Lewandowski's group studies cold molecular ions and cold ion-neutral chemistry in traps, using precision spectroscopy and controlled reaction dynamics to probe molecular structure and fundamental interactions (borderline inclusion: precision molecular AMO with a strong physics-education program). For context, this complements the established paradigm of NV-diamond ensemble magnetometry (Hahn-echo/DEER, nanoscale NMR, T1 relaxometry) operating near pT/√Hz sensitivity.