Figure 2. Measured and modeled coherence of the NV spin under dynamical decoupling (DD) sequences when the scanning nanopillar is in contact with the sample.

(a): Optical and MW pulses used in DD measurements with total evolution time t = 2nτ, where n is the number of π-pulses in the Hahn-echo and XY sequences. (b–e): Measurements of the NV spin state as a function of t running DD sequences as labeled. The solid lines show the calculated coherence using the model and parameters described in the main text. In the calculation we account for revivals induced by ¹³C nuclear spins by the Gaussian function and parameters as applied in Fig. 1c. (f): Coherence time T₂ determined from measurements as a function of n. The solid line shows the power-law fit .