Fig. 4: Microwave sensing by up-conversion and down-conversion.
From: Wideband coherent microwave conversion via magnon nonlinearity in a hybrid quantum system
a Microwave sensing by up-conversion. b Microwave sensing by second-order down-conversion. The signal is detected by equation: f2 = 2 ⋅ f1∓ + fESR±. The off-axis peak shown in the figure is contributed by one of the four possible orientations of the NV axes, which is nearly perpendicular to the bias field.
