Keywords:NV centre, Sensing, Dynamic range
Quantum sensing holds promise for several applications due to its potential for ultra-high resolution and exquisite sensitivity. For example, the electron spins of nitrogen-vacancy (NV) centres are used for magnetic and temperature sensing given its strong interaction with the environment. However, the downside of spin systems for sensing is the limited dynamic range, given its rotational symmetry: e. g. the phase of the spin can only be determined up to 2pi at best. In earlier work with NV centres, for DC magnetic fields, a dynamic range improvement of 26 was achieved, while a recent technique for AC magnetic fields increased this range by a theoretical maximum of 5000 times. Here, we demonstrate a technique to increase the dynamic range for AC magnetic fields, which maximum enhancement is merely constrained by technical limitations.
For our experiments, we use individual electron spins of NV centres in phosphorus-doped diamond at room temperature. The used sample was epitaxially grown by chemical-vapour deposition onto a Ib-type (111)-oriented diamond substrate with enriched 12C (99.998%) and a phosphorus concentration of 6x1016 atoms/cm3. As demonstration, we measured AC magnetic fields with amplitudes ranging from 1 nT to 12 uT (the maximum we can apply in our setup) with the same accuracy throughout the entire range.