A single-qubit position verification protocol that is secure against multi-qubit attacks

TL;DR

This paper introduces a position verification protocol using only a single qubit and classical communication, which is secure against multi-qubit entangled attacks and feasible with current quantum technology.

Contribution

It demonstrates that minimal quantum resources combined with classical communication can secure position verification against entangled quantum adversaries.

Findings

Single-qubit protocol resists multi-qubit entangled attacks.

Increasing classical communication enhances security against entanglement.

Protocols are noise-robust and experimentally feasible.

Abstract

The position of a device or agent is an important security credential in today's society, both online and in the real world. Unless in direct proximity, however, the secure verification of a position is impossible without further assumptions. This is true classically, but also in any future quantum-equipped communications infrastructure. We show in this work that minimal quantum resources, in the form of a single qubit, combined with classical communication are sufficient to thwart quantum adversaries that pretend to be at a specific position and have the ability to coordinate their action with entanglement. More precisely, we show that the adversaries using an increasing amount of entanglement can be combatted solely by increasing the number of classical bits used in the protocol. The presented protocols are noise-robust and within reach of current quantum technology.