Operational Threat Modeling of Adversarial Noise in Continuous-Variable Quantum Communication

Recent work has shown that finite measurement resolution and estimator tolerances can create operational vulnerabilities in quantum integrity verification, enabling adversarial probing strategies that evade static detection criteria [1]. Building on these insights, we examine how analogous adversarial mechanisms arise in continuous-variable quantum communication (CVQC), where security and performance-critical decisions are made directly from finite-resolution phase-space measurements. We develop an operational threat-modeling framework that classifies adversarial interference in CVQC into three regimes: (i) low-amplitude reconnaissance noise engineered to remain within estimator tolerances, (ii) moderate exploratory noise designed to probe stability margins and system sensitivities, and (iii) high-intensity denial-of-service (DoS) interference intended to force operational failure. Using a receiver-centric Gaussian-channel representation, we characterize how each regime perturbs second-order quadrature statistics and induces systematic degradation of state coherence and purity. To quantify adversarial impact in an implementation-relevant manner, we introduce an energy-deviation metric derived from the trace of the covariance matrix, directly linking excess noise accumulation to estimator degradation and operational failure thresholds under finite-sample constraints. The resulting taxonomy and metric establish a structured foundation for analyzing physical-layer adversarial behavior in continuous-variable quantum communication.