Experimental Communication Through Superposition of Quantum Channels

Information capacity enhancement through the coherent control of channels has attracted much attention of late, with work exploring the effect of coherent control of channel causal orders, channel superpositions, and information encoding. Coherently controlling channels necessitates a non-trivial expansion of the channel description, which for superposing qubit channels, is equivalent to expanding the channel to act on qutrits. Here we explore the nature of this capacity enhancement for the superposition of channels by comparing the maximum coherent information through depolarizing qubit channels and relevant superposed and qutrit channels. We show that the expanded qutrit channel description in itself is sufficient to explain the capacity enhancement without any use of superposition.

Automated summary

Enhancing information capacity through coherent control of channels has recently garnered attention, with studies focusing on the effect of causal orders, channel superpositions, and information encoding. Expanding channel descriptions for superposing qubit channels, equivalent to acting on qutrits, has been shown to explain capacity enhancement without the need for superposition.