Multi-node information network detection scheme

Abstract Photons provide an excellent platform for information transfer and processing. The detection and extraction of information carried by photons are essential for quantum communication and computation. However, current schemes are difficult to meet the anticipation of scaling up information processing networks. Here, we propose a multi-node information network detection (MIND) scheme and experimentally verify its feasibility for a large-scale free-space optical communication network. By retrieving the spatial information and arrival time correlation of photons from multiple nodes, we experimentally demonstrate the establishment of three crosstalk-free concurrent communication links using a single detection terminal. The potential for scaling up to 650 crosstalk-free links is discussed. With high robustness to loss and noise, our scheme is feasible when the detected signal is only $8.4 \times 10^{-5}$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>8.4</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> </mml:math> photons per pulse and the noise is 1.7 times greater than signal. Extracting information from moving signals and multiple overlapping signals is also demonstrated. Our work provides a scalable and general approach for processing concurrent signals at the single photon level and opens up new avenues for constructing large-scale information processing networks.