High-dimensional quantum communication with scalable photonic entanglement in time and frequency

Quantum Physics [Submitted on 18 Mar 2026] High-dimensional quantum communication with scalable photonic entanglement in time and frequency Kai-Chi Chang, Murat Can Sarihan, Nicky Kai Hong Li, Florian Kanitschar, Kemal Enes Akyuz, Yujie Chen, Dong-Il Lee, Jin Ho Kang, Alwaleed Aldhafeeri, Andrew Mueller, Matthew D. Shaw, Boris Korzh, Maria Spiropulu, Paul Erker, Marcus Huber, Chee Wei Wong High-dimensional photonic entanglement holds significant promise for advancing quantum communication, computation, and metrology. For example, large-alphabet quantum communication protocols are known to benefit from enhanced noise resilience and information capacity via multi-bit time-bin encoding. Yet, characterizing high-dimensional entangled states is challenging, as full state tomography becomes prohibitively costly and often requires unrealizable measurements. Here, we demonstrate a scan-free method to characterize high-dimensional entanglement in the time-frequency domain. Our reconstruction achieves a record 5.70\pm0.07 ebits and a fidelity of 65.4\pm0.4\% with the maximally entangled state of local dimension 1021, certifying the presence of 668-dimensional entanglement. We further prove the attainability of a secure key rate of 15.6 kB/s in a composable finite-size, entanglement-based protocol, and show that in continuous operation, the setup can quickly approach asymptotic key rates. Using commercial telecom components and state-of-the-art low-jitter single-photon detectors, our scalable architecture offers a practical path towards high-rate, noise-resilient quantum communication testbeds. Comments: 19+20 pages, 6 figures, 3 tables Subjects: Quantum Physics (quant-ph); Optics (physics.optics) Cite as: arXiv:2603.18212 [quant-ph]   (or arXiv:2603.18212v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.18212 Focus to learn more Submission history From: Nicky Kai Hong Li [view email] [v1] Wed, 18 Mar 2026 19:00:00 UTC (4,310 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 Change to browse by: physics physics.optics References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)