On the impossibility of non-static quantum bit commitment between two parties

TL;DR

This paper extends the Mayers-Lo-Chau no-go theorem to non-static quantum bit commitment protocols, demonstrating their fundamental impossibility regardless of the static or non-static nature, and introduces a new proof approach.

Contribution

It shows that the no-go theorem applies to non-static QBC, removing the previous assumption that limited it to static protocols, and offers a novel proof method.

Findings

MLC no-go theorem applies to non-static QBC

Non-static QBC protocols are impossible to implement securely

A new proof technique for quantum bit commitment impossibility

Abstract

Recently, Choi \emph{et al}. proposed an assumption on Mayers-Lo-Chau (MLC) no-go theorem that the state of the entire quantum system is invariable to both participants before the unveiling phase. This means that the theorem is only applicable to static quantum bit commitment (QBC). This paper find that the assumption is unnecessary and the MLC no-go theorem can be applied to not only static QBC, but also non-static one. A non-static QBC protocol proposed by Choi \emph{et al.} is briefly reviewed and analyzed to work as a supporting example. In addition, a novel way to prove the impossibility of the two kinds of QBC is given.