  Shuttling ions at high speed and with low motional excitation is essential
for realizing fast and high-fidelity algorithms in many trapped-ion based
quantum computing architectures. Achieving such performance is challenging due
to the sensitivity of an ion to electric fields and the unknown and imperfect
environmental and control variables that create them. Here we implement a
closed-loop optimization of the voltage waveforms that control the trajectory
and axial frequency of an ion during transport in order to minimize the final
motional excitation. The resulting waveforms realize fast round-trip transport
of a trapped ion across multiple electrodes at speeds of $0.5$
electrodes/$\mu$s ($35 \text{m/s}$) with a maximum of $0.36\pm0.08$ quanta
gain. This sub-quanta gain is independent of the phase of the secular motion at
the distal location, obviating the need for an electric field impulse or time
delay to eliminate the coherent motion
