Berengut works on the atomic structure theory underpinning next-generation clocks: highly charged ions, whose optical transitions are both extremely narrow and exceptionally sensitive to variation of fundamental constants and to new physics, and the thorium-229 nuclear clock. He identifies which ionic species and transitions maximise sensitivity to the physics of interest while remaining experimentally accessible, and computes the many-body structure needed to interpret them — work that has directly guided the experimental HCI clock programmes at PTB, MPIK and NIST. 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 — clocks and magnetometers are the two great classes of quantum sensor; his work is on the frequency side of the same estimation problem that fixes pT/sqrt(Hz) performance on the magnetic side. Theory PI with close experimental collaborations.
Flambaum is one of the most cited atomic theorists alive and the intellectual source of a large fraction of the modern precision-AMO new-physics programme. His group computes the atomic and molecular structure factors that convert an experimental frequency shift into a bound on new physics: enhancement factors for electron and nuclear EDMs, atomic parity violation, the sensitivity of clock transitions to variation of the fine-structure constant, and — most relevant to quantum sensing — the response of atomic clocks, magnetometers and comagnetometers to ultralight/axion-like dark matter fields. He proposed much of the theory behind using networks of quantum sensors as dark matter detectors. 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 — his theory is what tells an experimentalist what a pT/sqrt(Hz) magnetometer or a 10^-18 clock actually constrains: without it, a spin-precession measurement is just a number. Theory group; a sensing postdoc would collaborate rather than join.
Hollberg works on optical atomic clocks, laser frequency stabilization, and frequency-comb metrology, including chip-scale and field-deployable clock technology with applications to relativistic geodesy and precision tests of fundamental physics.
Jean-Philippe Karr's trapped-ions group at LKB performs precision spectroscopy of molecular ions (HD+, H2+) to test quantum electrodynamics and determine fundamental constants. Research: (1) laser spectroscopy of HD+ molecular ions in ion traps for proton-electron mass ratio determination; (2) tests of quantum electrodynamics in simple molecular systems; (3) search for physics beyond the standard model via precision measurement. Published in Physics (April 2026) on simplest molecules testing quantum theory.
Stefan Schäffer leads the Quantum Metrology group at NBI together with Jörg Müller. Research focuses on superradiant strontium lasers: (1) quasi-continuous superradiant lasing with sub-natural linewidth; (2) Ramsey spectroscopy enhanced by cavity sub-to-superradiant phase transitions for improved atomic clock sensing; (3) continuous atom beam for Dicke-effect-free superradiant interrogation. Key work published in PRL (2023) and Nature Communications (2024). Part of EU iqClock and ESA collaborations.