Środowiskowe Seminarium z Informacji i Technologii Kwantowych

Quantum channels enable the implementation of communication tasks inaccessible to their classical counterparts. However, in the absence of quantum repeaters the rate at which these tasks can be performed is dictated by the losses in the quantum channel. In practice, channel losses have limited the reach of quantum protocols to short distances. Quantum repeaters have the potential to significantly increase the rates and reach beyond the limits of direct transmission. In the first part of this talk I will present our proposal of four quantum repeater schemes and assess their ability to generate secret key when implemented on a setup using NV centers in diamond with near-term experimental parameters. We find that one of these schemes surpasses the capacity - the highest secret-key rate achievable with direct transmission - establishing it as a prime candidate for the experimental realization of a scalable quantum repeater. In the second part of this talk I will focus on another building block of quantum repeater networks – entanglement distillation. Specifically, I will present our framework for optimizing practical entanglement distillation, which we used to prove optimality of various experimentally relevant distillation schemes. Finally, I will describe our on-going efforts to integrate our models of scalable proof of principle repeaters with practical entanglement distillation and classical control to simulate a pan-European quantum Internet.