Curator's Take
This article demonstrates a barium‑based Rydberg platform in which a near‑zero two‑photon wavevector eliminates Doppler‑limited dephasing, delivering coherence times limited only by the intrinsic radiative lifetime of the $6sng\,^1G_4$ state. By pairing that long coherence with a small Förster defect that yields strong dipole–dipole interactions, the work offers a route to higher‑fidelity neutral‑atom gates and to robust Rydberg polaritons for all‑optical quantum networking—an advance over the more commonly used rubidium or cesium schemes whose gate errors are often dominated by motional decoherence. If the required 649–658 nm laser system can be stabilized at scale, the approach could markedly improve both neutral‑atom quantum processors and hybrid light‑matter interfaces.
— Mark Eatherly
Summary
The short Doppler-limited coherence time of the laser-excited Rydberg state, usually orders of magnitude shorter than the lifetime of the Rydberg state, hinders the Rydberg-mediated quantum technologies. Here, we show that a 649~nm~$-$~658~nm two-photon excitation of the $6sng~^1G_4$ Rydberg state from a long-lived d-orbital clock state of barium can be achieved with a two-photon wavevector that is tiny, which effectively removes the Doppler-limited decoherence. Moreover, the $6sng~^1G_4$ Rydberg state has strong dipole-dipole interaction due to small Förster defect with nearby Rydberg states and possesses long radiative lifetime. These can benefit quantum computing based on individually trapped neutral atoms, and can enable long-lived Rydberg polaritons in atomic media, which brings fresh opportunities in all-optical quantum information.