Pustelny Group — Quantum Sensing, Fundamental Physics, Spin Systems

PUSTELNY GROUP

Quantum Sensing, Fundamental Physics, Spin Systems

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NANOSCALE MAGNETIC RESONANCE IMAGING

Exploring molecular structure and dynamics with diamond quantum sensors

Magnetic resonance offers rich information about molecular structure and dynamics, but extending these measurements to individual molecules remains a major challenge. Our research explores nitrogen-vacancy (NV) centers in diamond as quantum sensors capable of detecting extremely weak magnetic signals from nearby spins. By combining quantum sensing, coherent spin control, and spatially encoded magnetic resonance measurements, we aim to develop new approaches to nanoscale imaging and spectroscopy. Our long-term goal is to investigate proteins, confined liquids, and other complex molecular systems under ambient conditions.

THE NANOSCALE MRI CHALLENGE

Magnetic resonance is the gold standard for non-invasive chemical spectroscopy and clinical diagnostics. However, translating its diagnostic capabilities to individual molecules requires overcoming fundamental physical detection barriers.

1. Macroscopic Inductive Limit

Conventional NMR and MRI rely on Faraday induction in macroscopic RF pick-up coils. In nanometer-scale volumes, thermal Johnson noise dominates over the magnetic dipole signal, requiring billions (>1012) of identical nuclear spins for a detectable signal.

2. Static Freeze vs. Native Dynamics

Cryo-EM and X-ray crystallography provide atomic spatial resolution, but require rigid crystal lattices or flash-frozen vitreous ice. In contrast, functional biomolecular machines and intrinsically disordered proteins operate through continuous conformational fluctuations in liquid.

3. Optical Diffraction Barrier

Far-field optical and fluorescence microscopies are fundamentally bounded by the Abbe diffraction limit (~250 nm). Resolving nanometer-scale intermolecular features, magnetic dipole couplings, and sub-cellular spin distributions requires spatial encoding beyond optical wavelengths.

Our Solution: To resolve these three fundamental physical limitations, our consortium integrates atomic-scale diamond quantum sensors with on-chip gradient Fourier magnetic imaging. Below, we describe the four core technological pillars of our nanoscale MRI platform—from sensor engineering to ambient biomolecular spectroscopy:

Diamond Quantum Sensors & Optical Readout

At the heart of our approach are nitrogen-vacancy (NV) centers in diamond—atomic-scale spin defects whose quantum states are sensitive to extremely weak magnetic fields. Their proximity to the sample makes them promising probes of nanoscale magnetic resonance. We are developing methods to control and optically read out ensembles of these quantum sensors, providing a foundation for sensitive, spatially resolved magnetic measurements.

Diamond Quantum Sensors & Optical Readout - NV Layer
Fourier Magnetic Imaging with On-Chip Microcoil Gradients

Fourier Magnetic Imaging Beyond the Diffraction Limit

Conventional optical microscopy cannot resolve the nanometer-scale details we seek to investigate. Fourier Magnetic Imaging (FMI) offers a different approach: spatial information is encoded in quantum-spin evolution using controlled magnetic-field gradients, rather than relying solely on optical resolution. We are exploring this principle to develop high-resolution magnetic resonance imaging of nanoscale structures.

Quantum Control & Image Reconstruction

Detecting weak magnetic signals from nanoscale systems requires careful control of spin dynamics and efficient extraction of information from experimental data. We investigate advanced quantum-control methods to improve sensor performance, together with computational approaches for magnetic resonance signal analysis and image reconstruction. These efforts aim to enhance the sensitivity, resolution, and practical capabilities of diamond-based quantum sensing.

Pulse sequences for interaction-enhanced many-body spin sensing
2D van der Waals nanofluidic confinement on diamond sensor

Molecular-Scale Magnetic Resonance & Biophysics

Our long-term goal is to extend nanoscale magnetic resonance measurements to molecular structure and dynamics under ambient conditions. We are exploring ways to bring diamond quantum sensors into close contact with chemical and biological samples, including confined liquids and complex biomolecules. Such measurements could open new opportunities in molecular spectroscopy, structural biology, and the study of proteins whose conformations and interactions are difficult to investigate using conventional methods.

