  The precise control of complex quantum mechanical systems can unlock
applications ranging from quantum simulation to quantum computation.
Controlling strongly interacting many-body systems often relies on Floquet
Hamiltonian engineering that is achieved by fast switching between Hamiltonian
primitives via external control. For example, in our solid-state NMR system, we
perform quantum simulation by modulating the natural Hamiltonian with control
pulses. As the Floquet heating errors scale with the interpulse delay, $\delta
t$, it is favorable to keep $\delta t$ as short as possible, forcing our
control pulses to be short duration and high power. Additionally, high-power
pulses help to minimize undesirable evolution from occurring during the
duration of the pulse. However, such pulses introduce an appreciable
phase-transient control error, a form of unitary error. In this work, we detail
our ability to diagnose the error, calibrate its magnitude, and correct it for
$\pi/2$-pulses of arbitrary phase. We demonstrate the improvements gained by
correcting for the phase transient error, using a method which we call the
``frame-change technique'', in a variety of experimental settings of interest.
Given that the correction mechanism adds no real control overhead, we recommend
that any resonance probe be checked for these phase transient control errors,
and correct them using the frame-change technique.
