Sensitivity improvement of Hahn echo magnetometry via template-margin-thresholding method in N-V centers

Nitrogen-vacancy (N-V) centers in diamond are the prominent physical platform for magnetometry as they have high spatial resolution and optical addressability. However, their sensitivity is ultimately limited by the photon shot noise (PSN) entailed to the optical spin readout. In previous paper [E. T. Guldeste and C. Bulutay, Phys. Rev. App. 22, 044030 (2024)], we have demonstrated that by utilizing wavelet-based template-margin-thresholding (TMT) method, it is possible to suppress PSN significantly for low-time-budget applications due to large bias introduced during the TMT denoising. Here, we improve the TMT by changing the philosopy in determining the a priori template to suppress the bias contribution to the overall mean squared error. Moreover, we show that the performance of the TMT can be further enhanced if this modified-TMT approach is used recursively for the Hahn echo magnetometry.