Experimental secure entanglement-free quantum remote sensing over 50 km of optical fiber

TL;DR

This paper demonstrates a secure quantum remote sensing method over 50 km of optical fiber that estimates phase without entanglement, simplifying implementation and advancing long-distance quantum sensing applications.

Contribution

It introduces an entanglement-free quantum remote sensing protocol and experimentally validates phase estimation over 50 km fiber, enhancing practical long-distance quantum sensing.

Findings

Successful phase estimation over 50 km fiber

Entanglement-free quantum sensing demonstrated

Practical approach for long-distance quantum remote sensing

Abstract

Secure quantum remote sensing (SQRS) uses quantum states to gather information about distant objects or environments while ensuring secure data transmission against eavesdropping. It has potential applications in various fields, including environmental monitoring, military surveillance, and disaster response, where both data accuracy and transmission security are critical. Recent experiments have demonstrated the feasibility of SQRS using entanglement states. Here, we experimentally demonstrate an SQRS that can estimate a phase without requiring entanglement, offering the practical advantage that single-qubit states are easier to prepare. We successfully estimate the preset phase information at a remote site over a fiber distance of 50 km, which serves as a key step toward long-distance applications.