Robust Covert Quantum Communication under Bounded Channel Uncertainty

2026-04-13

AI Summary

This work addresses the challenge that uncertainty in transmissivity and background thermal noise in practical quantum optical channels undermines the reliability and secrecy guarantees of conventional covert communication schemes, which rely on idealized assumptions. We develop a robust framework that simultaneously ensures both secrecy and reliability over compound channels where both parameters exhibit bounded uncertainty. Our analysis reveals a fundamental trade-off between these two criteria, as each is governed by distinct worst-case channel realizations. For the first time, we derive a closed-form lower bound on the performance of covert quantum communication applicable to channels with bounded uncertainty. By integrating QuTiP-based simulations of a four-mode bosonic model with analytical reliability bounds, we establish a robust payload bound valid across all admissible channel instances, explicitly characterizing the feasibility region for non-zero covert communication and quantifying the security penalty incurred by parameter uncertainty.

Technology Category

• Machine Learning: Calibration & Uncertainty Quantification
• Reasoning under Uncertainty: Uncertainty Representations
• Planning, Routing, and Scheduling: Scheduling under Uncertainty

Application Category

• Security and Privacy: Large-scale security measurements
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Economics, Online Markets and Human Computation: Trust and reliance of crowd workers and data experts on GenAI

Abstract

Covert quantum communication is usually analyzed under idealized assumptions that channel parameters, such as transmissivity and background noise, are perfectly known and constant. In realistic optical links, including satellite, fiber, and free-space systems, these parameters vary because of environmental fluctuations, calibration noise, and estimation errors. We study covert quantum communication over compound quantum optical channels with bounded uncertainty in both transmissivity and thermal noise, and derive guarantees that hold for all admissible channel realizations. We develop a robust framework for certifying both covertness and reliability under uncertainty. A central finding is that robustness cannot be obtained by simply inserting worst-case parameter values into known-channel bounds: the channel realizations that are most adverse for covertness and reliability generally occur at different corners of the uncertainty set. This creates a fundamental trade-off in secure system design. We derive a closed-form lower bound on the worst-case guaranteed number of covert qubits that can be transmitted reliably, identify a sharp feasibility boundary beyond which the guaranteed payload drops to zero, and quantify the security penalty caused by uncertainty. We validate the covertness term with QuTiP simulations of a four-mode bosonic model and combine it with an analytical reliability bound to evaluate the robust payload. Our results move covert quantum communication from nominal perfect-knowledge analysis to certified worst-case operation under uncertainty.

Problem

• covert quantum communication
• channel uncertainty
• transmissivity
• thermal noise
• robustness

Innovation

• covert quantum communication
• channel uncertainty
• robustness
• compound quantum channel
• worst-case guarantee