Advancements in Single Nuclear Spin Measurement Using Microwave Techniques

Recent advancements in quantum physics have led to significant developments in the ability to measure and manipulate individual nuclear spins. A new paper titled "All-microwave readout, spectroscopy, and dynamic polarization of individual nuclear spins in a crystal" by J. Travesedo and 12 co-authors presents a method that enhances nuclear magnetic resonance (NMR) spectroscopy sensitivity to the single spin level. This breakthrough could have profound implications for fields such as chemistry and biology, where understanding molecular interactions at the atomic level is crucial.

The research focuses on detecting individual (^{183}\mathrm{W}) nuclear spins within a (\mathrm{CaWO}_4) crystal. The authors utilized microwave photon counting at millikelvin temperatures to observe the hyperfine interaction between the nuclear spins and a neighboring (\mathrm{Er}^{3+}) ion. This approach allowed them to witness real-time quantum jumps of the nuclear spin state, confirming the individual nature of the spins.

Moreover, the team successfully performed single-spin electron-electron double resonance (ELDOR)-detected NMR spectroscopy by driving transitions in the (^{183}\mathrm{W}-\mathrm{Er}^{3+}) coupled system. They achieved single-spin solid-effect dynamical nuclear polarization through repeated microwave driving of these transitions.

The methods introduced in this study are noteworthy because they rely solely on microwave techniques, making them applicable to any nuclear spin coupled to a paramagnetic impurity. This universality opens the door to single-nuclear-spin spectroscopy across a wide range of materials, potentially revolutionizing how scientists study and manipulate matter at the quantum level.

For further details, the full paper can be accessed at arXiv:2408.14282.