Extended Data Fig. 8: Time traces with weakly coupled QDs.
a–d, Charge-stability diagram measured by quantum capacitance (panel a) in a weak interdot coupling regime (VH = 1.445 V). The dotted grey box marks the region in which time traces were measured to estimate the signal-to-noise ratio (SNRM, panel b), parity polarization (PM, panel c) and average switching time (τavg, panel d). We infer the weak coupling from the presence of signal when a QD is aligned to the lowest-energy state in the hybrid, as highlighted by the arrows in panels a and b and discussed in Fig. 2. In these panels, the grey contours indicate where SNRM = 0.5. The probing frequency for the middle resonator was 341 MHz instead of 340.8 MHz, as in the rest of the text. The time traces in this figure were averaged in time bins of 200 μs (instead of 150 μs) to ensure that the averaging time is an exact multiple of inverse of the sampling rate (10 kHz). e–h, Same measurements by charge sensing. Charge-stability diagram of QDL and QDR (panel e). Outside the QDL resonance, QDR shows fixed charge when its energy is above the hybrid gap EABS. Below this gap, parity switching is visible as signal noise. Near the QDL resonance, the region of visible switching is reduced when QDL becomes lower in energy than QDR. The region in which even and odd states are indistinguishable is narrower than in Extended Data Figs. 7 and 9, consistent with small coupling between QDs (see Methods section ‘Model’). i, Pearson correlation coefficient between time traces measured with quantum capacitance and charge sensing. Similarly to Extended Data Fig. 5q, the transition region between positive and negative correlation (black arrows) is tilted. Furthermore, this transition is more sharply defined, in line with the low coupling (see Methods section ‘Model’).
