Fig. 2: Experimental results.

a Calibration curve for the small-angle XX(\(\theta\)) gate. b Bootstrap distribution of the HF+2 energy with mean and \(1\sigma\) uncertainty indicated by the orange diamond and experimentally determined energy surfaces for HF+1 (c) and HF+2 (d). Each data point (orange diamond) represents an average of \(\gtrsim\!\!1000\) experimental runs, with the blue dash-dotted lines indicating in silico results. e Comparison of ground-state energy estimates as additional interactions are included in the UCC ansatz state (labeled HF+\(N\), for \(N\) significant determinants). The orange diamonds indicate experimental results, with error bars indicating \(1\sigma\) uncertainty from the bootstrap distribution. The remaining points are from the in silico VQE simulation as detailed in Fig. 1 and show how the ansatz states converge to the full configuration-interaction ground state, indicated by the dot-dashed blue line. Computational error equivalent to the bound for chemical accuracy (\(1.6\) mHa) is indicated by the shaded green region in all figures.