Abstract

Using different quantum states (e.g., two mode squeezed-state, multipartite GHZ-like-states) as quantum resources, two protocols for "continuous variable (CV) controlled quantum conference" are proposed. These CV protocols for controlled quantum conferences (CQCs) are the first of their kind and can be reduced to CV protocols for various other cryptographic tasks. In the proposed protocols, Charlie is considered the controller, having the power to terminate the protocol at any time and to control the flow of information among the other users by using a parameterised control switch. Based on the information shared by Charlie with the participants of the conference, the control power of Charlie is evaluated and compared to the proposed protocols. The comparison of the efficiency of the proposed protocols has revealed that, under certain constraints, the 4-mode GHZ state-based protocol is more efficient than the two-mode squeezed state-based protocol. The control power Charlie is evaluated for the proposed protocols under certain constraints. A security analysis is also performed, and it is observed that the proposed protocols are secure against a variety of attacks, including but not limited to disturbance attacks, man-in-the-middle attacks, Trojan horse attacks, laser seeding attacks, cloning attacks, beam splitter attacks, and malicious user(s) attacks.