Quantum Optics Seminar by Ming Lai Chan – University of Copenhagen

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Quantum Optics Seminar by Ming Lai Chan

Optimized protocol to create repeater graph states in all-photonic quantum repeater

Quantum repeater is a device that enables long-distance transmission of quantum information. However, the difficulty in generation of repeater graph states (RGS) in all-photonic quantum repeater prevents it from being commercially applicable. Recently, several deterministic generation schemes for RGS have been proposed, yet they can only create RGS that are not robust against photon loss. In addition, an estimation of the performance of the repeater is not known for deterministic schemes. We present an optimized deterministic protocol to create fault-tolerant RGS, and calculate the secret key rate achievable and resources required in our scheme. We found that the secret key rate generated with our repeater is at least 4.9 times higher than that of the traditional probabilistic scheme, along with a significant reduction in the total number of single-photon sources by 2 orders of magnitude. The duration of our scheme is halved compared with the existing deterministic schemes. We also suggest two novel experimental techniques to demonstrate the feasibility of our protocol.