Jean-Baptiste Béguin's research at QUANTOP centers on optical nanofibre-trapped atom interfaces for quantum memories and quantum networks. Research: (1) nanofibre-trapped cold Cs atoms — quantum noise spectroscopy of atom-light spin coupling; (2) single-photon storage and retrieval from nanofibre-guided modes; (3) sub-Poissonian atom loading. Key direction in CBQS center for quantum sensing via coherent atom-photon interfaces.
Tulio Brito Brasil focuses on multimode quantum optics, squeezed and entangled states of light, and their application for quantum sensing and communication. Research: (1) generation of two-colour high-purity EPR photonic states; (2) squeezed light for quantum noise reduction in measurement; (3) continuous variable quantum optics protocols for networks. Recently joined QUANTOP at NBI.
Brune leads the Circular Rydberg Atom / Cavity QED group at LKB (Collège de France site), continuing the work of Serge Haroche (Nobel 2012). Note: Brune is employed by ENS, not Sorbonne Université; postdoc contracts are typically ENS/CNRS. Research directions: (1) Circular Rydberg atoms — atoms in extremely high principal quantum number states (n~50) with extremely long radiative lifetimes (~30 ms) and large dipole moments; (2) Cavity QED quantum sensing — single circular atoms probe the microwave field in a superconducting cavity photon-by-photon via quantum non-demolition measurement; (3) Quantum state engineering — generating Fock states, Schrödinger cat states, and entangled atom-field states in the cavity; (4) Tests of quantum complementarity — observing decoherence of mesoscopic superpositions in real time as a probe of quantum-to-classical transition. The 'quantum radio receiver' using single atoms to sense individual microwave photons is a landmark quantum sensing demonstration.
Rémi Geiger (CNRS DR, SYRTE/Observatoire de Paris; IUF 2020) leads atom interferometry for inertial sensing. Research: (1) interleaved cold-atom gyroscope — world record 3.75 Hz sampling rate with 801ms interrogation time; (2) EQUIP-G Horizon Europe project for quantum gravimeter network deployment across Europe (2025); (3) ESA ODIN gyroscope for X-ray space mission; (4) entangled-atom tests of Einstein equivalence principle. Key figure in precision cold-atom inertial sensors. Note: formally at SYRTE (PSL/Obs. Paris), entered under ENS (same PSL network).
Arnaud Landragin (CNRS DR, SYRTE) is director of the cold-atom inertial sensors team and one of the world's leading experts in quantum gravimeters and gyroscopes. Research: (1) GIRAFE transportable cold-atom gravimeter for marine and airborne campaigns; (2) QAFCA project (PEPR Quantique) for gravity sensors for geoscience and navigation; (3) ESA ODIN ultra-high performance gyroscope for space. CNRS Innovation Medal 2020. Co-authored key reviews on cold-atom inertial sensors.
Peter Lodahl's Quantum Photonics Group develops deterministic photon-emitter interfaces using semiconductor quantum dots embedded in photonic nanostructures (nanowires, photonic crystal waveguides). Research targets: single-photon sources with near-unity efficiency and indistinguishability; spin-photon interfaces for quantum repeaters; integrated quantum photonic circuits; and quantum networks based on single emitters. The group leads the Hy-Q Centre for Hybrid Quantum Networks and holds several quantum technology patents and spin-out companies. Borderline case — primarily quantum photonics for networking but with quantum sensing applications (single photon sensing, spin-photon).
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.
Franck Pereira dos Santos (CNRS DR, SYRTE) develops dual-species (Rb/Cs) atom interferometers and gravimeters with the highest accuracy. Research: (1) cold-atom gravimeters for absolute gravity measurement; (2) dual Rb/Cs fountain for equivalence principle tests; (3) interleaved interferometry to eliminate dead-time and aliasing noise; (4) quantum optimal control for Raman/Bragg pulse sequences. Key SYRTE inertial sensor PI.
Eugene Polzik's QUANTOP centre uses hot and ultracold atomic spin ensembles and mechanical membranes to generate squeezed, entangled, and single-photon states for quantum sensing and communication. Key directions include: (1) atomic magnetometry and electromagnetic induction imaging for biomedical applications (MEG/MCG-quality sensors); (2) entanglement between a macroscopic mechanical oscillator and an atomic spin ensemble; (3) quantum memory for light; (4) back-action-evading measurement schemes beyond the SQL; and (5) optical preamplification for MRI. QUANTOP heads the Copenhagen Center for Biomedical Quantum Sensing (CBQS), targeting quantum-enhanced disease diagnostics.
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.