skip to main content


Title: Reaching the quantum limit of sensitivity in electron spin resonance

The detection and characterization of paramagnetic species by electron spin resonance (ESR) spectroscopy is widely used throughout chemistry, biology and materials science, from in vivo imaging to distance measurements in spin-labelled proteins. ESR relies on the inductive detection of microwave signals emitted by the spins into a coupled microwave resonator during their Larmor precession. However, such signals can be very small, prohibiting the application of ESR at the nanoscale (for example, at the single-cell level or on individual nanoparticles). Here in this work, using a Josephson parametric microwave amplifier combined with high-quality-factor superconducting microresonators cooled at millikelvin temperatures, we improve the state-of-the-art sensitivity of inductive ESR detection by nearly four orders of magnitude. We demonstrate the detection of 1,700 bismuth donor spins in silicon within a single Hahn echo with unit signal-to-noise ratio, reduced to 150 spins by averaging a single Carr-Purcell-Meiboom-Gill sequence. This unprecedented sensitivity reaches the limit set by quantum fluctuations of the electromagnetic field instead of thermal or technical noise, which constitutes a novel regime for magnetic resonance. In conclusion, the detection volume of our resonator is ~0.02nl, and our approach can be readily scaled down further to improve sensitivity, providing a new versatile toolbox for ESRmore » at the nanoscale.« less
 [1] ;  [2] ; ORCiD logo [1] ;  [3] ;  [4] ;  [2] ;  [5] ;  [5] ;  [6] ;  [1] ;  [1] ;  [7] ;  [7] ;  [2] ;  [1]
  1. Univ. Paris-Saclay, Gif-sur-Yvette (France). Quantronics Group, SPEC, CEA, CNR
  2. University College London (United Kingdom). London Centre for Nanotechnology
  3. Univ. Paris-Saclay, Gif-sur-Yvette (France). Quantronics Group, SPEC, CEA, CNR; Bar Ilan University, Ramat Gan (Israel). Quantum Nanoelectronics Laboratory, BINA
  4. Univ. Paris-Saclay, Gif-sur-Yvette (France). Quantronics Group, SPEC, CEA, CNR; Institute of Electronics Microelectronics and Nanotechnology. ISEN Department
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Accelerator Technology and Applied Physics Division
  6. Simon Fraser University, Burnaby (British Columbia). Department of Physics
  7. Aarhus University (Denmark). Department of Physics and Astronomy
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Nanotechnology
Additional Journal Information:
Journal Volume: 11; Journal Issue: 3; Journal ID: ISSN 1748-3387
Nature Publishing Group
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
OSTI Identifier: