Technique - (14) T1 relaxometry

Type: Experimental

Description: Longitudinal spin relaxation measurement for thermometry, noise spectroscopy, paramagnetic detection.

Department(s)/lab(s): Physics – Institute for Quantum Electronics | Quantum Control for Fundamental Physics Group (Craik Group) @ ETH Zurich
Summary:

Craik leads the RAVIOLIS project (SNSF Starting Grant, started July 2025) measuring atomic parity violation in barium ions at <0.1% precision. Her entanglement protocol uses multi-ion entangled states with photonic integrated waveguide addressing to common-mode-reject parity-conserving systematics. Previous work: precision measurement of Ba+ dipole transition probabilities below 1% uncertainty; first laser-guided individual addressing of Ba+ qubits with <10^-4 intensity crosstalk; isotope-shift spectroscopy in Ca+ for fifth-force searches. She is actively recruiting for postdocs and PhD students for the new Ba+ ion trap experiment.

Department(s)/lab(s): Physics / PME | Awschalom Group @ UChicago
Summary:

Pioneer in spintronics and quantum information engineering. Research spans: (1) NV-center spin qubits in diamond for quantum sensing and communication including nanomagnetic imaging; (2) spin defects in SiC and Er-doped hosts for quantum network nodes at telecom wavelengths; (3) molecular and protein-based spin qubits (2025 fluorescent-protein spin qubit, Physics World Top-10); (4) coherent Er spin defects in colloidal nanocrystal hosts (2024, with Alivisatos). Founding Director Chicago Quantum Exchange. Joint Senior Scientist Argonne. Large infrastructure-rich group with strong industry ties (IBM, Intel, Google quantum).

Department(s)/lab(s): Physics – Laboratoire Kastler Brossel (ENS / CollΓ¨ge de France site) | Cavity QED / Circular Rydberg Atom Group (Brune/Raimond, LKB at CollΓ¨ge de France) @ Sorbonne
Summary:

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, Schrâdinger 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.

Department(s)/lab(s): Physics – Laboratory for Solid State Physics | Hybrid Quantum Systems Group (Chu Group) @ ETH Zurich
Summary:

Chu leads the Hybrid Quantum Systems Group coupling mechanical resonators to superconducting circuits and diamond color centers. Research directions: (1) Circuit quantum acousto-dynamics (cQAD) β€” HBAR resonators coupled to transmon qubits achieve single-phonon nonlinearity (coherence/anharmonicity ratio 6.8), mechanical qubit gates demonstrated (arXiv 2406.07360, 2024); (2) Optimal control for high Fock state preparation in bulk resonators; (3) Ultra-cold mechanical quantum sensor β€” cryogenically cooled nanomechanical oscillators as probes for new physics beyond the standard model; (4) Coupling NV/SiV color centers in diamond to acoustic waves for hybrid quantum memory and transduction. Targets long-lived phonon storage for quantum networking and quantum sensing beyond the standard quantum limit.

Department(s)/lab(s): Physics – Laboratoire Kastler Brossel, Sorbonne UniversitΓ© / ENS | Optomechanics and Quantum Measurements Group (Cohadon & Heidmann / LKB) @ Sorbonne
Summary:

Cohadon and Heidmann co-lead the Optomechanics and Quantum Measurements group at LKB. Research directions: (1) Back-action evasion and Standard Quantum Limit (SQL) β€” early demonstration of radiation-pressure back-action in a micro-mirror (Nature 2006), subsequent beating of SQL via quantum correlations; (2) Micro/nanomechanical resonators β€” 2D photonic crystal deformable slabs, membrane-in-the-middle cavities, micropillar resonators for radiation-pressure optomechanics; (3) Superconducting qubit–macroscopic membrane coupling β€” Jacqmin & DelΓ©glise team: resonant coupling of transmon qubit to MHz membrane oscillator, tracking quantum motion with 300 repeated interactions (2025); high-impedance hyperinductors for electromechanics; (4) Gravitational wave detector contributions β€” VIRGO/LIGO data analysis and quantum noise modeling. Applications include back-action-evading force sensing and tests of quantum mechanics at macroscopic scales.

