Quantum repeaters and quantum key distribution: Analysis of secret-key rates

摘要

We analyze various prominent quantum repeater protocols in the context of long-distance quantum keyndistribution. These protocols are the original quantum repeater proposal by Briegel, D¨ur, Cirac and Zoller, thenso-called hybrid quantum repeater using optical coherent states dispersively interacting with atomic spin qubits,nand the Duan-Lukin-Cirac-Zoller-type repeater using atomic ensembles together with linear optics and, in itsnmost recent extension, heralded qubit amplifiers. For our analysis, we investigate the most important experimentalnparameters of every repeater component and find their minimally required values for obtaining a nonzero secretnkey. Additionally, we examine in detail the impact of device imperfections on the final secret key rate and on thenoptimal number of rounds of distillation when the entangled states are purified right after their initial distribution.