Robust implementations of quantum repeaters (14 pages)

Marco G. Genoni, Matteo G. A. Paris

Adnan N. Kadhim, Jawad A. K. Hasan, Wijdan M. Alkhalidy

Nicolas Sangouard, Christoph Simon, Bo Zhao +4 more

In the last few years there has been a lot of interest in quantum repeater protocols using only atomic ensembles and linear optics. Here we show that the local generation of high-fidelity entangled pairs of atomic excitations, in combination with the use of two-photon detections for long-distance entanglement generation, permits the implementation of a very attractive quantum repeater protocol. Such a repeater is robust with respect to phase fluctuations in the transmission channels, and at the same time achieves higher entanglement generation rates than other protocols using the same ingredients. We propose an efficient method of generating high-fidelity entangled pairs locally, based on the partial readout of the ensemble-based memories. We also discuss the experimental implementation of the proposed protocol.

A. Kuzmich

Ахмеджанов Ринат Абдулхаевич, Yurii Yu. Balega, Andrey D. Deev +1 more

Alexander Klein, U. Dorner, Carolina Moura Alves +1 more

We show how to efficiently exploit decoherence free subspaces (DFSs), which are immune to collective noise, for realizing quantum repeaters with long-lived quantum memories. Our setup consists of an assembly of simple modules and we show how to implement them in systems of cold, neutral atoms in arrays of dipole traps. We develop methods for realizing robust gate operations on qubits encoded in a DFS using collisional interactions between the atoms. We also give a detailed analysis of the performance and stability of all required gate operations and emphasize that all modules can be realized with current or near future experimental technology.