Observing the steady-state visual evoked potentials with a compact quad-channel spin exchange relaxation-free magnetometer

Du Peng-Cheng^{1, 3}, Li Jian-Jun^{1, 3}, Yang Si-Jia^{2, 4, 6}, Wang Xu-Tong¹, Zhuo Yan^{2, 4, 6}, Wang Fan^{2, 4, 5, 6, ‡}, Wang Ru-Quan^{1, 3, §}

The response to visual stimuli at a fixed frequency of 12.5 Hz. The PSD of 60 s of SSVEP data for a single channel and gradiometer.