-output quantum pulse gate. We achieve fidelities of more than 99\% for 3- and 5-dimensional states without the need for calibration or post-processing. We demonstrate the robustness of SGT against statistical and environmental noise, highlighting its efficacy in the photon-starved regime typical of quantum information applications.
@article{arxiv.2411.19277,
title = {Self-guided tomography of time-frequency qudits},
author = {Laura Serino and Markus Rambach and Benjamin Brecht and Jacquiline Romero and Christine Silberhorn},
journal= {arXiv preprint arXiv:2411.19277},
year = {2025}
}