Quantum repeaters with individual rare-earth ions at telecommunication wavelengths

TL;DR

This paper proposes a quantum repeater scheme using individual erbium and europium ions, leveraging telecom-wavelength photon emission and long-term spin coherence for efficient entanglement distribution over long distances.

Contribution

It introduces a novel quantum repeater protocol combining telecom-compatible photon emission, high Purcell factor microcavities, and electric-dipole gate operations for improved entanglement distribution.

Findings

Enhanced entanglement distribution rates using microcavities and multiplexing.

Deterministic gate operations enable efficient entanglement swapping.

Potential for long-distance quantum communication with telecom-wavelength photons.

Abstract

We present a quantum repeater scheme that is based on individual erbium and europium ions. Erbium ions are attractive because they emit photons at telecommunication wavelength, while europium ions offer exceptional spin coherence for long-term storage. Entanglement between distant erbium ions is created by photon detection. The photon emission rate of each erbium ion is enhanced by a microcavity with high Purcell factor, as has recently been demonstrated. Entanglement is then transferred to nearby europium ions for storage. Gate operations between nearby ions are performed using dynamically controlled electric-dipole coupling. These gate operations allow entanglement swapping to be employed in order to extend the distance over which entanglement is distributed. The deterministic character of the gate operations allows improved entanglement distribution rates in comparison to atomic ensemble-based protocols. We also propose an approach that utilizes multiplexing in order to enhance the entanglement distribution rate.