Optimal superadiabatic population transfer and gates by dynamical phase corrections

Abstract

In many quantum technologies adiabatic processes are used for coherent\nquantum state operations, offering inherent robustness to errors in the control\nparameters. The main limitation is the long operation time resulting from the\nrequirement of adiabaticity. The superadiabatic method allows for faster\noperation, by applying counterdiabatic driving that corrects for excitations\nresulting from the violation of the adiabatic condition. In this article we\nshow how to construct the counterdiabatic Hamiltonian in a system with\nforbidden transitions by using two-photon processes and how to correct for the\nresulting time-dependent ac-Stark shifts in order to enable population transfer\nwith unit fidelity. We further demonstrate that superadiabatic stimulated Raman\npassage can realize a robust unitary NOT-gate between the ground state and the\nsecond excited state of a three-level system. The results can be readily\napplied to a three-level transmon with the ladder energy level structure.\n