An optical implementation of quantum bit commitment using infinite-dimensional systems

TL;DR

This paper proposes a quantum optical implementation of an unconditionally secure quantum bit commitment protocol using an approximation of infinite-dimensional systems, enabling practical experiments and potential applications in cryptography.

Contribution

It introduces a feasible optical method to implement a theoretically secure QBC protocol based on infinite-dimensional systems, bridging theory and experiment.

Findings

Successful approximation of infinite-dimensional systems with Mach-Zehnder interferometer

Proof-of-principle experimental setup demonstrated

Potential for practical secure quantum cryptographic protocols

Abstract

Unconditionally secure quantum bit commitment (QBC) was widely believed to be impossible for more than two decades. But recently, based on an anomalous behavior found in quantum steering, we proposed a QBC protocol which can be unconditionally secure in principle. The protocol requires the use of infinite-dimensional systems, therefore it may seem less feasible in practice. Here we propose a quantum optical method based on Mach-Zehnder interferometer, which gives a very good approximation to such infinite-dimensional systems. Thus, it enables a proof-of-principle experimental implementation of our protocol, which can also serve as a practically secure QBC scheme. Other multi-party cryptographic protocols such as quantum coin tossing can be built upon it too. Our approach also reveals a relationship between infinity and non-locality, which may have an impact on the research of fundamental theories.