  The single electron double quantum dot architecture is a versatile qubit
candidate, profiting from the advantages of both the spin qubit and the charge
qubit, while also offering ways to mitigate their drawbacks. By carefully
controlling the electrical parameters of the device, it can be imparted greater
spinlike or greater chargelike characteristics, yielding long coherence times
with the former and, with the latter, allowing electrically driven spin
rotations or coherent interaction with a microwave photon. In this work, we
demonstrate that applying the GRAPE algorithm to design the control pulses
needed to alter the operating regime of this device while preserving the
logical state encoded within can yield higher fidelity transfers than can be
achieved using standard linear methods.
