Fig. 5: Performance of the variational algorithm.
From: Variational preparation of finite-temperature states on a quantum computer
a Fidelity to the Gibbs state as a function of inverse temperature β for experimental states obtained by optimization and cheating. b Purity of experimental states as a function of β, and comparison to the purity of the Gibbs state. Added curves in both panels are obtained by numerical simulation of a noisy quantum processor with incremental error models based on calibrated error sources for our device: qubit relaxation and dephasing times, increased dephasing from flux noise during CZ gates, residual ZZ crosstalk at the bias point, and leakage during CZ gates. Leakage is identified as the dominant error source.
