Non-Markovianity as a Resource for Quantum Technologies

Abstract: Quantum technologies rely on the ability to coherently manipulate, process and transfer information, encoded in quantum states, along quantum channels. Decoherence induced by the environment introduces errors, thus setting limits on the efficiency of any quantum-enhanced protocol or device. A fundamental bound on the ability of a noisy quantum channel to transmit quantum (classical) information is given by its quantum (classical) capacity. Generally, the longer is a quantum channel the more are the introduced errors, and hence the worse is its capacity. In this Letter we show that for non-Markovian quantum channels this is not always true: surprisingly the capacity of a longer channel can be greater than the one of a shorter channel. We introduce a general theoretical framework linking non-Markovianity to the capacities of quantum channels, and demonstrate in full generality how harnessing non-Markovianity may improve the efficiency of quantum information processing and communication.