Summary: Large comprehensive German research university (~30k students) whose Institute of Physics hosts >40 professors and the PRISMA+ Cluster of Excellence for precision physics. The QUANTUM working group (Budker, Schmidt-Kaler, Walz, Windpassinger, Wendt, Pohl, van Loock) is one of Europe's strongest concentrations of precision AMO and quantum-sensing work: optically pumped magnetometers, ZULF NMR, NV diamond, trapped-ion quantum logic, muonic-atom spectroscopy, and dark-matter searches (CASPEr, GNOME, XENON). Co-located with the Helmholtz Institute Mainz (HIM) and the Max Planck Institute for Polymer Research; MAMI/MESA accelerators on campus. Notably, JGU has no engineering faculty, so applied-physics/EE-style groups sit inside Physics or Chemistry.
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Rentschler's group synthesizes and characterizes molecular magnetic materials: single-molecule magnets, spin-crossover complexes and polynuclear coordination clusters, with magnetic anisotropy engineered through ligand-field design and characterized by SQUID magnetometry, EPR and ab-initio calculations. The overlap with this search is the molecular-qubit angle -- these are the same chemical objects being pursued elsewhere as optically or electrically addressable spin qubits and as molecular quantum sensors. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the value here is chemical: designed spin systems with tunable coherence and anisotropy, rather than defects in a host crystal. Borderline-strong inclusion; the group is chemistry-first, so a physicist postdoc would bring the spin-readout side.
Quantenbit operates segmented micro-structured Paul traps for scalable trapped-ion quantum information and, increasingly, for quantum sensing. Directions: (i) trapped Rydberg ions -- combining the tight confinement of a Paul trap with the giant polarizability of Rydberg states, which is simultaneously a fast-gate resource and an extremely sensitive electric-field probe; (ii) motional-mode sensing of electric fields and surface noise; (iii) deterministic single-ion implantation, where a cold ion is extracted from the trap and implanted with nm-scale placement -- directly relevant to building NV/donor arrays with known ion counts, and to single-ion detection validation; (iv) TACTICa, applying ion-trapping and quantum-logic spectroscopy to 229Th toward a nuclear clock; (v) single-atom heat engines and quantum thermodynamics. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the deterministic-implantation line is the natural upstream complement: it is the route to engineering NV ensembles/arrays with controlled density rather than relying on stochastic implantation. Strong local coupling to Budker (Th-229, exotic physics) and Wendt (laser ionization).
van Loock leads theoretical quantum optics and quantum information at Mainz, with a long-standing focus on continuous-variable quantum optics: squeezed and other nonclassical Gaussian states, non-Gaussian resources such as cat and GKP states, hybrid discrete/continuous-variable encodings, and the error-correction and repeater architectures built on them. The group also works on the fundamental limits of quantum-enhanced measurement and on how nonclassical light can be used as a metrological resource. He is theory-first, with output that directly serves the experimental quantum-optics and trapped-ion groups in Mainz. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the relevance is on the fundamental-light-physics axis rather than the magnetometry axis: this is where the squeezing/nonclassical-state theory sits that would let a spin-ensemble sensor beat the standard quantum limit.
Walz works on precision spectroscopy of exotic atoms and antimatter. The group is known for continuous-wave Lyman-alpha (121.6 nm) laser sources -- the enabling technology for laser cooling of antihydrogen -- and for antihydrogen and positronium spectroscopy aimed at CPT tests and at antimatter gravity measurements, in collaboration with CERN antiproton-decelerator experiments. Complementary work at Mainz covers laser development, exotic-atom trapping and detection. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), this is a fundamental-symmetry pivot: the sensing content is in ultra-stable lasers, extreme-vacuum trapping and single-particle detection rather than solid-state spins, and it suits a postdoc looking to move from quantum sensors toward fundamental-physics tests.
The LARISSA group develops multi-step resonance ionization laser spectroscopy and RIMS: element- and isotope-selective laser ionization used both as an ultratrace analytical technique (actinide detection at extreme selectivity, environmental and nuclear-forensic samples) and as a spectroscopy tool for exotic and short-lived isotopes, feeding ion-source development for facilities such as ISOLDE/CERN. A major current thrust is the atomic and ionic spectroscopy of thorium, including the 229mTh isomer that underpins the nuclear-clock effort, done jointly with Schmidt-Kaler's trap group and Duellmann's nuclear chemistry. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), the transferable capability here is selective, quantum-state-resolved detection of single atoms/ions -- the readout problem, approached spectroscopically rather than magnetically.
Windpassinger's group works on cold neutral atoms as both a platform for fundamental light-matter physics and a deployable sensing technology. The fundamental line uses dysprosium -- the most magnetic element -- to study light propagation in dense dipolar media, where interatomic spacings fall below the optical wavelength and light-induced plus magnetic dipole-dipole interactions produce cooperative effects (superradiance, subradiance); controlled transport in optical dipole traps and microfocusing let them tune from single-atom to collective behaviour. The applied line builds ultracold-atom quantum sensors that survive outside the lab: atom interferometers and BEC sources flown in the Bremen drop tower, on sounding rockets, and on the ISS, aimed at inertial sensing, gravimetry and tests of fundamental constants under microgravity. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), this is the complementary 'cold and fragile but absolutely calibrated' end of the sensing spectrum; the group's real distinguishing asset for a postdoc is the space/microgravity engineering pipeline, which is rare. The group states it is continuously looking for motivated researchers and lists open positions via the PI.
Wurm's group builds and exploits large liquid-scintillator neutrino detectors, principally JUNO (reactor neutrinos, mass ordering) plus low-energy solar and geo-neutrino physics; work spans scintillator chemistry and optical purity, photosensor characterization, and reconstruction. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), included as a detector-instrumentation pivot -- the transferable content is ultra-low-noise photon counting and calibration at scale, not spin physics.