Dissipative Landau Zener transition beyond the weak coupling limit with a superconducting flux qubit*

The Landau-Zener problem for a two-level system is a suitable toy problem for studying quantum tunnelling in an annealer. Coupling to the environment can influence the tunnelling probability and theoretical understanding is only available for specific coupling limits or noise models. We present experimental results on Landau-Zener measurements on a capacitively-shunted flux qubit. The result shows crossover from weak to strong coupling to the environment, consistent with different master equations in different limits. The result gives insight into the scaling of tunnelling probability in a large-scale quantum annealer.