A photon-interfaced ten qubit quantum network node

TL;DR

This paper demonstrates a scalable method to entangle ten atomic ion qubits with individual photons, enabling potential applications in distributed quantum networks and quantum sensing.

Contribution

It introduces a novel technique for entangling multiple ion qubits with photons using cavity-mediated Raman transitions, scalable to larger registers.

Findings

Achieved 92% ion-photon Bell state fidelity

Photon detection probability of 9.1% per photon

Scalable approach for larger ion-qubit networks

Abstract

We entangle each individual matter-qubit in a register of ten to a separate travelling photon. The qubits are encoded in a string of cotrapped atomic ions. By switching the trap confinement, ions are brought one at a time into the waist of an optical cavity and emit a photon via a laser-driven cavity-mediated Raman transition. The result is a train of photonic-qubits, each near-maximally entangled by their polarisation with a different ion-qubit in the string. An average ion-photon Bell state fidelity of 92(1)% is achieved, for an average probability for detecting each single photon of 9.1(8)%. The technique is directly scalable to larger ion-qubit registers and opens up the near-term possibility of entangling distributed networks of trapped-ion quantum processors, sensing arrays and clocks.