  A frequently encountered source of systematic error in quantum computations
is imperfections in the control pulses which are the classical fields that
control qubit gate operations. From an analysis of the quantum mechanical
time-evolution operator of the spin wavefunction, it has been demonstrated that
composite pulses can mitigate certain systematic errors and an appealing
geometric interpretation was developed for the design of error-suppressing
composite pulses. Here we show that these same pulse sequences can be obtained
within a quasi-classical framework. This raises the question of whether
error-correction procedures exist that exploit entanglement in a manner that
can not be reproduced in the quasi-classical formulation.
