Fig. 6. Comparing SET and qubit performance in sensing DC electric potential and DC magnetic fields.

a DC electric potential measurement: we slowly ramp the potential of a single gate (V₄) up and down (sawtooth) with a period of ~100 s, and probe it using the device in SET modality (blue) or by detecting qubit state transitions using the time domain sequence described in Fig. 4a (red). The potential scale is shown by the vertical bar. b Similarly, but now for DC magnetic field measurement. In both quantities, we observe a significant improvement in sensitivity when the device operates in qubit modality rather than SET modality.