Quantum bit commitment under Gaussian constraints

TL;DR

This paper introduces a quantum bit commitment protocol that is asymptotically secure under Gaussian constraints, leveraging continuous-variable quantum optics to prevent non-Gaussian cheating strategies.

Contribution

It presents a novel quantum bit commitment protocol that is secure when parties are limited to Gaussian operations, relevant for practical optical implementations.

Findings

Protocol is asymptotically secure under Gaussian restrictions.

High optical nonlinearity needed for non-Gaussian cheating is experimentally inaccessible.

Demonstrates feasibility of secure quantum commitments with continuous-variable systems.

Abstract

Quantum bit commitment has long been known to be impossible. Nevertheless, just as in the classical case, imposing certain constraints on the power of the parties may enable the construction of asymptotically secure protocols. Here, we introduce a quantum bit commitment protocol and prove that it is asymptotically secure if cheating is restricted to Gaussian operations. This protocol exploits continuous-variable quantum optical carriers, for which such a Gaussian constraint is experimentally relevant as the high optical nonlinearity needed to effect deterministic non-Gaussian cheating is inaccessible.