近日，美国中佛罗里达大学Ayman F. Abouraddy团队报道了单光子时空波包的局域和远程合成。这一研究成果于2026年4月2日发表在《自然—光子学》杂志上。
自发参量下转换过程中的能量和横向动量守恒，对所产生的纠缠信号光子和闲频光子施加了严格的光子间量子关联——其空间自由度和时间自由度分别表现出这种关联。有限长度的非线性晶体仅施加松散的光子内时空关联，这掩盖了任何角色散诱导效应的观测，并阻碍了量子光学借鉴时空结构光领域的最新进展。
研究组展示：将时空光谱调制器置于预示信号光子的路径中，可产生一个单光子“时空波包”，该波包具有精确构造的时空光谱，从而能够在可调群速度下实现无衍射传播。此外，通过将多模、时空结构的信号光子投影到单个空间模式上以预示闲频光子的到达，研究组远程制备了一个未通过光谱调制器的闲频光子中的无衍射单光子时空波包。
由于信号光子和闲频光子之间固有的光谱反关联，它们具有互补的亚光速/超光速群速度，这种反关联会反转远程制备光子的时空光谱曲率的符号。这些结果为时空结构光在量子通信、成像和传感等背景下影响量子光学的应用铺平了道路。
附：英文原文
Title: Local and remote synthesis of single-photon space-time wave packets
Author: Turo, Bryan L., Saleh, Bahaa E. A., Abouraddy, Ayman F.
Issue&Volume: 2026-04-02
Abstract: The conservation of energy and transverse momentum in the process of spontaneous parametric downconversion enforces on the generated entangled signal and idler photons strict inter-photon quantum correlations—with the spatial and temporal degrees of freedom separately exhibiting such correlations. Nonlinear crystals of realistic lengths enforce only loose intra-photon spatiotemporal correlations, which obscure the observation of any angular-dispersion-induced effects and have barred quantum optics from appropriating the recent progress in spatiotemporally structured light. Here we show that placing a spatiotemporal spectral modulator in the path of a heralded signal photon yields a single-photon ‘space-time wave packet’ that is endowed with a precisely structured spatiotemporal spectrum required for diffraction-free propagation at a tunable group velocity. Furthermore, by projecting the multimoded, spatiotemporally structured signal photon onto a single spatial mode to herald the arrival of the idler photon, we remotely prepare a diffraction-free single-photon space-time wave packet in the idler that did not traverse the spectral modulator. The signal/idler photons have complementary subluminal/superluminal group velocities as a consequence of their intrinsic inter-photon spectral anti-correlation, which reverses the sign of the spatiotemporal spectral curvature for the remotely prepared photon. These results pave the way for the applications of spatiotemporally structured light to impact quantum optics in the context of quantum communications, imaging and sensing.
DOI: 10.1038/s41566-026-01872-9
Source: https://www.nature.com/articles/s41566-026-01872-9