A new quantum position verification (QPV) protocol combines multiple measurement bases to achieve efficiency and security against adversaries with more general capabilities than previously considered. Quantum position verification allows a verifier to confirm that a party is at a specific geographic location based solely on relativity (the finite speed of light) and the laws of quantum mechanics, without requiring pre-shared secrets or trusted hardware.

Earlier QPV protocols suffered a twofold limitation: they were either secure only against idealized adversaries (for example, with limited quantum memory or attacks restricted to certain strategy types), or they demanded disproportionate experimental resources, such as a growing number of qubits or communication rounds. The new work addresses both fronts by proposing a multi-basis scheme that exploits the structure of measurements to reduce the experimental burden without compromising security against adversaries who can use arbitrary, coordinated quantum strategies.

The protocol relies on the idea that the measurement bases chosen by the verifier in each round act as an unpredictable challenge for the party that must prove its position. By requiring the response to be correct in several complementary bases, the space of admissible attacks is drastically restricted, even when the adversary possesses long-lived quantum memory and can perform joint operations on all the qubits it controls. Security is established through a formal analysis that bounds the success probability of any attack strategy, generalizing previous results that covered only particular cases.

Regarding efficiency, the multi-basis scheme reduces the number of qubits and rounds needed compared to earlier proposals with comparable security guarantees, bringing quantum position verification closer to realistic experimental implementations with photons and linear optics. The practical relevance extends beyond geolocation: efficient and robust QPV protocols are a key building block for quantum cryptography with minimal trust assumptions and for future distributed quantum networks. A full experimental demonstration of the protocol and an empirical comparison of its performance against concrete attacks in real implementations remain to be done.