Interfacing ions and photons

Leon Karpa, Marko Cetina, Alexei Bylinskii +5 more

Jonathan David Sterk, T.A. Manning, Le Luo +2 more

Kazuhiro Hayasaka

Recent developments towards photon-atom quantum interface are described. The quantum interface is realized by reversible time evolution of an atom-cavity coupled system. Proof of principle experiments have been demonstrated with neutral atoms recently. With trapped ions, the interface has not been realized yet, although single photon generation with tailored waveforms has been achieved in an ion-cavity system, in which a same calcium ion has been kept localized in a cavity for more than 90 minutes. Strategies towards the photon-ion quantum interface are described.

Jungwoo Choi, Inhyuk Oh, Chanyang Im +2 more

Trapped-ion quantum networks rely on efficient ion-photon interfaces, while objective-based free-space collection systems must balance high photon collection with sufficient working distance for practical integration with ion-trap hardware. Here, we design and characterize an ion-photon interface with a long working distance of 26.15 mm and a high numerical aperture of 0.5. The core of the interface is a photon-collection objective consisting of six commercial spherical lenses with optimized spacing. The interface achieved an overall fiber-coupled photon-detection efficiency of (1.29$\pm$0.09)% from the ion to the detector and maintains fiber coupling over several hours without active realignment, supporting stable operation of the ion-to-fiber interface. Photon-correlation measurements show clear antibunching in the fiber-coupled fluorescence, confirming the preservation of non-classical photon statistics. These results demonstrate a practical implementation of a long-working-distance photon collection interface for trapped-ion quantum network experiments.

Christopher R. Monroe, David J. Wineland