Fundamental Limits of Eavesdropper Detection and Localization in Optical Fiber via Stimulated Brillouin Scattering

TL;DR

This paper analyzes the fundamental quantum limits of detecting and localizing eavesdroppers in optical fibers using Stimulated Brillouin Scattering, comparing classical and quantum detection methods.

Contribution

It derives an input-output model for SBS and evaluates detection methods including the quantum limit, highlighting potential advantages of quantum technology.

Findings

Quantum technology can improve eavesdropper detection sensitivity.

The paper compares classical, photon-counting, and quantum limit detection methods.

Quantum error exponents and metrology frameworks are used for analysis.

Abstract

Recent work investigated the use of Stimulated Brillouin Scattering (SBS) to measure changes in fiber parameters, thereby enhancing the security of a Quantum Key Distribution (QKD) system. In this work, we focus solely on the impact of quantum technology on the task of intrusion-detection. We derive an effective input-output model for the SBS interaction, and utilize it to compare three detection methods: First, the established state of the art. Second, a photon-counting based method which will likely be available in the near future and, finally, the ultimate quantum limit. We illustrate the potential benefit from modern quantum technology within two different mathematical frameworks: First by using the quantum error exponent of asymmetric hypothesis testing, and second in the context of parameter-estimation and quantum metrology.