The Trojan Horse Attacks on Continuous Variable Quantum Teleportation

ABSTRACT Trojan horse attacks provide an effective means for the eavesdropper to access the sender which has a significant threat to the continuous variable quantum communication protocols. This study specifically focuses on the adverse effects of Trojan horse attacks on the fidelity of continuous‐variable quantum teleportation. A side‐channel attack scenario is considered in which an adversary injects ancillary photons into the transmission channel or measurement apparatus to probe or disrupt legitimate quantum signals. A comprehensive theoretical model is developed to describe how such injected photons interact with the teleportation channel, altering key parameters such as modulation variance and effective transmittance. Extensive numerical simulations quantify the explicit dependence of teleportation fidelity on the number of injected photons, demonstrating significant performance degradation under high injection rates. Furthermore, the study analyzes and evaluates the effectiveness of several practical countermeasures. This work not only establishes a rigorous theoretical framework for understanding Trojan horse vulnerabilities in quantum teleportation systems, but also provides actionable guidance for designing attack‐resistant quantum communication architectures.