Fig. 2: Hahn Echo-based Quantum Sensing of amplitude and phase of AC magnetic fields.

a–c Dependence of Hahn echo on the amplitude of the RF magnetic field for the VO(TPP) sample. a 2D map of the echo signal measured in time domain for different amplitudes of RF magnetic field. Echo amplitude (b) and phase (c) extracted from the map in a as a function of the RF amplitude. The phase of the output echo, which is wrapped between −90° and 90° for better clarity, linearly increases with the RF amplitude. dashed line is a linear fit. d–f Dependence of Hahn echo on the phase of the RF magnetic field for the VO(TPP) sample. d 2D map of the echo signal measured in time domain for different phase values of RF magnetic field. Echo amplitude (e) and phase (f) extracted from the map in d as a function of the RF phase.