1 Department of Computer Science, Science and Technology, Aarhus University2 TU Münche3 Centre for Quantum Technologies at the National University of Singapore4 Department of Computer Science, Science and Technology, Aarhus University
Most coding theorems in quantum Shannon theory can be proven using the decoupling technique. To send data through a channel, one guarantees that the environment gets no information about it. Uhlmann's theorem then ensures that the receiver must be able to decode. While a wide range of problems can be solved this way, one of the most basic coding problems remains impervious to a direct application of this method, sending classical information through a quantum channel. We will show that this problem can, in fact, be solved using decoupling ideas, specifically by proving a dequantizing theorem, which ensures that the environment is only classically correlated with the sent data. Our techniques naturally yield a generalization of the Holevo-Schumacher-Westmoreland theorem to the one-shot scenario, where a quantum channel can be applied only once.
I E E E Transactions on Information Theory, 2014, Vol 60, Issue 3, p. 1562-1572