Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Perfect cheating is impossible for single-qubit position verification



Carl A. Miller, Yusuf Alnawakhtha


In quantum position verification, a prover certifies her location by performing a quantum computation and returning the results (at the speed of light) to a set of trusted verifiers. One of the very first protocols for quantum position verification was proposed in (Kent, Munro, Spiller 2011): the prover receives a qubit Q from one direction, receives an orthogonal basis v, v⊥} from the opposite direction, then measures Q in v, v⊥} and broadcasts the result. A number of variants of this protocol have been proposed and analyzed, but the question of whether the original protocol itself is secure has never been fully resolved. In this work we show that there is no perfect finite-dimensional cheating strategy for the original KMS measurement protocol. Our approach makes use of tools from real algebraic geometry.


PNT, quantum cryptography, authentication, algebraic geometry


Miller, C. and Alnawakhtha, Y. (2024), Perfect cheating is impossible for single-qubit position verification, arXiv, [online],, (Accessed July 12, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created June 28, 2024, Updated July 1, 2024