We introduce the concept of Quantum Ping (QPing) as a diagnostic primitive for future quantum networks, designed to assess whether two or more end nodes can establish practical quantum entanglement with efficient resource consumption, limited overhead, and time-adaptive fidelity thresholds. Unlike classical ping, which probes network-layer connectivity through ICMP messages, our proposed quantum version is adapted to the unique features of quantum networks, where connectivity depends on the availability and quality of shared entanglement. We develop a formal framework for QPing and leverage different tools such as sequential hypothesis testing to probe quantum connectivity. We present several strategies, including active strategies, with path-based and segment-based variants, and passive strategies that utilize pre-shared entangled resources. QPing can serve as a flexible diagnostic building block for quantum networks, designed to work alongside fundamental network operations, while remaining suitable to different architectural and protocol design approaches.

This work has been partially funded by the European Union under the ERC grant QNattyNet, n.101169850