Long-distance entanglement sharing using hybrid states of discrete and continuous variables

Abstract

We introduce a feasible scheme to produce high-rate long-distance entanglement which uses hybrid entanglement (HE) between continuous variables (CV) and discrete variables (DV). We show that HE can effectively remove the experimental limitations of existing CV and DV systems to produce long range entanglement. We benchmark the resulting DV entangled states using an entanglement-based quantum key distribution (EB-QKD) protocol. We show that, using HE states, EB-QKD is possible with standard telecommunication fibers for 300 km. The key idea is using the CV part, which can be adjusted to be robust against photon losses, for increasing the transmission distance, while using the DV part for achieving high secure key rates. Our results point out that HE states provide a clear advantage for practical long-distance and high-rate entanglement generation that may lead to further applications in quantum information processing.