EIC PATHFINDER OPEN CONSORTIUM

This Nanoscale MRI project (Magnetic resonance imaging at nanoscale via atom-like defects in diamond) is funded by the European Union within the EIC Pathfinder Open program of the European Innovation Council and brings together four partner institutions:

  • Jagiellonian University in Kraków, Poland (Coordinator): Prof. Szymon Pustelny & Dr. Piotr Put — Wide-field FMI apparatus, pulsed 3D microcoil gradients on chip, SPAD-array readout, and system integration
  • Ulm University (Institute for Quantum Optics / Center for Quantum Biosciences), Germany: Prof. Fedor Jelezko & Dr. Yuliya Mindarava — Delta-doped CVD diamond growth, nanoscale FMI benchmarks, and single-molecule bio-nanoMRI
  • Max Planck Institute of Quantum Optics (MPQ), Garching, Germany: Prof. Ignacio Cirac & Dr. Nathaniel Leitao — Many-body spin-1 Hamiltonian engineering, sparse k-space reconstruction, and open-source simulation tools
  • EPFL (Laboratory of Nanoscale Biology), Lausanne, Switzerland: Prof. Aleksandra Radenovic — 2D van der Waals nanofluidic bio-interfaces, solid-state nanopores, and single-molecule immobilization

Funded by the European Union under the European Innovation Council (EIC Pathfinder Open) programme, Grant Agreement No. 101166311 (Nano-MRI). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Innovation Council and SMEs Executive Agency (EISMEA). Neither the European Union nor the granting authority can be held responsible for them.

Opportunities

Join the Nanoscale MRI Team

We have open positions for motivated Postdoctoral Researchers and PhD Candidates with backgrounds in quantum optics, magnetic resonance, diamond NV sensing, nanofluidics, or quantum control to join our group in Kraków.

BACKGROUND LITERATURE & FURTHER READING ON NANOSCALE NV NMR/MRI

Key publications from the international research community introducing NV-diamond nanoscale NMR and Fourier magnetic imaging:

  • R. Budakian, A. Finkler, A. Eichler, M. Poggio, C. L. Degen, S. Tabatabaei, I. Lee, P. C. Hammel, E. S. Polzik, T. H. Taminiau, R. L. Walsworth, P. London, A. Bleszynski Jayich, A. Ajoy, A. Pillai, J. Wrachtrup, F. Jelezko, Y. Bae, A. J. Heinrich, C. R. Ast, P. Bertet, P. Cappellaro, C. Bonato, Y. Altmann & E. Gauger, Roadmap on nanoscale magnetic resonance imaging, Nanotechnology 35, 412001 (2024) — DOI
  • N. Arunkumar, K. S. Olsson, J. T. Oon, C. A. Hart, D. B. Bucher, D. R. Glenn, M. D. Lukin & R. L. Walsworth, Quantum Logic Enhanced Sensing in Solid-State Spin Ensembles, Physical Review Letters 131, 100801 (2023) — DOI
  • H. Zhou, J. Choi, Z. Li, S. Choi, R. Landig, A. M. Douglas, J. Isoya, F. Jelezko, S. Onoda, H. Sumiya, P. Cappellaro, H. S. Knowles, H. Park & M. D. Lukin, Quantum Metrology with Strongly Interacting Spin Systems, Physical Review X 10, 031003 (2020) — DOI
  • D. R. Glenn, D. B. Bucher, J. Lee, M. D. Lukin, H. Park & R. L. Walsworth, High-resolution magnetic resonance spectroscopy using a solid-state spin sensor, Nature 555, 351–354 (2018) — DOI
  • I. Lovchinsky, A. O. Sushkov, E. Urbach, N. P. de Leon, S. Choi, K. De Greve, R. Evans, R. Gertner, E. Bersin, C. Müller, L. McGuinness, F. Jelezko, R. L. Walsworth, H. Park & M. D. Lukin, Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic, Science 351, 836–841 (2016) — DOI
  • K. Arai, C. Belthangady, H. Zhang, N. Bar-Gill, S. J. DeVience, P. Cappellaro, A. Yacoby & R. L. Walsworth, Fourier magnetic imaging with nanoscale resolution and compressed sensing speed-up using electronic spins in diamond, Nature Nanotechnology 10, 859–864 (2015) — DOI
  • T. Staudacher, F. Shi, S. Pezzagna, J. Meijer, J. Du, C. A. Meriles, F. Reinhard & J. Wrachtrup, Nuclear Magnetic Resonance Spectroscopy on a (5-Nanometer)3 Sample Volume, Science 339, 561–563 (2013) — DOI