# Secure alignment of coordinate systems by using quantum correlation

## TL;DR

This paper presents a secure quantum method for two distant parties to align their coordinate systems with high fidelity using shared entangled states and classical communication, offering advantages over previous approaches.

## Contribution

The authors introduce a novel quantum protocol that achieves secure and high-fidelity coordinate system alignment using single qubit measurements, improving security and simplicity over prior methods.

## Key findings

- High-fidelity alignment achieved with shared entanglement
- Method uses only single qubit measurements
- Protocol is secure against third-party eavesdropping

## Abstract

We show that two parties far apart can use shared entangled states and classical communication to align their coordinate systems with a very high fidelity. Moreover compared with previous methods proposed for such a task, i.e. sending parallel or anti-parallel pairs or groups of spin states, our method has the extra advantages of using single qubit measurements and also being secure, so that third parties do not extract any information about the aligned coordinate system established between the two parties. The latter property is important in many other quantum information protocols in which measurements inevitably play a significant role.