Subnanotesla Magnetometry with a Fiber-Coupled Diamond Sensor
R. L. Patel, Li Zhou, Angelo Frangeskou, G. A. Stimpson, Ben G. Breeze, Alexander P. Nikitin, Matthew W. Dale, Eleanor C. Nichols, William Thornley, Ben L. Green, Mark E. Newton, Andrew M. Edmonds, Matthew Markham, D. J. Twitchen, Gavin W. Morley
Abstract
Nitrogen-vacancy centers (NVCs) in diamond are being explored for future quantum technologies, and in particular ensembles of NVC are the basis for sensitive magnetometers. We present a fiber-coupled NVC magnetometer with an unshielded sensitivity of $(310\ifmmode\pm\else\textpm\fi{}20)\phantom{\rule{0.2em}{0ex}}\mathrm{pT}/\sqrt{\mathrm{Hz}}$ in the frequency range of 10--150 Hz at room temperature. This takes advantage of low-strain ${}^{12}\mathrm{C}$ diamond, lenses for fiber coupling and optimization of microwave modulation frequency, modulation amplitude, and power. Fiber coupling means the sensor can be conveniently brought within 2 mm of the object under study.