Diffraction unlimited all-optical recording of electron spin resonances.

We show stimulated emission depletion microscopy to break the diffraction limit in the all-far-field-optical detection of magnetic fields and resonances. Electron spin resonances from single nitrogen-vacancy centers in diamond located at subdiffraction proximities are fully discerned. Since diffraction is overcome by disallowing the signaling state through an optical transition such as stimulated emission, the spin state remains unaffected and amenable to microwave manipulation. Stimulated emission depletion presents a universal scheme for superresolving spin resonances detectable by fluorescence.