Four Phase States Eavesdropping with no Quantum Interaction

Quantum mechanics is the pillar that holds the security of quantum key distribution and it has been proven that perfect security can be done with some non-ideal component. In this paper we experimentally demonstrate the Trojan horse attack, which is one of the possible methods of conventional optical eavesdropping. It eliminates the need of immediate interaction with transmitted quantum states. We will demonstrates method to distinguish between phase settings of Alice´s or Bob´s phase modulator, depending on parameters of the interrogating pulse and apparatus.