Design and fabrication of metal-shielded fiber-cavity mirrors for ion-trap systems

Trapped ions in micro-cavities constitute a key platform for advancing quantum information processing and quantum networking. By providing an efficient light–matter interface within a compact architecture, they serve as highly efficient quantum nodes with strong potential for a scalable quantum network. However, in such systems, ion trapping stability is often compromised by surface charging effects, and nearby dielectric materials are known to cause a dramatic increase in the ion heating rate by several orders of magnitude. These challenges significantly hinder the practical implementation of ion trap systems integrated with micro-cavities. To overcome these limitations, we present the design and fabrication of metal-shielded fiber-cavity mirrors, enabling the stable realization of ion trap systems integrated with fiber cavities. Using this method, we constructed a needle ion trap integrated with a fiber Fabry–Pérot cavity and successfully achieved stable trapping of a single ion within the cavity. The measured ion heating rate was reduced by more than an order of magnitude compared with unshielded configurations. This work establishes a key technique toward fully integrated ion–photon interfaces for scalable quantum networks.