In high dimensional quantum communication networks, quantum frequency convertor (QFC) is indispensable as an interface in the frequency domain. For example, many QFCs have been built to link atomic memories and fiber channels. However, almost all of QFCs work in a two-dimensional space. It is still a pivotal challenge to construct a high-quality QFC for some complex quantum states, e.g., a high dimensional single-photon state that refers to a qudit. Here, we firstly propose a high-dimensional QFC for an orbital angular momentum qudit via sum frequency conversion with a flat top beam pump. As a proof-of-principle demonstration, we realize quantum frequency conversions for a qudit from infrared to visible range. Based on the qudit quantum state tomography, the fidelities of converted state are 98.29(95.02)\%, 97.42(91.74)\%, and 86.75(67.04)\% for a qudit without (with) dark counts in 2,3, and 5 dimensions, respectively. The demonstration is very promising for constructing a high capacity quantum communication network.
@article{arxiv.1908.10569,
title = {A high-dimensional quantum frequency converter},
author = {Shilong Liu and Chen yang and Zhaohuai Xu and Shikai Liu and Yan Li and Yinhai Li and Zhiyuan Zhou and Guangcan Guo and Baosen Shi},
journal= {arXiv preprint arXiv:1908.10569},
year = {2020}
}
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We add the theoretical calculations with a new figure, some new references, and the appendix. Welcome comments