Fig. 2: Conditional fluorescence readout.
From: Electron shelving of a superconducting artificial atom
a Complex plane representation and b real part of the reflection coefficient r as a function of readout drive frequency ω at various powers represented by the \(\left|0\right\rangle -\left|3\right\rangle\) transition Rabi frequency Ω (inset). The experimental data (colored dots) are fitted by the theory of Eq. (1) (lines) with Γ = 2π × 1.74 MHz and p0 = 0.78 due to the thermal occupation of excited states. In the limit Ω → 0, the data in Fig. 2a becomes a circle with a radius p0 (gray circle, p0 = 1 and dashed circle, p0 = 0.78). The optimal readout settings are highlighted by the black star and arrow (see text below Eq. (1)). c Rabi oscillations (left panel), energy relaxation (right panel, yellow circles), and spin-echo coherence decay (green triangles) were measured using conditional fluorescence readout at optimal settings. Fitting to exponential decay yields (coincidentally) T1 = T2 = 52 μs.
