Covert Capacity of Compound Classical-Quantum Channels

Abstract:
We consider a three party communication problem where a sender communication over a memoryless classicalquantum wiretap channel in the presence of an eavesdropper who should be kept unaware of the ongoing transmission. His ability to detect the transmission is quantified via the relative entropy between a reference state and his received average state. This received average state takes into account the presence of an arbitrarily large amount of shared randomness between sender and legitimate receiver, allowing the legitimate parties to communicate using randomly selected codebooks. In this scenario, we quantify the impact of channel uncertainty both relative to the receiver and the eavesdropper by extending the square-root law to this class of channels and exactly determining the constant.