Quantum key distribution based on orthogonal states allows secure quantum bit commitment

TL;DR

This paper presents a quantum bit commitment protocol based on orthogonal states that evades previous no-go proofs, is feasible with current technology, and could enable new secure multi-party cryptographic protocols.

Contribution

It introduces a QBC protocol using orthogonal states that bypasses no-go proofs, challenging previous assumptions about quantum bit commitment impossibility.

Findings

Protocol is fault-tolerant and feasible with current technology

Enables secure quantum bit string commitment and coin tossing

Challenges existing no-go theorems for QBC

Abstract

For more than a decade, it was believed that unconditionally secure quantum bit commitment (QBC) is impossible. But basing on a previously proposed quantum key distribution scheme using orthogonal states, here we build a QBC protocol in which the density matrices of the quantum states encoding the commitment do not satisfy a crucial condition on which the no-go proofs of QBC are based. Thus the no-go proofs could be evaded. Our protocol is fault-tolerant and very feasible with currently available technology. It reopens the venue for other "post-cold-war" multi-party cryptographic protocols, e.g., quantum bit string commitment and quantum strong coin tossing with an arbitrarily small bias. This result also has a strong influence on the Clifton-Bub-Halvorson theorem which suggests that quantum theory could be characterized in terms of information-theoretic constraints.