Quantum magnetic resonance microscopy

Magnetic resonance spectroscopy is universally regarded as one of the most important tools in chemical and bio‐medical research. However, sensitivity limitations typically restrict imaging resolution to length scales greater than 10 µm. Here we bring quantum control to the detection of chemical systems to demonstrate high resolution electron spin imaging using the quantum properties of an array of nitrogen‐vacancy (NV) centres in diamond. Our quantum magnetic resonance microscope selectively images electronic spin species by precisely tuning a magnetic field to bring the quantum probes into resonance with the external target spins. This provides diffraction limited spatial resolution of the target spin species over a field of view of 5050 µm 2. We demonstrate imaging and spectroscopy on aqueous Cu 2+ ions over microscopic volumes (0.025 µm 3), with detection sensitivity at resonance of 10 4 spins/voxel, or 100 zeptomol (10 ‐19 mol). The ability to image, perform spectroscopy and dynamically monitor spin‐dependent redox reactions and transition metal biochemistry at these scales opens up a new realm of nanoscopic electron spin resonance and zepto‐chemistry in the physical and life sciences. Magnetic resonance spectroscopy techniques have revolutionised detection and imaging capabilities across the life and physical sciences. Electron spin resonance (ESR), nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are now essential tools in many areas of science and clinical research. State‐of‐the‐art ambient NMR [1] and ESR‐ based systems [2] employing field gradients have demonstrated imaging resolution as low as 10 µm. However, exploring nanoscale biological and chemical processes with sub‐micron requires a major technological shift. Conventional ESR‐based imaging approaches demonstrated detection from as few as 10 4 spins with sub‐micron spatial resolution, by reducing the size of the surface loop and scanning, however such measurements require cryogenic temperatures [3]. Other high resolution imaging techniques such as magnetic resonance force microscopy [4] and