Transmission losses in optical qubits for controlled teleportation

Abstract

In this work, we investigate the controlled teleportation protocol using optical qubits within the single-rail logic. The protocol makes use of an entangled tripartite state shared by the controller and two further parties (users) who will perform standard teleportation. The goal of the protocol is to guarantee that the teleportation is successful only with the permission of the controller. Optical qubits based on either superpositions of vacuum and single-photon states or superposition of coherent states are employed here to encode a tripartite maximal slice state upon which the protocol is based. We compare the performances of these two encodings under losses which are present when the qubits are guided through an optical fiber to the users. Finally, we investigate the non-locality of the shared tripartite state to see whether or not it impacts the efficiency of the protocol.Comment: 8 pages, 6 figure

Optimal quantum channel for perfect controlled super-dense coding protocol

“…Here, following the Refs. [42][43][44][45][46], we make use of a quantity called control power which is a newly introduced indicator reflecting the power of the controller in a quantitative manner. By calculating and analyzing the control power in dependence on the parameters of various possible quantum channels we can find out which quantum channel is optimal from the point of view of the amount of transferrable information without the cooperation of the controller.…”