Grassellino directs the DOE's SQMS Center, a Fermilab-Northwestern-led national quantum initiative center, and pioneered nitrogen-doping surface treatments that give niobium superconducting RF (SRF) cavities record-high quality factors. Beyond their traditional use in particle accelerators, these ultra-high-Q cavities are now deployed as extremely sensitive electromagnetic detectors: the Dark SRF experiment set new sensitivity limits on dark-photon light-shining-through-wall searches, and SRF cavities (e.g. the MAGO design) are being explored as high-frequency gravitational-wave and axion detectors, alongside long-lived multimode quantum memories for superconducting quantum computing.
O'Hare is a dark-matter phenomenologist whose work sits unusually close to instrumentation: he is the principal theorist of the 'neutrino fog' that limits direct-detection experiments, of directional dark matter detection (using the daily modulation of the WIMP wind to distinguish signal from background), and of the axion and ultralight dark-matter searches that increasingly rely on quantum sensors — haloscopes, comagnetometers, NMR-based searches and atomic magnetometers. He writes the sensitivity projections that tell experimentalists which quantum sensor to build. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — the axion/ALP search programme he works on consumes spin-ensemble magnetometry directly: CASPEr-class experiments are, in effect, precision NMR magnetometers operating far below pT/sqrt(Hz), and his phenomenology sets the sensitivity targets they aim at. Theory PI with strong experimental engagement.
Romanenko leads the Quantum Technology thrust at the SQMS Center, using ultra-high-coherence 3D niobium SRF cavities as both long-lived quantum memories for multimode superconducting quantum computing and as ultra-sensitive detectors for fundamental physics. He conceived and led the Dark SRF experiment, the first demonstration of SRF cavities used as light-shining-through-wall detectors, achieving new sensitivity limits for hidden-sector dark photons, and continues to explore SRF-based sensing of dark matter and gravitational waves.