Non-static Quantum Bit Commitment

TL;DR

This paper introduces a non-static quantum bit commitment protocol with a trusted third party, achieving unconditional security by removing the staticity assumption that underpins previous impossibility proofs.

Contribution

It presents a novel quantum bit commitment protocol that remains secure without assuming static quantum states, differing from prior no-go theorems.

Findings

Protocol is unconditionally secure with a trusted third party.

Security fails without the third party, highlighting its necessity.

Different proof approach from Mayers-Lo-Chau no-go theorem.

Abstract

Quantum bit commitment has been known to be impossible by the independent proofs of Mayers, and Lo and Chau, under the assumption that the whole quantum states right before the unveiling phase are static to users. We here provide an unconditionally secure non-static quantum bit commitment protocol with a trusted third party, which is not directly involved in any communications between users and can be limited not to get any information of commitment without being detected by users. We also prove that our quantum bit commitment protocol is not secure without the help of the trusted third party. The proof is basically different from the Mayers-Lo-Chau's no-go theorem, because we do not assume the staticity of the finally shared quantum states between users.