Fault-tolerant entanglement-assisted communication

Paula Belzig (University of Copenhagen)

The process of communicating information between two devices, a sender and a receiver, is modelled by a noisy channel which maps an encoded message to a potentially corrupted output signal. Then, the capacity of a given channel quantifies the optimal asymptotic rate of sending information over the channel where the original message can always be recovered. Usually, the study of capacities assumes that the circuits which the sender and the receiver use for encoding and decoding the information consist of perfect gates without noise. While this assumption is realistic for classical computers, is not believed to be true for quantum devices manufactured in the near-term and even long-term future. Using techniques from fault-tolerant quantum computing, we prove a lower bound on the entanglement-assisted capacity under the assumption of noisy gates, and we prove in particular that this capacity approaches the usual, faultless case for vanishing gate error probability.