Relativistic position verification with coherent states

A secure approach to determining the position of an entity can enable schemes such as position-based authorization for transactions and tracking of high-value targets. However, classical methods are incapable of providing secure position verification in the untrusted-prover case, meaning that a prover can mislead verifiers about its actual position. Here we propose and experimentally realize a secure position verification protocol that combines quantum optics and relativity within an information-theoretic framework. Using phase-randomized weak coherent states, two verifiers separated by 2 km securely verify the prover’s position with an accuracy better than 75 m. These results establish secure position-based authentication as a practical possibility, paving the way for applications in financial transactions, disaster response and authenticated secure communications. By combining quantum and relativistic physics, it is possible to verify someone’s position remotely without needing to trust them. Such a position verification protocol has now been introduced and demonstrated with a quantum optics experiment.

Source: https://www.nature.com/articles/s41567-026-03439-5. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.