Efficient quantum repeater based on deterministic Rydberg gates

We propose an efficient quantum repeater architecture with mesoscopic atomic ensembles, where the Rydberg blockade is employed for deterministic local entanglement generation, entanglement swapping, and entanglement purification. Compared to a conventional atomic-ensemble-based quantum repeater, the entanglement distribution rate is improved by up to two orders of magnitude with the help of the deterministic Rydberg gate. This quantum repeater scheme is robust and fast, and thus opens up a way for practical long-distance quantum communication.

Figure 1

Schematic view of the quantum repeater protocol with mesoscopic atomic ensembles based on a Rydberg gate, including local entanglement generation, entanglement linking, entanglement swapping, and entanglement purification.

Figure 2

(a) Average errors in local entanglement generation (gray) and entanglement swapping (black) versus dipole-dipole shift. The dashed and solid curves are for $\tau =200$ and 300 $\mu$s, respectively. (b) Performance of the quantum repeater. The solid curve represents the result without entanglement purification, which requires local errors on the order of ${10}^{-3}$. The dashed and dot-dashed lines are the results for $F_{\mathrm{loc}}=F_{\mathrm{CNOT}}=0.99$ and $0.98$, where active entanglement purification is implemented twice and four times, respectively, when the fidelity is no larger than $0.9$. The final fidelity is higher than $0.94$ and the probability of getting the entangled state is larger than $0.95$ in both cases. The dotted line is the result of the best-known protocol with atomic ensembles and linear optics proposed in [5].