近日，南京大学王慧田团队研究了预言的高维光子-光子量子门。相关论文于2026年2月10日发表在《自然—光子学》杂志上。

量子信息的高维编码通过扩大固定寄存器尺寸下的可访问态空间，并减少所需纠缠门数量，有望大幅提升现有器件的计算能力。然而，基于qudit的量子计算发展仍远滞后于传统qubit方案，特别是在光子领域——作为天然的多能级信息载体，光子在量子网络构建中扮演关键角色。实现两个独立光子间量子门的主要障碍在于线性介质中光子直接相互作用的限制。对于光学量子信息处理而言，诸如原生qudit-qudit纠缠门等量子运算的核心逻辑组件至今仍付之阙如。

研究组通过提出任意维度下双光子qudit纠缠门——受控相位翻转门的实现协议，成功应对了这一挑战。通过实验演示了四维qudit-qudit受控相位翻转门，该门的分解至少需要13个双量子比特纠缠门。该光子qudits编码于轨道角动量，并研发了新型主动式高精度锁相技术，构建了高维轨道角动量分束器，显著提升了受控相位翻转门的稳定性，最终实现[0.71±0.01, 0.85±0.01]范围的过程保真度。该实验标志着高维光学量子信息处理的重要突破，并具备向光学系统之外更广泛领域拓展的潜力。

附：英文原文

Title: Heralded high-dimensional photon–photon quantum gate

Author: Liu, Zhi-Feng, Ren, Zhi-Cheng, Wan, Pei, Zhu, Wen-Zheng, Cheng, Zi-Mo, Wang, Jing, Shi, Yu-Peng, Xi, Han-Bing, Huber, Marcus, Friis, Nicolai, Gao, Xiaoqin, Wang, Xi-Lin, Wang, Hui-Tian

Issue&Volume: 2026-02-10

Abstract: High-dimensional encoding of quantum information holds the potential to greatly increase the computational power of existing devices by enlarging the accessible state space for a fixed register size and by reducing the number of required entangling gates. However, qudit-based quantum computation remains far less developed than conventional qubit-based approaches, particularly for photons, which represent natural multilevel information carriers that play a crucial role in the development of quantum networks. A major obstacle for realizing quantum gates between two individual photons is the restriction of direct interaction between photons in linear media. In particular, essential logic components for quantum operations such as native qudit–qudit entangling gates are still missing for optical quantum information processing. Here we address this challenge by presenting a protocol for realizing an entangling gate—the controlled phase-flip gate—for two photonic qudits in an arbitrary dimension. We experimentally demonstrate this protocol by realizing a four-dimensional qudit–qudit controlled phase-flip gate, whose decomposition would require at least 13 two-qubit entangling gates. Our photonic qudits are encoded in orbital angular momentum, and we have developed a new active high-precision phase-locking technology to construct a high-dimensional orbital angular momentum beamsplitter that increases the stability of the controlled phase-flip gate, resulting in a process fidelity within a range of [0.71 ± 0.01, 0.85 ± 0.01]. Our experiment represents an important advance for high-dimensional optical quantum information processing and has the potential for wider applications beyond optical system.

DOI: 10.1038/s41566-026-01846-x

Source: https://www.nature.com/articles/s41566-026-01846-x