High-Dimensional Quantum Photonics: Roadmap

Quantum Physics [Submitted on 7 Apr 2026] High-Dimensional Quantum Photonics: Roadmap Mehul Malik, Micheal Kues, Takuya Ikuta, Hiroki Takesue, Daniele Bajoni, David J. Moss, Roberto Morandotti, Andrew Forbes, Stephen Walborn, Ebrahim Karimi, Yunhong Ding, Stefano Paesani, Caterina Vigliar, Benjamin Brecht, Christine Silberhorn, Frédéric Bouchard, Michał Karpiński, Benjamin Sussman, Joseph M. Lukens, Yaron Bromberg, Robert Fickler, Taira Giordani, Fabio Sciarrino, Yun Zheng, Jianwei Wang, Marcus Huber, Armin Tavakoli, Roope Uola, Nicolas Brunner, Nicolai Friis, Natalia Herrera Valencia, Jacquiline Romero, Will McCutcheon The field of high-dimensional quantum photonics involves the use of multimode photonic degrees-of-freedom such as the spatial, temporal, or spectral structure of light to encode multi-level quantum states. Recent years have seen rapid progress in the development of methods to generate, manipulate, and distribute such quantum states of light and their use in a range of quantum technology applications that offer practical advantages over conventional qubit-based approaches. High-dimensional quantum states of light encoded in photonic time-bins, frequency-bins, transverse-spatial modes, waveguide paths, and temporal modes have enabled noise-robust fundamental tests of quantum mechanics, error-resilient and high-capacity quantum communication protocols, andas well as efficient approaches for quantum information processing, to name just a few examples. However, research in this field has progressed fairly independently, with little exchange across different photonic degrees-of-freedom or between experiment and theory and no comprehensive comparison between degrees-of-freedom. This roadmap aims to bridge this gap by surveying progress in each area and identifying shared challenges and opportunities that cut across two or more photonic degrees-of-freedoms. We review early work and state-of-the-art experimental techniques under development for high-dimensional quantum states encoded in single and entangled photons, as well as theoretical tools for their measurement and certification. We outline the main outstanding challenges for theory and each experimental degree-of-freedom, identifying promising future directions of research that may enable these to be overcome. We end by discussing interconnections and shared challenges centered around their distribution, measurement, and manipulation, with a view towards their integration into next-generation quantum technology platforms and applications. Comments: 89+28 pages, 36 figures Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.06528 [quant-ph]   (or arXiv:2604.06528v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.06528 Focus to learn more Submission history From: Will McCutcheon Dr [view email] [v1] Tue, 7 Apr 2026 23:57:08 UTC (29,374 KB) Access Paper: view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 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?)