Department(s)/lab(s): Physics – Laboratory for Solid State Physics | Degen Group (Spin Physics and Imaging) @ ETH Zurich
Summary:

Degen leads the Spin Physics and Imaging group, one of the world's leading NV-center magnetometry labs. Research directions (as of 2025): (1) Scanning NV magnetometry of quantum materials β€” NV-tipped cantilevers image current flow (≲50 nm resolution) in graphene heterostructures and resolve domain walls in antiferromagnets/ferroelectrics; cryogenic scanning down to 350 mK in dilution refrigerator (published Appl. Phys. Lett. 2022). (2) Single-molecule NMR β€” shallow NV centers detect nuclear spins from surface-adsorbed molecules with sub-nanometer 3D resolution; 2022 Nano Lett. on amine-functionalized diamond surfaces; exploring chirality-induced spin selectivity at few-molecule level. (3) NV magnetometry protocols β€” reconstruction-free waveform sensing (1.1 ns time resolution, Nature 2025), gradiometric detection, spectrum demodulation for rapid scanning, multi-NV addressing. (4) Diamond nanoengineering β€” multicone pillar waveguides, surface engineering, scanning probe fabrication. ERC Proof-of-Concept 2025 for photonic IC single-photon NV excitation/detection for commercial quantum sensing.

Department(s)/lab(s): Physics & Astronomy – AMOPP | Hogan Group (Rydberg Atoms and Molecules) @ UCL
Summary:

Hogan's group studies atoms and molecules in high Rydberg states for precision measurements and quantum sensing. Research directions: (1) Rydberg atom electric field sensing β€” Rydberg atoms exhibit enormous electric polarizabilities; Stark-map and EIT-based electrometry with sub-mV/cm sensitivity and GHz-range frequency coverage; (2) Rydberg molecule spectroscopy β€” long-range Rydberg molecules as probes of intermolecular forces; (3) Stark deceleration and trapping of Rydberg atoms/molecules β€” producing cold samples for precision spectroscopy and scattering experiments; (4) Circular Rydberg states β€” extremely long-lived states for quantum information storage and sensing. Collaborates on quantum-enhanced sensing of RF/microwave fields.

Department(s)/lab(s): School of Physics | Quantum Biotechnology and Diamond Sensing Group (Hollenberg) @ UMelb
Summary:

Hollenberg is the intellectual centre of gravity for diamond quantum sensing in Australia: a theorist-turned-programme-leader whose group develops NV-based quantum probes for biological systems and quantum-computing architectures in silicon and diamond. Current directions include the quantum-probe hyperspectral microscope, in which NV ensembles in a bulk diamond substrate report magnetic and spin-noise contrast from cells cultured directly on the surface; nanodiamond quantum probes for intracellular relaxometry and free-radical detection; theory of decoherence-based sensing (T1 relaxometry as a chemical-specificity channel rather than a nuisance); and single-cell magnetic resonance. He co-leads the Melbourne node of the ARC Centre of Excellence in Quantum Biotechnology (QUBIC) with Simpson and Hinde, which is explicitly chartered to build quantum sensors for live biology, including portable brain imagers. Positioned against the established body of NV-ensemble quantum sensing work β€” DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity β€” his programme is one of the small number worldwide that has carried those ensemble protocols all the way into cell culture and tissue rather than stopping at proof-of-principle magnetometry. Preferred attribute present: the group's emphasis is on sensitivity and biological specificity rather than device fabrication, and QUBIC funding runs to 2030 with recurring postdoc recruitment.

Department(s)/lab(s): Physics – Institute for Quantum Electronics | Trapped Ion Quantum Information Group (Home Group) @ ETH Zurich
Summary:

Home leads the TIQI group working with Be+ and Ca+ trapped ions. Research directions: (1) Quantum error correction β€” fault-tolerant gates, surface code implementations with multi-ion chains; (2) Precision metrology β€” ytterbium ion optical clock, mixed-species ion chain spectroscopy and ytterbium HFS measurements; (3) Macroscopic superposition and quantum contextuality β€” creating nonclassical motional states in harmonic oscillators for tests of quantum foundations; (4) Scalable architectures β€” photonic integrated waveguides for individual ion addressing, quantum logic detection of spectroscopy ions. Key publications include first two-qubit gates with mixed species and records in quantum state readout fidelity. Lab is investigating quantum logic-enhanced spectroscopy of complex atomic systems.

Department(s)/lab(s): Physics (Cavendish Laboratory – AMOP Group) | Coherent Quantum Lab (Knowles Group) @ Cambridge
Summary:

Knowles leads the Coherent Quantum Lab at the Cavendish Laboratory. Her research focuses on using NV centers in diamond as quantum sensors to probe matter at the nanoscale in two main thrusts: (1) nanoscale NMR / spin imaging β€” scanning-probe NV magnetometry of topological and unconventional magnets, Hamiltonian engineering in dense spin ensembles using global dynamical decoupling, and error-correction-enhanced sensor readout; (2) quantum biosensing in living systems β€” employing diamond nanocrystals functionalized for intracellular delivery to perform simultaneous nanothermometry and nanorheometry in single HeLa cells and C. elegans, using the Q-BiC integrated biocompatible chip platform. She co-leads CANSIS. The lab has a second new instrument running since mid-2025 for biosensing experiments.