Hidden Multidimensional Modulation Side Channels in Quantum Protocols
Amita Gnanapandithan, Li Qian, Hoi‐Kwong Lo · Physical Review Letters · 2025
Quantum protocols including quantum key distribution and blind quantum computing often require the preparation of quantum states of known dimensions. Here, we show that, rather surprisingly, hidden multidimensional modulation is often performed by practical devices. This violates the dimensional assumption in quantum protocols, thus creating side channels and security loopholes. Our work has important impacts on the security of quantum cryptographic protocols.