Convolutional neural network approach to ion Coulomb crystal image analysis

James Allsopp; Jake Diprose; Brianna R. Heazlewood; Chase Zagorec-Marks; H. J. Lewandowski; Lorenzo S. Petralia; Timothy P. Softley

arXiv · 2503.18846

Convolutional neural network approach to ion Coulomb crystal image analysis

James Allsopp·Jake Diprose·Brianna R. Heazlewood·Chase Zagorec-Marks·H. J. Lewandowski·Lorenzo S. Petralia·Timothy P. Softley

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Abstract

This paper reports on the use of a convolutional neural network (CNN) methodology to analyse fluorescence images of calcium-ion Coulomb crystals in the gas phase. A transfer-learning approach is adopted using the publicly available RESNET50 model. It is demonstrated that by training the neural network on around 500,000 simulated images, we are able to determine ion-numbers not only for a verification set of 100,000 simulated images, but also for experimental calcium-ion images from two different laboratories using a wide range of ion-trap parameters. Absolute ion numbers in the crystal were determined for the experimental data with a percentage error of approximately 10%. This analysis can be performed in a few seconds for an individual crystal image, and therefore the method enables the objective, and efficient, analysis of such images in real time, thereby facilitating time-dependent kinetic measurements on ion-molecule chemistry. The approach adopted also shows promising performance for identifying Ca+ ion numbers in images of mixed-species crystals.

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James Allsopp, Jake Diprose, Brianna R. Heazlewood, Chase Zagorec-Marks, H. J. Lewandowski, Lorenzo S. Petralia, Timothy P. Softley. 2025-03-24. Convolutional neural network approach to ion Coulomb crystal image analysis. https://arxiv.org/abs/2503.18846

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