Distribution of non-Gaussian states in a deployed telecommunication fiber channel

Optical non-Gaussian states hold great promise as a pivotal resource for advanced optical quantum information processing and fault-tolerant long-distance quantum communication. Establishing their faithful transmission in a real-world communication channel, therefore, marks an important milestone. In this study, we experimentally demonstrate the distribution of such non-Gaussian states in a functioning telecommunication channel that connects separate buildings within the DTU campus premises. We send photon-subtracted squeezed states, exhibiting pronounced Wigner negativity, through 300 m of deployed optical fibers to a distant building. Using quantum homodyne tomography, we fully characterize the states upon arrival. Our results show the survival of the Wigner function negativity after transmission when correcting for detection losses, indicating that the established link can potentially facilitate the violation of Bell's inequality and enable quantum steering. This achievement not only validates the practical feasibility of distributing non-Gaussian states in real-world settings, but also provides an exciting impetus towards realizing fully coherent quantum networks for high-dimensional, continuous-variable quantum information processing.