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  • Open Access

Efficient anomaly detection in a quantum network

Kiran Adhikari* and Janis Nötzel†

  • *Contact author: kiran.adhikari@tum.de
  • †Contact author: janis.noetzel@tum.de
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APS Open Sci. 1, 000104 – Published 24 August, 2026

DOI: https://doi.org/10.1103/t1bf-fxb9

Abstract

A quantum network enables the execution of advanced protocols, such as distributed quantum computing, quantum metrology, quantum cryptography, and long-distance quantum communication. Anomalous nodes pose significant threats to these protocols, as they are notoriously difficult to detect and can cause severe disruption. In this work, we introduce a quantum-walk-based protocol for detecting such anomalies. The protocol exploits the sensitivity of coherent quantum transport to local perturbations of the network Hamiltonian. In particular, anomalous on-site potentials or modified hopping amplitudes alter the quantum walker's interference pattern, thereby shifting the time-averaged arrival probability between two trusted end points and offering the detection signal. We develop the protocol for one-dimensional quantum networks, derive spectral criteria for detectability, and discuss how the resulting ideas may extend to more general graph topologies.

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APS Open Sci. 1, 000104– Published 24 August, 2026
Vol. 1
  • Received 11 March 2026
  • Accepted 4 August 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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