Fiber-coupled spin defect magnetometry

A magnetometer comprising:

• an electron spin defect body comprising a plurality of lattice point defects;
• a microwave field transmitter to apply a microwave field to the electron spin defect body;
• an optical source configured to emit input light of a first wavelength that excites the plurality of lattice point defects of the electron spin defect body from a ground state to an excited state;
• a first optical fiber having an input end optically coupled to the optical source and an output end, wherein the output end is attached to a first face of the electron spin defect body and is arranged to direct the input light into the first face of the electron spin defect body;
• a second optical fiber having an output end and an input end, wherein the input end of the second optical fiber is attached to a second face of the electron spin defect body and is arranged to receive photoluminescence of a second wavelength emitted from the electron spin defect body through the second face of the electron spin defect body, wherein the second wavelength is different from the first wavelength and wherein the second face is different from the first face;
• a photodetector optically coupled to the output end of the second optical fiber;
• and
• a third optical fiber, the third optical fiber having an output end optically coupled to the photodetector and an input end, wherein the input end of the third optical fiber is attached to a third face of the electron spin defect and is arranged to receive the photoluminescence through the third face, and wherein the third face is different from the first face and the second face.