Scaling Enhancement in Distributed Quantum Sensing via Bidirectional Causal Routing

Abstract:Sensing networks underpin applications ranging from fundamental physics to real-world engineering. Distributed quantum sensing (DQS) can improve measurement performance, but existing protocols typically require multipartite entanglement, which poses substantial challenges for scalable implementation. Here, we introduce a DQS protocol based on bidirectional causal routing in a cyclic network, where a single probe sequentially interrogates M independent sensors along two opposite causal routes. By exploiting the noncommutativity between inter-sensor propagation and local sensing operations, the protocol turns propagation from a passive transport process into a source of sensing information, yielding an asymptotic 1/M^2 scaling of the estimation precision without multipartite entanglement. We experimentally demonstrate the protocol for distributed beam-tilt sensing in a free-space quantum optical network comprising up to 9 sensors, achieving picoradian-level precision in estimating the average tilt angle. These results identify propagation dynamics and routing geometry as active metrological resources for scalable distributed quantum sensing.

Quantum Physics (quant-ph); Optics (physics.optics)

arXiv:2601.14708 [quant-ph]

(or arXiv:2601.14708v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2601.14708 Focus to learn more arXiv-issued DOI via DataCite

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