Multicore fibers are expected to be a game-changer in the coming decades thanks to their intrinsic properties, allowing a larger transmission bandwidth and a lower footprint in optical communications. In addition, multicore fibers have recently been explored for quantum communication, attesting to their uniqueness in transporting high-dimensional quantum states. However, investigations and experiments reported in literature have been carried out in research laboratories, typically making use of short fiber links in controlled environments. Thus, the possibility of using long-distance multicore fibers for quantum applications is still to be proven. We characterize here for the first time, to the best of our knowledge, in terms of phase stability, multiple strands of a four-core multicore fiber installed underground in the city of L’Aquila, with an overall fiber length up to about 25 km. In this preliminary study, we investigate the possibility of using such an infrastructure to implement quantum-enhanced schemes, such as high-dimensional quantum key distribution, quantum-based environmental sensors, and more, in general, quantum communication protocols.

中文翻译：

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用于量子应用的已部署多芯光纤的表征和稳定性测量

由于其固有特性，多芯光纤有望在未来几十年内成为游戏规则的改变者，可在光通信中实现更大的传输带宽和更低的占用空间。此外，最近已经探索了多芯光纤用于量子通信，证明了它们在传输高维量子态方面的独特性。然而，文献中报道的调查和实验是在研究实验室中进行的，通常在受控环境中使用短光纤链路。因此，将长距离多芯光纤用于量子应用的可能性仍有待证明。据我们所知，我们第一次在这里表征相位稳定性，多股四芯多芯光纤安装在拉奎拉市的地下，总光纤长度可达约 25 公里。在这项初步研究中，我们研究了使用这种基础设施来实现量子增强方案的可能性，例如高维量子密钥分发、基于量子的环境传感器，以及更多一般的量子通信协议。