Fidelity of the Kitaev honeycomb model under a quench

We theoretically study the influence of quenched outside disturbances in an intermediately long-time limit. We consider localized imperfections, uniform fields, noise, and couplings to an environment within a unified framework using a prototypical but idealized interacting quantum device - the Kitaev honeycomb model. As a measure of stability we study the Uhlmann fidelity of quantum states after a quench. To treat the unperturbed dynamics as a free-fermion model without neglecting evolution of states between flux sectors, we push the flux degree of freedom into the perturbation. For noisy quenches, both gapped and gapless systems exhibit a universal form for the long-time fidelity, Ce-αtt-β where the values of C, α, and β depend on physical parameters such as system size and disturbance strength. Finally, we show that selective filling of the spinon Brillouin zone can be used to greatly increase the fidelity over the ground-state value. Our work provides estimates for the intermediate long-time stability of a quantum device, offering engineering guidelines for quantum devices in quench design and system size.