Trapped-ion applications, such as in quantum information processing1, precision measurements2–5, optical clocks6 and mass spectrometry7, rely on specialized high-performance ion traps. The last three of these applications typically use traditional machining to customize macroscopic 3D Paul traps8, whereas quantum information processing experiments usually rely on photolithographic techniques to miniaturize the traps and meet scalability requirements9,10. Using photolithography, however, it is challenging to fabricate the complex 3D electrode structures required for optimal confinement. Here we demonstrate a high-resolution 3D printing technology based on two-photon polymerization (2PP)11 that is capable of fabricating large arrays of high-performance miniaturized 3D traps. We show that 3D-printed ion traps combine the advantages, such as strong radial confinement, of traditionally machined 3D traps with on-chip miniaturization. We trap calcium ions in 3D-printed ion traps with radial trap frequencies ranging from 2 MHz to 24 MHz. The tight confinement eases ion cooling requirements and allows us to implement high-quality Rabi oscillations with Doppler cooling only. Also, we demonstrate a two-qubit gate with a Bell-state fidelity of 0.978 ± 0.012. With 3D printing technology, the design freedom is greatly expanded without sacrificing scalability and precision, so that ion trap geometries can be optimized for higher performance and better functionality.
