Quantum channels in free-space, an essential prerequisite for fundamental tests of quantum mechanics and quantum technologies in open space, have so far been based on direct line-of-sight because the predominant approaches for photon-encoding, including polarization and spatial modes, are not compatible with randomly scattered photons. Here we demonstrate a novel approach to transfer and recover quantum coherence from scattered, non-line-of-sight photons analyzed in a multimode and imaging interferometer for time-bins, combined with photon detection based on a 8 × 8 single-photon-detector-array. The observed time-bin visibility for scattered photons remained at a high 95% over a wide scattering angle range of −45⁰ to +45⁰, while the individual pixels in the detector array resolve or track an image in its field of view of ca. 0.5°. Using our method, we demonstrate the viability of two novel applications. Firstly, using scattered photons as an indirect channel for quantum communication thereby enabling non-line-of-sight quantum communication with background suppression, and secondly, using the combined arrival time and quantum coherence to enhance the contrast of low-light imaging and laser ranging under high background light. We believe our method will instigate new lines for research and development on applying photon coherence from scattered signals to quantum sensing, imaging, and communication in free-space environments.

自由空间中的量子通道是开放空间中量子力学和量子技术基本测试的必要先决条件，迄今为止一直基于直接视线，因为光子编码的主要方法，包括偏振和空间模式，与随机散射的光子不兼容。在这里，我们展示了一种新方法，用于从在多模和成像干涉仪中分析的散射、非视距光子传输和恢复量子相干性，结合基于 8 × 8 单光子探测器的光子检测-大批。在 -45 ⁰到 +45 ⁰的宽散射角范围内，观察到的散射光子的时间段可见度保持在 95% 的高位，而探测器阵列中的各个像素解析或跟踪其视场中的图像。0.5°。使用我们的方法，我们证明了两个新应用程序的可行性。一是利用散射光子作为量子通信的间接通道，实现带背景抑制的非视距量子通信；二是结合到达时间和量子相干性，增强微光成像和激光测距的对比度在高背景光下。我们相信我们的方法将激发新的研究和开发路线，将散射信号的光子相干应用于自由空间环境中的量子传感、成像和通信。