Parallelized telecom quantum networking with a ytterbium-171 atom array

TL;DR

This paper demonstrates high-fidelity entanglement between ytterbium-171 atoms and photons in the telecom band, enabling parallelized quantum networking and coherence preservation for scalable quantum communication.

Contribution

It introduces a method for entangling ytterbium-171 atomic spins with telecom-band photons and implements a parallelized networking protocol with preserved coherence, advancing quantum network integration.

Findings

Atom-photon Bell state fidelity of ~0.95

Parallelized protocol boosts entanglement rate

Coherence preserved during networking operations

Abstract

The integration of quantum computers and sensors into a quantum network opens a new frontier for quantum information science. We demonstrate high-fidelity entanglement between ytterbium-171 atoms -- the basis for state-of-the-art atomic quantum processors and optical atomic clocks -- and optical photons directly generated in the telecommunication wavelength band where loss in optical fiber is minimal. We entangle the nuclear spin of the atom with a single photon in the time bin basis, and find an atom measurement-corrected (raw) atom-photon Bell state fidelity of $0.950(9)\pm0.005(3)_\text{bound}$ ($0.90(1)\pm0.014(3)_\text{bound}$). Photon measurement errors contribute $\approx0.037$ to our infidelity and can be removed with straightforward upgrades. Additionally, by imaging our atom array onto an optical fiber array, we demonstrate a parallelized networking protocol that can provide an $N$-fold boost in the remote entanglement rate. Finally, we demonstrate the ability to preserve coherence on a memory qubit while performing networking operations on communication qubits. Our work is a major step towards the integration of atomic processors and optical clocks into a high-rate or long-distance quantum network.