Nanoscale magnetic sensing with an individual electronic spin in diamond
 
Amir Yakobi
Harvard University
 
 
Detection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the
biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron 
produces a magnetic field of about 1 micro Tesla, and the corresponding field from a single proton is a 
few nano Tesla. A sensor able to detect such magnetic fields with nanometer spatial resolution would
 enable powerful applications, ranging from the detection of magnetic resonance signals from individual
 electrons or nuclear spins in complex biological molecules to readout of classical or quantum bits of
information encoded in an electron or nuclear spin memory. Here we experimentally demonstrate an
 approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin
 qubit associated with a nitrogen-vacancy impurity in diamond at room temperature. Using an ultra-pure
 diamond sample, we achieve detection of 30 nT magnetic fields at kilohertz frequencies after 1s of
 averaging. In addition, we demonstrate a sensitivity of 0.5 mT/Hz1/2 for a diamond nanocrystal with a
 diameter of 30 nm.