Quantum-enhanced Network Tomography

2026-04-28

AI Summary

This study addresses the challenge of efficiently and accurately estimating link-wise transmittance in optical networks. The authors propose a quantum probing scheme leveraging continuous-variable squeezed states or weakly temporally entangled states, combined with homodyne detection and all-optical switching nodes to route probes through the network for link tomography. They introduce an innovative probe design algorithm that ensures both link identifiability and information orthogonality, and—marking the first application of quantum probes to network tomography—they employ a Fisher information matrix–based metric to quantify estimation performance. Experimental results demonstrate that the proposed method substantially enhances the accuracy of transmittance estimation across general optical networks and provides a quantitative assessment of the performance gain attributable to quantum resources.

Abstract

Network tomography refers to the use of inference techniques for inferring internal network states from end-to-end probes. Quantum probes, implemented by sending blocks of $n$ coherent-state pulses augmented with continuous-variable (CV) squeezing ($n=1$) or weak temporal-mode entanglement ($n>1$) over a lossy channel to a receiver with homodyne detection capabilities, are known to carry information about the channel transmissivity. Assuming a subset of nodes in an optical network is capable of sending and receiving such probes through intermediate nodes with all-optical switching capabilities, we leverage these quantum probes to estimate link transmissivities. To determine how to route the probes in a network, we propose a probe construction algorithm that guarantees link identifiability, while maximizing the number of information orthogonal sets of transmissivities. A set of probes induces a Fisher information matrix (FIM). We then derive two metrics, the determinant of the FIM and the trace of its inverse, to evaluate the performance of the probes. In particular, our results can be used to characterize the quantum improvement in estimating link transmissivities in a general optical network.

Problem

• quantum-enhanced
• network tomography
• link transmissivity
• optical network
• quantum probes

Innovation

• quantum-enhanced network tomography
• continuous-variable squeezing
• temporal-mode entanglement
• Fisher information matrix
• link transmissivity estimation