Sensitivity improvement of a single-NV diamond magnetometer using a chiral waveguide

A single nitrogen-vacancy (NV) center in diamond is utilized to perform nanoscale magnetic measurements. However, the low contrast and poor collection efficiency of spin-dependent emitted photons limited the instrument sensitivity to approximately several nT/Hz. Here, we design a diamond magnetometer based on a chiral waveguide. We numerically demonstrate that the proposed device achieves a sensitivity of 170 pT/Hz owing to near-unity contrast and efficient photon collection. We also confirm that the device sensitivity is robust against position misalignment and dipole misorientation of an NV center. The proposed approach will enable the construction of a highly-sensitive magnetometer with high spatial resolution.