Simulating a topological transition in a superconducting phase qubit by fast adiabatic trajectories

Abstract

The significance of topological phases has been widely recognized in thecommunity of condensed matter physics. The well controllable quantum systemsprovide an artificial platform to probe and engineer various topologicalphases. The adiabatic trajectory of a quantum state describes thechange of the bulk Bloch eigenstates with the momentum, and this adiabatic simulation method is however practicallylimited due to quantum dissipation. Here we apply the “shortcut to adiabaticity” (STA)protocol to realize fast adiabatic evolutions in the system of a superconducting phase qubit.The resulting fast adiabatic trajectories illustratethe change of the bulk Bloch eigenstates in the Su-Schrieffer-Heeger (SSH) model. A sharp transitionis experimentally determined for the topological invariant of a winding number.Our experiment helps identify the topological Chern number of a two-dimensionaltoy model, suggesting the applicability of the fast adiabatic simulationmethod for topological systems.