In this paper, a new model for arbitrarily varying classical-quantum channels is proposed. In this model, a jammer has side information. The communication scenario in which a jammer can select only classical inputs as a jamming sequence is considered in the first part of the paper. This situation corresponds to the standard model of arbitrarily varying classicalquantum channels. Two scenarios are considered. In the first scenario, the jammer knows the channel input, while in the second scenario the jammer knows both the channel input and the message. The transmitter and receiver share a secret random key with a vanishing key rate. The capacity for both average and maximum error criteria for both scenarios is determined in this paper. A strong converse is also proved. It is shown that all these corresponding capacities are equal, which means that additionally revealing the message to the jammer does not change the capacity. The communication scenario with a fully quantum jammer is considered in the second part of the paper. A single letter characterization for the capacity with secret random key as assistance for both average and maximum error criteria is derived in the paper.
Quantum information theory has developed into a very active field of research in the last years and its study provides many potential advantages. Secure communication is one of the most practical applications of quantum communications In this work, Prof. Ning Cai and his collaborators have determined the capacities of AVCQC in the scenario that the jammer knows the input codeword but not the message to be sent (Scenario 1) and in the scenario that the jammer knows both the input codeword and the message to be sent (Scenario 2), with a strong converse coding theorem. The results were recently published by IEEE Transactions on Information Theory.
Left: Scenario 1. Jammer knows coding scheme and input codeword
Right: Scenario 2. Jammer knows coding scheme, input codeword, and the message