The efficient detection of light from trapped ions in free space is paramount for most of their applications. We propose a scheme to enhance the photon collection from linear ion strings. It employs the constructive interference of light scattered from ions along the axial direction in linear Paul traps. The coherent enhancement of photon collection is numerically optimized for a range of feasible spatial angles and realistic ion positions in a single harmonic Coulomb potential. Despite the large mutual distance of scatterers on the order of many wavelengths of scattered light, the experimental tests presented confirm the feasibility of enhancements by a factor of 3.05 ± 0.09 with a crystal of nine 40Ca+ ions. The proposed collection geometry is intrinsic to diverse linear ion trap designs, and the methodology can be directly applied to an observation of scattering from ion crystals prepared in collective electronic excitations.

The presented data resulted from measurements supported by national funding from the Ministry of Education, Youth and Sports under grant agreement No. 731473, by the QUANTERA ERA-NET cofund in quantum technologies implemented within the European Union’s Horizon 2020 Program (project PACE-IN, 8C20004), by the Czech Science Foundation under the project GA21-13265X, the Ministry of Education, Youth and Sports under the project CZ.02.01.01/00/22 008/0004649, the Ministry of Interior of the Czech Republic within the Program OPSEC under the project VK01030193, and the Palacký University grant IGA-PrF-2024-008.