Sushkov, A. O., Chisholm, N., Lovchinsky, I., Kubo, M., Lo, P. K., Bennett, S. D., Hunger, D., Akimov, A., Walsworth, Ronald L., Park, H. and Lukin, M. D.
Abstract
We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd$^{3 }$) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to co-localize one NV center and one Gd$^{3 }$-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.
