Photon-Mediated Quantum Gate between Two Trapped Neutral Atoms in an Optical Cavity

TL;DR

This paper demonstrates a fast, photon-mediated quantum gate between two neutral atoms in an optical cavity, achieving high-fidelity entanglement and operation, advancing quantum networking capabilities.

Contribution

The work introduces a novel photon-mediated gate between two atoms inside an optical cavity, enabling efficient quantum operations for networking.

Findings

Achieved a 76% fidelity Bell state.

Gate operation completed in 2 microseconds.

Demonstrated the gate functions as a CNOT.

Abstract

Quantum logic gates are fundamental building blocks of quantum computers. Their integration into quantum networks requires strong qubit coupling to network channels, as can be realized with neutral atoms and optical photons in cavity quantum electrodynamics. Here we demonstrate that the long-range interaction mediated by a flying photon performs a gate between two stationary atoms inside an optical cavity from which the photon is reflected. This single step executes the gate in $2\,\mathrm{\mu s}$. We show an entangling operation between the two atoms by generating a Bell state with 76(2)% fidelity. The gate also operates as a CNOT. We demonstrate 74.1(1.6)% overlap between the observed and the ideal gate output, limited by the state preparation fidelity of 80.2(0.8)%. As the atoms are efficiently connected to a photonic channel, our gate paves the way towards quantum networking with multiqubit nodes and the distribution of entanglement in repeater-based long-distance quantum networks.