Jörg Müller's Quantum Metrology group works on next-generation optical atomic clocks and superradiant lasers. Key experiments: cold strontium continuous superradiant laser (subnatural linewidth, pushing beyond traditional clock limitations); microresonator-based frequency combs; ultra-stable optical reference cavities; and cavity QED many-atom systems for clocks and sensing. The group is part of the EU iqClock project targeting operational optical lattice clocks.
The Odom Group studies trapped molecular ions at millikelvin temperatures using radio-frequency ion traps. Key directions: (1) Controlled preparation and single-quantum-state readout of trapped molecular ions (e.g., AlH⁺, SiO⁺, N₂⁺) — combining laser cooling, blackbody-radiation-assisted state preparation, and fluorescence detection for single-molecule precision spectroscopy; (2) Search for time-variation of fundamental constants (electron-to-proton mass ratio, fine structure constant α) using molecular vibrational/rotational transitions as highly sensitive probes; (3) Quantum effects in sub-Kelvin chemistry — probing tunneling, orbiting resonances, and quantum state control of reactive collisions between cold molecules. Member of CFP Northwestern.
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.
Schuessler combines optical frequency combs with cavity-enhanced and mid-IR spectroscopy for ultrasensitive trace-gas and isotopic detection, and runs ion-trap precision mass/laser spectroscopy of exotic species. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work is a comb-metrology counterpart to spin-based chemical sensing.
Treps leads the Multimode Quantum Optics group at LKB. Research directions: (1) Multimode quantum frequency combs — synchronously pumped OPO (SPOPO) generates entangled networks of squeezed modes with configurable graph structure; first demonstration of quantum frequency comb with multimode squeezing (PRL 2012); (2) Quantum-enhanced multiparameter estimation — quantum Fisher information and multimode squeezing for simultaneous beyond-shot-noise parameter estimation (e.g., frequency comb spectral centroid and energy, PRX 2020); (3) Non-Gaussian quantum states — heralded generation of non-Gaussian cluster states for CV quantum computing; (4) Quantum metrological inequalities — relating non-locality to parameter estimation. Spin-off: Cailabs (multimode fiber light-shaping for telecom and industrial lasers). Co-director of QICS. ERC-funded.