Unforgeable Noise-Tolerant Quantum Tokens

TL;DR

This paper introduces a new class of noise-tolerant quantum tokens that are secure against forgery, even with realistic imperfections, using only basic quantum memory operations, thus advancing practical quantum money implementations.

Contribution

The authors propose and rigorously prove the security of noise-tolerant quantum tokens requiring only single-qubit memories, making quantum money more feasible with current technology.

Findings

Protocols tolerate realistic noise levels

Security proven with tight fidelity thresholds

Experimental feasibility with current quantum technologies

Abstract

The realization of devices which harness the laws of quantum mechanics represents an exciting challenge at the interface of modern technology and fundamental science. An exemplary paragon of the power of such quantum primitives is the concept of "quantum money". A dishonest holder of a quantum bank-note will invariably fail in any forging attempts; indeed, under assumptions of ideal measurements and decoherence-free memories such security is guaranteed by the no-cloning theorem. In any practical situation, however, noise, decoherence and operational imperfections abound. Thus, the development of secure "quantum money"-type primitives capable of tolerating realistic infidelities is of both practical and fundamental importance. Here, we propose a novel class of such protocols and demonstrate their tolerance to noise; moreover, we prove their rigorous security by determining tight fidelity thresholds. Our proposed protocols require only the ability to prepare, store and measure single qubit quantum memories, making their experimental realization accessible with current technologies.