Quantum network loss estimation with quantum enhanced precision metrology

Quantum metrology promises to revolutionize precision measurements in quantum networks, particularly for accurate channel transmission loss estimation, which is critical for loss-sensitive and security protocols. Traditional methods using coherent states are limited by shot noise. However, quantum states like Two-Mode Squeezed Vacuum (TMSV) states can surpass this limit. Our theoretical and experimental study shows that measurement with TMSV states with no post selection provide up to 3.9 dB higher Fisher Information (FI) than coherent states, allowing for superior transmission loss characterization over fibers up to 35 km. This demonstrates TMSV's potential in enhancing quantum network applications.