Fig. 3: Charge sensing and single-shot spin readout.
a, Charge stability diagram of the last-electron regime of a QD, measured with a sensing dot in the other fin. The points ‘w’, ‘r’ and ‘e’ refer to the wait, readout and empty stages of the gate voltage pulse, respectively. b, Real-time current through the sensing dot indicating a spin-up (purple line) and spin-down (orange line) electron, recorded with a measurement bandwidth of 3 kHz set by an external low-pass filter. c, Spin-up probability as a function of load time at a magnetic field of 1 T. The exponential fit yields T1 of 1.6 ± 0.6 s. d, Relaxation rate (1/T1) as a function of the applied magnetic field (purple dots). The relaxation rate is fitted by a model (orange line) that includes the effect of Johnson noise and phonon coupling to the spin via spin–orbit interaction. From this fit, we extract a valley splitting of Ev = 260 ± 2 µeV.
