Induced-Photorefraction Attack against Quantum Key Distribution

Lithium niobate (LiNbO3, LN) devices play critical roles in quantum information processing. However, for special applications like key distribution (QKD), the characteristics of materials and their impact on practical systems must be intensively inquired. For first time, we reveal that photorefractive effect LN can utilized as a potential loophole to carry out malicious attacks by eavesdroppers. We take commercial LN-based variable optical attenuator an example demonstrate method named Induced-photorefractive attack (IPA) propose two techniques enable controllable attacks. Our results show eavesdroppers fulfill efficient source-side injecting optimized irradiation beam with only several nanowatts, which is realistic when accessing fiber channels. These measure employed all individual on-chip initially explored new security branch system design standardization real-life QKD.