Usenko V. The use of the two-mode coherently-correlated states in quantum cryptography

The work is dedicated to the development and examination of the new quantum cryptography protocol based on the multiphoton two-mode coherently-correlated states of light. The correlative properties of the coherently-correlated quantum states are investigated for the first time. The possibility to use the states for the generation and secure transmission of a bit sequence which can be used as the cryptographic key is shown. The security of the proposed protocol is investigated concerning the realistic eavesdropping with beam splitting and state reconstruction. The interception of the multiphoton quantum cryptography protocol with the quantum nondemolition measurements is considered for the first time. The security of the proposed protocol against the considered eavesdropping methods is shown. The possibility to increase the protocol effectiveness and security by means of the multiphoton states coding alphabet extension is shown. The correlative properties and the possibility of the cryptographic use ofthe modified two-mode coherently-correlated states are examined.